- Email: [email protected]
Medical Imaging of Common Orthopedic Conditions in Childhood
Medical Imaging of Common Orthopedic Conditions in Childhood Elizabeth H. Ey, MD
History of Radiology in Medicine
istic effect is not observed. Over time, the early practitioners in radiation were observed to develop a ithin months of Conrad Roentgen’s publicavariety of cancers and to have a higher death rate tion of his discovery of the x-ray in late from cancer than the general population. By the 1896, fluoroscopy was in widespread use on 1950s, the biology of radiation effect and how to human subjects by practitioners with minimal trainminimize exposure with appropriate shielding of the ing. The ability to visualize the human anatomy x-ray tube, the patient, and the practitioner were beneath the skin surface without understood. Also, the developdisrupting the skin revolutionment of very sensitive image reized the practice of medicine. ceptors (such as film screen sysFluoroscopy was used to diagtems and the image intensifier in Information on radiation exposure to nose a variety of disorders, such fluoroscopy) allowed significant as fractures and bone deformi- children from medical radiation exposure reduction in radiation dose in ties, as well as to “treat” a variety is available to practitioners and families at medical imaging. The excess of conditions (Tinea capitis and www.etc. Smaller children and infants are death rate of radiologists in Great enlarged thymus in children). Britain decreased from 41% to more sensitive to ionizing radiation and Never in history had a new inno0% between 1954 and 1997.1 have a longer life expectancy in which to vation been used so widely on The effect of acute radiation see the effect of radiation exposure. the population with little underexposure on a large population standing of the potential risks has been extensively studied. involved. It was not long before The health and outcomes of reports of the deleterious effects 84,000 survivors of the 1945 of high radiation exposure to humans began to atomic bombs were followed for nearly 55 years. In appear. Shortly after patients were exposed to 2000, Pierce and Preston reported an increased lengthy fluoroscopic procedures (large, 1-time radicancer death rate in atomic bomb survivors who ation dose), they developed skin reddening, hair were exposed to low-dose radiation (0.05-0.15 Sv or loss, reddening of the eyes, and with large enough 50-150 mSv).2 The increased cancer death rate is an doses, skin ulcerations. Today, we know the dose example of the stochastic effect of radiation exporange for these effects is between 200 and 1500 rad sure. It is nonlinear and there is no lower limit (2-15 Sv or 2000-15,000 mSv). These effects are threshold below which the effect is not observed.2,3 now referred to as deterministic effects of radiation Currently, prolonged fluoroscopy during cardiac exposure. The onset and severity of the effect are in and interventional procedures and the widespread linear relationship to the amount of radiation expouse of computed tomography (CT) have become sure. Below a certain radiation dose, the determinrecognized as potential significant sources of radiation exposure to the population. The dose range From the Dayton Children’s Medical Center, Dayton, OH. from a single CT examination (depending on how it Curr Probl Pediatr Adolesc Health Care 2011;41:29-32 is performed) can overlap the lower range of radi1538-5442/$ - see front matter ation exposure observed in the atomic bomb survi© 2011 Mosby, Inc. All rights reserved. doi:10.1016/j.cppeds.2010.10.003 vors.2 An individual’s increased cancer death rate
W
Curr Probl Pediatr Adolesc Health Care, January 2011
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legs. Conventional radiography can be performed from a CT scan has been estimated at between 1 in with the patient in a scoliosis brace. Bone detail on 1000 and 1 in 5000 over a lifetime.4 To put this in CR is limited when a cast is in place. Radiation dose perspective, a male in the US would have an range: 0.015-1.5 mSv skin dose. increase in the risk of dying from cancer over his Ultrasound (US) uses no ionizlifetime after 1 CT scan from a ing radiation and is very useful baseline of 23.24% to a life time for evaluating the musculoskelerisk of dying from cancer of 5 tal system in children. No seda23.241%. The individual inConventional radiography is the most creased risk of cancer death is tion or IV contrast is required in widely available and most often used very small, but it is not zero. The US. Dynamic imaging of the inmodality for imaging in pediatric age of the individual at the time fant hip with US permits visualof radiation exposure is also very orthopedic conditions. It has relatively low ization of the unossified femoral important. Infants and young head and its relationship to the radiation dose, especially for the children are more sensitive to the acetabulum throughout the range extremities. effects of radiation and they have of motion. Soft tissue masses a longer life expectancy in which can be evaluated with US using to observe the effect.4 both grayscale imaging as well The Image Gently campaign is a recent collaboDoppler imaging for blood flow and vascularity. rative effort to raise awareness among patients, US is useful for evaluating the spinal canal and physicians, and practitioners in radiology of the risk spinal cord in infants for tethered cord or spinal of radiation exposure from medcanal extension of vascular malical imaging in children. Valuformations. able information for physicians Magnetic resonance imaging and families can be found at the (MR) also uses no ionizing radiUltrasound and magnetic resonance web site http://www.ImageGently. ation and provides the highest org. Significant progress has aldetail in anatomy of the soft imaging use no ionizing radiation and ready been made to raise awaretissues, such as muscles, tenhave ness of radiation risk in children dons, ligaments, articular cartithe highest anatomic detail for and what techniques can be used lage, and synovium. Although nonossified, to reduce medical radiation exnormal cortical bone provides no soft tissues. posure to children. signal in MR, edema from bone contusion or inflammation is well demonstrated on MR. The time required for MR imaging is Medical Imaging of much longer than other modaliPediatric Orthopedic ties and sedation is required Conditions CT has the highest dose of ionizing more frequently. IV gadoliniumConventional radiography (CR) radiation but provides the highest detail of based contrast is useful to evalucomplex bony structures. The radiation is the most frequently used and ate for tumor, tumor viability often the most appropriate form dose should be adjusted to accommodate after therapy, inflammation, inof imaging used in pediatric orfection (soft tissue abscess), hythe patient’s size. thopedic conditions. The radiaperemia, and vascular malformation exposure and cost are low. tions. Intra-articular gadolinium The examination is performed contrast is useful to evaluate for quickly and without sedation. Judicious use of labral tears in the hip and shoulder, for ligamentous patient immobilization and patient shielding is very and cartilage tears in the wrist, and to identify loose important in pediatric conventional radiography to bodies within a joint. MR is limited by metal artifact minimize radiation exposure to the young. The from pins and rods in the skeleton. MR of the spine effect of weight-bearing is useful when evaluating provides the highest detail of the spinal cord for scoliosis, congenital foot deformity, and bowed congenital anomalies and trauma.
30
Curr Probl Pediatr Adolesc Health Care, January 2011
Table 1. Medical imaging of pediatric orthopedic conditions
Indication
Recommended first study
Special instructions
Additional imaging if needed
Nonaccidental trauma Torticollis, congenital
Skeletal survey CR
Full 20 views according to AAP
NM bone scan if needed
Cervical spine CR
AP and lateral views
Torticollis, new onset with pain Torticollis, new onset, no pain or trauma Down syndrome prior to athletics Scoliosis, congenital
Cervical spine CR
AP and lateral views
Neck US for SCM fibromatosis CT neck with contrast for abscess/adenitis
Scoliosis, idiopathic
C spine CR-5 views Entire spine CR, AP and lat
Kyphosis Low back pain
Lumbar spine CR
Low back pain, radiculopathy Developmental hip dysplasia (breech, twin, family history) Hip pain, acute
Lumbar spine CR Hip US
AP, lat, odontoid, lateral in flexion, and extension Entire spine in 1 AP and 1 lateral view Upright AP, include iliac apophyses Upright, arms resting in front of patient AP, lat, and both oblique views AP, lat, and both oblique views Age at least 4 weeks and before 4 months for first study
Hips CR, AP, and frog lateral Hips CR, AP, and frog lateral Hips CR, AP, and frog lateral
1 view should include gonad shield 1 view should include gonad shield 1 view with gonad shield
Bowed legs, crooked legs Hemihypertrophy, BW syndrome Leg length inequality
CR lower extremities
AP standing lower extremities, patella forward
Joint, sports injury
Joint CR, at least 2 orthogonal views
Joint, synovitis
Joint CR, at least 2 orthogonal views Ankle CR; AP, lat, oblique views
Hip pain, acute with fever
Ankle fracture, Salter III or IV
MR C spine for anomaly
MR brain without and with IV contrast for tumor
Thoacolumbar spine CR, AP and lat views Thoracic spine, lateral view
Hip pain, recurrent
Other
MR C, T, L spine for anomaly
CT L spine L3-S1 for spondylolysis MR L spine no contrast for disc Hips, AP, and frog lateral
MR hips no contrast for AVN, SCFE US hips for effusion or MR hips without and with IV contrast
Follow up per protocol AP hips, knees, ankles with full length ruler MR joint no contrast for ligamentous or cartilage injury MR joint without and with IV contrast CT ankle no contrast for alignment at articular surface MR joint/bone without and with IV contrast
Osteomyelitis/cellulitis Joint or bone, CR
2 orthogonal views
Congenital foot deformity
Foot CR
AP and lat with forced dorsiflexion or forced plantar flexion
Foot, pain, tarsal coalition
Foot CR AP, lat, oblique views
MR foot, no contrast
Foot, high arch
Foot CR AP, lat, oblique
Foot, pain, possible infection or tumor Foot pain, overuse, or recurrent pain
Foot CR AP, lat, oblique views Foot CT AP, lat, oblique
MR spine without contrast for tethered cord/syrinx MR foot without and with IV contrast MR foot to confirm osteochondrosis
Curr Probl Pediatr Adolesc Health Care, January 2011
Can perform US with patient in Pavlik harness
US hip for effusion
US abdomen CR scanogram
Bone scan with SPECT lumbar area
CT foot also consideration for tarsal coalition
31
CT uses ionizing radiation to provide the highest detail of bony anatomy. CT scans are accomplished quickly and rarely require sedation; both are important in the acute trauma patient. 3D surface and multiplanar reconstructions are routinely acquired during CT and provide surface evaluation of the bone for deformity from trauma or congenital anomaly. CT can also be used to evaluate growth plate injuries while the extremity is still in a cast. IV contrast is useful to evaluate the position and integrity of vascular structures when evaluating for complicated fractures, tumors, and soft tissue abscesses associated with musculoskeletal infection. Intra-articular iodine-based contrast is useful to evaluate for loose bodies within a joint. Radiation dose range: 2-30 mSv. Nuclear medicine applications in pediatric orthopedic conditions include bone scan and positron-emission tomography scan. Bone scan is useful for localizing the source of pain in young children. Three-phase bone scan includes a vascular flow phase and a soft tissue blood pool image, which can be helpful in differentiating cellulitis from
32
osteomyelitis. MR is being used more frequently now to evaluate musculoskeletal infections. Single-photon emission computed tomography imaging with bone scan is useful to localize spondyloysis in a patient with persistent back pain. Radiation dose range: 4-5.3 millisieverts bone scan, 7-9 mSv PET scan (Table 1).
References 1. Berrington A, Darby SC, Weiss HA, Doll R. 100 years of observation on British radiologists: mortality from cancer and other causes 1897-1997. Br J Radiol 2001;74:507-19. 2. Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiat Res 2000;154: 178-86. 3. Evaluation of the Linear-Nonthreshold-Dose Response Model for Ionizing Radiation. The National Council on Radiation Protection and Measurements. Report No. 136 Available via http://NCRPpublications.org. 4. Brenner DJ. Estimating cancer risks from pediatric CT: going from qualitative to the quantitative. Pediatr Radiol 2002;32: 228-31. 5. The American Cancer Society. Cancer facts and figures 2010.
Curr Probl Pediatr Adolesc Health Care, January 2011
History of Radiology in Medicine
istic effect is not observed. Over time, the early practitioners in radiation were observed to develop a ithin months of Conrad Roentgen’s publicavariety of cancers and to have a higher death rate tion of his discovery of the x-ray in late from cancer than the general population. By the 1896, fluoroscopy was in widespread use on 1950s, the biology of radiation effect and how to human subjects by practitioners with minimal trainminimize exposure with appropriate shielding of the ing. The ability to visualize the human anatomy x-ray tube, the patient, and the practitioner were beneath the skin surface without understood. Also, the developdisrupting the skin revolutionment of very sensitive image reized the practice of medicine. ceptors (such as film screen sysFluoroscopy was used to diagtems and the image intensifier in Information on radiation exposure to nose a variety of disorders, such fluoroscopy) allowed significant as fractures and bone deformi- children from medical radiation exposure reduction in radiation dose in ties, as well as to “treat” a variety is available to practitioners and families at medical imaging. The excess of conditions (Tinea capitis and www.etc. Smaller children and infants are death rate of radiologists in Great enlarged thymus in children). Britain decreased from 41% to more sensitive to ionizing radiation and Never in history had a new inno0% between 1954 and 1997.1 have a longer life expectancy in which to vation been used so widely on The effect of acute radiation see the effect of radiation exposure. the population with little underexposure on a large population standing of the potential risks has been extensively studied. involved. It was not long before The health and outcomes of reports of the deleterious effects 84,000 survivors of the 1945 of high radiation exposure to humans began to atomic bombs were followed for nearly 55 years. In appear. Shortly after patients were exposed to 2000, Pierce and Preston reported an increased lengthy fluoroscopic procedures (large, 1-time radicancer death rate in atomic bomb survivors who ation dose), they developed skin reddening, hair were exposed to low-dose radiation (0.05-0.15 Sv or loss, reddening of the eyes, and with large enough 50-150 mSv).2 The increased cancer death rate is an doses, skin ulcerations. Today, we know the dose example of the stochastic effect of radiation exporange for these effects is between 200 and 1500 rad sure. It is nonlinear and there is no lower limit (2-15 Sv or 2000-15,000 mSv). These effects are threshold below which the effect is not observed.2,3 now referred to as deterministic effects of radiation Currently, prolonged fluoroscopy during cardiac exposure. The onset and severity of the effect are in and interventional procedures and the widespread linear relationship to the amount of radiation expouse of computed tomography (CT) have become sure. Below a certain radiation dose, the determinrecognized as potential significant sources of radiation exposure to the population. The dose range From the Dayton Children’s Medical Center, Dayton, OH. from a single CT examination (depending on how it Curr Probl Pediatr Adolesc Health Care 2011;41:29-32 is performed) can overlap the lower range of radi1538-5442/$ - see front matter ation exposure observed in the atomic bomb survi© 2011 Mosby, Inc. All rights reserved. doi:10.1016/j.cppeds.2010.10.003 vors.2 An individual’s increased cancer death rate
W
Curr Probl Pediatr Adolesc Health Care, January 2011
29
legs. Conventional radiography can be performed from a CT scan has been estimated at between 1 in with the patient in a scoliosis brace. Bone detail on 1000 and 1 in 5000 over a lifetime.4 To put this in CR is limited when a cast is in place. Radiation dose perspective, a male in the US would have an range: 0.015-1.5 mSv skin dose. increase in the risk of dying from cancer over his Ultrasound (US) uses no ionizlifetime after 1 CT scan from a ing radiation and is very useful baseline of 23.24% to a life time for evaluating the musculoskelerisk of dying from cancer of 5 tal system in children. No seda23.241%. The individual inConventional radiography is the most creased risk of cancer death is tion or IV contrast is required in widely available and most often used very small, but it is not zero. The US. Dynamic imaging of the inmodality for imaging in pediatric age of the individual at the time fant hip with US permits visualof radiation exposure is also very orthopedic conditions. It has relatively low ization of the unossified femoral important. Infants and young head and its relationship to the radiation dose, especially for the children are more sensitive to the acetabulum throughout the range extremities. effects of radiation and they have of motion. Soft tissue masses a longer life expectancy in which can be evaluated with US using to observe the effect.4 both grayscale imaging as well The Image Gently campaign is a recent collaboDoppler imaging for blood flow and vascularity. rative effort to raise awareness among patients, US is useful for evaluating the spinal canal and physicians, and practitioners in radiology of the risk spinal cord in infants for tethered cord or spinal of radiation exposure from medcanal extension of vascular malical imaging in children. Valuformations. able information for physicians Magnetic resonance imaging and families can be found at the (MR) also uses no ionizing radiUltrasound and magnetic resonance web site http://www.ImageGently. ation and provides the highest org. Significant progress has aldetail in anatomy of the soft imaging use no ionizing radiation and ready been made to raise awaretissues, such as muscles, tenhave ness of radiation risk in children dons, ligaments, articular cartithe highest anatomic detail for and what techniques can be used lage, and synovium. Although nonossified, to reduce medical radiation exnormal cortical bone provides no soft tissues. posure to children. signal in MR, edema from bone contusion or inflammation is well demonstrated on MR. The time required for MR imaging is Medical Imaging of much longer than other modaliPediatric Orthopedic ties and sedation is required Conditions CT has the highest dose of ionizing more frequently. IV gadoliniumConventional radiography (CR) radiation but provides the highest detail of based contrast is useful to evalucomplex bony structures. The radiation is the most frequently used and ate for tumor, tumor viability often the most appropriate form dose should be adjusted to accommodate after therapy, inflammation, inof imaging used in pediatric orfection (soft tissue abscess), hythe patient’s size. thopedic conditions. The radiaperemia, and vascular malformation exposure and cost are low. tions. Intra-articular gadolinium The examination is performed contrast is useful to evaluate for quickly and without sedation. Judicious use of labral tears in the hip and shoulder, for ligamentous patient immobilization and patient shielding is very and cartilage tears in the wrist, and to identify loose important in pediatric conventional radiography to bodies within a joint. MR is limited by metal artifact minimize radiation exposure to the young. The from pins and rods in the skeleton. MR of the spine effect of weight-bearing is useful when evaluating provides the highest detail of the spinal cord for scoliosis, congenital foot deformity, and bowed congenital anomalies and trauma.
30
Curr Probl Pediatr Adolesc Health Care, January 2011
Table 1. Medical imaging of pediatric orthopedic conditions
Indication
Recommended first study
Special instructions
Additional imaging if needed
Nonaccidental trauma Torticollis, congenital
Skeletal survey CR
Full 20 views according to AAP
NM bone scan if needed
Cervical spine CR
AP and lateral views
Torticollis, new onset with pain Torticollis, new onset, no pain or trauma Down syndrome prior to athletics Scoliosis, congenital
Cervical spine CR
AP and lateral views
Neck US for SCM fibromatosis CT neck with contrast for abscess/adenitis
Scoliosis, idiopathic
C spine CR-5 views Entire spine CR, AP and lat
Kyphosis Low back pain
Lumbar spine CR
Low back pain, radiculopathy Developmental hip dysplasia (breech, twin, family history) Hip pain, acute
Lumbar spine CR Hip US
AP, lat, odontoid, lateral in flexion, and extension Entire spine in 1 AP and 1 lateral view Upright AP, include iliac apophyses Upright, arms resting in front of patient AP, lat, and both oblique views AP, lat, and both oblique views Age at least 4 weeks and before 4 months for first study
Hips CR, AP, and frog lateral Hips CR, AP, and frog lateral Hips CR, AP, and frog lateral
1 view should include gonad shield 1 view should include gonad shield 1 view with gonad shield
Bowed legs, crooked legs Hemihypertrophy, BW syndrome Leg length inequality
CR lower extremities
AP standing lower extremities, patella forward
Joint, sports injury
Joint CR, at least 2 orthogonal views
Joint, synovitis
Joint CR, at least 2 orthogonal views Ankle CR; AP, lat, oblique views
Hip pain, acute with fever
Ankle fracture, Salter III or IV
MR C spine for anomaly
MR brain without and with IV contrast for tumor
Thoacolumbar spine CR, AP and lat views Thoracic spine, lateral view
Hip pain, recurrent
Other
MR C, T, L spine for anomaly
CT L spine L3-S1 for spondylolysis MR L spine no contrast for disc Hips, AP, and frog lateral
MR hips no contrast for AVN, SCFE US hips for effusion or MR hips without and with IV contrast
Follow up per protocol AP hips, knees, ankles with full length ruler MR joint no contrast for ligamentous or cartilage injury MR joint without and with IV contrast CT ankle no contrast for alignment at articular surface MR joint/bone without and with IV contrast
Osteomyelitis/cellulitis Joint or bone, CR
2 orthogonal views
Congenital foot deformity
Foot CR
AP and lat with forced dorsiflexion or forced plantar flexion
Foot, pain, tarsal coalition
Foot CR AP, lat, oblique views
MR foot, no contrast
Foot, high arch
Foot CR AP, lat, oblique
Foot, pain, possible infection or tumor Foot pain, overuse, or recurrent pain
Foot CR AP, lat, oblique views Foot CT AP, lat, oblique
MR spine without contrast for tethered cord/syrinx MR foot without and with IV contrast MR foot to confirm osteochondrosis
Curr Probl Pediatr Adolesc Health Care, January 2011
Can perform US with patient in Pavlik harness
US hip for effusion
US abdomen CR scanogram
Bone scan with SPECT lumbar area
CT foot also consideration for tarsal coalition
31
CT uses ionizing radiation to provide the highest detail of bony anatomy. CT scans are accomplished quickly and rarely require sedation; both are important in the acute trauma patient. 3D surface and multiplanar reconstructions are routinely acquired during CT and provide surface evaluation of the bone for deformity from trauma or congenital anomaly. CT can also be used to evaluate growth plate injuries while the extremity is still in a cast. IV contrast is useful to evaluate the position and integrity of vascular structures when evaluating for complicated fractures, tumors, and soft tissue abscesses associated with musculoskeletal infection. Intra-articular iodine-based contrast is useful to evaluate for loose bodies within a joint. Radiation dose range: 2-30 mSv. Nuclear medicine applications in pediatric orthopedic conditions include bone scan and positron-emission tomography scan. Bone scan is useful for localizing the source of pain in young children. Three-phase bone scan includes a vascular flow phase and a soft tissue blood pool image, which can be helpful in differentiating cellulitis from
32
osteomyelitis. MR is being used more frequently now to evaluate musculoskeletal infections. Single-photon emission computed tomography imaging with bone scan is useful to localize spondyloysis in a patient with persistent back pain. Radiation dose range: 4-5.3 millisieverts bone scan, 7-9 mSv PET scan (Table 1).
References 1. Berrington A, Darby SC, Weiss HA, Doll R. 100 years of observation on British radiologists: mortality from cancer and other causes 1897-1997. Br J Radiol 2001;74:507-19. 2. Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiat Res 2000;154: 178-86. 3. Evaluation of the Linear-Nonthreshold-Dose Response Model for Ionizing Radiation. The National Council on Radiation Protection and Measurements. Report No. 136 Available via http://NCRPpublications.org. 4. Brenner DJ. Estimating cancer risks from pediatric CT: going from qualitative to the quantitative. Pediatr Radiol 2002;32: 228-31. 5. The American Cancer Society. Cancer facts and figures 2010.
Curr Probl Pediatr Adolesc Health Care, January 2011