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Ultrasound of Wrist Pain
Ultrasound of Wrist Pain Srinivasan Harish, FRCR,a John O’Neill, FRCR,a Karen Finlay, MD,b Erik Jurriaans, FRCR,b and Lawrence Friedman, MB BChb
Ultrasound is a valuable imaging modality for evaluation of patients presenting with wrist pain. An important advantage is the ability to correlate the site of pain or discomfort with the underlying sonographic appearance. The capacity to dynamically assess the wrist and use the contralateral asymptomatic wrist for comparison purposes are strengths of ultrasound as a diagnostic tool. This pictorial review deals with the sonographic assessment of the commonly encountered wrist pathologies.
Musculoskeletal ultrasound (US) is an effective established technique for the imaging of joints and soft tissues of the wrist. Inherent advantages include cost effectiveness, lack of ionizing radiation, accessibility, and multiplanar capability in real time. In addition, it is an interactive examination with the patient, thereby allowing a pertinent history and localization of the symptoms to be obtained during the examination. Once pathology is identified, comparison with the contralateral side can confirm subtle abnormalities with images viewed side by side on split-screen. Dynamic imaging may expose pathologies, such as intermittent tendon subluxation, not present on a static examination. As in all imaging techniques, a thorough understanding of the regional anatomy is essential. We present a review of the appropriate anatomy, technique, and differential diagnosis of wrist pain diagnosable by US and, finally, a more detailed review of some of these pathologies.
a From the Radiology Department, St. Joseph’s Healthcare, Hamilton, Ontario, Canada; and bRadiology Department, McMaster Health Sciences, Hamilton, Ontario, Canada. Reprint requests: John O’Neill, FRCR, Radiology Department, St. Joseph’s Hospital, 50 Charlton Avenue East, Hamilton, Ontario, Canada. E-mail: [email protected]. Curr Probl Diagn Radiol 2009;38:111-125. © 2009 Mosby, Inc. All rights reserved. 0363-0188/2009/$36.00 ⫹ 0 doi:10.1067/j.cpradiol.2008.02.001
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Indications for wrist US examination include softtissue injury, tendon pathology, arthritis, soft-tissue masses/swelling, nerve entrapment, effusion, and bone injury. The examination is usually tailored to the patient’s clinical symptoms.
Anatomy and Technique The patient is seated with hands resting on a table placed anteriorly or on a pillow placed on the patient’s thighs. Volar examination requires the wrists to be placed flat or in mild extension with palm up and both ulnar and radial deviation to delineate all the necessary anatomy. For the dorsal examination, the wrist is placed palm down with mild flexion. Axial and longitudinal images should be obtained from the volar wrist crease to the thenar muscles in assessing the volar compartments. The transducer will require angulation to compensate for the normal contour of the wrist.
Volar The wrists are placed flat with palm up and scanned in ulnar and radial deviation. The carpal tunnel is a fibro-osseous canal delimited by the carpal bones dorsally and by the flexor retinaculum (FR) on the volar aspect. The FR attaches to the scaphoid, the pisiform, the hook of hamate, and the tubercle of trapezium. On US, the FR is seen as an echogenic curvilinear band connecting the pisiform to the scaphoid (Fig 1).1 It encloses nine tendons within the carpal tunnel including the flexor digitorum profundus, flexor digitorum superficialis, and the flexor pollicis longus tendons. Laterally, the flexor carpi radialis tendon lies within its own canal, formed by a septum that takes origin from the FR. The flexor tendons have a fibrillar, linear echogenic pattern on US. Within the carpal tunnel, the flexor tendons are enclosed in two synovial sheaths: a lateral sheath that encloses the flexor pollicis longus and a medial sheath enclosing the remaining flexor
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FIG 1. Transverse anatomy illustration of the wrist at the level of the hook of hamate. 1: Extensor carpi ulnaris; 2: Extensor digiti minimi; 3: Extensor indicis and extensor digitorum; 4: Extensor carpi radialis and brevis; 5: Radial artery; 6: Extensor pollicis longus; 7: Extensor pollicis brevis; 8: Flexor carpi ulnaris; 9: Median nerve; 10: Palmaris longus; 11: Flexor retinaculum; 12: Ulnar artery and nerve; 13: Superficial and deep flexor tendons.
FIG 2. Transverse US image through the wrist at the level of the hook of the hamate (HH). The echogenic flexor retinaculum (FR) runs between the HH and the tubercle of the trapezium (T). The hypoechoic median nerve (MN) is situated superficially in the carpal tunnel, with the echogenic flexor tendons deep to it.
tendons.1 The median nerve lies superficially in the carpal tunnel (Figs 1 and 2). It moves with less amplitude compared with the tendons.2 On longitudinal scanning, the median nerve has longitudinal hypoechoic bands, separated by discontinuous bands of increased echogenicity, corresponding to the epineurium.3,4 Axially, the median nerve has a reticular pattern.5 Guyon’s canal is situated medial to the carpal tunnel and contains the ulnar nerve, ulnar artery/vein,
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FIG 3. Coronal anatomical illustration of the wrist. 1: Ulnar collateral ligament; 2: Meniscus homologue; 3: Triangular fibrocartilage; 4: Lunotriquetral ligament; 5: Scapholunate ligament.
and connective tissue (Fig 1).6 The boundaries of this canal are the pisiform medially and the hook of the hamate laterally; floor is formed by the hypothenar muscles and FR, and roof is formed by the palmar
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FIG 4. Normal ultrasound image of the TFC. Longitudinal, paracoronal image at the ulnar aspect of the wrist shows the normal TFC (straight arrow), distal to the ulnar styloid (UST) and proximal to the triquetral (TRI) bone. The TFC is identified deep to the ECU (curved arrow).
carpal ligament.1,7,8 US, on axial views, demonstrates the ulnar nerve at the pisiform level as a thin, rounded structure medial to the ulnar artery and lateral to the pisiform.
Ulnar The important structures on the ulnar side of the wrist are the triangular fibrocartilage complex (TFCC) and the extensor carpi ulnaris (ECU) tendon. The TFCC consists of the triangular fibrocartilage (TFC), a meniscal homologue, ulnar collateral ligament, dorsal and volar radio-ulnar ligaments, and the ECU sheath. The TFC is examined with the forearm pronated, wrist flexed and radially deviated, draped over a volar pad.9,10 The TFC is hyperechoic and is an inverted triangular structure with the wider base on the dorsal aspect and the thinner apex on the volar side on longitudinal scanning (Figs 3 and 4).9,11 Placing the transducer transversely on the ulnar styloid and moving distally will allow visualization of the TFC. The ECU tendon lies superficial to the TFC in a separate groove on the distal ulna and is used as an acoustic window to visualize the TFC (Fig 4).10,11
Dorsal The extensor retinaculum divides the dorsal wrist into six compartments. Lister’s tubercle (LT) is an important landmark on the dorsal radius and is identified on transverse scanning (Fig 5A). The extensor pollicis longus (EPL) is located in a groove just ulnar to the tubercle (Fig 5A) and deviates toward the radial aspect beyond the tubercle. On the ulnar aspect of the EPL are the extensor digitorum and indicis tendons, followed more medially by the extensor digiti minimi
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(EDM) tendon lying dorsal to the distal radioulnar joint (Fig 5B). Radial to the LT, the extensor carpi radialis brevis (ECRB) and longus (ECRL) tendons are located in sequence. The scapholunate (SLL) and lunotriquetral (LTL) ligaments (Fig 6) are assessed in the neutral position, in flexion and also in ulnar and radial deviation.9 After the LT is identified, the transducer is moved distally to identify the scaphoid. The scapholunate articulation is seen distal and ulnar to LT12 and is the first sagittally oriented joint space once the probe is past the radiocarpal joint. It is recognized by the rounded opposing surfaces of the lunate and scaphoid.13 The SLL is an echogenic fibrillar structure,12 best seen in the neutral position.13 The normal ligament is U-shaped with thick dorsal and ventral portions and a thinner central portion.14 The dorsal aspect of the SLL is the sonographically accessible portion, visualized in up to 78% of normal wrists.13
Radial The first extensor compartment consisting of the abductor pollicis longus and the extensor pollicis brevis tendons lie on the radial side of the wrist. The radial artery is seen slightly volar to the first extensor compartment.
Pathology The differential diagnosis of wrist pain can be presented as acute or chronic conditions, by compartment or by tissue of origin as presented. We present examples of both common and uncommon causes of wrist pain with US features and, where available, correlation with other imaging modalities with salient features of the pathology.
Tendon Tendon pathology in the wrist may present as tenosynovitis, tendonosis, or tendon tears including partial, interstitial, full-thickness, and complete tears. Tendonosis causes focal or diffuse thickening of the tendon. Hypoechoic areas seen in tendonitis correspond to either microtears or degeneration (Fig 7). Tenosynovitis presents as thickening of the sheath of the tendon with a “target” appearance on axial scans (Fig 8).15 Rheumatoid arthritis (RA) is a common cause of tenosynovitis. In active tenosynovitis, Doppler US may show increased vascularity of the hypoechoic material within the tendon sheath (Fig 8).
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FIG 5. Transverse US images through the dorsum of the wrist at the level of the LT and at the level of the distal radioulnar joint. EPL is ulnar to the LT and the ECRB and ECRL are radial to LT (A). Extensor digitorum communis (EDC) is situated between the EPL and the DRUJ, and the EDM is dorsal to the DRUJ (B). DRUJ ⫽ distal radioulnar joint.
FIG 6. Normal transverse ultrasound images of the SLL (A) and the LTL (B). The black arrow in (A) indicates the SLL, bridging between the lunate (L) and scaphoid (S). The white arrow in (B) indicates the normal LTL in the same patient positioned between the lunate (L) and the triquetrum (T).
Diffuse blurring of the fibrillar echogenic pattern or focal hypoechoic defects are the second common US manifestation of tendon pathology in RA.16 In nearly half of the cases of RA in the wrist, the ECU is involved. Tears of the tendon are a potential complication of tenosynovitis, and in RA, the EPL and EDM are the tendons that usually tear.16,17 US performs better than magnetic resonance imaging in detecting partial extensor tendon tears in RA patients (Fig 9).18 Infectious tenosynovitis must also be considered in the differential diagnosis of inflammatory tenosynovitis in the appropriate circumstances. In chronic recalcitrant cases, the possibility of infections such as mycobacteria should be considered.16
FIG 7. A 48-year-old woman with nodular tendonosis of the EPL with history of previous radius fracture. Longitudinal image of the wrist at the level of LT shows focal hypoechoic region in the deep portion of the tendon (between calipers).
De Quervain Tenosynovitis De Quervain tenosynovitis is a stenosing tenosynovitis of the first dorsal compartment wrist which contains the abductor pollicis longus and extensor pollicis brevis tendons. Patients usually complain of pain in
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the dorsolateral aspect of the wrist with referral to thumb or lateral forearm. Increased prevalence is seen in those using hands in repetitive fashion (repetitive
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FIG 8. A 45-year-old woman with severe De Quervain’s disease. Transverse (A and B) and longitudinal (C and D) images through the first extensor compartment demonstrates hypoechoic active vascular tenosynovitis within the tendon sheath (arrow in C and D). Transverse images demonstrate the hypoechoic area (arrow in A) between the two tendons, suggesting presence of a septum. There is also increased vascularity with the tendon (B) suggestive of active tendonitis. (Color version of figure is available online.)
microtrauma) or post isolated acute injury, with increased incidence in women, especially in pregnancy and the postpartum period, and in RA. On US normal tendons are oval or round in crosssectional profile with linear parallel reflecting lines within, described as a fibrillar pattern on longitudinal view. In De Quervain’s tenosynovitis, US features include one or more of the following: stenosing tenosynovitis where tendons are thickened or of normal size; increased or decreased echogenicity; and/or partial tears (Fig 8). The dorsal retinaculum may be thickened and the synovial sheaths may be distended with anechoic fluid with or without septations or echogenic tissue. It is important to assess if separate or combined tendon sheaths are present if steroid injections are contemplated for treatment.19 Alternative diagnosis, which may present with the same symptoms, such as syno-
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vitis and erosions of an inflammatory arthropathy, first carpometacarpal joint (CMCJ) osteoarthritis and flexor carpi radialis tenosynovitis, can be assessed during the same examination. US can be used to demonstrate postoperative complications, such as volar subluxation of the tendons due to excessive release of the retinaculum.16,20,21 Intersection Syndrome This involves tenosynovitis or periligamentous edema at the intersection of the ECRL and ECRB tendons with abductor pollicis longus and extensor pollicis brevis, 3 to 5 cm proximal to the Lister’s tubercle.22 It is common in rowers. The tendons may be swollen and hypoechoic and may demonstrate tenosynovitis or bursitis or show inflammatory reaction in the overlying soft tissue.16
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FIG 9. A 50-year-old woman with longstanding RA with partial tear of extensor tendon in compartment 4. Longitudinal (A) and transverse (B) images at the level of the LT demonstrate focal fluid-filled area (arrows) within the extensor tendon in keeping with a partial tear.
Nerve Neural pathology causing or presenting as wrist pain include nerve compression syndromes, neural tumors and posttraumatic transaction. Carpal Tunnel Syndrome Carpal Tunnel Syndrome (CTS) is a compressive neuropathy of the median nerve within the carpal tunnel and was first described in the mid-1800s by Sir James Paget. Symptoms can be sensory and/or motor and include numbness and tingling localized to the sensory distribution of the median nerve exacerbated by wrist flexion and extension activities and weakness in its motor distribution. The cause of CTS can be classified as primary and secondary. The diagnosis is made clinically, supported by nerve conduction studies.23 The main use of US in CTS is in excluding secondary causes and in the equivocal cases where there is doubt about the clinical diagnosis, eg, to distinguish flexor tenosynovitis from ganglia.24,25 In cases of persistent CTS after carpal tunnel release, US can be used to assess integrity of FR and the median nerve. On longitudinal imaging, the nerve is ovoid, hypoechoic with parallel echogenic lines (perineurium) and hyperechoic circumference (nerve sheath), and tapers as it courses distally. Axially it is circular proximal to, elliptical at, and wedged-shaped distal to carpal tunnel, with multiple hyperechoic foci (perineurium) within. The shape of the nerve may change with different wrist positions and examination of the wrist in a neutral position is advocated. Increase in cross-sectional area (CSA) of the median nerve at the pisiform level is a consistent finding in CTS.26 This is done as a continuous trace around the nerve (Fig 10) or can be calculated by the formula for an ellipsoid by measuring the long and short axes.
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The cutoff values of CSA above which the diagnosis of CTS is made ranges from 9 to 12 mm2.27-34 While some authors obtain measurements for CSA from the inner border of the echogenic perineurium,27,28 others include the perineurium in the measurements.30 This range of values in the literature is due to factors such as patient selection, the gold standard used to compare with and the variation of the severity and symptom duration of CTS.26 We consider a cross-sectional diameter greater than 10 mm, at the level of the pisiform, as abnormal.18 In addition, secondary signs such as contour deformities, eg, notch sign identified as dilation proximal to carpal ligament with sharp anterior caliber change and flattening within the carpal tunnel, palmar bowing of the flexor retinaculum ⬎2.5 mm, may be helpful (Fig 10). Additional measurements such as swelling ratio and flattening ratio need further studied to assess their benefit in assessment of CTS.18 The flexor retinaculum, adjacent tendons, and lesions that may be causing mass affect on the median nerve should be carefully examined (Fig 11).28 The commonest focal mass encountered is the ganglion cyst. Anatomical variants, such as a bifid median nerve proximal to carpal tunnel (2.8%), can be identified with US preoperatively.35 Postoperatively, patients may present with recurrent symptoms and US can, in addition to the above, confirm transection flexor retinaculum and assess integrity of the median nerve and morphological changes from preoperative US. Guyon’s Canal Syndrome (GCS) In this entity, the ulnar nerve is compressed in the Guyon’s canal. Important causes of GCS include ganglia and anomalous muscles. In the majority, the cause of GCS is idiopathic or trauma; uncommon causes include thrombosis of ulnar artery, synovitis, prominent hook of
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FIG 10. A 35-year-old woman with severe idiopathic CTS in the right wrist. Transverse images of the right wrist at the level of the pisiform (A and B) show increased CSA (36 mm2) in (A) and increased palmar bowing of the FR in (B). Longitudinal image (C) of the symptomatic right wrist shows the swelling of the median nerve (MN) compared to the normal asymptomatic left wrist in (D). White arrow in (A) indicates the ulnar nerve in the Guyon’s canal and black arrows in (B) point to the FR.
the hamate, schwannoma (Fig 12), and aberrant fibrous band.36 Harvie and coworkers performed US on asymptomatic volunteers and found anomalous muscles (variants of abductor digiti minimi) in 35% of wrists with a mean muscle thickness of 1.7 mm.37 The size of the anomalous muscle could be important in determining its significance in cases of GCS.37 Nerve Sheath Tumors Neurofibromas and schwannomas rarely affect the wrist.38 US demonstrates nerve sheath tumors as fusiform hypoechoic masses with well-defined margins with internal vascularity (Fig 12). A mass can be
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diagnosed as nerve sheath tumor if a nerve is seen to enter and exit the mass.39
Wrist Ligament and Cartilage Abnormalities TFCC includes the TFC, dorsal and volar radioulnar ligaments, ulnar collateral ligament, meniscus homologue, and the ECU. It functions as a cushion and stabilizer to forces during axial loading on the ulnar aspect of the wrist and distal radioulnar joint. Any component may be the site of pathology but the TFC is the commonest to demonstrate abnormalities. The patient may present with ulnar side pain, a clicking
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change in the scapholunate interval occurs in asymptomatic wrists on scanning the wrist in ulnar and radial deviation.40 Although detection of a normal dorsal SLL on US virtually excludes the presence of scapholunate instability, nonvisualization does not imply instability. Lunotriquetral Ligament Tear
FIG 11. A 43-year-old woman with longstanding RhA who developed symptoms of CTS. Axial US carpal tunnel demonstrates enlarged median nerve (arrow) with synovial thickening flexor synovial sheath with prominent flow within on power Doppler. Symptoms of CTS relieved posttreatment synovitis. (Color version of figure is available online.)
sensation, or a decreased range of motion. Clinical examination may demonstrate a positive load test or direct tenderness, which may also represent ulnar abutment or chondromalacia of the hamate. Palmer classification for TFC tears divides TFC injuries into traumatic and degenerative with subdivision by location.40,41 In general TFC traumatic tears, if peripheral have a good blood supply and can be repaired. The central avascular region requires debridement. Pathology affecting the triangular fibrocartilage complex includes triangle fibrocartilage partial/fullthickness tears; detachment and degeneration; extensor carpi ulnaris tenosynovitis/subluxation; ulnar collateral; and radioulnar ligament tears. TFC tears appear as loss of the homogeneous echotexture and triangular structural appearance, absence of a portion of the structure (Fig 13), hypoechoic clefts, or linear clefts/cysts.9,11 Thickness measurements of TFC have been proposed for detecting tears11; however, this is unreliable.40,42 Although US has high specificity for detecting TFC tears, the sensitivity is low.9 Radialsided tears are difficult to visualize on US. SLL Tear Tear of the dorsal SLL is diagnosed on US if the normal hyperechoic fibrillar structure of the ligament becomes hypoechoic, discontinuous or is absent (Fig 14),12 or in the presence of concurrent fluid or associated ganglion.9 More stringent criteria for diagnosing dorsal SLL tear on US include actual demonstration of the torn fragments and unilateral diastasis on dynamic scanning.41 No predictable
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Injury of the LTL is uncommon compared with scapholunate instability. US criteria used to diagnose SLL tears are applied for LTL tears as well (Fig 15).9 US has high specificity and positive predictive value, but poor sensitivity and negative-predictive value for diagnosing dorsal LTL tears.9 Extensor carpi radialis (ECR) tendon lies normally in the ulnar styloid groove. A subluxing ECU may be felt as a palpable snap with wrist flexed in ulnar deviation. Abnormal subluxation may occur in wrist flexion and ulnar deviation. The ECR is also a common site for tenosynovitis. Flat and convex grooves in the distal ulna predispose to ECU subluxation.42 Abnormal motion of the ECU should be sought for during supination and pronation.15
Proliferative Synovitis US is a very sensitive imaging technique for the detection of synovial hypertrophy. This is one of the indications for US that is rapidly increasing as synovial proliferation can be detected in its early stages. Careful assessment of the joint is required from volar and dorsal surfaces including synovial recesses, which may also contain synechia and pannus at the site of an articular bare area as in RA. US is useful in differentiating joint effusion from proliferative synovitis. Graded compression is used in distinguishing fluid from proliferative synovitis.43 While joint fluid is predominantly hypoechoic and is displaceable with pressure from the transducer, synovitis is hypoechoic to surrounding tissue and is deformable but not displaceable with pressure.41,43 Proliferative synovitis in the wrist can distend the joint and elevate the volar and dorsal aspects of the capsule and give a pseudotumoral appearance (Fig 15A).43 Doppler US is used to differentiate between fibrous and active pannus. Increased flow on Doppler is seen in active synovitis (Fig 16). The gain on color Doppler should be adjusted until artifactual signal from bone cortices disappears. Vascularity on Doppler US has been shown to have good correlation with inflammatory activity in RA.44 The differential diagnosis of proliferative synovitis in-
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FIG 12. A 65-year-old man with proven schwannoma of the ulnar nerve in the Guyon’s canal. Transverse US image (A) shows normal Guyon’s canal with ulnar nerve (UN) and relationship to ulnar artery (UA) and flexor carpi ulnaris (FCU). (B) A well-defined, hypoechoic soft-tissue mass with posterior acoustic enhancement (white arrow), lateral to the pisiform (P) with internal vascularity on Doppler (not shown).
FIG 13. A 45-year-old man with TFC tear of right wrist confirmed on MR arthrogram (not shown). Longitudinal ultrasound of the symptomatic right wrist at the level of the TFC demonstrates focal decreased echogenicity (arrow) in keeping with absence of a portion of the structure. Compare with the normal echogenic TFC (Fig 4). TQM ⫽ triquetrum; DU ⫽ distal ulna.
FIG 14. A 42-year-old man with dorsal SLL tear of the left wrist confirmed on arthrogram (not shown). Transverse image dorsal left wrist shows the absent SLL and fluid in the scapholunate space (arrows). Compare with the normal SLL with compact fibrillar echotexture (Fig 6A).
FIG 15. LTL tear confirmed on arthrogram with contrast injected into the midcarpal joint space (not shown). Transverse images (A and B) at the level of the lunate (L) and triquetral (T) bones show the tear of the LTL with disruption of the normal hyperechoic linear structure and fluid filling the interval (arrows in A and B).
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FIG 16. A 41-year-old woman with RA. Longitudinal images (A and B) through the mid dorsum of the wrist show proliferative synovitis/pannus as hypoechoic, soft tissue (curved arrow in B), and distension of the dorsal recess of the joint (straight arrow). Power Doppler shows flow in the pannus (A) indicating active synovitis.
FIG 17. A 26-year-old woman with RA. Longitudinal image shows multiple small erosions (white arrows) medial to the border of the distal ulna. Curved arrow points to the ECU with distension sheath with hypoechoic soft tissue in keeping with tenosynovitis.
cludes RA, septic arthritis, crystal-induced arthropathies, amyloid arthropathy, pigmented villonodular synovitis, synovial osteochondromatosis, and hemophilic arthropathy. Erosions Nearly 50% of patients with RA may develop erosions within 1 year of onset of disease.45 In RA affecting the wrist joint, the distal ulna (Fig 17), lunate, and the triquetrum are common sites for erosions.41 In early RA, US depicts erosions reliably and demonstrates more erosions than conventional radiographs.46 Erosions appear as interruption or defect of cortex with irregular margins.
Masses Ganglion cysts are the commonest benign softtissue tumor of the wrist (50-70%).34 It is composed of a mucin-filled, fibrous-lined cyst. Hippocrates
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initially described it as “knots of tissue containing mucoid flesh.” The etiology is unknown but is postulated to be secondary to microtrauma, producing hyaluronic acid at the synovial– capsular interface with secondary production of mucin lakes that coalesce to form a ganglion. It is commoner in women and between the ages 10 and 40 years. Symptoms vary from a painless mass to pressure on adjacent structures. Symptoms may also be related to associated pathologies such as scapholunate ligament tears. US helps to confirm the clinical diagnosis.47On US, ganglion cysts are usually noncompressible anechoic well-defined lesions with posterior acoustic enhancement (Fig 18). Occasionally, they may be multiloculated and contain debris. Careful assessment is required to identify the tract to an adjacent joint or tendon sheath. The dorsal aspect of the wrist, adjacent to scapholunate ligament (60-70%), is the commonest location but may also occur on the volar aspect of the wrist adjacent to radioscaphoid, scaphotrapezial or pisotriquetral joint (20%), and volar retinaculum between A1 and A2 pulleys (10%). Less common sites include the carpal tunnel, Guyon canal, CMCJ, and extensor tendon compartment. Giant cell tumor of the tendon sheath is the second commonest benign soft-tissue mass in the wrist. First described by Chassignac in 1852, it is an extraarticular localized form of pigmented villonodular synovitis. Typically, it occurs between the ages of 20 and 40 years, being more common in women. Etiology is unknown but is likely a reactive hyperplasia secondary to an inflammatory process. Clinically, patients
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FIG 18. A 40-year-old woman with dorsal wrist ganglion. Axial ultrasound dorsal aspect wrist of a well-defined heterogeneous hypoechoic mass pre- (A) and post- (B) compression. No flow on power Doppler, associated with a scapholunate tear (not shown). (C) Pathological specimen. (Color version of figure is available online.)
FIG 19. Giant cell tumor: Sagittal ultrasound of the volar wrist in a 24-year-old man presenting with mild swelling and hand discomfort for 1 year. US demonstrates localized tendon sheath distension with soft tissue. Mild internal flow noted on power Doppler (not shown). Remaining flexor tendon sheaths were normal. Confirmed on pathology as giant cell tumor flexor tendon sheath.
usually present with a slow-growing lobulated painless soft-tissue mass on the volar surface of the hand and wrist. Degenerative changes at a local joint may be
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related. Satellite lesions are a common cause of recurrence. On US, it appears as a solid, hypoechoic, lobulated soft-tissue mass with well-defined margins partly or completely surrounding a tendon that otherwise appears normal (Fig 19).48 There is a lack of acoustic enhancement posteriorly and internal vascularity is seen on Doppler.48 Occasionally, giant cell tumor may cause pressure erosion of the underlying bone. Vascular Lesions A hemangioma is a heterogeneous, hypoechoic mass on US. It may contain hyperechoic foci with posterior shadowing, which can be confirmed on radiographs as pheboliths. It is partially compressible and demonstrates increased internal flow on Doppler with compression, features that suggest the diagnosis (Fig 20).14
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FIG 20. Hemangioma: Well-defined soft-tissue lesion presenting as an asymptomatic soft-tissue mass on the volar aspect of the wrist in a 19-year-old man. (A) On US lesion (arrow) is inhomogenous iso/ hyperechoic, partially compressible (B), with increased internal flow on color Doppler with compression (C). No pheboliths are identified within lesion. Confirmed on pathology as a hemangioma. (Color version of figure is available online.) FIG 22. Synovial osteochondromatosis (SO): A 39-year-old woman with primary SO of the flexor digitorum tendon sheaths extending to the DRUJ. Lat and AP DRUJ (A) with corresponding axial ultrasound image (B), demonstrating multiple ossified bodies, hyperechoic with posterior shadowing, within the tendon sheaths with synovial proliferation, hyperechoic soft tissue surrounding the tendons (arrows).
FIG 21. Myxoma: Axial ultrasound volar wrist, radial aspect, in a 59-year-old woman presenting with a non-tender soft-tissue mass (arrow) of heterogeneous echogenicity with displacement of the radial artery over its volar surface, shown as vascular flow on power Doppler. Ultrasound imaging features are of a nonspecific soft-tissue mass.
Pseudoaneurysms of the radial artery can occur following blunt or penetrating trauma, and US can show the relationship of the mass to the main vessel.
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Juxtaarticular myxoma is a rare solid, benign, softtissue mass of connective tissue origin that may occur at any age but is most common in the fifth and six decades and slightly more common in women. Virchow in 1871 noted the tumor’s gelatinous nature resembled Wharton’s jelly of the umbilical cord and coined the term myxoma. Intramuscular (cardiac and skeletal), subcutaneous, and soft tissues, bone, periosteum, and genitourinary tract are sites of occurrence. Occasionally, it is associated with fibrous dysplasia and is known as Mazabraud’s syndrome. On US, it is a well-defined hypoechoic mass, which may have small cystic spaces within (Fig 21).
Synovial Osteochondromatosis Synovial osteochondromatosis (SOC) may be primary or secondary. Primary SOC is a benign synovial
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FIG 23. Foreign body: Sagittal wrist, volar aspect, adult male with 8 ⫻ 2 mm splinter of wood embedded in the soft tissues noted on ultrasound as a well-defined linear focus of hyperechogenicity, surrounded by a hypoechoic soft-tissue rim secondary to foreign body reaction.
metaplasia of unknown etiology resulting in the formation of multiple chondral (chondromatosis) or osteochondral nodules (osteochondromatosis). Secondary SOC occurs in joints affected by arthritis and usually contains less intra-articular bodies, which are of varying sizes. Symptoms are directly related to the stability of the intra-articular bodies. On US, a joint effusion is common with well-defined intra-articular mass/masses with posterior acoustic shadowing (Fig 22). Stability can be assessed with dynamic movement of the joint in an attempt to displace the bodies. Synovial hypertrophy is identified as hyperechoic villous projections floating in the joint effusion.49
Foreign Bodies US is extremely sensitive in the detection of softtissue foreign bodies and is the first-line investigation if bodies are radiolucent, such as wood. Foreign bodies (FB) are echogenic initially but some such as wood become less echogenic with time (Fig 23). Artifacts deep to the FB can aid in identification and include reverberation and shadowing. Acutely, a hypoechoic inflammatory reaction surrounds the FB and may alter the sonographic appearance.1,50 US is ideally suited to assessment of injury to the surrounding soft tissues. In addition, the site of the FB can be marked for retrieval.
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Conclusion The clinical presentation of wrist pain can be due to a wide variety of pathology, including abnormalities of regional bones, joints, and soft-tissue structures. US can assist in determining the specific cause for wrist pain, along with assessment of important regional anatomical relationships. US is a readily accessible valuable diagnostic tool and we strongly advocate its role as a primary imaging modality.
REFERENCES 1. Bianchi S, Montet X, Martinoli C, et al. High-resolution sonography of compressive neuropathies of the wrist. J Clin Ultrasound 2004;32:451-61. 2. Chen P, Maklad N, Redwine M, et al. Dynamic highresolution sonography of the carpal tunnel. AJR 1997;168: 533-7. 3. Stuart RM, Koh ES, Breidahl WH. Sonography of peripheral nerve pathology. AJR 2004;182:123-9. 4. Silvestri E, Martinoli C, Derchi LE, et al. Echotexture of peripheral nerves: correlation between US and histologic findings and criteria to differentiate tendons. Radiology 1995; 197:291-6. 5. Chiou HJ, Chou YH, Chiou SY, et al. Peripheral nerve lesions: Role of high-resolution US. Radiographics 2003;23:e15. 6. Zeiss J, Jakab E, Khimji T, et al. The ulnar tunnel at the wrist (Guyon’s canal): Normal MR anatomy and variants. AJR 1992;158:1081-5.
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7. Bozkurt MC, Tagil SM, Ozcakar L, et al. Anatomical variations as potential risk factors for ulnar tunnel syndrome: A cadaveric study. Clin Anat 2005;18:274-80. 8. Martinoli C, Bianchi S, Gandolfo N, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000;20:S199-213. 9. Finlay K, Lee R, Friedman L. Ultrasound of intrinsic wrist ligament and triangular fibrocartilage injuries. Skeletal Radiol 2004;33:85-90. 10. Keogh CF, Wong AD, Wells NJ, et al. High resolution sonography of the triangular fibrocartilage: Initial experience and correlation with MRI and arthroscopic findings. AJR 2004;182:333-6. 11. Chiou HJ, Chang CY, Chou YH, et al. Triangular fibrocartilage of wrist: Presentation on high resolution ultrasonography. J Ultrasound Med 1998;17:41-8. 12. Jacobson JA, Oh E, Propeck T, et al. Sonography of the scapholunate ligament in four cadaveric wrists: correlation with MR arthrography and anatomy. AJR 2002;179:523-7. 13. Griffith JF, Chan DP, Ho PC, et al. Sonography of the normal scapholunate ligament and scapholunate joint space. J Clin Ultrasound 2001;29:223-9. 14. Linkous MD, Pierce SD, Gilula LA. Scapholunate ligamentous communicating defects in symptomatic and asymptomatic wrists: Characteristics. Radiology 2000;216:846-50. 15. Chiou HJ, Chou YH, Chang CY. Ultrasonography of the wrist. Can Assoc Radiol J 2001;52:302-11. 16. Daenen B, Houben G, Bauduin E, et al. Sonography in wrist tendon pathology. J Clin Ultrasound 2004;32:462-9. 17. De Maeseneer M, Marcelis S, Osteaux M, et al. Sonography of a rupture of the tendon of the extensor pollicis longus muscle: Initial clinical experience and correlation with findings at cadaveric dissection. AJR 2005;184:175-9. 18. Swen WA, Jacobs JW, Hubach PC, et al. Comparison of sonography and magnetic resonance imaging for the diagnosis of partial tears of finger extensor tendons in rheumatoid arthritis. Rheumatology (Oxford) 2000;39:55-62. 19. Giovagnorio F, Andreoli C, De Cicco ML. Ultrasonographic evaluation of de Quervain disease. J Ultrasound Med 1997; 16:685-9. 20. Ramesh R, Britton JM. A retinacular sling for subluxing tendons of the first extensor compartment. A case report. J Bone Joint Surg Br 2000;82:424-5. 21. White GM, Weiland AJ. Symptomatic palmar tendon subluxation after surgical release for de Quervain’s disease: A case report. J Hand Surg [Am] 1984;9:704-6. 22. de Lima JE, Kim HJ, Albertotti F, et al. Intersection syndrome: MR imaging with anatomic comparison of the distal forearm. Skeletal Radiol 2004;33:627-31. 23. Sternbach G. The carpal tunnel syndrome. J Emerg Med 1999;17:519-23. 24. El Miedany YM, Aty SA, Ashour S. Ultrasonography versus nerve conduction study in patients with carpal tunnel syndrome: Substantive or complimentary tests? Rheumatology (Oxford) 2004;43:887-95. 25. Wilson D. Ultrasound assessment of carpal tunnel syndrome. Clin Radiol 2004;59:909.
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26. Beekman R, Visser LH. Sonography in the diagnosis of carpal tunnel syndrome: A critical review of the literature. Muscle Nerve 2003;27:26-33. 27. Altinok T, Baysal O, Karakas HM, et al. Ultrasonographic assessment of mild and moderate idiopathic carpal tunnel syndrome. Clin Radiol 2004;59:916-25. 28. Yesildag A, Kutluhan S, Sengul N, et al. The role of ultrasonographic measurements of the median nerve in the diagnosis of carpal tunnel syndrome. Clin Radiol 2004;59: 910-15. 29. Keles I, Karagulle Kendi AT, Aydin G, et al. Diagnostic precision of ultrasonography in patients with carpal tunnel syndrome. Am J Phys Med Rehabil 2005;84:443-50. 30. Sarria L, Cabada T, Cozcolluela R, et al. Carpal tunnel syndrome: usefulness of sonography. Eur Radiol 2000;10: 1920-5. 31. Duncan I, Sullivan P, Lomas F. Sonography in the diagnosis of carpal tunnel syndrome. AJR 1999;173:681-4. 32. Buchberger W, Judmaier W, Birbamer G, et al. Carpal tunnel syndrome: Diagnosis with high-resolution sonography. AJR 1992;159:793-8. 33. Nakamichi K, Tachibana S. Ultrasonographic measurement of median nerve cross-sectional area in idiopathic carpal tunnel syndrome: Diagnostic accuracy. Muscle Nerve 2002;26:798803. 34. Lee D, van Holsbeeck MT, Janevski PK, et al. Diagnosis of carpal tunnel syndrome. Ultrasound versus electromyography. Radiol Clin North Am 1999;37:859-72. 35. Popeck T, Quinn TJ, Jacobson JA, et al. Sonography and MR imaging of bifid median nerve with anatomic and histologic correlation. AJR 2000;175:1721-5. 36. Murata K, Shih JT, Tsai TM. Causes of ulnar tunnel syndrome: A retrospective study of 31 subjects. J Hand Surg [Am] 2003;28:647-51. 37. Harvie P, Patel N, Ostlere SJ. Prevalence and epidemiological variation of anomalous muscles at Guyon’s canal. J Hand Surg [Br] 2004;29:26-9. 38. Garcia J, Bianchi S. Diagnostic imaging of tumors of the hand and wrist. Eur Radiol 2001;11:1470-82. 39. Middleton WD, Teefey SA, Boyer MI. Hand and wrist sonography. Ultrasound Q 2001;17:21-36. 40. Palmer AK. Triangular fibrocartilage complex lesions: A classification. J Hand Surg [Am] 1989 Jul;14:594-606. 41. Bianchi S, Martinoli C, Cohen M, et al. Ultrasound of the hand and wrist. In: Practical Musculoskeletal Ultrasound. Philadelphia, PA: Churchill Livingstone, 2004. p. 95-117. 42. Allende C, Le Viet D. Extensor carpi ulnaris problems at the wrist classification, surgical treatment and results. J Hand Surg [Br] 2005;30:265-72. 43. Chhem RK, van Holsbeeck MT. Sonography of rheumatoid disease. In: Musculoskeletal ultrasound, 2nd edition. St. Louis, MO: Mosby, 2001. p. 373-92. 44. Walther M, Harms H, Krenn V, et al. Correlation of power Doppler sonography with vascularity of the synovial tissue of the knee joint in patients with osteoarthritis and rheumatoid arthritis. Arthritis Rheum 2001;44:331-8. 45. Fex E, Jonsson K, Johnson U, et al. Development of radiographic damage during the first 5-6 yr of rheumatoid arthritis.
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A prospective follow-up study of a Swedish cohort. Br J Rheumatol 1996;35:1106-15. 46. Wakefield RJ, Gibbon WW, Conaghan PG, et al. The value of sonography in the detection of bone erosions in patients with rheumatoid arthritis: A comparison with conventional radiography. Arthritis Rheum 2000;43:2762-70. 47. Hoglund M, Tordai P, Muren C. Diagnosis of ganglions in the hand and wrist by sonography. Acta Radiol 1994;35:35-9.
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48. Teefey SA, Middleton WD, Boyer MI. Sonography of the hand and wrist. Semin Ultrasound CT MR 2000;21:192-204. 49. Frankel DA, Baegiela A, Bouffard JA, et al. Synovial joints: Evaluation of intraarticular bodies with US. Radiology 1998; 206:41-4. 50. Jacobson JA, Powell A, Craig JG, et al. Wooden foreign bodies in soft tissue: Detection at US. Radiology 1998; 206:45-8.
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Ultrasound is a valuable imaging modality for evaluation of patients presenting with wrist pain. An important advantage is the ability to correlate the site of pain or discomfort with the underlying sonographic appearance. The capacity to dynamically assess the wrist and use the contralateral asymptomatic wrist for comparison purposes are strengths of ultrasound as a diagnostic tool. This pictorial review deals with the sonographic assessment of the commonly encountered wrist pathologies.
Musculoskeletal ultrasound (US) is an effective established technique for the imaging of joints and soft tissues of the wrist. Inherent advantages include cost effectiveness, lack of ionizing radiation, accessibility, and multiplanar capability in real time. In addition, it is an interactive examination with the patient, thereby allowing a pertinent history and localization of the symptoms to be obtained during the examination. Once pathology is identified, comparison with the contralateral side can confirm subtle abnormalities with images viewed side by side on split-screen. Dynamic imaging may expose pathologies, such as intermittent tendon subluxation, not present on a static examination. As in all imaging techniques, a thorough understanding of the regional anatomy is essential. We present a review of the appropriate anatomy, technique, and differential diagnosis of wrist pain diagnosable by US and, finally, a more detailed review of some of these pathologies.
a From the Radiology Department, St. Joseph’s Healthcare, Hamilton, Ontario, Canada; and bRadiology Department, McMaster Health Sciences, Hamilton, Ontario, Canada. Reprint requests: John O’Neill, FRCR, Radiology Department, St. Joseph’s Hospital, 50 Charlton Avenue East, Hamilton, Ontario, Canada. E-mail: [email protected]. Curr Probl Diagn Radiol 2009;38:111-125. © 2009 Mosby, Inc. All rights reserved. 0363-0188/2009/$36.00 ⫹ 0 doi:10.1067/j.cpradiol.2008.02.001
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Indications for wrist US examination include softtissue injury, tendon pathology, arthritis, soft-tissue masses/swelling, nerve entrapment, effusion, and bone injury. The examination is usually tailored to the patient’s clinical symptoms.
Anatomy and Technique The patient is seated with hands resting on a table placed anteriorly or on a pillow placed on the patient’s thighs. Volar examination requires the wrists to be placed flat or in mild extension with palm up and both ulnar and radial deviation to delineate all the necessary anatomy. For the dorsal examination, the wrist is placed palm down with mild flexion. Axial and longitudinal images should be obtained from the volar wrist crease to the thenar muscles in assessing the volar compartments. The transducer will require angulation to compensate for the normal contour of the wrist.
Volar The wrists are placed flat with palm up and scanned in ulnar and radial deviation. The carpal tunnel is a fibro-osseous canal delimited by the carpal bones dorsally and by the flexor retinaculum (FR) on the volar aspect. The FR attaches to the scaphoid, the pisiform, the hook of hamate, and the tubercle of trapezium. On US, the FR is seen as an echogenic curvilinear band connecting the pisiform to the scaphoid (Fig 1).1 It encloses nine tendons within the carpal tunnel including the flexor digitorum profundus, flexor digitorum superficialis, and the flexor pollicis longus tendons. Laterally, the flexor carpi radialis tendon lies within its own canal, formed by a septum that takes origin from the FR. The flexor tendons have a fibrillar, linear echogenic pattern on US. Within the carpal tunnel, the flexor tendons are enclosed in two synovial sheaths: a lateral sheath that encloses the flexor pollicis longus and a medial sheath enclosing the remaining flexor
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FIG 1. Transverse anatomy illustration of the wrist at the level of the hook of hamate. 1: Extensor carpi ulnaris; 2: Extensor digiti minimi; 3: Extensor indicis and extensor digitorum; 4: Extensor carpi radialis and brevis; 5: Radial artery; 6: Extensor pollicis longus; 7: Extensor pollicis brevis; 8: Flexor carpi ulnaris; 9: Median nerve; 10: Palmaris longus; 11: Flexor retinaculum; 12: Ulnar artery and nerve; 13: Superficial and deep flexor tendons.
FIG 2. Transverse US image through the wrist at the level of the hook of the hamate (HH). The echogenic flexor retinaculum (FR) runs between the HH and the tubercle of the trapezium (T). The hypoechoic median nerve (MN) is situated superficially in the carpal tunnel, with the echogenic flexor tendons deep to it.
tendons.1 The median nerve lies superficially in the carpal tunnel (Figs 1 and 2). It moves with less amplitude compared with the tendons.2 On longitudinal scanning, the median nerve has longitudinal hypoechoic bands, separated by discontinuous bands of increased echogenicity, corresponding to the epineurium.3,4 Axially, the median nerve has a reticular pattern.5 Guyon’s canal is situated medial to the carpal tunnel and contains the ulnar nerve, ulnar artery/vein,
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FIG 3. Coronal anatomical illustration of the wrist. 1: Ulnar collateral ligament; 2: Meniscus homologue; 3: Triangular fibrocartilage; 4: Lunotriquetral ligament; 5: Scapholunate ligament.
and connective tissue (Fig 1).6 The boundaries of this canal are the pisiform medially and the hook of the hamate laterally; floor is formed by the hypothenar muscles and FR, and roof is formed by the palmar
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FIG 4. Normal ultrasound image of the TFC. Longitudinal, paracoronal image at the ulnar aspect of the wrist shows the normal TFC (straight arrow), distal to the ulnar styloid (UST) and proximal to the triquetral (TRI) bone. The TFC is identified deep to the ECU (curved arrow).
carpal ligament.1,7,8 US, on axial views, demonstrates the ulnar nerve at the pisiform level as a thin, rounded structure medial to the ulnar artery and lateral to the pisiform.
Ulnar The important structures on the ulnar side of the wrist are the triangular fibrocartilage complex (TFCC) and the extensor carpi ulnaris (ECU) tendon. The TFCC consists of the triangular fibrocartilage (TFC), a meniscal homologue, ulnar collateral ligament, dorsal and volar radio-ulnar ligaments, and the ECU sheath. The TFC is examined with the forearm pronated, wrist flexed and radially deviated, draped over a volar pad.9,10 The TFC is hyperechoic and is an inverted triangular structure with the wider base on the dorsal aspect and the thinner apex on the volar side on longitudinal scanning (Figs 3 and 4).9,11 Placing the transducer transversely on the ulnar styloid and moving distally will allow visualization of the TFC. The ECU tendon lies superficial to the TFC in a separate groove on the distal ulna and is used as an acoustic window to visualize the TFC (Fig 4).10,11
Dorsal The extensor retinaculum divides the dorsal wrist into six compartments. Lister’s tubercle (LT) is an important landmark on the dorsal radius and is identified on transverse scanning (Fig 5A). The extensor pollicis longus (EPL) is located in a groove just ulnar to the tubercle (Fig 5A) and deviates toward the radial aspect beyond the tubercle. On the ulnar aspect of the EPL are the extensor digitorum and indicis tendons, followed more medially by the extensor digiti minimi
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(EDM) tendon lying dorsal to the distal radioulnar joint (Fig 5B). Radial to the LT, the extensor carpi radialis brevis (ECRB) and longus (ECRL) tendons are located in sequence. The scapholunate (SLL) and lunotriquetral (LTL) ligaments (Fig 6) are assessed in the neutral position, in flexion and also in ulnar and radial deviation.9 After the LT is identified, the transducer is moved distally to identify the scaphoid. The scapholunate articulation is seen distal and ulnar to LT12 and is the first sagittally oriented joint space once the probe is past the radiocarpal joint. It is recognized by the rounded opposing surfaces of the lunate and scaphoid.13 The SLL is an echogenic fibrillar structure,12 best seen in the neutral position.13 The normal ligament is U-shaped with thick dorsal and ventral portions and a thinner central portion.14 The dorsal aspect of the SLL is the sonographically accessible portion, visualized in up to 78% of normal wrists.13
Radial The first extensor compartment consisting of the abductor pollicis longus and the extensor pollicis brevis tendons lie on the radial side of the wrist. The radial artery is seen slightly volar to the first extensor compartment.
Pathology The differential diagnosis of wrist pain can be presented as acute or chronic conditions, by compartment or by tissue of origin as presented. We present examples of both common and uncommon causes of wrist pain with US features and, where available, correlation with other imaging modalities with salient features of the pathology.
Tendon Tendon pathology in the wrist may present as tenosynovitis, tendonosis, or tendon tears including partial, interstitial, full-thickness, and complete tears. Tendonosis causes focal or diffuse thickening of the tendon. Hypoechoic areas seen in tendonitis correspond to either microtears or degeneration (Fig 7). Tenosynovitis presents as thickening of the sheath of the tendon with a “target” appearance on axial scans (Fig 8).15 Rheumatoid arthritis (RA) is a common cause of tenosynovitis. In active tenosynovitis, Doppler US may show increased vascularity of the hypoechoic material within the tendon sheath (Fig 8).
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FIG 5. Transverse US images through the dorsum of the wrist at the level of the LT and at the level of the distal radioulnar joint. EPL is ulnar to the LT and the ECRB and ECRL are radial to LT (A). Extensor digitorum communis (EDC) is situated between the EPL and the DRUJ, and the EDM is dorsal to the DRUJ (B). DRUJ ⫽ distal radioulnar joint.
FIG 6. Normal transverse ultrasound images of the SLL (A) and the LTL (B). The black arrow in (A) indicates the SLL, bridging between the lunate (L) and scaphoid (S). The white arrow in (B) indicates the normal LTL in the same patient positioned between the lunate (L) and the triquetrum (T).
Diffuse blurring of the fibrillar echogenic pattern or focal hypoechoic defects are the second common US manifestation of tendon pathology in RA.16 In nearly half of the cases of RA in the wrist, the ECU is involved. Tears of the tendon are a potential complication of tenosynovitis, and in RA, the EPL and EDM are the tendons that usually tear.16,17 US performs better than magnetic resonance imaging in detecting partial extensor tendon tears in RA patients (Fig 9).18 Infectious tenosynovitis must also be considered in the differential diagnosis of inflammatory tenosynovitis in the appropriate circumstances. In chronic recalcitrant cases, the possibility of infections such as mycobacteria should be considered.16
FIG 7. A 48-year-old woman with nodular tendonosis of the EPL with history of previous radius fracture. Longitudinal image of the wrist at the level of LT shows focal hypoechoic region in the deep portion of the tendon (between calipers).
De Quervain Tenosynovitis De Quervain tenosynovitis is a stenosing tenosynovitis of the first dorsal compartment wrist which contains the abductor pollicis longus and extensor pollicis brevis tendons. Patients usually complain of pain in
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the dorsolateral aspect of the wrist with referral to thumb or lateral forearm. Increased prevalence is seen in those using hands in repetitive fashion (repetitive
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FIG 8. A 45-year-old woman with severe De Quervain’s disease. Transverse (A and B) and longitudinal (C and D) images through the first extensor compartment demonstrates hypoechoic active vascular tenosynovitis within the tendon sheath (arrow in C and D). Transverse images demonstrate the hypoechoic area (arrow in A) between the two tendons, suggesting presence of a septum. There is also increased vascularity with the tendon (B) suggestive of active tendonitis. (Color version of figure is available online.)
microtrauma) or post isolated acute injury, with increased incidence in women, especially in pregnancy and the postpartum period, and in RA. On US normal tendons are oval or round in crosssectional profile with linear parallel reflecting lines within, described as a fibrillar pattern on longitudinal view. In De Quervain’s tenosynovitis, US features include one or more of the following: stenosing tenosynovitis where tendons are thickened or of normal size; increased or decreased echogenicity; and/or partial tears (Fig 8). The dorsal retinaculum may be thickened and the synovial sheaths may be distended with anechoic fluid with or without septations or echogenic tissue. It is important to assess if separate or combined tendon sheaths are present if steroid injections are contemplated for treatment.19 Alternative diagnosis, which may present with the same symptoms, such as syno-
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vitis and erosions of an inflammatory arthropathy, first carpometacarpal joint (CMCJ) osteoarthritis and flexor carpi radialis tenosynovitis, can be assessed during the same examination. US can be used to demonstrate postoperative complications, such as volar subluxation of the tendons due to excessive release of the retinaculum.16,20,21 Intersection Syndrome This involves tenosynovitis or periligamentous edema at the intersection of the ECRL and ECRB tendons with abductor pollicis longus and extensor pollicis brevis, 3 to 5 cm proximal to the Lister’s tubercle.22 It is common in rowers. The tendons may be swollen and hypoechoic and may demonstrate tenosynovitis or bursitis or show inflammatory reaction in the overlying soft tissue.16
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FIG 9. A 50-year-old woman with longstanding RA with partial tear of extensor tendon in compartment 4. Longitudinal (A) and transverse (B) images at the level of the LT demonstrate focal fluid-filled area (arrows) within the extensor tendon in keeping with a partial tear.
Nerve Neural pathology causing or presenting as wrist pain include nerve compression syndromes, neural tumors and posttraumatic transaction. Carpal Tunnel Syndrome Carpal Tunnel Syndrome (CTS) is a compressive neuropathy of the median nerve within the carpal tunnel and was first described in the mid-1800s by Sir James Paget. Symptoms can be sensory and/or motor and include numbness and tingling localized to the sensory distribution of the median nerve exacerbated by wrist flexion and extension activities and weakness in its motor distribution. The cause of CTS can be classified as primary and secondary. The diagnosis is made clinically, supported by nerve conduction studies.23 The main use of US in CTS is in excluding secondary causes and in the equivocal cases where there is doubt about the clinical diagnosis, eg, to distinguish flexor tenosynovitis from ganglia.24,25 In cases of persistent CTS after carpal tunnel release, US can be used to assess integrity of FR and the median nerve. On longitudinal imaging, the nerve is ovoid, hypoechoic with parallel echogenic lines (perineurium) and hyperechoic circumference (nerve sheath), and tapers as it courses distally. Axially it is circular proximal to, elliptical at, and wedged-shaped distal to carpal tunnel, with multiple hyperechoic foci (perineurium) within. The shape of the nerve may change with different wrist positions and examination of the wrist in a neutral position is advocated. Increase in cross-sectional area (CSA) of the median nerve at the pisiform level is a consistent finding in CTS.26 This is done as a continuous trace around the nerve (Fig 10) or can be calculated by the formula for an ellipsoid by measuring the long and short axes.
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The cutoff values of CSA above which the diagnosis of CTS is made ranges from 9 to 12 mm2.27-34 While some authors obtain measurements for CSA from the inner border of the echogenic perineurium,27,28 others include the perineurium in the measurements.30 This range of values in the literature is due to factors such as patient selection, the gold standard used to compare with and the variation of the severity and symptom duration of CTS.26 We consider a cross-sectional diameter greater than 10 mm, at the level of the pisiform, as abnormal.18 In addition, secondary signs such as contour deformities, eg, notch sign identified as dilation proximal to carpal ligament with sharp anterior caliber change and flattening within the carpal tunnel, palmar bowing of the flexor retinaculum ⬎2.5 mm, may be helpful (Fig 10). Additional measurements such as swelling ratio and flattening ratio need further studied to assess their benefit in assessment of CTS.18 The flexor retinaculum, adjacent tendons, and lesions that may be causing mass affect on the median nerve should be carefully examined (Fig 11).28 The commonest focal mass encountered is the ganglion cyst. Anatomical variants, such as a bifid median nerve proximal to carpal tunnel (2.8%), can be identified with US preoperatively.35 Postoperatively, patients may present with recurrent symptoms and US can, in addition to the above, confirm transection flexor retinaculum and assess integrity of the median nerve and morphological changes from preoperative US. Guyon’s Canal Syndrome (GCS) In this entity, the ulnar nerve is compressed in the Guyon’s canal. Important causes of GCS include ganglia and anomalous muscles. In the majority, the cause of GCS is idiopathic or trauma; uncommon causes include thrombosis of ulnar artery, synovitis, prominent hook of
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FIG 10. A 35-year-old woman with severe idiopathic CTS in the right wrist. Transverse images of the right wrist at the level of the pisiform (A and B) show increased CSA (36 mm2) in (A) and increased palmar bowing of the FR in (B). Longitudinal image (C) of the symptomatic right wrist shows the swelling of the median nerve (MN) compared to the normal asymptomatic left wrist in (D). White arrow in (A) indicates the ulnar nerve in the Guyon’s canal and black arrows in (B) point to the FR.
the hamate, schwannoma (Fig 12), and aberrant fibrous band.36 Harvie and coworkers performed US on asymptomatic volunteers and found anomalous muscles (variants of abductor digiti minimi) in 35% of wrists with a mean muscle thickness of 1.7 mm.37 The size of the anomalous muscle could be important in determining its significance in cases of GCS.37 Nerve Sheath Tumors Neurofibromas and schwannomas rarely affect the wrist.38 US demonstrates nerve sheath tumors as fusiform hypoechoic masses with well-defined margins with internal vascularity (Fig 12). A mass can be
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diagnosed as nerve sheath tumor if a nerve is seen to enter and exit the mass.39
Wrist Ligament and Cartilage Abnormalities TFCC includes the TFC, dorsal and volar radioulnar ligaments, ulnar collateral ligament, meniscus homologue, and the ECU. It functions as a cushion and stabilizer to forces during axial loading on the ulnar aspect of the wrist and distal radioulnar joint. Any component may be the site of pathology but the TFC is the commonest to demonstrate abnormalities. The patient may present with ulnar side pain, a clicking
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change in the scapholunate interval occurs in asymptomatic wrists on scanning the wrist in ulnar and radial deviation.40 Although detection of a normal dorsal SLL on US virtually excludes the presence of scapholunate instability, nonvisualization does not imply instability. Lunotriquetral Ligament Tear
FIG 11. A 43-year-old woman with longstanding RhA who developed symptoms of CTS. Axial US carpal tunnel demonstrates enlarged median nerve (arrow) with synovial thickening flexor synovial sheath with prominent flow within on power Doppler. Symptoms of CTS relieved posttreatment synovitis. (Color version of figure is available online.)
sensation, or a decreased range of motion. Clinical examination may demonstrate a positive load test or direct tenderness, which may also represent ulnar abutment or chondromalacia of the hamate. Palmer classification for TFC tears divides TFC injuries into traumatic and degenerative with subdivision by location.40,41 In general TFC traumatic tears, if peripheral have a good blood supply and can be repaired. The central avascular region requires debridement. Pathology affecting the triangular fibrocartilage complex includes triangle fibrocartilage partial/fullthickness tears; detachment and degeneration; extensor carpi ulnaris tenosynovitis/subluxation; ulnar collateral; and radioulnar ligament tears. TFC tears appear as loss of the homogeneous echotexture and triangular structural appearance, absence of a portion of the structure (Fig 13), hypoechoic clefts, or linear clefts/cysts.9,11 Thickness measurements of TFC have been proposed for detecting tears11; however, this is unreliable.40,42 Although US has high specificity for detecting TFC tears, the sensitivity is low.9 Radialsided tears are difficult to visualize on US. SLL Tear Tear of the dorsal SLL is diagnosed on US if the normal hyperechoic fibrillar structure of the ligament becomes hypoechoic, discontinuous or is absent (Fig 14),12 or in the presence of concurrent fluid or associated ganglion.9 More stringent criteria for diagnosing dorsal SLL tear on US include actual demonstration of the torn fragments and unilateral diastasis on dynamic scanning.41 No predictable
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Injury of the LTL is uncommon compared with scapholunate instability. US criteria used to diagnose SLL tears are applied for LTL tears as well (Fig 15).9 US has high specificity and positive predictive value, but poor sensitivity and negative-predictive value for diagnosing dorsal LTL tears.9 Extensor carpi radialis (ECR) tendon lies normally in the ulnar styloid groove. A subluxing ECU may be felt as a palpable snap with wrist flexed in ulnar deviation. Abnormal subluxation may occur in wrist flexion and ulnar deviation. The ECR is also a common site for tenosynovitis. Flat and convex grooves in the distal ulna predispose to ECU subluxation.42 Abnormal motion of the ECU should be sought for during supination and pronation.15
Proliferative Synovitis US is a very sensitive imaging technique for the detection of synovial hypertrophy. This is one of the indications for US that is rapidly increasing as synovial proliferation can be detected in its early stages. Careful assessment of the joint is required from volar and dorsal surfaces including synovial recesses, which may also contain synechia and pannus at the site of an articular bare area as in RA. US is useful in differentiating joint effusion from proliferative synovitis. Graded compression is used in distinguishing fluid from proliferative synovitis.43 While joint fluid is predominantly hypoechoic and is displaceable with pressure from the transducer, synovitis is hypoechoic to surrounding tissue and is deformable but not displaceable with pressure.41,43 Proliferative synovitis in the wrist can distend the joint and elevate the volar and dorsal aspects of the capsule and give a pseudotumoral appearance (Fig 15A).43 Doppler US is used to differentiate between fibrous and active pannus. Increased flow on Doppler is seen in active synovitis (Fig 16). The gain on color Doppler should be adjusted until artifactual signal from bone cortices disappears. Vascularity on Doppler US has been shown to have good correlation with inflammatory activity in RA.44 The differential diagnosis of proliferative synovitis in-
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FIG 12. A 65-year-old man with proven schwannoma of the ulnar nerve in the Guyon’s canal. Transverse US image (A) shows normal Guyon’s canal with ulnar nerve (UN) and relationship to ulnar artery (UA) and flexor carpi ulnaris (FCU). (B) A well-defined, hypoechoic soft-tissue mass with posterior acoustic enhancement (white arrow), lateral to the pisiform (P) with internal vascularity on Doppler (not shown).
FIG 13. A 45-year-old man with TFC tear of right wrist confirmed on MR arthrogram (not shown). Longitudinal ultrasound of the symptomatic right wrist at the level of the TFC demonstrates focal decreased echogenicity (arrow) in keeping with absence of a portion of the structure. Compare with the normal echogenic TFC (Fig 4). TQM ⫽ triquetrum; DU ⫽ distal ulna.
FIG 14. A 42-year-old man with dorsal SLL tear of the left wrist confirmed on arthrogram (not shown). Transverse image dorsal left wrist shows the absent SLL and fluid in the scapholunate space (arrows). Compare with the normal SLL with compact fibrillar echotexture (Fig 6A).
FIG 15. LTL tear confirmed on arthrogram with contrast injected into the midcarpal joint space (not shown). Transverse images (A and B) at the level of the lunate (L) and triquetral (T) bones show the tear of the LTL with disruption of the normal hyperechoic linear structure and fluid filling the interval (arrows in A and B).
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FIG 16. A 41-year-old woman with RA. Longitudinal images (A and B) through the mid dorsum of the wrist show proliferative synovitis/pannus as hypoechoic, soft tissue (curved arrow in B), and distension of the dorsal recess of the joint (straight arrow). Power Doppler shows flow in the pannus (A) indicating active synovitis.
FIG 17. A 26-year-old woman with RA. Longitudinal image shows multiple small erosions (white arrows) medial to the border of the distal ulna. Curved arrow points to the ECU with distension sheath with hypoechoic soft tissue in keeping with tenosynovitis.
cludes RA, septic arthritis, crystal-induced arthropathies, amyloid arthropathy, pigmented villonodular synovitis, synovial osteochondromatosis, and hemophilic arthropathy. Erosions Nearly 50% of patients with RA may develop erosions within 1 year of onset of disease.45 In RA affecting the wrist joint, the distal ulna (Fig 17), lunate, and the triquetrum are common sites for erosions.41 In early RA, US depicts erosions reliably and demonstrates more erosions than conventional radiographs.46 Erosions appear as interruption or defect of cortex with irregular margins.
Masses Ganglion cysts are the commonest benign softtissue tumor of the wrist (50-70%).34 It is composed of a mucin-filled, fibrous-lined cyst. Hippocrates
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initially described it as “knots of tissue containing mucoid flesh.” The etiology is unknown but is postulated to be secondary to microtrauma, producing hyaluronic acid at the synovial– capsular interface with secondary production of mucin lakes that coalesce to form a ganglion. It is commoner in women and between the ages 10 and 40 years. Symptoms vary from a painless mass to pressure on adjacent structures. Symptoms may also be related to associated pathologies such as scapholunate ligament tears. US helps to confirm the clinical diagnosis.47On US, ganglion cysts are usually noncompressible anechoic well-defined lesions with posterior acoustic enhancement (Fig 18). Occasionally, they may be multiloculated and contain debris. Careful assessment is required to identify the tract to an adjacent joint or tendon sheath. The dorsal aspect of the wrist, adjacent to scapholunate ligament (60-70%), is the commonest location but may also occur on the volar aspect of the wrist adjacent to radioscaphoid, scaphotrapezial or pisotriquetral joint (20%), and volar retinaculum between A1 and A2 pulleys (10%). Less common sites include the carpal tunnel, Guyon canal, CMCJ, and extensor tendon compartment. Giant cell tumor of the tendon sheath is the second commonest benign soft-tissue mass in the wrist. First described by Chassignac in 1852, it is an extraarticular localized form of pigmented villonodular synovitis. Typically, it occurs between the ages of 20 and 40 years, being more common in women. Etiology is unknown but is likely a reactive hyperplasia secondary to an inflammatory process. Clinically, patients
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FIG 18. A 40-year-old woman with dorsal wrist ganglion. Axial ultrasound dorsal aspect wrist of a well-defined heterogeneous hypoechoic mass pre- (A) and post- (B) compression. No flow on power Doppler, associated with a scapholunate tear (not shown). (C) Pathological specimen. (Color version of figure is available online.)
FIG 19. Giant cell tumor: Sagittal ultrasound of the volar wrist in a 24-year-old man presenting with mild swelling and hand discomfort for 1 year. US demonstrates localized tendon sheath distension with soft tissue. Mild internal flow noted on power Doppler (not shown). Remaining flexor tendon sheaths were normal. Confirmed on pathology as giant cell tumor flexor tendon sheath.
usually present with a slow-growing lobulated painless soft-tissue mass on the volar surface of the hand and wrist. Degenerative changes at a local joint may be
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related. Satellite lesions are a common cause of recurrence. On US, it appears as a solid, hypoechoic, lobulated soft-tissue mass with well-defined margins partly or completely surrounding a tendon that otherwise appears normal (Fig 19).48 There is a lack of acoustic enhancement posteriorly and internal vascularity is seen on Doppler.48 Occasionally, giant cell tumor may cause pressure erosion of the underlying bone. Vascular Lesions A hemangioma is a heterogeneous, hypoechoic mass on US. It may contain hyperechoic foci with posterior shadowing, which can be confirmed on radiographs as pheboliths. It is partially compressible and demonstrates increased internal flow on Doppler with compression, features that suggest the diagnosis (Fig 20).14
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FIG 20. Hemangioma: Well-defined soft-tissue lesion presenting as an asymptomatic soft-tissue mass on the volar aspect of the wrist in a 19-year-old man. (A) On US lesion (arrow) is inhomogenous iso/ hyperechoic, partially compressible (B), with increased internal flow on color Doppler with compression (C). No pheboliths are identified within lesion. Confirmed on pathology as a hemangioma. (Color version of figure is available online.) FIG 22. Synovial osteochondromatosis (SO): A 39-year-old woman with primary SO of the flexor digitorum tendon sheaths extending to the DRUJ. Lat and AP DRUJ (A) with corresponding axial ultrasound image (B), demonstrating multiple ossified bodies, hyperechoic with posterior shadowing, within the tendon sheaths with synovial proliferation, hyperechoic soft tissue surrounding the tendons (arrows).
FIG 21. Myxoma: Axial ultrasound volar wrist, radial aspect, in a 59-year-old woman presenting with a non-tender soft-tissue mass (arrow) of heterogeneous echogenicity with displacement of the radial artery over its volar surface, shown as vascular flow on power Doppler. Ultrasound imaging features are of a nonspecific soft-tissue mass.
Pseudoaneurysms of the radial artery can occur following blunt or penetrating trauma, and US can show the relationship of the mass to the main vessel.
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Juxtaarticular myxoma is a rare solid, benign, softtissue mass of connective tissue origin that may occur at any age but is most common in the fifth and six decades and slightly more common in women. Virchow in 1871 noted the tumor’s gelatinous nature resembled Wharton’s jelly of the umbilical cord and coined the term myxoma. Intramuscular (cardiac and skeletal), subcutaneous, and soft tissues, bone, periosteum, and genitourinary tract are sites of occurrence. Occasionally, it is associated with fibrous dysplasia and is known as Mazabraud’s syndrome. On US, it is a well-defined hypoechoic mass, which may have small cystic spaces within (Fig 21).
Synovial Osteochondromatosis Synovial osteochondromatosis (SOC) may be primary or secondary. Primary SOC is a benign synovial
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FIG 23. Foreign body: Sagittal wrist, volar aspect, adult male with 8 ⫻ 2 mm splinter of wood embedded in the soft tissues noted on ultrasound as a well-defined linear focus of hyperechogenicity, surrounded by a hypoechoic soft-tissue rim secondary to foreign body reaction.
metaplasia of unknown etiology resulting in the formation of multiple chondral (chondromatosis) or osteochondral nodules (osteochondromatosis). Secondary SOC occurs in joints affected by arthritis and usually contains less intra-articular bodies, which are of varying sizes. Symptoms are directly related to the stability of the intra-articular bodies. On US, a joint effusion is common with well-defined intra-articular mass/masses with posterior acoustic shadowing (Fig 22). Stability can be assessed with dynamic movement of the joint in an attempt to displace the bodies. Synovial hypertrophy is identified as hyperechoic villous projections floating in the joint effusion.49
Foreign Bodies US is extremely sensitive in the detection of softtissue foreign bodies and is the first-line investigation if bodies are radiolucent, such as wood. Foreign bodies (FB) are echogenic initially but some such as wood become less echogenic with time (Fig 23). Artifacts deep to the FB can aid in identification and include reverberation and shadowing. Acutely, a hypoechoic inflammatory reaction surrounds the FB and may alter the sonographic appearance.1,50 US is ideally suited to assessment of injury to the surrounding soft tissues. In addition, the site of the FB can be marked for retrieval.
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Conclusion The clinical presentation of wrist pain can be due to a wide variety of pathology, including abnormalities of regional bones, joints, and soft-tissue structures. US can assist in determining the specific cause for wrist pain, along with assessment of important regional anatomical relationships. US is a readily accessible valuable diagnostic tool and we strongly advocate its role as a primary imaging modality.
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