In-Training Examination for Diagnostic Radiology Residents Rationales

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1 28th Annual In-Training Examination for Diagnostic Radiology Residents Rationales Sponsored by: Commission on Education Committee on Residency Training in Diagnostic Radiology February 3, 2005 The American College of Radiology

headaches. What is the MOST likely diagnosis? A.

2 Figure 1A Figure 1B 35. You are shown axial T2 (Figure 1A) and post contrast axial (Figure 1B) and coronal (Figure 1C) T1-weighted images of a 39-year-old African-American woman with a long history of headaches. What is the MOST likely diagnosis? A. Viral encephalitis B. Cryptococcal meningitis C. Sarcoidosis D. Multiple sclerosis Figure 1C American College of Radiology

3 Question #35 Findings: There is nodular pachymeningeal enhancement involving the basilar meninges and the falx. This pattern is typical of granulomatous processes. A. Incorrect. This appears to be an extraaxial process with fairly marked enhancement. Encephalitis is an intraaxial process involving the brain parenchyma. This would also be an atypical distribution for viral encephalitis. B. Incorrect. While fungal meningitis would be a possible differential, there is little parenchymal involvement in this case. Cryptococcosis typically involves the perivascular spaces at the base of the brain, and there is little contrast enhancement. C. Correct. This is a case of sarcoidosis. Sarcoidosis and tuberculosis are both granulomatous processes with a similar imaging appearance in the brain. Contrast-enhanced scans reveal thick basilar meningeal enhancement. Chest x-ray (not shown) demonstrates classic bihilar adenopathy in this relatively asymptomatic patient. One of the hallmarks of sarcoidosis is a radiographic finding that is discordant from the clinical findings. Patients with tuberculous meningitis are frequently quite symptomatic. D. Incorrect. While multiple sclerosis may involve the cortex, it is uncommon and the degree of enhancement with no white matter abnormalities would make this a most unlikely diagnosis. Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994: Diagnostic In-Training Exam 2005

$What is the MOST likely diagnosis? A. Blowout fracture B. Maxillary sinusitis C. Neoplasm of the maxillary sinus D.$

4 Figure You are shown a coronal CT view of the face (Figure 2) in a 25-year-old man with eye pain. What is the MOST likely diagnosis? A. Blowout fracture B. Maxillary sinusitis C. Neoplasm of the maxillary sinus D. Orbital lipoma American College of Radiology

5 Question #36 Findings: There is a fracture of the right orbital floor, with downward protrusion of orbital fat, and swelling and rotation of the inferior rectus muscle. A. Correct. By definition, the floor or walls of the orbit are fractured and depressed with a blowout injury. This patient had a lack of right upward gaze due to edema or entrapment of the inferior rectus muscle. B. Incorrect. Buphthalmos is a congenital enlargement of the globe without significant osseous defects of the orbit. C. Incorrect. No destruction of bone is seen, and the mass arises from the orbit, not the maxilla. D. Incorrect. The fat in the maxilla is normal, but inferiorly depressed intraorbital fat. Lipomas of the orbit usually occur in the lacrimal gland. Grossman RI, Youssem DM, eds. Neuroradiology. Philadelphia, Pa: Elsevier, Inc; 2003: Diagnostic In-Training Exam 2005

What is the MOST likely diagnosis? A. Congenital hydrocephalus B.

6 Figure 3A Figure 3B 37. You are shown sagittal T1-weighted (Figure 3A), axial T2-weighted (Figure 3B) and axial FLAIR (Figure 3C) MR images in a newborn with questionable ventriculomegaly on prenatal ultrasound. What is the MOST likely diagnosis? A. Congenital hydrocephalus B. Hydranencephaly C. Dandy Walker malformation D. Agenesis of the corpus callosum Figure 3C American College of Radiology

7 Question #37 A. Incorrect. Though the occipital horns of the lateral ventricle are dilated, the frontal horns as well as the third ventricle are small. The ventricles have a parallel appearance. In congenital stenosis the third and lateral ventricles are enlarged. In this case no evidence of transependymal flow of CSF is apparent in the periventricular region on FLAIR, a finding frequently seen with hydrocephalus. B. Incorrect. Hydranencephaly has the appearance of absence of that part of the brain supplied by the anterior and middle cerebral arteries. The posterior circulation is spared. Clear evidence of the cortex in the frontal, temporal, and parietal regions is present in this case. C. Incorrect. Dandy-Walker malformations classically appear as partial or complete absence of the vermis with dilatation of the fourth ventricle in an enlarged posterior fossa with associated hydrocephalus. As is seen on the sagittal, the vermis is present and no fourth ventricular dilatation or posterior fossa enlargement is apparent. Many variations of Dandy-Walker exist though in all some malformation of the vermis is appreciated. D. Correct. Agenesis of the corpus callosum with absence of the splenium is what causes colpocephaly, dilatation of the occipital horns secondary to a decrease in white matter mass. Longitudinal Probst bundles running anterior to posterior are identified, as these are alternative white matter tracts when the corpus callosum is missing. The medial hemispheric sulci extend down to the third ventricle as a result of eversion of the cingulate gyrus and lack of formation of the cingulate sulcus. Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994: Diagnostic In-Training Exam 2005

8 Figure 4A Figure 4B Figure 4C Figure 4D American College of Radiology

9 38. You are shown axial FLAIR (Figure 4A), T2-weighted (Figure 4B), gadolinium-enhanced T1- weighted (Figure 4C), and diffusion-weighted (Figure 4D) MR images of the brain of an 18-yearold woman with a history of sinusitis and increasing headaches. What is the MOST likely diagnosis? A. Glioblastoma multiforme B. Abscess C. Epidermoid D. Recent infarction Question #38 Findings: The axial FLAIR and T2 images demonstrate edema and mass effect within the left frontal lobe. A thin rim enhances and the center of the mass is low on the T1 image and increased in signal on the FLAIR image but not to the degree of CSF. The DWI image exhibits restricted diffusion. A. Incorrect. Glioblastoma multiforme may have a necrotic nonenhancing center but with a thick, irregular rim. DWI uncommonly shows restricted diffusion. B. Correct. These findings are characteristic of pyogenic abscess, including a thin enhancing rim, low-signal rim with T2 weighting, and restricted diffusion. C. Incorrect. Epidermoid tumors are extraaxial in location. Their contents follow CSF in imaging with the exception of FLAIR, on which they tend to have slightly greater signal than CSF, and DWI, on which they exhibit restricted diffusion. The mixed signal on the T2 weighted image and parenchymal location as well as enhancing rim make answer C incorrect. D. Incorrect. Rim enhancement of this cystic or necrotic appearance lesion is inappropriate for infarction. High signal intensity with DWI does not always indicate ischemia. Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby; 1994: , Diagnostic In-Training Exam 2005

$Langerhans cell histiocytosis B. Traumatic compression fracture C.$

10 Figure 5A Figure 5B 39. You are shown sagittal T1-weighted (Figure 5A), T2-weighted (Figure 5B), and gadolinium-enhanced T1- weighted (Figure 5C) MR images of the thoracolumbar spine in a 17-month-old girl with back pain. What is the MOST likely diagnosis? A. Langerhans cell histiocytosis B. Traumatic compression fracture C. Leukemia D. Osteomyelitis Figure 5C American College of Radiology

11 Question #39 Findings: A lower thoracic vertebral body is completely collapsed. Adjacent intervertebral disks are intact. There is no associated paraspinous soft tissue mass and there is no pathologic enhancement. A. Correct. This appearance of vertebra plana, or total collapse and flattening of a vertebral body, is characteristic of eosinophilic granuloma of Langerhans cell histiocytosis. There is notable lack of extraosseous soft tissue. B. Incorrect. A compression vertebral body fracture would be most unusual at this patient s age even in the setting of nonaccidental trauma. If present, one would expect a wedge compression or other pattern rather than this vertebra plana appearance. C. Incorrect. Osseous destruction is possible with leukemia but is less likely to present as a solitary lesion with the vertebra plana appearance. Diffuse marrow involvement would be expected. Dural or lepto-meningeal involvement would be likely as well to support the diagnosis of leukemia. D. Incorrect. Incorrect because there are no supporting findings to indicate infection. One would expect paraspinous inflammation as well as disk involvement. Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby; 1994: Diagnostic In-Training Exam 2005

12 40. Concerning a tripod fracture, ALL of the following are involved EXCEPT: A. Postero-lateral wall of the maxillary sinus B. Orbital roof C. Zygomatic arch D. Orbital floor Question #40 Findings: One portion of the tripod fracture involves the maxillary sinus including the anterior and postero-lateral walls and the floor of the orbit. The second portion involves the zygomatic arch. The third portion involves the lateral orbital rim, usually including the lateral orbital wall, or the fronto-zygomatic suture. The orbital roof is spared. A. Incorrect. The anterior and postero-lateral walls of the maxially sinus are an integral part of the tripod fracture. B. Correct. The orbital roof is not involved in tripod fracture. C. Incorrect. Fracture of the zygomatic arch makes up one of the pods. D. Incorrect. The fractures in (A) necessarily include the floor of the orbit. Som PM, Curtin HD. Head and Neck Imaging. St Louis, Mo: Mosby; 1996: American College of Radiology

13 41. Which one of the following statements regarding orbital infections is CORRECT? A. Pre-septal cellulitis usually presents with pain and restriction of ocular motion. B. Orbital cellulitis usually involves the intraconal space. C. Opportunistic infection in AIDS patients usually involves the extraconal space. D. Subperiosteal abscess usually involves the medial orbit. Question #41 : A. Incorrect. Preseptal cellulitis generally causes painless swelling and there is no restriction of ocular motion. B. Incorrect. Orbital cellulitis is usually confined to the extraconal space except in severe cases. C. Incorrect. Opportunistic infections in AIDS more commonly involve the globe. D. Correct. Orbital abscesses most commonly result from infection in the adjacent ethmoid sinus. Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994: Diagnostic In-Training Exam 2005

14 42. Lumbar spine radiographs demonstrate a grade I anterior spondylolisthesis at L4-L5 and bilateral L4 pars interarticularis defects. Lumbar MRI at this level would MOST likely reveal which one of the following findings? A. Stenosis of the central spinal canal and widening of neural foramina B. Stenosis of the central spinal canal and stenosis of the neural foramina C. Widening of the central spinal canal and widening of the neural foramina D. Widening of the central spinal canal and stenosis of the neural foramina Question #42 Anterior spondylolisthesis in the lumbar spine commonly results from either degenerative facet disease or spondylolysis. With either cause, there is frequently narrowing of the neural foramina. A. Incorrect. Disc herniations and other epidural masses may produce central stenosis without foraminal stenosis. There is typically no spondylolisthesis. B. Incorrect. Spondylolisthesis due to degenerative facet disease frequently causes central spinal canal stenosis and foraminal stenosis. C. Incorrect. These findings may occur with trauma but are not typical of degenerative disease. D. Correct. Spondylolisthesis due to spondylolysis usually results in enlargement of the central spinal canal, at least with grades I and II. When spondylolytic spondylolisthesis becomes severe (grade IV), there may also be central stenosis. DH Yock. Magnetic Resonance Imaging of CNS Disease. 2nd ed. St Louis, Mo: Mosby; 2002: American College of Radiology

15 43. Which one of the following is MOST likely to be an intradural, extramedullary lesion of the spine? A. Meningioma B. Disk herniation C. Astrocytoma D. Metastasis Question #43 A. Correct. The classic meningioma is outside the spinal cord or nerve roots, but within the dura. B. Incorrect. Almost all disk herniations produce impingement on the spinal canal from outside the dura. C. Incorrect. An astrocytoma is intradural, but is within the spinal cord (intramedullary). D. Incorrect. Most metastases produce impingement on the spinal canal from outside the dura. Intradural extramedullary metastases include leptomeningeal disease and drop metastases. These lesions are much less frequent than extradural disease when all metastatic lesions are considered. Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994: Diagnostic In-Training Exam 2005

16 44. Which one of the following is MOST likely to cause a jugular foramen mass? A. Paraganglioma B. Astrocytoma C. Schwannoma D. Meningioma Question #44 A. Correct. Paraganglioma (glomus jugulare) is the most common primary tumor of the jugular foramen. B. Incorrect. Astrocytoma is the most common primary brain parenchymal tumor, but would rarely involve the jugular foramen. C. Incorrect. Cranial nerves 10 and 11 do accompany the jugular bulb though the skull base, but Schwannomas of these nerves are uncommon. D. Incorrect. Meningiomas at the skull base are more common in the foramen magnum, parasellar region, and supraorbital region. Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994:332. American College of Radiology

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