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Classic signs in head and neck imaging
Clinical Radiology xxx (2016) e1ee12
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Pictorial Review
Classic signs in head and neck imagingq N.A. Koontz a, b, *, T.A. Seltman a, S.F. Kralik a, K.M. Mosier a, H.R. Harnsberger b a
Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 550 North University Blvd, Rm 0663, Indianapolis, IN 46202, USA b Department of Radiology, University of Utah Health Sciences Center, 30 North 1900 East #1A071, Salt Lake City, UT 84132-2140, USA
art icl e i nformat ion Article history: Received 9 July 2016 Received in revised form 9 July 2016 Accepted 8 September 2016
Radiologists have long relied upon the use of metaphoric imaging signs to attribute meaning to disease or anatomy-specific imaging patterns encountered in clinical imaging. Teachers of radiology often employ the use of such signs to help learners rapidly identify the typical appearance of various pathologies. Head and neck (H&N) imaging is no exception, and as a specialty that deals with uncommon pathologies and complex anatomy, learners and practising radiologists alike may benefit from this simplistic, pattern-based approach. In this review, we present a compendium of classic imaging signs of H&N lesions, including signs related to traumatic, infectious, neoplastic, congenital, and inflammatory aetiologies found throughout the spectrum of H&N sites (temporal bones, orbits, paranasal sinuses, larynx, salivary glands, and neck soft tissues). Additionally, we identify potential pitfalls and detail critical clinical ramifications related to the rapid and accurate diagnosis of these pathologies. Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Radiologists have long relied upon the use of metaphoric imaging signs to attribute meaning to disease or anatomyspecific imaging patterns encountered in clinical practice. Dating back to 1918, when Crane first reported the “inverted comma” sign1 on pulmonary radiographs, radiologists have taken advantage of fortuitous similarities between certain imaging findings and the appearance of common daily objects or patterns to rapidly recall certain diagnoses, thus q This manuscript was presented, in part, as an accepted electronic educational exhibit at the American Society of Head and Neck Radiology 49th Annual Meeting, Naples, Florida in September 2015.
* Guarantor and correspondent: N. A. Koontz, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 550 North University Blvd, Rm 0663, Indianapolis, IN 46202, USA. Tel.: þ1 (317) 963 7195; fax: þ1 (317) 715 6474. E-mail address: [email protected] (N.A. Koontz).
harnessing man’s innate ability to extract pattern information from a visual stimulus and rapidly match it to a specific, finite entity recalled from memory. Such instantaneous processing of pattern-based visual cues to decipher a specific, pathognomonic entity is often referred to in the medical community as the “Aunt Minnie” phenomenon.2,3 Although its mechanism is not well understood, it may have roots in the Gestalt theory of perception and hold significance for radiology learners.4,5 Due to the complex anatomy and uncommon pathologies encountered in clinical practice, head and neck (H&N) imaging has historically been viewed with trepidation by learners, who may benefit from a simplified, pattern-based approach to learning. As such, we propose that both radiology trainees and practising radiologists may be greatly aided by familiarity with several imaging signs that have been attributed to H&N lesions. In this review, we present a compendium of these classic imaging signs, highlight the
http://dx.doi.org/10.1016/j.crad.2016.09.006 0009-9260/Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
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salient imaging findings, identify potential pitfalls, and detail important clinical ramifications. Images were retrospectively obtained through review of the electronic medical records and picture archiving and communication system (PACS), maintaining compliance with the Health Insurance Portability and Accountability Act (HIPAA) and policies of the institutional review boards at the authors’ institutions. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. All photos and artwork are courtesy of the authors’ personal collections or open-source internet collections.
the temporal bones, vestibular schwannomas may resemble an “ice-cream cone” with the bulbous extension of tumour within the cerebellopontine angle (CPA) resembling the icecream sitting upon a cone of tumour within the internal auditory canal (IAC; Fig 2). Vestibular schwannomas are the most common mass involving the CPA and IAC,11 as well as the most common mass accounting for sensorineural hearing loss.12 The vast majority of vestibular schwannomas are unilateral and sporadic, but the presence of bilateral vestibular schwannomas is essentially pathognomonic for neurofibromatosis type 2 (NF2).13
Temporal bones
“Corkscrew cochlea” sign of X-linked stapes gusher
“Broken heart” and “Y” signs of incudomalleolar disarticulation Trauma, typically blunt injury, may result in disarticulation of the incudomalleolar joint, which manifests as subtle joint widening and lateral displacement of the incus.6,7 Patients present with conductive hearing loss on the affected side. While this can be seen in the axial plane, conspicuity of the finding is increased when viewed in coronal reconstruction (Fig 1), which has previously described as the “Y” sign in the earenoseethroat (ENT) literature8 and by the pithy moniker of the “broken heart” sign by neuroradiologists.9 Incudomalleolar disarticulation has been reported as the one of the most common ossicular chain injuries,6,7 thus multiplanar imaging is advised to scrutinise for subtle incudomalleolar disarticulation.
“Ice-cream cone” sign of vestibular schwannoma Schwannomas are a commonly encountered nerve sheath tumour, which grow eccentric to the nerve of origin.10 On high-resolution magnetic resonance imaging (MRI) of
X-linked stapes gusher is a rare congenital aetiology for mixed conductive and profound sensorineural hearing loss due to POU3F4 gene mutation.14 At temporal bone computed tomography (CT), these patients demonstrate a characteristic “corkscrew” configuration of the cochlea (Fig 3) due to absence of the interscalar septum and modiolus, as well as a bulbous configuration of the lateral internal auditory canal with deficient lamina cribrosa.15 This allows communication between subarachnoid cerebrospinal fluid (CSF) and cochlear perilymph, which may result in a perilympheCSF gusher and perilymph fistula if stapedectomy or cochleostomy is attempted.
Orbits “Tram-track” sign of optic nerve sheath meningioma Optic nerve sheath meningiomas are the most common tumour of the optic nerve sheath, but only account for around 2% of orbital tumours.16,17 At MRI, they characteristically demonstrate linear, often parallel enhancement along the periphery of the nerve sheath due to spread of
Figure 1 “Broken Heart” and “Y” signs of incudomalleolar disarticulation. (a) Coronal non-contrast enhanced CT shows widening of the incudomalleolar joint (white solid arrow) with lateral displacement of the short process of the incus (white open arrow) relative to the head of the malleus (white arrowhead). (b) This configuration of the ossicles observed on coronal CT has been likened to the appearance of a “broken heart” or “Y”. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 2 “Ice-cream cone” sign of vestibular schwannoma. (a) Axial T1 SPGR post-contrast image shows an avidly enhancing mass (white solid arrow) extending from the CPA to the fundus of the IAC. (b) When large enough, vestibular schwannomas viewed in the axial plane resemble an “ice-cream cone” with the bulbous extension of tumour in the CPA resembling the ice-cream sitting upon a cone of tumour in the IAC.
Figure 3 “Corkscrew cochlea” sign of X-linked stapes gusher. (a) Axial non-contrast CT of the temporal bones demonstrates an abnormal morphology of the cochlea (white solid arrow) with absent interscalar septum and modiolus, as well as a bulbous configuration of the lateral internal auditory canal (white open arrow). (b) This abnormal cochlear configuration resembles a corkscrew and is typical of X-linked stapes gusher.
tumour in a vector paralleling the sheath18; however, the “tram-track” pattern of enhancement on MRI is not specific to optic nerve sheath meningioma, and similar enhancement can also be seen with idiopathic orbital inflammatory disease, optic neuritis, orbital sarcoidosis, lymphoproliferative disease, ErdheimeChester, and uncommonly with metastases.19 Although MRI is the preferred imaging technique, CT is complimentary and may demonstrate “tram-track” calcification specific to meningioma, confirming the diagnosis20 (Fig 4).
incomplete regression of the embryonic ocular blood supply, resulting in leukocoria, impaired vision, microphthalmia, and retinal detachment.21e23 At MRI, this manifests as abnormal, triangular-shaped retrolenticular tissue that resembles a “martini glass” (Fig 5). PHPV lacks calcification often seen in retinoblastoma, which can be a helpful discriminator.24
“Martini glass” sign of persistent hyperplastic primary vitreous
“Convoluted cerebriform pattern” of inverted papilloma
Persistent hyperplastic primary vitreous (PHPV) is a congenital developmental malformation of the eye due to
Paranasal sinuses
Inverted papilloma is an uncommon benign epithelial tumour of the sinonasal tract.25 At MRI, they demonstrate a characteristic gently lobulate morphology resembling the
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Figure 4 “Tram-track” sign of optic nerve sheath meningioma. (a) Axial post-contrast T1-weighted fat-saturated image shows parallel linear enhancement along the orbital segment of the optic nerve sheath (white solid arrows), which resembles the parallel orientation of light rail or train tracks (Powell/Hyde cable car line, San Francisco, California). This pattern of enhancement is sensitive, but not specific for optic nerve sheath meningioma. (b) Non-contrast enhanced CT reveals “tram-track” calcification of the optic nerve sheath (white open arrows), which, in comparison, is highly specific for meningioma.
Figure 5 “Martini glass” sign of PHPV. (a) Axial fat-saturated T2-weighted image demonstrates a small right globe with abnormal triangularshaped retrolenticular soft tissue (white open arrow) in a child with PHPV. (b) This configuration of the retrolenticular soft tissue resembles the shape of a martini glass.
gyral and sulcal pattern of the brain (Fig 6). This “convoluted cerebriform pattern” has a reported sensitivity of 100% and specificity of 87% for diagnosing inverted papilloma, and focal loss of this pattern within an inverted papilloma may signal the presence of a coexistent malignancy.25 Despite a benign histopathology, inverted papilloma is locally aggressive with high rate of recurrence, multicentricity, and can have coexistent squamous cell carcinoma.26,27 Most commonly found at the lateral nasal wall near the middle turbinate and maxillary ostium, inverted papilloma can also be found within the paranasal sinuses.25,28
commonly seen in adolescent males, patients present with painless nasal blockage and epistaxis. On imaging, including cross-sectional and radiographs, anterior bowing of the posterior wall of the maxillary antrum may be observed, the so-called “bow” or “antral” signs30 (Fig 7). Radiologists must keep in mind that this sign is only indicative of a relatively slow-growing mass that results in osseous remodelling of the posterior wall of the maxillary sinus, thus it is not specific for JNA. Differential considerations include sinonasal polyp, nerve sheath tumour, adenoid hypertrophy, lymphoma, and rhabdomyosarcoma.
“Bow” and “antral” signs of juvenile nasopharyngeal angiofibroma
“Black turbinate” sign of invasive fungal sinusitis
Juvenile nasopharyngeal angiofibroma (JNA) is a rare, benign neoplasm thought to originate from a vascular nidus in the posterolateral wall of the nasal cavity at the sphenopalatine foramen margin or the pterygoid canal.29 Most
Invasive fungal sinusitis is a potentially fatal, rapidly progressive transmucosal sinus infection that occurs in immunocompromised patients with neutropenia, including diabetics with functional neutropenia.31,32 The nasal cavity is typically the primary site of infection, involving the middle
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Figure 6 “Convoluted cerebriform pattern” of inverted papilloma. (a) Axial T1 SPGR post-contrast image demonstrates a large, heterogeneously enhancing mass (white solid arrow) centred in the right frontal sinus. (b) This lobular morphology with repetitive curvilinear striations resembles the surface topography of the brain and is specific for inverted papilloma.
Figure 7 “Bow” sign of JNA. (a) Axial CT of the paranasal sinuses demonstrates a large soft-tissue mass (white solid arrow) expanding the right pterygopalatine fossa and extending into the nasal cavity via a widened sphenopalatine foramen (white arrowhead). Note relatively benign remodelling of the posterior wall of the maxillary sinus (white open arrow). (b) This pattern of anterior displacement of the antrum resembles the shape of a bow and is suggestive of JNA or other slow-growing retroantral mass.
turbinate in approximately two-thirds of patients.33 Transmucosal hyphal invasion results in vascular compromise, yielding tissue infarction and dry gangrene, which corresponds with areas of loss of contrast enhancement in the sinonasal mucosa, which ordinarily enhances avidly. The socalled “black turbinate” sign identifies areas of invaded nonviable mucosa, which correspond to the black eschar seen on endoscopy (Fig 8). Due to the significant morbidity and mortality, this is truly a “can’t miss” diagnosis.
Larynx
nucleus in the medulla to the recurrent laryngeal nerve may result in vocal cord paralysis. Aetiologies are sundry, including trauma, neoplasm, ischaemia, iatrogenic, toxic, and idiopathic causes.34 At CT, patients with vocal cord paralysis reliably demonstrate dilatation of the ipsilateral pyriform sinus, medialisation, and thickening of the ipsilateral aryepiglottic fold, and dilatation of the ipsilateral laryngeal ventricle, the latter resembling the appearance of a flying spinnaker sail34 (Fig 9). When encountered on imaging, vocal cord paralysis must be considered pathological and warrants an exhaustive search for inciting causes.35
“Spinnaker sail” sign of vocal cord paralysis
“Thumb” sign of epiglottitis
The vocal cords receive innervation from the vagus nerve, and a lesion injuring it anywhere from the origin
Epiglottitis is a critical diagnosis that radiologists must be able to diagnose rapidly and accurately, as life-
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Figure 8 “Black turbinate” sign of invasive fungal sinusitis. (a) Axial fat-saturated contrast-enhanced T1-weighted image in a diabetic patient with facial pain demonstrates loss of mucosal contrast enhancement of the left middle turbinate (white open arrow) and medial wall of the left maxillary sinus, which corresponds with the black eschar of necrotic tissue (b) observed on nasal endoscopy (image courtesy of Richard H. Wiggins, III, MD, University of Utah Health Sciences Center). Normally, the mucosa of the nasal cavity and paranasal sinuses should enhance avidly (white solid arrows) and in neutropenic or functionally neutropenic patients, areas of loss of contrast enhancement are highly concerning for invasive fungal sinusitis.
Figure 9 “Spinnaker sail” sign of vocal cord paralysis. (a) Axial contrast-enhanced CT of the neck in a young man with left vocal cord paralysis due to an upper mediastinal mass demonstrates marked dilatation of the ipsilateral laryngeal ventricle (white solid arrow), which resembles the appearance of a flying spinnaker sail (b). In this case, the spinnaker sails are the striped sails.
threatening airway compromise is possible.36 On lateral radiographs of the neck, epiglottitis manifests as soft-tissue swelling of the supraglottic larynx with the epiglottis resembling a “thumb” in approximately 80% of cases37 (Fig 10). Patients present with high fever, sore throat, and difficulty swallowing, which may manifest as drooling in children.38 It may occur at any age with its prevalence increasing in adults.36,39 Most commonly due to Haemophilus influenza type B (Hib), other causes, including group A beta-haemolytic streptococci are on the rise, likely related to widespread Hib vaccine use.40
“Steeple” and “wine bottle” signs of laryngotracheobronchitis Laryngotracheobronchitis (i.e., croup) is a viral airway infection affecting children between the age of 6 months and 3 years, usually due to parainfluenza or respiratory syncytial virus.41,42 Typically self-limited, patients exhibit a stereotypical “barking” cough and inspiratory stridor.43 Frontal radiographs demonstrate narrowing of the lateral convexities of the subglottic larynx and trachea due to subglottic oedema, which resembles the shape of a “steeple” or “wine
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Figure 10 “Thumb” sign of epiglottitis. (a) Lateral radiograph of the soft tissues of the neck in a child with fever and sore throat demonstrates thickening and enlargement of the epiglottis (white open arrow). (b) The appearance of the oedematous epiglottis resembles a thumb and heralds an emergent finding.
bottle”44 (Fig 11). Radiologists must be aware that false positives can occur if expiratory films are obtained.
Salivary glands “Panda” sign of sarcoidosis Sarcoidosis is a chronic granulomatous disease commonly resulting in reactive cervical adenopathy, but also demonstrating symmetric involvement of the salivary and lacrimal glands in approximately 80% of patients.45 Patients with sarcoidosis may demonstrate increased radiotracer activity symmetrically in the lacrimal and parotid glands, as well as avid physiological uptake in the nasopharynx on gallium-67 scintigraphy, an appearance that has been likened to the dark facial markings of a giant
panda46 (Fig 12). Although the “panda” sign is most commonly seen with sarcoidosis, less common aetiologies of symmetric accumulation of radiotracer within the lacrimal and salivary glands also include lymphoma post€ gren’s syndrome, and human immuradiation therapy, Sjo nodeficiency virus (HIV).46
Neck soft tissues “Target” sign of neurofibroma Neurofibromas are typically benign nerve sheath tumours that arise central to the nerve of origin.10 When viewed in cross-section on MRI, they commonly demonstrate concentric dark and bright T2 signal intensity resembling a “target” (Fig 13). This “target” sign is highly
Figure 11 “Steeple” and “wine bottle” signs of laryngotracheobronchitis. (a) Anteroposterior radiograph of the neck in a child with cough and fever demonstrates narrowing of the lateral convexities of the subglottic larynx and upper trachea (white open arrow) due to subglottic oedema from croup. (b) This appearance resembles the silhouette of a steeple or wine bottle. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 12 “Panda” sign of sarcoidosis. (a) Gallium-67 scintigraphy demonstrates abnormal symmetric radiotracer uptake in the parotid (white solid arrow) and lacrimal glands (black solid arrow), as well as avid physiological activity in the nasopharynx (white arrowhead). (b) This pattern of radiotracer uptake resembles the facial markings of the giant panda and is most typically associated with sarcoidosis, although several other less common aetiologies can demonstrate this pattern.
Figure 13 “Target” sign of neurofibroma. (a) Axial T2-weighted image demonstrates a heterogeneously hyperintense extradural mass extending into the left C2eC3 neuroforamen, which shows concentric rings of signal intensity (white solid arrow). (b) This cross-sectional appearance resembles a “target” and is a characteristic, but not pathognomonic finding of neurofibromas. (c) Coronal short tau inversion recovery (STIR) in a child with NF1 demonstrates numerous “target” signs (white open arrows) in a plexiform neurofibroma of the right face.
suggestive of neurofibromas,47,48 but can also be encountered in schwannomas with areas of intramural cyst or high Antoni B content49 and malignant peripheral nerve sheath tumours.47 The vast majority of neurofibromas are sporadic with only about 10% associated with neurofibromatosis type 1 (NF1).50 The “target” sign can also be seen in the setting of plexiform neurofibromas (Fig 13), which are encountered in approximately 30% of NF1 patients and are pathognomonic for NF1 if present.51 It is critical to keep in mind that approximately 5% of patients with NF1 will develop a malignant peripheral nerve sheath tumour at some point during life, which necessitates vigilant surveillance.52
“Salt and pepper” sign of paraganglioma Paragangliomas are vascular masses of chemoreceptor cells found within the carotid space in the H&N. Paragangliomas of the H&N most commonly present a slowgrowing, painless, pulsatile carotid space mass,53 typically
lacking the “pain, pallor, palpitations, and perspiration” phenomena seen with paragangliomas elsewhere in the body.54 Paragangliomas within the middle ear, jugular foramen, and carotid space are avidly enhancing with pathognomonic speckled MRI signal intensity resembling “salt and pepper”55,56 (Fig 14). The black “pepper” corresponds to prominent flow voids, often seen at the periphery of the mass and best appreciated on T2-weighted imaging.56 The white “salt” corresponds to slow flow or subacute haemorrhage seen on non-contrast T1-weighted imaging.56 In a minority of cases, paragangliomas are multiple and can be seen in the setting of several syndromes, including succinate dehydrogenase deficiency, multiple endocrine neoplasia type 2, von HippeleLindau, and NF1.57e59
“Lyre” sign of carotid body tumour Due to characteristic splaying of the internal carotid artery (pushed posterolateral) and external carotid artery
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Figure 14 “Salt and pepper” sign of paraganglioma. (a) Axial non-contrast enhanced T1-weighted image demonstrates a circumscribed mass (white arrowhead) splaying the internal and external carotid arteries and demonstrating a speckled appearance with foci of intrinsic bright T1 signal (white open arrows). (b) Axial T2-weighted imaging shows the mass (white arrowhead) to have areas of peripheral dark T2 signal (white solid arrows). (c) This pattern has been likened to the appearance of “salt and pepper” and is pathognomonic for paraganglioma.
(pushed anteromedial), the angiographic appearance of a carotid body tumour has been likened to the shape of a lyre (Fig 15).60 As with other paragangliomas, carotid body tumours demonstrate the typical “salt and pepper” appearance on MRI.
“Tiger stripe” sign of non-suppurative tonsillopharyngitis Non-suppurative tonsillopharyngitis is an acute infection-related inflammation of the tonsils and pharynx that is frequently encountered in children and young adults.61 Most commonly due to respiratory viral infection, at least one-third of cases are bacterial, most commonly group A b-haemolytic streptococci.62 On contrast-enhanced CT imaging of the neck, patients demonstrate enlargement and hyperenhancement of the nasopharyngeal, palatine, and base of tongue lymphoid tissue with subjacent tonsillar oedema, which results in a
striated pattern resembling the striped coat of a tiger (Fig 16). Progression of non-suppurative tonsillopharyngitis to abscess or mediastinitis can occur, but is extremely rare.63 When the “tiger stripe” sign is identified, it essentially excludes a concurrent intratonsillar abscess.
“Kissing carotids” sign of medialised internal carotid arteries A medialised course of the internal carotid arteries is a benign, normal anatomical variant commonly encountered by H&N imagers. When the carotid arteries approximate at the midline they are referred to as “kissing carotids” (Fig 17). Although this is typically an incidental finding, it may uncommonly manifest as a pulsatile retropharyngeal mass and mimic a submucosal mass on fluoroscopy.64 Although most commonly encountered in the neck, often
Figure 15 “Lyre” sign of carotid body tumour. (a) Lateral digital subtraction angiography image demonstrates a hypervascular mass (white solid arrow) located at the carotid bifurcation (black solid arrow). (b) Characteristic splaying of the internal carotid artery (white open arrow) and external carotid artery (white arrowhead) by a paraganglioma of the carotid body resembles the lyre, a harp-like instrument of classic Greek antiquity. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 16 “Tiger stripe” sign of non-suppurative tonsillopharyngitis. (a) Coronal contrast-enhanced CT image demonstrates enlargement of the palatine tonsils, which are hyperaemic and show a striated pattern of enhancement (white open arrows). (b) This pattern of enhancement resembles the striped coat of a tiger and when present usually excludes the diagnosis of tonsillar abscess.
Figure 17 “Kissing carotids” sign of medialised course of the internal carotid arteries. (a) Axial contrast-enhanced CT image shows a markedly medialised course of the internal carotid arteries, which nearly contact at midline (white open arrow). (b) The close proximity of the carotids has been described as resembling the kissing embrace of lovers (Unconditional Surrender sculpture, San Diego, California). Although typically an incidental finding, a medialised course of the internal carotid arteries may place them at increased risk of iatrogenic injury during surgery or instrumentation.
at the level of the oropharynx, intracranial “kissing carotids” can occur within the sphenoid sinus, sphenoid bone, or sella.65 Due to the risk for vascular injury during routine surgical procedures or instrumentation, this finding warrants mention on staging CT or MRI of pharyngeal or intracranial malignancy to prevent iatrogenic injury.66,67
Conclusion Radiology learners and practising radiologists alike may benefit from familiarity with classic imaging signs of H&N imaging. This simplified, pattern-based approach allows for rapid recognition of complex and critical pathologies,
several of which may result in poor patient outcomes if the diagnosis is not made correctly or in a timely manner.
References 1. Crane AW. Inverted comma sign in pulmonary roentgenology. AJR Am J Roentgenol 1918;5:124e8. 2. Cunningham AS, Blatt SD, Fuller PG, et al. The art of precepting: Socrates or Aunt Minnie? Arch Pediatr Adolesc Med 1999;153(2):114e6. 3. Johnson EW. The “Aunt Minnie” abilitydrevisited. Am J Phys Med Rehabil 1999;78(4):305. 4. Koontz NA, Gunderman RB. Gestalt theory: implications for radiology education. AJR Am J Roentgenol 2008;190(5):1156e60. 5. Hall FM, Griscom NT. Gestalt: radiology’s aunt Minnie. AJR Am J Roentgenol 2008;191(4):1272.
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N.A. Koontz et al. / Clinical Radiology xxx (2016) e1ee12 6. Yetiser S, Hidir Y, Birkent H, et al. Traumatic ossicular dislocations: etiology and management. Am J Otolaryngol 2008;29(1):31e6. 7. Meriot P, Veillon F, Garcia JF, et al. CT appearances of ossicular injuries. RadioGraphics 1997;17(6):1445e54. 8. Lourenco MT, Yeakley JW, Ghorayeb BY. The “Y” sign of lateral dislocation of the incus. Am J Otol 1995;16(3):387e92. 9. Pierson NS, Wiggins RH. Don’t break my heart: a new sign of subtle malleoincudal ossicular dislocation. In: American Society of Head and Neck Radiology 48th Annual Meeting, Seattle, Washington; 2014. 10. Koontz NA, Wiens AL, Agarwal A, et al. Schwannomatosis: the overlooked neurofibromatosis? AJR Am J Roentgenol 2013;200(6):W646e53. 11. Moffat DA, Ballagh RH. Rare tumours of the cerebellopontine angle. Clin Oncol 1995;7(1):28e41. 12. Oh JH, Chung JH, Min HJ, et al. Clinical application of 3D-FIESTA image in patients with unilateral inner ear symptom. Korean J Audiol 2013;17(3):111e7. 13. Baser ME, Friedman JM, Wallace AJ, et al. Evaluation of clinical diagnostic criteria for neurofibromatosis 2. Neurology 2002;59(11):1759e65. 14. de Kok YJ, van der Maarel SM, Bitner-Glindzicz M, et al. Association between X-linked mixed deafness and mutations in the POU domain gene POU3F4. Science 1995;267(5198):685e8. 15. Phelps PD, Reardon W, Pembrey M, et al. X-linked deafness, stapes gushers and a distinctive defect of the inner ear. Neuroradiology 1991;33(4):326e30. 16. Eddleman CS, Liu JK. Optic nerve sheath meningioma: current diagnosis and treatment. Neurosurg Focus 2007;23(5):E4. 17. Miller NR. Primary tumours of the optic nerve and its sheath. Eye 2004;18(11):1026e37. 18. Hendrix LE, Kneeland JB, Haughton VM, et al. MR imaging of optic nerve lesions: value of gadopentetate dimeglumine and fat-suppression technique. AJNR Am J Neuroradiol 1990;11(4):749e54. 19. Kanamalla US. The optic nerve tram-track sign. Radiology 2003;227(3):718e9. 20. Ortiz O, Schochet SS, Kotzan JM, et al. Radiologic-pathologic correlation: meningioma of the optic nerve sheath. AJNR Am J Neuroradiol 1996;17(5):901e6. 21. Smirniotopoulos JG, Bargallo N, Mafee MF. Differential diagnosis of leukokoria: radiologic-pathologic correlation. RadioGraphics 1994;14(5):1059e79. quiz 1081e1052. 22. Kuker W, Ramaekers V. Persistent hyperplastic primary vitreous: MRI. Neuroradiology 1999;41(7):520e2. 23. Sun MH, Kao LY, Kuo YH. Persistent hyperplastic primary vitreous: magnetic resonance imaging and clinical findings. Chang Gung Med J 2003;26(4):269e76. 24. Edward DP, Mafee MF, Garcia-Valenzuela E, et al. Coats’ disease and persistent hyperplastic primary vitreous. Role of MR imaging and CT. Radiol Clin N Am 1998;36(6):1119e31. x. 25. Jeon TY, Kim HJ, Chung SK, et al. Sinonasal inverted papilloma: value of convoluted cerebriform pattern on MR imaging. AJNR Am J Neuroradiol 2008;29(8):1556e60. 26. Melroy CT, Senior BA. Benign sinonasal neoplasms: a focus on inverting papilloma. Otolaryngol Clin N Am 2006;39(3):601e17. x. 27. Hyams VJ. Papillomas of the nasal cavity and paranasal sinuses. A clinicopathological study of 315 cases. Ann Otol Rhinol Laryngol 1971;80(2):192e206. 28. Lesperance MM, Esclamado RM. Squamous cell carcinoma arising in inverted papilloma. Laryngoscope 1995;105(2):178e83. 29. Mishra S, Praveena NM, Panigrahi RG, et al. Imaging in the diagnosis of juvenile nasopharyngeal angiofibroma. J Clin Imaging Sci 2013;3(Suppl. 1):1. 30. Maurice M, Milad M. Pathogenesis of juvenile nasopharyngeal fibroma. (A new concept). J Laryngol Otol 1981;95(11):1121e6. 31. Safder S, Carpenter JS, Roberts TD, et al. The “black turbinate” sign: an early MR imaging finding of nasal mucormycosis. AJNR Am J Neuroradiol 2010;31(4):771e4. 32. Aribandi M, McCoy VA, Bazan 3rd C. Imaging features of invasive and noninvasive fungal sinusitis: a review. RadioGraphics 2007;27(5):1283e96. 33. Parikh SL, Venkatraman G, DelGaudio JM. Invasive fungal sinusitis: a 15year review from a single institution. Am J Rhinol 2004;18(2):75e81. 34. Chin SC, Edelstein S, Chen CY, et al. Using CT to localize side and level of vocal cord paralysis. AJR Am J Roentgenol 2003;180(4):1165e70.
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35. Richardson BE, Bastian RW. Clinical evaluation of vocal fold paralysis. Otolaryngol Clin N Am 2004;37(1):45e58. 36. Abdallah C. Acute epiglottitis: trends, diagnosis and management. Saudi J Anaesth 2012;6(3):279e81. 37. Chan KO, Pang YT, Tan KK. Acute epiglottitis in the tropics: is it an adult disease? J Laryngol Otol 2001;115(9):715e8. 38. Tibballs J, Watson T. Symptoms and signs differentiating croup and epiglottitis. J Paediatr Child Health 2011;47(3):77e82. 39. Shah RK, Stocks C. Epiglottitis in the United States: national trends, variances, prognosis, and management. Laryngoscope 2010;120(6):1256e62. 40. Mathoera RB, Wever PC, van Dorsten FR, et al. Epiglottitis in the adult patient. Neth J Med 2008;66(9):373e7. 41. Everard ML. Acute bronchiolitis and croup. Pediatr Clin N Am 2009;56(1):119e33. xexi. 42. Denny FW, Murphy TF, Clyde Jr WA, et al. Croup: an 11-year study in a pediatric practice. Pediatrics 1983;71(6):871e6. 43. Bjornson CL, Johnson DW. Croup in the paediatric emergency department. Paediatr Child Health 2007;12(6):473e7. 44. Salour M. The steeple sign. Radiology 2000;216(2):428e9. 45. Sulavik SB, Spencer RP, Weed DA, et al. Recognition of distinctive patterns of gallium-67 distribution in sarcoidosis. J Nuclear Med 1990;31(12):1909e14. 46. Kurdziel KA. The panda sign. Radiology 2000;215(3):884e5. 47. Bhargava R, Parham DM, Lasater OE, et al. MR imaging differentiation of benign and malignant peripheral nerve sheath tumors: use of the target sign. Pediatr Radiol 1997;27(2):124e9. 48. Jee WH, Oh SN, McCauley T, et al. Extraaxial neurofibromas versus neurilemmomas: discrimination with MRI. AJR Am J Roentgenol 2004;183(3):629e33. 49. Wippold 2nd FJ, Lubner M, Perrin RJ, et al. Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns. AJNR Am J Neuroradiol 2007;28(9):1633e8. 50. Kim DH, Murovic JA, Tiel RL, et al. A series of 397 peripheral neural sheath tumors: 30-year experience at Louisiana State University Health Sciences Center. J Neurosurg 2005;102(2):246e55. 51. Hassell DS, Bancroft LW, Kransdorf MJ, et al. Imaging appearance of diffuse neurofibroma. AJR Am J Roentgenol 2008;190(3):582e8. 52. Ferrari A, Bisogno G, Carli M. Management of childhood malignant peripheral nerve sheath tumor. Paediatric Drugs 2007;9(4):239e48. 53. Davidovic LB, Djukic VB, Vasic DM, et al. Diagnosis and treatment of carotid body paraganglioma: 21 years of experience at a clinical center of Serbia. W J Surg Oncol 2005;3(1):10. 54. Erickson D, Kudva YC, Ebersold MJ, et al. Benign paragangliomas: clinical presentation and treatment outcomes in 236 patients. J Clin Endocrinol Metab 2001;86(11):5210e6. 55. Elsayes KM, Narra VR, Leyendecker JR, et al. MRI of adrenal and extraadrenal pheochromocytoma. AJR Am J Roentgenol 2005;184(3):860e7. 56. Olsen WL, Dillon WP, Kelly WM, et al. MR imaging of paragangliomas. AJR Am J Roentgenol 1987;148(1):201e4. 57. Benn DE, Gimenez-Roqueplo AP, Reilly JR, et al. Clinical presentation and penetrance of pheochromocytoma/paraganglioma syndromes. J Clin Endocrinol Metab 2006;91(3):827e36. 58. Boedeker CC, Erlic Z, Richard S, et al. Head and neck paragangliomas in von Hippel-Lindau disease and multiple endocrine neoplasia type 2. J Clin Endocrinol Metab 2009;94(6):1938e44. 59. Bausch B, Borozdin W, Neumann HP. EuropeaneAmerican Pheochromocytoma Study G. Clinical and genetic characteristics of patients with neurofibromatosis type 1 and pheochromocytoma. N Engl J Med 2006;354(25):2729e31. 60. Venkatanarasimha N, Olubaniyi B, Freeman SJ, et al. Usual and unusual causes of splaying of the carotid artery bifurcation: the Lyre signda pictorial review. Emerg Radiol 2011;18(1):75e9. 61. Tewfik TL, Al Garni M. Tonsillopharyngitis: clinical highlights. J Otolaryngol 2005;34(Suppl. 1):S45e9. 62. Brook I, Dohar JE. Management of group A beta-hemolytic streptococcal pharyngotonsillitis in children. J Fam Pract 2006;55(12):S1e11. quiz S12. 63. Bell Z, Menezes AA, Primrose WJ, et al. Mediastinitis: a life-threatening complication of acute tonsillitis. J Laryngol Otol 2005;119(9):743e5.
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64. Jackel M. [Anatomic variants of the internal carotid artery as differential parapharyngeal space-occupying lesions diagnosis]. Hno 1997;45(12):1018e21. 65. Pereira Filho Ade A, Gobbato PL, Pereira Filho Gde A, et al. Intracranial intrasellar kissing carotid arteries: case report. Arq Neuropsiquiatr 2007;65(2A):355e7.
66. Marcucci C, Thomas P, Sewell DA. Retropharyngeal carotid artery: an important anatomic variation for the anesthesiologist. Anesthesiology 2009;111(2):454e5. 67. Ozgur Z, Celik S, Govsa F, et al. A study of the course of the internal carotid artery in the parapharyngeal space and its clinical importance. Eur Arch Oto-rhino-laryngol 2007;264(12):1483e9.
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Pictorial Review
Classic signs in head and neck imagingq N.A. Koontz a, b, *, T.A. Seltman a, S.F. Kralik a, K.M. Mosier a, H.R. Harnsberger b a
Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 550 North University Blvd, Rm 0663, Indianapolis, IN 46202, USA b Department of Radiology, University of Utah Health Sciences Center, 30 North 1900 East #1A071, Salt Lake City, UT 84132-2140, USA
art icl e i nformat ion Article history: Received 9 July 2016 Received in revised form 9 July 2016 Accepted 8 September 2016
Radiologists have long relied upon the use of metaphoric imaging signs to attribute meaning to disease or anatomy-specific imaging patterns encountered in clinical imaging. Teachers of radiology often employ the use of such signs to help learners rapidly identify the typical appearance of various pathologies. Head and neck (H&N) imaging is no exception, and as a specialty that deals with uncommon pathologies and complex anatomy, learners and practising radiologists alike may benefit from this simplistic, pattern-based approach. In this review, we present a compendium of classic imaging signs of H&N lesions, including signs related to traumatic, infectious, neoplastic, congenital, and inflammatory aetiologies found throughout the spectrum of H&N sites (temporal bones, orbits, paranasal sinuses, larynx, salivary glands, and neck soft tissues). Additionally, we identify potential pitfalls and detail critical clinical ramifications related to the rapid and accurate diagnosis of these pathologies. Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Radiologists have long relied upon the use of metaphoric imaging signs to attribute meaning to disease or anatomyspecific imaging patterns encountered in clinical practice. Dating back to 1918, when Crane first reported the “inverted comma” sign1 on pulmonary radiographs, radiologists have taken advantage of fortuitous similarities between certain imaging findings and the appearance of common daily objects or patterns to rapidly recall certain diagnoses, thus q This manuscript was presented, in part, as an accepted electronic educational exhibit at the American Society of Head and Neck Radiology 49th Annual Meeting, Naples, Florida in September 2015.
* Guarantor and correspondent: N. A. Koontz, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 550 North University Blvd, Rm 0663, Indianapolis, IN 46202, USA. Tel.: þ1 (317) 963 7195; fax: þ1 (317) 715 6474. E-mail address: [email protected] (N.A. Koontz).
harnessing man’s innate ability to extract pattern information from a visual stimulus and rapidly match it to a specific, finite entity recalled from memory. Such instantaneous processing of pattern-based visual cues to decipher a specific, pathognomonic entity is often referred to in the medical community as the “Aunt Minnie” phenomenon.2,3 Although its mechanism is not well understood, it may have roots in the Gestalt theory of perception and hold significance for radiology learners.4,5 Due to the complex anatomy and uncommon pathologies encountered in clinical practice, head and neck (H&N) imaging has historically been viewed with trepidation by learners, who may benefit from a simplified, pattern-based approach to learning. As such, we propose that both radiology trainees and practising radiologists may be greatly aided by familiarity with several imaging signs that have been attributed to H&N lesions. In this review, we present a compendium of these classic imaging signs, highlight the
http://dx.doi.org/10.1016/j.crad.2016.09.006 0009-9260/Ó 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
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salient imaging findings, identify potential pitfalls, and detail important clinical ramifications. Images were retrospectively obtained through review of the electronic medical records and picture archiving and communication system (PACS), maintaining compliance with the Health Insurance Portability and Accountability Act (HIPAA) and policies of the institutional review boards at the authors’ institutions. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. All photos and artwork are courtesy of the authors’ personal collections or open-source internet collections.
the temporal bones, vestibular schwannomas may resemble an “ice-cream cone” with the bulbous extension of tumour within the cerebellopontine angle (CPA) resembling the icecream sitting upon a cone of tumour within the internal auditory canal (IAC; Fig 2). Vestibular schwannomas are the most common mass involving the CPA and IAC,11 as well as the most common mass accounting for sensorineural hearing loss.12 The vast majority of vestibular schwannomas are unilateral and sporadic, but the presence of bilateral vestibular schwannomas is essentially pathognomonic for neurofibromatosis type 2 (NF2).13
Temporal bones
“Corkscrew cochlea” sign of X-linked stapes gusher
“Broken heart” and “Y” signs of incudomalleolar disarticulation Trauma, typically blunt injury, may result in disarticulation of the incudomalleolar joint, which manifests as subtle joint widening and lateral displacement of the incus.6,7 Patients present with conductive hearing loss on the affected side. While this can be seen in the axial plane, conspicuity of the finding is increased when viewed in coronal reconstruction (Fig 1), which has previously described as the “Y” sign in the earenoseethroat (ENT) literature8 and by the pithy moniker of the “broken heart” sign by neuroradiologists.9 Incudomalleolar disarticulation has been reported as the one of the most common ossicular chain injuries,6,7 thus multiplanar imaging is advised to scrutinise for subtle incudomalleolar disarticulation.
“Ice-cream cone” sign of vestibular schwannoma Schwannomas are a commonly encountered nerve sheath tumour, which grow eccentric to the nerve of origin.10 On high-resolution magnetic resonance imaging (MRI) of
X-linked stapes gusher is a rare congenital aetiology for mixed conductive and profound sensorineural hearing loss due to POU3F4 gene mutation.14 At temporal bone computed tomography (CT), these patients demonstrate a characteristic “corkscrew” configuration of the cochlea (Fig 3) due to absence of the interscalar septum and modiolus, as well as a bulbous configuration of the lateral internal auditory canal with deficient lamina cribrosa.15 This allows communication between subarachnoid cerebrospinal fluid (CSF) and cochlear perilymph, which may result in a perilympheCSF gusher and perilymph fistula if stapedectomy or cochleostomy is attempted.
Orbits “Tram-track” sign of optic nerve sheath meningioma Optic nerve sheath meningiomas are the most common tumour of the optic nerve sheath, but only account for around 2% of orbital tumours.16,17 At MRI, they characteristically demonstrate linear, often parallel enhancement along the periphery of the nerve sheath due to spread of
Figure 1 “Broken Heart” and “Y” signs of incudomalleolar disarticulation. (a) Coronal non-contrast enhanced CT shows widening of the incudomalleolar joint (white solid arrow) with lateral displacement of the short process of the incus (white open arrow) relative to the head of the malleus (white arrowhead). (b) This configuration of the ossicles observed on coronal CT has been likened to the appearance of a “broken heart” or “Y”. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 2 “Ice-cream cone” sign of vestibular schwannoma. (a) Axial T1 SPGR post-contrast image shows an avidly enhancing mass (white solid arrow) extending from the CPA to the fundus of the IAC. (b) When large enough, vestibular schwannomas viewed in the axial plane resemble an “ice-cream cone” with the bulbous extension of tumour in the CPA resembling the ice-cream sitting upon a cone of tumour in the IAC.
Figure 3 “Corkscrew cochlea” sign of X-linked stapes gusher. (a) Axial non-contrast CT of the temporal bones demonstrates an abnormal morphology of the cochlea (white solid arrow) with absent interscalar septum and modiolus, as well as a bulbous configuration of the lateral internal auditory canal (white open arrow). (b) This abnormal cochlear configuration resembles a corkscrew and is typical of X-linked stapes gusher.
tumour in a vector paralleling the sheath18; however, the “tram-track” pattern of enhancement on MRI is not specific to optic nerve sheath meningioma, and similar enhancement can also be seen with idiopathic orbital inflammatory disease, optic neuritis, orbital sarcoidosis, lymphoproliferative disease, ErdheimeChester, and uncommonly with metastases.19 Although MRI is the preferred imaging technique, CT is complimentary and may demonstrate “tram-track” calcification specific to meningioma, confirming the diagnosis20 (Fig 4).
incomplete regression of the embryonic ocular blood supply, resulting in leukocoria, impaired vision, microphthalmia, and retinal detachment.21e23 At MRI, this manifests as abnormal, triangular-shaped retrolenticular tissue that resembles a “martini glass” (Fig 5). PHPV lacks calcification often seen in retinoblastoma, which can be a helpful discriminator.24
“Martini glass” sign of persistent hyperplastic primary vitreous
“Convoluted cerebriform pattern” of inverted papilloma
Persistent hyperplastic primary vitreous (PHPV) is a congenital developmental malformation of the eye due to
Paranasal sinuses
Inverted papilloma is an uncommon benign epithelial tumour of the sinonasal tract.25 At MRI, they demonstrate a characteristic gently lobulate morphology resembling the
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Figure 4 “Tram-track” sign of optic nerve sheath meningioma. (a) Axial post-contrast T1-weighted fat-saturated image shows parallel linear enhancement along the orbital segment of the optic nerve sheath (white solid arrows), which resembles the parallel orientation of light rail or train tracks (Powell/Hyde cable car line, San Francisco, California). This pattern of enhancement is sensitive, but not specific for optic nerve sheath meningioma. (b) Non-contrast enhanced CT reveals “tram-track” calcification of the optic nerve sheath (white open arrows), which, in comparison, is highly specific for meningioma.
Figure 5 “Martini glass” sign of PHPV. (a) Axial fat-saturated T2-weighted image demonstrates a small right globe with abnormal triangularshaped retrolenticular soft tissue (white open arrow) in a child with PHPV. (b) This configuration of the retrolenticular soft tissue resembles the shape of a martini glass.
gyral and sulcal pattern of the brain (Fig 6). This “convoluted cerebriform pattern” has a reported sensitivity of 100% and specificity of 87% for diagnosing inverted papilloma, and focal loss of this pattern within an inverted papilloma may signal the presence of a coexistent malignancy.25 Despite a benign histopathology, inverted papilloma is locally aggressive with high rate of recurrence, multicentricity, and can have coexistent squamous cell carcinoma.26,27 Most commonly found at the lateral nasal wall near the middle turbinate and maxillary ostium, inverted papilloma can also be found within the paranasal sinuses.25,28
commonly seen in adolescent males, patients present with painless nasal blockage and epistaxis. On imaging, including cross-sectional and radiographs, anterior bowing of the posterior wall of the maxillary antrum may be observed, the so-called “bow” or “antral” signs30 (Fig 7). Radiologists must keep in mind that this sign is only indicative of a relatively slow-growing mass that results in osseous remodelling of the posterior wall of the maxillary sinus, thus it is not specific for JNA. Differential considerations include sinonasal polyp, nerve sheath tumour, adenoid hypertrophy, lymphoma, and rhabdomyosarcoma.
“Bow” and “antral” signs of juvenile nasopharyngeal angiofibroma
“Black turbinate” sign of invasive fungal sinusitis
Juvenile nasopharyngeal angiofibroma (JNA) is a rare, benign neoplasm thought to originate from a vascular nidus in the posterolateral wall of the nasal cavity at the sphenopalatine foramen margin or the pterygoid canal.29 Most
Invasive fungal sinusitis is a potentially fatal, rapidly progressive transmucosal sinus infection that occurs in immunocompromised patients with neutropenia, including diabetics with functional neutropenia.31,32 The nasal cavity is typically the primary site of infection, involving the middle
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Figure 6 “Convoluted cerebriform pattern” of inverted papilloma. (a) Axial T1 SPGR post-contrast image demonstrates a large, heterogeneously enhancing mass (white solid arrow) centred in the right frontal sinus. (b) This lobular morphology with repetitive curvilinear striations resembles the surface topography of the brain and is specific for inverted papilloma.
Figure 7 “Bow” sign of JNA. (a) Axial CT of the paranasal sinuses demonstrates a large soft-tissue mass (white solid arrow) expanding the right pterygopalatine fossa and extending into the nasal cavity via a widened sphenopalatine foramen (white arrowhead). Note relatively benign remodelling of the posterior wall of the maxillary sinus (white open arrow). (b) This pattern of anterior displacement of the antrum resembles the shape of a bow and is suggestive of JNA or other slow-growing retroantral mass.
turbinate in approximately two-thirds of patients.33 Transmucosal hyphal invasion results in vascular compromise, yielding tissue infarction and dry gangrene, which corresponds with areas of loss of contrast enhancement in the sinonasal mucosa, which ordinarily enhances avidly. The socalled “black turbinate” sign identifies areas of invaded nonviable mucosa, which correspond to the black eschar seen on endoscopy (Fig 8). Due to the significant morbidity and mortality, this is truly a “can’t miss” diagnosis.
Larynx
nucleus in the medulla to the recurrent laryngeal nerve may result in vocal cord paralysis. Aetiologies are sundry, including trauma, neoplasm, ischaemia, iatrogenic, toxic, and idiopathic causes.34 At CT, patients with vocal cord paralysis reliably demonstrate dilatation of the ipsilateral pyriform sinus, medialisation, and thickening of the ipsilateral aryepiglottic fold, and dilatation of the ipsilateral laryngeal ventricle, the latter resembling the appearance of a flying spinnaker sail34 (Fig 9). When encountered on imaging, vocal cord paralysis must be considered pathological and warrants an exhaustive search for inciting causes.35
“Spinnaker sail” sign of vocal cord paralysis
“Thumb” sign of epiglottitis
The vocal cords receive innervation from the vagus nerve, and a lesion injuring it anywhere from the origin
Epiglottitis is a critical diagnosis that radiologists must be able to diagnose rapidly and accurately, as life-
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Figure 8 “Black turbinate” sign of invasive fungal sinusitis. (a) Axial fat-saturated contrast-enhanced T1-weighted image in a diabetic patient with facial pain demonstrates loss of mucosal contrast enhancement of the left middle turbinate (white open arrow) and medial wall of the left maxillary sinus, which corresponds with the black eschar of necrotic tissue (b) observed on nasal endoscopy (image courtesy of Richard H. Wiggins, III, MD, University of Utah Health Sciences Center). Normally, the mucosa of the nasal cavity and paranasal sinuses should enhance avidly (white solid arrows) and in neutropenic or functionally neutropenic patients, areas of loss of contrast enhancement are highly concerning for invasive fungal sinusitis.
Figure 9 “Spinnaker sail” sign of vocal cord paralysis. (a) Axial contrast-enhanced CT of the neck in a young man with left vocal cord paralysis due to an upper mediastinal mass demonstrates marked dilatation of the ipsilateral laryngeal ventricle (white solid arrow), which resembles the appearance of a flying spinnaker sail (b). In this case, the spinnaker sails are the striped sails.
threatening airway compromise is possible.36 On lateral radiographs of the neck, epiglottitis manifests as soft-tissue swelling of the supraglottic larynx with the epiglottis resembling a “thumb” in approximately 80% of cases37 (Fig 10). Patients present with high fever, sore throat, and difficulty swallowing, which may manifest as drooling in children.38 It may occur at any age with its prevalence increasing in adults.36,39 Most commonly due to Haemophilus influenza type B (Hib), other causes, including group A beta-haemolytic streptococci are on the rise, likely related to widespread Hib vaccine use.40
“Steeple” and “wine bottle” signs of laryngotracheobronchitis Laryngotracheobronchitis (i.e., croup) is a viral airway infection affecting children between the age of 6 months and 3 years, usually due to parainfluenza or respiratory syncytial virus.41,42 Typically self-limited, patients exhibit a stereotypical “barking” cough and inspiratory stridor.43 Frontal radiographs demonstrate narrowing of the lateral convexities of the subglottic larynx and trachea due to subglottic oedema, which resembles the shape of a “steeple” or “wine
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Figure 10 “Thumb” sign of epiglottitis. (a) Lateral radiograph of the soft tissues of the neck in a child with fever and sore throat demonstrates thickening and enlargement of the epiglottis (white open arrow). (b) The appearance of the oedematous epiglottis resembles a thumb and heralds an emergent finding.
bottle”44 (Fig 11). Radiologists must be aware that false positives can occur if expiratory films are obtained.
Salivary glands “Panda” sign of sarcoidosis Sarcoidosis is a chronic granulomatous disease commonly resulting in reactive cervical adenopathy, but also demonstrating symmetric involvement of the salivary and lacrimal glands in approximately 80% of patients.45 Patients with sarcoidosis may demonstrate increased radiotracer activity symmetrically in the lacrimal and parotid glands, as well as avid physiological uptake in the nasopharynx on gallium-67 scintigraphy, an appearance that has been likened to the dark facial markings of a giant
panda46 (Fig 12). Although the “panda” sign is most commonly seen with sarcoidosis, less common aetiologies of symmetric accumulation of radiotracer within the lacrimal and salivary glands also include lymphoma post€ gren’s syndrome, and human immuradiation therapy, Sjo nodeficiency virus (HIV).46
Neck soft tissues “Target” sign of neurofibroma Neurofibromas are typically benign nerve sheath tumours that arise central to the nerve of origin.10 When viewed in cross-section on MRI, they commonly demonstrate concentric dark and bright T2 signal intensity resembling a “target” (Fig 13). This “target” sign is highly
Figure 11 “Steeple” and “wine bottle” signs of laryngotracheobronchitis. (a) Anteroposterior radiograph of the neck in a child with cough and fever demonstrates narrowing of the lateral convexities of the subglottic larynx and upper trachea (white open arrow) due to subglottic oedema from croup. (b) This appearance resembles the silhouette of a steeple or wine bottle. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 12 “Panda” sign of sarcoidosis. (a) Gallium-67 scintigraphy demonstrates abnormal symmetric radiotracer uptake in the parotid (white solid arrow) and lacrimal glands (black solid arrow), as well as avid physiological activity in the nasopharynx (white arrowhead). (b) This pattern of radiotracer uptake resembles the facial markings of the giant panda and is most typically associated with sarcoidosis, although several other less common aetiologies can demonstrate this pattern.
Figure 13 “Target” sign of neurofibroma. (a) Axial T2-weighted image demonstrates a heterogeneously hyperintense extradural mass extending into the left C2eC3 neuroforamen, which shows concentric rings of signal intensity (white solid arrow). (b) This cross-sectional appearance resembles a “target” and is a characteristic, but not pathognomonic finding of neurofibromas. (c) Coronal short tau inversion recovery (STIR) in a child with NF1 demonstrates numerous “target” signs (white open arrows) in a plexiform neurofibroma of the right face.
suggestive of neurofibromas,47,48 but can also be encountered in schwannomas with areas of intramural cyst or high Antoni B content49 and malignant peripheral nerve sheath tumours.47 The vast majority of neurofibromas are sporadic with only about 10% associated with neurofibromatosis type 1 (NF1).50 The “target” sign can also be seen in the setting of plexiform neurofibromas (Fig 13), which are encountered in approximately 30% of NF1 patients and are pathognomonic for NF1 if present.51 It is critical to keep in mind that approximately 5% of patients with NF1 will develop a malignant peripheral nerve sheath tumour at some point during life, which necessitates vigilant surveillance.52
“Salt and pepper” sign of paraganglioma Paragangliomas are vascular masses of chemoreceptor cells found within the carotid space in the H&N. Paragangliomas of the H&N most commonly present a slowgrowing, painless, pulsatile carotid space mass,53 typically
lacking the “pain, pallor, palpitations, and perspiration” phenomena seen with paragangliomas elsewhere in the body.54 Paragangliomas within the middle ear, jugular foramen, and carotid space are avidly enhancing with pathognomonic speckled MRI signal intensity resembling “salt and pepper”55,56 (Fig 14). The black “pepper” corresponds to prominent flow voids, often seen at the periphery of the mass and best appreciated on T2-weighted imaging.56 The white “salt” corresponds to slow flow or subacute haemorrhage seen on non-contrast T1-weighted imaging.56 In a minority of cases, paragangliomas are multiple and can be seen in the setting of several syndromes, including succinate dehydrogenase deficiency, multiple endocrine neoplasia type 2, von HippeleLindau, and NF1.57e59
“Lyre” sign of carotid body tumour Due to characteristic splaying of the internal carotid artery (pushed posterolateral) and external carotid artery
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Figure 14 “Salt and pepper” sign of paraganglioma. (a) Axial non-contrast enhanced T1-weighted image demonstrates a circumscribed mass (white arrowhead) splaying the internal and external carotid arteries and demonstrating a speckled appearance with foci of intrinsic bright T1 signal (white open arrows). (b) Axial T2-weighted imaging shows the mass (white arrowhead) to have areas of peripheral dark T2 signal (white solid arrows). (c) This pattern has been likened to the appearance of “salt and pepper” and is pathognomonic for paraganglioma.
(pushed anteromedial), the angiographic appearance of a carotid body tumour has been likened to the shape of a lyre (Fig 15).60 As with other paragangliomas, carotid body tumours demonstrate the typical “salt and pepper” appearance on MRI.
“Tiger stripe” sign of non-suppurative tonsillopharyngitis Non-suppurative tonsillopharyngitis is an acute infection-related inflammation of the tonsils and pharynx that is frequently encountered in children and young adults.61 Most commonly due to respiratory viral infection, at least one-third of cases are bacterial, most commonly group A b-haemolytic streptococci.62 On contrast-enhanced CT imaging of the neck, patients demonstrate enlargement and hyperenhancement of the nasopharyngeal, palatine, and base of tongue lymphoid tissue with subjacent tonsillar oedema, which results in a
striated pattern resembling the striped coat of a tiger (Fig 16). Progression of non-suppurative tonsillopharyngitis to abscess or mediastinitis can occur, but is extremely rare.63 When the “tiger stripe” sign is identified, it essentially excludes a concurrent intratonsillar abscess.
“Kissing carotids” sign of medialised internal carotid arteries A medialised course of the internal carotid arteries is a benign, normal anatomical variant commonly encountered by H&N imagers. When the carotid arteries approximate at the midline they are referred to as “kissing carotids” (Fig 17). Although this is typically an incidental finding, it may uncommonly manifest as a pulsatile retropharyngeal mass and mimic a submucosal mass on fluoroscopy.64 Although most commonly encountered in the neck, often
Figure 15 “Lyre” sign of carotid body tumour. (a) Lateral digital subtraction angiography image demonstrates a hypervascular mass (white solid arrow) located at the carotid bifurcation (black solid arrow). (b) Characteristic splaying of the internal carotid artery (white open arrow) and external carotid artery (white arrowhead) by a paraganglioma of the carotid body resembles the lyre, a harp-like instrument of classic Greek antiquity. Please cite this article in press as: Koontz NA, et al., Classic signs in head and neck imaging, Clinical Radiology (2016), http://dx.doi.org/10.1016/ j.crad.2016.09.006
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Figure 16 “Tiger stripe” sign of non-suppurative tonsillopharyngitis. (a) Coronal contrast-enhanced CT image demonstrates enlargement of the palatine tonsils, which are hyperaemic and show a striated pattern of enhancement (white open arrows). (b) This pattern of enhancement resembles the striped coat of a tiger and when present usually excludes the diagnosis of tonsillar abscess.
Figure 17 “Kissing carotids” sign of medialised course of the internal carotid arteries. (a) Axial contrast-enhanced CT image shows a markedly medialised course of the internal carotid arteries, which nearly contact at midline (white open arrow). (b) The close proximity of the carotids has been described as resembling the kissing embrace of lovers (Unconditional Surrender sculpture, San Diego, California). Although typically an incidental finding, a medialised course of the internal carotid arteries may place them at increased risk of iatrogenic injury during surgery or instrumentation.
at the level of the oropharynx, intracranial “kissing carotids” can occur within the sphenoid sinus, sphenoid bone, or sella.65 Due to the risk for vascular injury during routine surgical procedures or instrumentation, this finding warrants mention on staging CT or MRI of pharyngeal or intracranial malignancy to prevent iatrogenic injury.66,67
Conclusion Radiology learners and practising radiologists alike may benefit from familiarity with classic imaging signs of H&N imaging. This simplified, pattern-based approach allows for rapid recognition of complex and critical pathologies,
several of which may result in poor patient outcomes if the diagnosis is not made correctly or in a timely manner.
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