23204970

28th Annual

In-Training Examinationfor DiagnosticRadiology ResidentsRationalesSponsored by:Commission on EducationCommittee on Residency Training in Diagnostic Radiology

February 3, 2005

The American College of Radiology www.acr.org

American College of Radiology

Section II – Neuroradiology

Figure 1A Figure 1B

Figure 1C

35. You are shown axial T2 (Figure 1A) andpost contrast axial (Figure 1B) and coronal(Figure 1C) T1-weighted images of a39-year-old African-American woman witha long history of headaches. What is theMOST likely diagnosis?

A. Viral encephalitis

B. Cryptococcal meningitis

C. Sarcoidosis

D. Multiple sclerosis

Diagnostic In-Training Exam 2005


Question #35

Findings:There is nodular pachymeningeal enhancement involving the basilar meninges and the falx. This pattern istypical of granulomatous processes.

Rationales: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 viralencephalitis.

B. Incorrect. While fungal meningitis would be a possible differential, there is little parenchymal involvementin this case. Cryptococcosis typically involves the perivascular spaces at the base of the brain, and there islittle contrast enhancement.

C. Correct. This is a case of sarcoidosis. Sarcoidosis and tuberculosis are both granulomatous processes with asimilar imaging appearance in the brain. Contrast-enhanced scans reveal thick basilar meningealenhancement. Chest x-ray (not shown) demonstrates classic bihilar adenopathy in this relativelyasymptomatic patient. One of the hallmarks of sarcoidosis is a radiographic finding that is discordant fromthe 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 enhancementwith no white matter abnormalities would make this a most unlikely diagnosis.

Citations:Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994:196-197.



36. You are shown a coronal CT view of the face (Figure 2) in a 25-year-old man with eye pain. What isthe MOST likely diagnosis?

A. Blowout fracture

B. Maxillary sinusitis

C. Neoplasm of the maxillary sinus

D. Orbital lipoma

Figure 2



Question #36

Findings:There is a fracture of the right orbital floor, with downward protrusion of orbital fat, and swelling and rotationof the inferior rectus muscle.

Rationales: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 theorbit.

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 orbitusually occur in the lacrimal gland.

Citations:Grossman RI, Youssem DM, eds. Neuroradiology. Philadelphia, Pa: Elsevier, Inc; 2003:266-268.



Figure 3A Figure 3B

Figure 3C

37. You are shown sagittal T1-weighted (Figure3A), axial T2-weighted (Figure 3B) and axialFLAIR (Figure 3C) MR images in a newbornwith questionable ventriculomegaly onprenatal ultrasound. What is the MOSTlikely diagnosis?

A. Congenital hydrocephalus

B. Hydranencephaly

C. Dandy Walker malformation

D. Agenesis of the corpus callosum



Question #37

Rationales:

A. Incorrect. Though the occipital horns of the lateral ventricle are dilated, the frontal horns as well as thethird ventricle are small. The ventricles have a parallel appearance. In congenital stenosis the third andlateral ventricles are enlarged. In this case no evidence of transependymal flow of CSF is apparent in theperiventricular 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 anteriorand 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 withdilatation of the fourth ventricle in an enlarged posterior fossa with associated hydrocephalus. As is seenon the sagittal, the vermis is present and no fourth ventricular dilatation or posterior fossa enlargement isapparent. Many variations of Dandy-Walker exist though in all some malformation of the vermis isappreciated.

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 bundlesrunning anterior to posterior are identified, as these are alternative white matter tracts when the corpuscallosum is missing. The medial hemispheric sulci extend down to the third ventricle as a result of eversionof the cingulate gyrus and lack of formation of the cingulate sulcus.




Figure 4A Figure 4B

Figure 4C Figure 4D



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-year-old 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 rimenhances and the center of the mass is low on the T1 image and increased in signal on the FLAIR image butnot to the degree of CSF. The DWI image exhibits restricted diffusion.

Rationales: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-signalrim with T2 weighting, and restricted diffusion.

C. Incorrect. Epidermoid tumors are extraaxial in location. Their contents follow CSF in imaging with theexception of FLAIR, on which they tend to have slightly greater signal than CSF, and DWI, on which theyexhibit restricted diffusion. The mixed signal on the T2 weighted image and parenchymal location as wellas 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.

Citations:Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby; 1994:540-543, 680-694.



Figure 5A Figure 5B

Figure 5C

39. You are shown sagittal T1-weighted(Figure 5A), T2-weighted (Figure 5B),and gadolinium-enhanced T1- weighted(Figure 5C) MR images of the thoraco-lumbar spine in a 17-month-old girl withback pain. What is the MOST likelydiagnosis?

A. Langerhans cell histiocytosis

B. Traumatic compression fracture

C. Leukemia

D. Osteomyelitis



Question #39

Findings:A lower thoracic vertebral body is completely collapsed. Adjacent intervertebral disks are intact. There is noassociated paraspinous soft tissue mass and there is no pathologic enhancement.

Rationales: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 ofextraosseous soft tissue.

B. Incorrect. A compression vertebral body fracture would be most unusual at this patient’s age even in thesetting of nonaccidental trauma. If present, one would expect a wedge compression or other pattern ratherthan this “vertebra plana” appearance.

C. Incorrect. Osseous destruction is possible with leukemia but is less likely to present as a solitary lesion withthe “vertebra plana” appearance. Diffuse marrow involvement would be expected. Dural or lepto-meningealinvolvement 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 expectparaspinous inflammation as well as disk involvement.

Citations:Osborn AG. Diagnostic Neuroradiology. St Louis, Mo: Mosby; 1994:311-313.



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 wallsand the floor of the orbit. The second portion involves the zygomatic arch. The third portion involves thelateral orbital rim, usually including the lateral orbital wall, or the fronto-zygomatic suture. The orbital roof isspared.

Rationales: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.

Citations:Som PM, Curtin HD. Head and Neck Imaging. St Louis, Mo: Mosby; 1996:274 - 278.



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

Rationales::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.




42. Lumbar spine radiographs demonstrate a grade I anterior spondylolisthesis at L4-L5 and bilateralL4 pars interarticularis defects. Lumbar MRI at this level would MOST likely reveal which one ofthe 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

Rationales:Anterior spondylolisthesis in the lumbar spine commonly results from either degenerative facet disease orspondylolysis. With either cause, there is frequently narrowing of the neural foramina.

A. Incorrect. Disc herniations and other epidural masses may produce central stenosis without foraminalstenosis. There is typically no spondylolisthesis.

B. Incorrect. Spondylolisthesis due to degenerative facet disease frequently causes central spinal canal stenosisand 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, atleast with grades I and II. When spondylolytic spondylolisthesis becomes severe (grade IV), there may alsobe central stenosis.

Citations:DH Yock. Magnetic Resonance Imaging of CNS Disease. 2nd ed. St Louis, Mo: Mosby; 2002:592-593.



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

Rationales: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 aremuch less frequent than extradural disease when all metastatic lesions are considered.




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

Rationales: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 involvethe jugular foramen.

C. Incorrect. Cranial nerves 10 and 11 do accompany the jugular bulb though the skull base, butSchwannomas of these nerves are uncommon.

D. Incorrect. Meningiomas at the skull base are more common in the foramen magnum, parasellar region, andsupraorbital region.

Citations:Grossman R, Yousem D. Neuroradiology: The Requisites. St Louis, Mo: Mosby; 1994:332.

Health & Medicine

23204970