VIQ - CNS Flashcards

1
Q

@# 24. Which of the following best describes the typical appearance of intracranial haemorrhage in the late subacute phase (8-30 days)?

A. Increased T1, decreased T2

B. Isointense T1, decreased T2

C. IsointenseT1, increased T2

D. Increased T1, increased T2

E. Decreased T1, decreased T2

A

D. Increased T1, increased T2

A represents early subacute haemorrhage,

B represents acute (12-72 hours),

C represents hyperacute (less than 12 hours)

and E represents chronic haemorrhage (> 1 month).

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2
Q

@# 8) A 62-year-old man with a history of falls and confusion undergoes MR of the brain. This demonstrates a subdural haematoma of high signal intensity on T1W images and of high signal intensity with a hypointense rim on T2W images. What is the most likely age of the haematoma?

a. ,6 hours

b. 8–72 hours

c. 3 days to 1 week

d. 1 week to several months

e. several months to several years

A

d. 1 week to several months

In the first 3–6 hours (hyperacute stage) following haemorrhage, the intact red cells contain mostly oxyhaemoglobin, which appears hyperintense on T2W images.

Desaturation occurs peripherally, forming deoxyhaemoglobin, which is seen as hypointensity on T2W images.

In the acute stage (8–72 hours), there is rapid deoxygenation of the oxyhaemoglobin to deoxyhaemoglobin, which, together with the high protein content of the clot and susceptibility effects, results in isoto hypointensity on T1W images and hypointensity on T2W images.

In the early subacute stage (37 days), oxidation of deoxyhaemoglobin to methaemoglobin occurs inside the red cell, resulting in characteristic hyperintensity on T1W images due to paramagnetic effects, and marked hypointensity on T2W images.

In the late subacute stage (1 week to months), extracellular methaemoglobin results in persistent hyperintensity on T1W images, but increasing signal intensity on T2W images, with peripheral susceptibility effects causing a low intensity rim.

In the chronic stage (months to years), iron atoms are deposited as haemosiderin and ferritin, which cause susceptibility effects resulting in low signal intensity on both T1W and T2W images.

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3
Q

@# 34) An unenhanced CT scan of the brain is performed 3 hours after the onset of signs suggestive of ischaemic stroke. Which of the following image window parameters is most likely to reveal the early CT changes?

a. width 400 HU, centre 40 HU

b. width 80 HU, centre 20 HU

c. width 8 HU, centre 32 HU

d. width 0 HU, centre 0 HU

e. width 1500, centre –500 HU

A

c. width 8 HU, centre 32 HU

Loss of grey–white matter differentiation, obscuration of the lentiform nucleus and the insular ribbon sign are manifestations of cytotoxic oedema that can be seen on CTas early as 2 hours after middle cerebral artery infarction. With normal window settings (width 80 HU, centre 20 HU), the sensitivity and specificity for acute ischaemic stroke detection on unenhanced CT are 57% and 100% respectively.

The sensitivity is improved to 71% with window settings of width 8 HU and centre 32 HU.

This setting accentuates the difference between normal and oedematous brain tissue.

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4
Q

@# 43) A patient with multiple previous ischaemic strokes has an MRI including T2W and DWI sequences. In the left frontal lobe, there is a region of increased T2 signal. The same area is dark on the DWI and bright on the ADC map. Which of the following is the most likely age of this region of ischaemia?

a. 10 minutes

b. 30 minutes

c. 3 days

d. 2 weeks

e. 4 months

A

e. 4 months

The imaging findings are in keeping with a chronic infarct, in which the unrestricted extra water within gliosis gives a high T2 signal, dark DWI and bright ADC.

Cytotoxic oedema occurs because of early ischaemic damage to the cell membrane Na+/K+ ATPase pump. This can be seen as early as 30 minutes after symptom onset as a bright DWI region. T2W images will be normal this early and the corresponding ADC map dark.

DWI signal increases during the first week due to restricted diffusion but may remain bright for a prolonged period due to T2 ‘shine-through’. ADC will return to normal at 1–4 weeks (pseudonormalization) when restricted diffusion is matched by increasing amounts of vasogenic oedema that is not restricted.

Long-term gliosis has extra water that is not restricted. DWI can be usefully thought of as a T2 signal diminished by net water movement. Since the DWI can be bright because of T2 ‘shine-through’ rather than restricted diffusion, comparison of DWI findings with the ADC map is mandatory.

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5
Q

@#e2 18 An elderly, hypertensive man is found collapsed. CT imaging demonstrates a large intracerebral haematoma. The mean CT attenuation is 70 HU, and there are fluid/ fluid levels. How old is the haematoma likely to be?

(a) 0-2 hours

(b) 3-48 hours

(c) 3-7 days

(d) 2-4 weeks

(e) 2 months

A

(b) 3-48 hours

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6
Q

@# 47 A pregnant lady patient presents with headache and a focal neurological deficit. A non-enhanced CT shows increased attenuation in the superior sagittal sinus. Following the administration of intravenous contrast medium, the dura surrounding the sinus enhances but the sinus itself does not. MR imaging is performed. Given the most likely diagnosis, which appearances would be unusual for this condition?

(a) Low T2W signal intensity at 2 days

(b) lso/high T1W signal intensity in 20 days

(c) High T1W signal intensity in 10 days

(d) Low T2W signal intensity in 20 days

(e) High T2W signal intensity in 10 days

A

(d) Low T2W signal intensity in 20 days

This patient has suffered a venous sinus thrombosis.

The pattern of signal intensities is as follows:

Acute (< 5 days): T1W isointense, T2W low;

Subacute: T1W high, T2W high;

Chronic: T1W isointense/ high, T2W, isointense/ high.

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7
Q

@# 32 An elderly gentleman has an episode of amaurosis fugax and undergoes Doppler ultrasound assessment of his carotid arteries. Which of the following features is not an indication of either internal carotid artery or common carotid artery stenosis?

(a) Peak systolic velocity of 160 cm/s

(b) Significant quantities of visible plaque

(c) End diastolic velocity of 120 cm/s

(d) Spectral broadening

(e) ICA/ CCA peak systolic velocity ratio of 1.5

A

(e) ICA/ CCA peak systolic velocity ratio of 1.5

A consensus panel has recently defined the US criteria for gauging carotid artery stenosis. Quantitative criteria include: (table)

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8
Q

@#e2 35 An elderly, hypertensive man is found collapsed. MR imaging demonstrates a large intracerebral haematoma, with intermediate. signal intensity on T1W and high signal intensity on T2W. How old is the haematoma likely to be?

(a) 0-12 hours·· ·

(b) 12-72 hours

(c) 4-7 days

(d) 8-30 days c

(e) More than 1 month

A

(a) 0-12 hours

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9
Q

@# 38 An elderly, hypertensive man was found collapsed. MR imaging reveals a large infarct, with low signal intensity on T1W, high signal intensity on T2W, high signal on DWI and low signal on the ADC map. How old is the infarct likely to be?

(a) 0-6 hours

(b) 6 hours to 4 days

(c) 4-14 days

(d) 14-30 days

(e) More than 1 month

A

(b) 6 hours to 4 days

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10
Q

@# 6. A 52-year-old man is investigated by MRI of brain for a possible transient ischaemic attack (TIA). Focal lesions of CSF signal intensity are identified adjacent to the anterior commissures. The referring neurologist suspects that these lesions are chronic lacunar infarcts. What MRI finding suggests prominent perivascular space?

A. No restricted diffusion on DWI.

B. Hypointense on T1WI.

C. Hyperintense on T2WI.

D. Suppress on FLAIR.

E. Normal surrounding brain parenchyma.

A
  1. E. Normal surrounding brain parenchyma.

Perivascular spaces (Virchow–Robin spaces) are pial lined interstitial fluid structures that accompany penetrating arteries, but do not communicate directly with the subarachnoid space. They can occur anywhere, but typically cluster around the anterior commissure. They follow CSF signal intensity, suppress on FLAIR, and do not exhibit restricted diffusion. They can occasionally be giant when located within the midbrain.

Lacunar infarcts will also be hypointense on T1WI and hyperintense on T2WI. Restricted diffusion will be seen when acute/subacute. They are typically of increased signal on FLAIR, although will suppress if there is central encephalomalacia. A halo of surrounding high signal on T2WI and FLAIR is typical of lacunar infarction, although up to 25% of prominent perivascular spaces can also demonstrate a slight halo of increased signal. Lacunar infarcts are also more typically seen more extensive white matter disease.

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11
Q

@# 8. A 32-year-old man presents with recent onset of migraine and TIAs. He also reports some cognitive decline. Cerebral angiogram is normal. An MRI of brain reveals discrete hyperintensities in the anterior temporal poles and external capsules. What is the most likely diagnosis?

A. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

B. Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke (MELAS).

C. Myoclonic epilepsy with ragged red fibres (MERRF).

D. Sporadic subcortical arteriosclerotic encephalopathy (sSAE).

E. Protein S deficiency.

A
  1. A. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

This is a hereditary small vessel disease, which causes stroke in young adults.

The genetic mutation is found on chromosome 19.

Presentation can include migraine, cognitive decline, psychiatric disturbance, TIAs, and stroke, the latter usually with substantial/complete recovery after individual strokes, particularly early in the disease process.

Imaging reveals subcortical lacunar infarcts and leukoencephalopathy in young adults.

The frontal lobe has the highest lesion load, followed by the temporal lobe and insula.

Anterior temporal pole and external capsule lesions have higher sensitivity and specificity for CADASIL.

The cerebral cortex is usually spared.

MRI is the investigation of choice: CT will reveal only areas of hypodensity and angiography is normal.

sSAE is associated with hypertension and results in multiple lacunar infarcts in the lenticular nuclei, pons, internal capsule, and caudate nuclei.

MELAS and MERRF are mitochondrial disorders.

MELAS results in bilateral multiple cortical and subcortical hyperintense lesions on FLAIR images;

MERRF has a propensity for the basal ganglia and caudate nuclei, and watershed ischaemia/ infarcts are common.

Hypercoagulable states such as protein S deficiency result in cortical and lacunar infarcts of various sizes, but the cerebral angiogram is abnormal.

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12
Q

@# 62. A 36-year-old man is admitted following a seizure. Unenhanced CT demonstrates a right frontal mixed attenuation lesion, which avidly enhances post contrast. Multiple flow voids are seen on MRI of brain. What finding on catheter angiography differentiates arteriovenous malformation (AVM) from other vascular lesions of the brain?

A. Early venous drainage.

B. Arterial stenoses of feeder vessels.

C. External carotid transdural supply.

D. Dilated medullary veins (caput medusa).

E. Dilated cortical veins.

A
  1. A. Early venous drainage.

Brain AVMs are abnormal connections between arteries that would normally supply the brain tissue and veins that normally drain the brain, resulting in shunting with an intervening network of vessels within the brain parenchyma.

The finding of early venous drainage is important in differentiating brain AVMs from other vascular lesions.

Cortical venous drainage may be seen in superficial lesions.

Recruitment of transdural supply is observed in large lesions, although this is a more typical feature of proliferative angiopathy, which is a diffuse type of AVM.

Classically, in this condition, normal brain parenchyma is interspersed between the abnormal vessels.

Stenoses of feeder vessels are also often identified in proliferative angiopathy.

The caput medusa of dilated medullary veins is a feature of DVAs, a normal variant.

Dilated cortical veins are seen in dural arteriovenous fistulas (DAVFs), which are abnormal connections between arteries that normally supply the meninges (but not the brain) and small venules within the dura.

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13
Q

@# 40) A 35-year-old man is involved in a low-velocity road traffic accident. Within minutes, he experiences an occipital headache and neck pain. On arrival in hospital, he complains of nausea, vertigo and diplopia. An unenhanced CT scan of the brain is performed. Which of the following abnormal findings is most likely?

a. high density seen in CSF of the sylvian fissure

b. low density and loss of grey–white matter differentiation in the insular region

c. expansion of a vertebral artery with a peripheral, high-density crescent

d. lenticular high attenuation between the temporal lobe and temporal bone

e. crescent-shaped high attenuation between the temporal lobe and temporal bone

A

c. expansion of a vertebral artery with a peripheral, high-density crescent

Minor trauma stretching the vertebral artery over the lateral mass of C2 can cause vertebral artery dissection.

Symptoms include headache and neck pain, and as many as 95% of patients develop a stroke after hours to weeks. Imaging will show an axially enlarged vessel with a narrow lumen and a periarterial rim sign.

Angiography may demonstrate tapering or occlusion of the artery or the dissection flap.

Predisposing factors to spontaneous arterial dissection include fibromuscular dysplasia, Marfan’s syndrome, collagen vascular disease and homocysteinuria.

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14
Q

@# 69) In the presence of raised intracranial pressure, the anterior cerebral artery is at risk of compression during which of the following types of brain herniation?

a. transforaminal herniation

b. sphenoid herniation

c. ascending transtentorial herniation

d. descending transtentorial herniation

e. subfalcine herniation

A

e. subfalcine herniation

Transtentorial herniation may be descending (towards the posterior fossa) or ascending (upward displacement of the cerebellum through the tentorial incisura).

Descending transtentorial herniation causes shift of the temporal lobe over the tentorium, which may compress the third cranial nerve, the posterior cerebral and anterior choroidal arteries, and the midbrain.

Contralateral hemiparesis may occur due to compression of the ipsilateral cerebral peduncle.

Ipsilateral hemiparesis may also occur due to compression of the contralateral cerebral peduncle against the tentorial edge (Kernohan’s notch phenomenon, a false localizing sign).

Subfalcine herniation occurs when the cingulate gyrus shifts beneath the falx, due to medially directed supratentorial mass effect. This may cause compression of the anterior cerebral artery (resulting in ipsilateral distal anterior cerebral infarction) and internal cerebral veins.

Sphenoid herniation involves herniation of the frontal lobe posteriorly across the edge of the sphenoid ridge, and rarely produces significant clinical symptoms.

Transforaminal herniation results in herniation of the inferior cerebellum downward through the foramen magnum, which can result in obtundation and death.

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15
Q

@#e2 1 A young man presents with a thunderclap headache. A CT examination is performed. Sub-arachnoid blood is seen with a localised clot which has a maximum thickness of 2 mm. No intraventricular nor parenchymal blood is seen. What is the Fisher Grade?

(a) Grade 0

(b) Grade I

(c) Grade II

(d) Grade Ill

(e) Grade IV

A

(d) Grade Ill

The Fisher scale is useful in communicating the description of SAH.

Grade 1: no haemorrhage evident,

grade 2: SAH < 1 mm,

grade 3: SAH > 1 mm,

grade 4: associated intra-ventricular haemorrhage or parenchymal extension.

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16
Q

@# 12. Which of the following best represents the decline in positive CT findings for a clinically suspected subarachnoid haemorrhage from scanning at 12 hours post-ictus to 3 days post-ictus?

a. 90% positive at 12 hours to 70% positive at 3 days

b. 90% positive at 12 hours to 60% positive at 3 days

c. 98% positive at 12 hours to 90% positive at 3 days

d. 98% positive at 12 hours to 75% positive at 3 days

e. 90% positive at 12 hours to 50% positive at 3 days

A

12.d. 98% positive at 12 hours to 75% positive at 3 days

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17
Q

@#e2 9. Which brain tumour has the greatest incidence across all age groups?

A. Meningioma

B. Metastases

C. Pituitary adenoma

D. Haemangioblastoma

E. Glioma

A

E. Glioma

Gliomas consist of astrocytomas, oligodendrogliomas, paragangliomas, ganglogliomas and medulloblastomas

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18
Q

@# 23. Which is the most common location of oligodendroglioma?

A. Temporal lobe

B. Parietal lobe

C. Occipital lobe

D. Frontal lobe

E. Cerebellum

A

D. Frontal lobe

Most commonly involve cortical & subcortical white matter, occasionally through CC as butterfly glioma.

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19
Q

@# 60) Which of the following is the most common radiation-induced CNS tumour?

a. ependymoma

b. oligodendroglioma

c. lymphoma

d. glioblastoma multiforme

e. meningioma

A

e. meningioma

Meningioma is the most common radiation-induced CNS tumour, and has been particularly associated with low-dose radiation treatment for tinea capitis.

For the diagnosis of radiation-induced meningioma to be made, the meningioma must arise in the radiation field, appear after a latency period of years and should not have been the primary tumour irradiated.

Radiation-induced meningiomas are more frequently multiple and have higher recurrence rates than non-radiation-induced tumours.

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20
Q

@#e2 26 An elderly man is admitted for assessment of focal neurological symptoms. An incidental supratentorial cystic lesion is demonstrated. Which of the following features would make the diagnosis of subdural hygroma, rather than arachnoid cyst, more likely?

(a) Isointense to CSF on T1W MR imaging

(b) Mass effect

(c) Isointense to CSF on T2W MR imaging

(d) Flattened sulci

(e) Bony remodeling

A

(e) Bony remodeling

Scalloping of the adjacent bone, possibly through transmitted pulsations, is often seen in arachnoid cysts. This is never seen in subdural hygromas, but can be seen with epidermoid cysts or porencephaly.?

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21
Q

@#e2 47 A 40 year old man presents with a seizure and a CT head reveals an intracranial lesion. An oligodendroglioma is suspected. Which feature would be least expected with this diagnosis?

(a) Ill-defined enhancement

(b) Cystic degeneration

(c) Absence of oedema

(d) Calcification

(e) Hyperdense on unenhanced imaging

A

(e) Hyperdense on unenhanced imaging

Oligodendrogliomas are slowly growing gliomas, most commonly located in the frontal lobes.

Large nodular calcification is present in approximately 90% of cases.

Cystic degeneration, ill-defined enhancement and a lack of oedema are all common.

Over 80% are either hypo- or iso- dense on unenhanced CT imaging.

22
Q

@#e2 47 A seven-year-old boy presented with sudden onset gait problems and subtle uncoordination on the finger nose test. CT demonstrated a low density cystic solid lesion with subtle calcification centred on the vermis. Thick heterogeneous enhancement was seen within the solid area along with obstructive hydrocephalus. What is diagnosis?

a Pilocytic astrocytoma

b Medulloblastoma

c Haemangioblastoma

d Ependymoma

e Brainstem glioma

A

47 Answer A: Pilocytic astrocytoma

Pilocytic astrocytoma is the most likely diagnosis as it is low density on CT with calcification and nodular enhancement. They are commonly located in the vermis (50%) and are complicated by hydrocephalus.

They commonly occur before the age of nine and are characteristically a cyst with an enhancing nodule.

Haemangioblastoma is a serious consideration, but more commonly occurs in the paravermian position; the nodule is hyperdense on non-contrast CT and they virtually never calcify.

Both lesions can be cystic with a solid enhancing nodule.

Haemangioblastomas occur more commonly in adults and as part of VHL syndrome.

23
Q

@# 48 A 62-year-old female presented to the Emergency Department with gradual onset weakness in the right upper and lower limbs. CT demonstrated multiple rounded hyperdense lesions with marked vasogenic oedema which showed prominent enhancement following IV contrast. Assuming the lesions are metastases, what is the most likely primary?

a Bladder

b Renal cell carcinoma

c Colon

d Adenocarcinoma of the lung

e Uterus

A

48 Answer B: Renal cell carcinoma

Malignant melanoma, choriocarcinoma, oat cell, thyroid and renal cell carcinoma all cause hyperdense cerebral metastases. They all enhance brightly with contrast.

24
Q

@#e2 (Ped) 58 A three-year-old boy is taken to an optician following problems reading. The optician finds the child has a loss of visual acuity and visual fields; he also did not think the boy looked well. He referred the child to the hospital. The paediatrician found the boy to be thin, hyperactive and unusually alert for his age. A CT brain was performed, which showed a mass in the suprasellar region that appeared to be extending into the optic chiasm. This had mixed enhancement with some cystic areas and calcifications. What is the most likely diagnosis?

a Hypothalamic glioma

b Hypothalamic hamartoma

C Craniopharyngioma

d Astrocytoma

e Pituitary adenoma

A

58 Answer A: Hypothalamic glioma

These are the most common hypothalamic masses accounting for 10-15% of supratentorial tumours in children and present between the ages of two and four years old.

This child is showing visual deficits and diencephalic syndrome, which is present in up to 20% of cases.

The inhomogeneous enhancement is caused by tumour necrosis.

Craniopharyngioma and astrocytomas are uncommon in these sites.

Hypothalamic hamartomas are rare and usually present before the age of two years old. They are round isodense lesions that do not enhance on CT.

25
Q

@# 37. A 40-year-old man presents with unilateral sensorineural hearing loss. MRI shows a well-defined mass in the left cerebellopontine angle. The lesion returns high signal on T1, T2 and FLAIR sequences. On fat-saturated T1 with contrast, the lesion returns low signal and no contrast enhancement is seen. What is the most likely diagnosis?

(a) Acoustic schwannoma with haemorrhage

(b) Lipoma

(c) Epidermoid cyst

(d) Giant aneurysm

(e) Arachnoid cyst

A
  1. (b) Cerebellopontine angle lipoma

Lesion has characteristics of fat on all sequences (high signal on T1 and T2 with loss of signal on fat-suppression imaging).

26
Q

@#e2 2.A 38-year-old male with Human Immunodeficiency Virus (HIV) stopped taking his retrovirals 6 months ago and now presents with confusion. CT brain shows non-enhancing hypodensities, with apparent dilated perivascular spaces, although these were not present on a CT brain from 2 years ago. What is the most likely cause?

A. Cryptococcus

B. Progressive multifocal leukoencephelopathy

C. Tuberculosis

D. CMV encephalitis

E. Toxoplasmosis

A

A. Cryptococcus

More commonly cryptococcus meningitis but Cryptococcus or gelatinous pseudocysts reside in dilated perivascular spaces

27
Q

@# 45. Which is the most common location for toxoplasmosis?

A. Basal ganglia

B. Frontal lobe

C. Occipital lobe

D. Temporal lobe

E. Brainstem

A

A. Basal ganglia

75% of cases are in the basal ganglia.

28
Q

@# 31. A patient known to have AIDS presents with increasing malaise and confusion. CT brain shows multiple cerebral hypoattenuating nodular lesions with varying degrees of surrounding oedema and mass effect. There is lesional enhancement post-contrast administration. Which of the following conditions can be confidently removed from the differential diagnosis?

a. Tuberculosis

b. Pyogenic abscesses

c. Progressive multifocal leukoencephalopathy

d. Lymphoma

e. Toxoplasmosis

A
  1. c. Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy affects about 4% of AIDS patients and is caused by reactivation of ubiquitous JC papovavirus. This causes lysis of oligodendrocytes resulting in demyelination. CT shows single or multiple hypoattenuating white matter lesions without oedema/mass effect. There may also be grey matter lesions in the thalamus/ basal ganglia from involvement of traversing white matter tracts. The majority of patients show mild cortical atrophy. The condition carries a poor prognosis with death within two to five months.
All the other conditions listed will have various amounts of surrounding oedema/mass effect and enhance post-contrast.
Toxoplasmosis is the most common cerebral mass lesion in AIDS and is two or three times more frequent than lymphoma (the second most common cause of a CNS mass in AIDS). Multiple lesions suggest toxoplasmosis over lymphoma, however when there is a solitary lesion the probability of lymphoma is at least equal to that of toxoplasmosis.

29
Q

@#e2 57. A four month old male undergoes investigation for microcephaly and hearing loss. Unenhanced CT brain shows several periventricular subependymal cysts and multiple coarse periventricular and parenchymal white matter calcifications. There is diffuse hypoplasia of the cerebellum. What is the most likely diagnosis?

a. Tuberous sclerosis

b. Sturge–Weber syndrome

c. Cytomegalovirus infection

d. Venous sinus thrombosis

e. Congenital rubella

A
  1. c. Cytomegalovirus infection

This is the most common intrauterine infection and the leading cause of brain disease and hearing loss in children.

Typical imaging findings include periventricular subependymal cysts representing focal areas of necrosis and glial reaction, periventricular postinflammatory calcifications, scattered calcifications in basal ganglia and brain parenchyma, microcephaly due to disturbance of cell proliferation and hypoplasia of the cerebellum. There may also be lissencephaly, cortical dysplasia, polymicrogyria and schizencephaly due to disturbed neuronal migration.

30
Q

@# 9. A 36-year-old patient with known AIDS is admitted to your hospital with a right-sided hemiparesis. His wife gives a history of cognitive decline, headache, and lethargy for the past few weeks, but with an acute deterioration in the last 36 hours. His CD4 counts are between 200 and 500 (category B). An MRI is carried out which shows multiple ring-enhancing lesions in the brain. These lesions are high signal on T2WI/FLAIR, but demonstrate a low intensity peripheral ring. Lesions are noted in the basal ganglia bilaterally. The cortical region and subcortical U-fibres are spared. A thallium SPECT is also carried out that shows abnormal uptake in the brain, which correlates with the areas identified on MRI. What is your primary diagnosis?

A. Nocardia abscesses.

B. Toxoplasmosis.

C. Progressive multifocal leukoencephalopathy.

D. Primary CNS lymphoma.

E. Cerebral cryptococcus infection.

A
  1. B. Toxoplasmosis.

This is the most common intracranial opportunistic infection in AIDS patients and the most common cause of intracranial mass lesions in this population, with lymphoma second and cryptococcus third.

Differentiating toxoplasmosis from lymphoma has been the subject of much debate in the literature and ultimately there is no definitive means of differentiating them on imaging alone.

As described toxoplasmosis causes multiple ring-enhancing lesions and often affects the basal ganglia.

Lymphoma tends to involve the subependymal regions and can cause leptomeningeal enhancement. Lymphoma can cause encasement of the ventricle, which is not seen with toxoplasmosis.

Toxoplasmosis tends to be higher intensity on T2WI/FLAIR than lymphoma.

PET and thallium SPECT have also been reported to show abnormal uptake in lymphoma, but not toxoplasmosis, although exceptions exist. Response to anti-toxoplasma treatment is often used as a clinical differentiator.

Cryptococcus classically causes dilatation of Virchow–Robin spaces.

PML is a demyelinating condition secondary to JC virus of oligodendrocytes and is differentiated from other HIV-related demyelinating conditions by affecting the subcortical U fibres.

31
Q

@#e2 (Ped) 25 You are asked to perform a cranial ultrasound scan on a neonate who was born with poor APGAR scores and made a poor inspiratory effort. On the ultrasound you find multiple irregular foci of calcification throughout the periventricular region, the thalamus and basal ganglia. What is the most likely diagnosis?

a Congenital Cytornegalovirus infection

b Tuberous sclerosis

c Congenital toxoplasmosis infection

d Grade IV acute haemorrhage

e Periventricular leukomalacia due to hypoxic injury

A

25 Answer C. Congenital toxoplasmosis infection

The presentation of congenital toxoplasmosis infection is very non-specific, as with most of the congenital infections.

The ultrasound characteristics are different from congenital Cytornegalovirus in that the calcifications are in the basal ganglia and thalamus as well as the periventricular region.

The calcifications can be lobulated or curvilinear and can be present in the choroid plexus.

The location also differentiates the findings from tuberous sclerosis.

Periventricular leukomalacia findings are a broad zone of periventricular echogenicity.

32
Q

@#e2 46 A 2 7-year-old HIV positive man was admitted with increasing confusion and lethargy. He had a CD4 count of 150 but had no history of an AIDS-defining illness. Cross-sectional imaging of the head was performed. What features make a diagnosis of toxoplasmosis more likely than lymphoma?

a Corpus callosum involved

b Haemorrhage on CT

C Basal ganglia lesions

d Single lesion

e Subependymal spread

A

46 Answer B: Haemorrhage on CT

Differentiating toxoplasmosis and cerebral lymphoma can be difficult as both can present as multiple ring enhancing lesions.

Features that are more likely to represent lymphoma are a single lesions, subependymal spread and lesions within the corpus callosum.

Features that are more likely to represent toxoplasmosis are haemorrhage on CT and high signal on T2 W imaging.

Toxoplasmosis has a predilection for the basal ganglia but lymphoma can also be found in this region.

33
Q

@#e2 70 A 27-year-old female with AIDS presented with a fit and following further investigations, including CT and MRI scans, her symptoms were felt to be attributable to HIV encephalitis. Which region of her brain is most likely to be abnormal on the MRI scan?

a Anteroinferior aspects of the temporal lobes

b White matter of the centrum semiovale

C Corpus striatum (putamen and caudate nuclei)

d Superior cerebellar peduncles

e Hypothalamus

A

70 Answer B: White matter of the centrum semiovale

Human immunodeficiency virus causes encephalitis in 60% of patients with AIDS.

It predominately affects the white matter, particularly the centrum semiovale and results in gliosis and demyelinating plaques.

These plaques are not dissimilar to plaques in multiple sclerosis as they are in a periventricular position and high signal on T2-weighted images. Unlike plaques in MS they tend not to enhance with contrast. (Acute plaques in MS can enhance for up to six weeks after they first appear.)

Generalised diffuse parenchymal atrophy is a feature.

34
Q

@#e2 12. Which is the cause of low attenuation in the basal ganglia?

A. Hypoparathyroidism

B. Pseudohypoparathyroidism

C. Hypothyroidism

D. Wilson’s disease

E. Radiation therapy

A

D. Wilson’s disease

Other causes increase CO poisoning, barbiturate intoxication, hypoxia, hypoglycaemia and lacunar infarcts.

35
Q

@#e2 31. A 58-year-old patient is found at home with a reduced GCS. CT brain reveals atrophy only. MRI brain reveals hyperintensity in the tegmentum (except for the red nucleus) and hypointensity of the superior colliculus on T2WI, as well as hyperintensity in the basal ganglia. What is the most likely cause?

A. Cocaine abuse.

B. Methanol poisoning.

C. Primary basal ganglia haemorrhage.

D. Wilson’s disease.

E. Carbon monoxide poisoning.

A
  1. D. Wilson’s disease.

Hyperintensity in the tegmentum (except for the red nucleus) and hypointensity of the superior colliculus are described as the ‘face of the giant panda sign’ and are seen in axial T2WI sections of the midbrain in Wilson’s disease.

A ‘double panda sign’ has also been described, with a second ‘panda cub face’ in the pons.

Abnormal signal can also be seen in the basal ganglia and thalamus in Wilson’s disease (putamen most commonly).

The signal abnormalities are due to copper deposition. Signal is generally reduced on T1WI sequences, although it may be increased due to the paramagnetic effects of copper and also due to the hepatic component of Wilson’s disease (a portocaval shunt can produce this latter finding). Signal is generally increased on T2WI sequences, but it can be of mixed or reduced intensity.

Similarly carbon monoxide poisoning and methanol poisoning can cause increased or reduced signal on T1WI.

Methanol poisoning typically causes abnormal signal in the putamen, with haemorrhagic necrosis being more typical, whereas carbon monoxide poisoning typically affects the globus pallidus. The latter would be expected to cause low attenuation in the basal ganglia on CT.

The findings on CT exclude basal ganglia haemorrhage.

Amphetamine and cocaine abuse can cause high T2WI signal in the basal ganglia due to small areas of infarction, but are not associated with the midbrain changes.

36
Q

@#e2 34. A 34-year-old liver transplant recipient presents to hospital with confusion and seizures. A CT brain reveals low attenuation in the deep and subcortical white matter of the occipital and parietal lobes bilaterally. There is no abnormal enhancement post IV contrast administration. As the reporting radiologist, you advise that the clinical team first:

A. measure blood glucose

B. measure serum alpha-feta protein

C. measure blood pressure

D. send coagulation screen

E. measure d-dimer.

A
  1. C. Measure blood pressure

The CT findings are consistent with PRES. This is a usually reversible neurological syndrome with a variety of presenting symptoms ranging from altered mental status to seizures, headache, and loss of vision. Common causes include hypertension, eclampsia and preeclampsia, immunosuppressive medications such as cyclosporine, various antineoplastic agents (including interferon), SLE, and various causes of renal failure. Hypertension is common in PRES, but may be mild and is not universally present, especially in the setting of immunosuppression. However, in the vignette given, hypertension is a possible cause and should be sought. Cyclosporin or tacrolimus might be causes; the former is thought to result in PRES both via a direct neurotoxic effect and by causing hypertension. The condition is not always reversible and may result in haemorrhagic infarcts. The classic MRI finding is of hyperintensity on FLAIR in the parieto-occipital and posterior frontal cortical and subcortical white matter. Less commonly the brainstem, basal ganglia, and cerebellum are involved. Atypical imaging appearances include contrast enhancement, haemorrhage, and restricted diffusion on MRI. Abnormalities can often be seen on CT, as described in the vignette.

37
Q

@# 35. A 34-year-old female presents with neurological symptoms suggestive of MS and is referred for an MRI of brain by the neurology team. Which of the following sequences is most useful for determining if there are plaques of differing ages (i.e. dissemination in time)?

A. FLAIR.

B. T2WI.

C. Pre- and post-contrast T1WI.

D. Proton density.

E. STIR.

A
  1. C. Pre- and post-contrast T1WI.

MS plaques are generally most conspicuous on FLAIR sequences.

However, if there are enhancing and non-enhancing plaques on T1WI post-contrast, this indicates plaques of differing ages, i.e. dissemination in time. While this is not diagnostic of MS (imaging alone never is), it is very suggestive.

Proton density sequences are useful, but not quite as useful as FLAIR sequences, in showing periventricular lesions.

T2WI sequences are superior to FLAIR sequences when it comes to detection of lesions in the posterior fossa and spinal cord.

T2W STIR is probably superior to standard T2WI sequences in detecting spinal cord lesions, but is not routinely used.

STIR sequences or fat suppression are useful when imaging the optic nerves, as contrast between lesions and the surrounding orbital fat is increased.

38
Q

@#e2 37. A 73-year-old has been referred for assessment of cognitive decline. A CT brain reveals cerebral atrophy and a dementia specialist refers her for PET-CT brain. Which of the following findings is most consistent with early Alzheimer’s disease?

A. Diffuse reduced activity.

B. Reduced activity in the precuneus and posterior cingulate gyrus.

C. Reduced activity in the frontotemporal regions.

D. Reduced activity in the caudate and lentiform nuclei.

E. Reduced activity bilaterally in the occipital cortex.

A
  1. B. Reduced activity in the precuneus and posterior cingulate gyrus.

FDG-PET-CT has been shown to have a sensitivity and specificity of 93% for mild to moderate Alzheimer’s disease. The technique has been shown to provide important prognostic information so that a negative PET-CT scan is indicative of unlikely progression of cognitive impairment for a mean follow-up of 3 years in those patients who initially present with cognitive symptoms of dementia.

The more specific findings on PET-CT in Alzheimer’s disease are early reduced activity in the precuneus/posterior cingulate gyrus and the superior, middle, and inferior temporal lobe gyrus, with relative sparing of the primary sensorimotor and visual cortex, and sparing of the striatum, thalamus, and cerebellum.

Diffuse reduced activity of the cortical/subcortical regions and cerebellum is more typical of multiinfarct dementia.

Reduced activity in the fronto-temporal regions is more consistent with fronto-temporal dementia.

Reduced activity in the occipital cortex reflects the visual problems encountered in lewy body dementia.

Reduced activity in the caudate and lentiform nuclei is more typical of Huntingdon’s chorea.

39
Q

@#e (CNS) 2) A child who undergoes MR of the brain for clinically apparent facial abnormalities is shown to have a defect of midline cleavage of the brain. What structure is abnormal or absent in all forms of holoprosencephaly, and therefore is the most sensitive indicator of a midline cleavage abnormality?

a. falx cerebri

b. third ventricle

c. fourth ventricle

d. corpus callosum

e. septum pellucidum

A

e. septum pellucidum

Holoprosencephaly is failure of the primitive brain to cleave into two hemispheres, and is commonly associated with midline facial abnormalities (ranging from cyclopia to hypertelorism) and absence of many intracranial midline structures.

There are three types, the most severe being the alobar form, which shows no cleavage at all, with absence of the falx cerebri and third ventricle, fusion of the cerebral hemispheres and thalami, and a single large lateral ventricle.

The semilobar form has variable cleavage with a partially formed falx, rudimentary third ventricle, and variable cleavage of the thalami, lateral ventricles and cerebral hemispheres.

In the lobar type of holoprosencephaly, brain formation may be nearly normal, but the septum pellucidum is always absent, as in all forms. The falx, corpus callosum and ventricular system may be normal in the lobar type.

40
Q

@#e2 (CNS) 9 A plain radiograph is performed on a male child. Unilateral, premature fusion of both the coronal and lambdoid sutures is evident. What is the most appropriate description?

(a) Scaphocephaly

(b) Brachycephaly

(c) Plagiocephaly

(d) Trigonocophaly

(e) Oxycephaly

A

(c) Plagiocephaly

The common craniosynostoses include:

41
Q

@#e2 11 A cranial US is performed in a pre-term neonate. There is hyperechoic material within the ventricles consistent with recent haemorrhage, but the ventricles are not dilated. How would you grade this germinal matrix bleed?

(a) Grade I

(b) Grade II

(c) Grade Ill

(d) Grade IV

(e) Grade V

A

(b) Grade II

Grade I: subependymal haemorrhage,

Grade II: intraventricular haemorrhage, no ventricular dilation (10% mortality),

Grade Ill: intraventricular hemorrhage with ventricular dilation (20% mortality),

Grade ·IV: intraparenchymal haemorrhage (>50% mortality).

There is no Grade V.

42
Q

@#e2 21 Which of the following is not a cause of secondary craniosynostosis?

(a) Crouzon’s syndrome

(b) Hypothyroidism

(c) Previous shunt procedures

(d) Rickets

(e) Thalassaemia

A

(b) Hypothyroidism

Craniosynostosis is the premature closure of the sutures, which may be primary (idiopathic) or secondary. Secondary causes include: metabolic (rickets, hypercalcaemia, hyperthyroidism, hypervitaminosis D), haematological (thalassaemia, SCD), and bone dysplasias (achondroplasia, metaphyseal dysplasia). It is also associated with syndromes (Crouzon, Apert, Treacher-Collins), and can occur following shunt surgery for hydrocephalus.

43
Q

@#e2 49 A 4 week old ex-premature baby has a witnessed seizure. A cranial US is performed which shows cystic structures bilaterally, adjacent to the trigone of the lateral ventricles. Which of the following favours a diagnosis of chronic periventricular leukomalacia over porencephaly?

(a) Anechoic cysts

(b) Persistenae of cysts on follow-up US

(c) Septated cysts

(d) Symmetrical distribution

(e) Watershed territory distribution

A

(d) Symmetrical distribution

PVL is more common in preterm children, is secondary to ischaemia and usually occurs in the watershed areas. Initially there will be hyperechoic changes which gradually become cystic (>2 wks); the cysts are never septated and usually resolve over time.

Porencephaly can be developmental or due to a vascular or infectious process which destroys brain tissue; it is almost always asymmetrical, rarely disappears over time and is often seen as an extension of the ventricle or sub-arachnoid space. If secondary to ischaemia it can also be in a watershed distribution.

44
Q

@#e2 53. Regarding rhabdomyosarcoma in the paediatric population. What is the most likely site of origin?

(a) Extremities

(b) Genito-urinary system

(c) Head and neck

(d) Orbits

(e) Retroperitoneal

A

(c) Head and neck

Rhabdomyosarcoma represents 4-8% of cancers in children and is the 4th commonest after CNS tumours, neuroblastoma and Willl)’s and is the commonest soft tissue sarcoma in children. The sites affected are: head and neck (28%), extremities (24%), genitourinary system, trunk (11%), orbits (7%), and retroperitoneum (6%); other sites in <3%.

45
Q

@#e2 (MSK) 58 A 30 year old patient presents with multiple bilateral renal angiomyolipomas, one of which has bled. She is also found to have a giant cell astrocytoma in her brain and bilateral interstitial lower lobe fibrosis on CXR. Which of the following bone lesions is most commonly associated with this condition?

(a) Bone cysts

(b) Osteochondroma

(c) Giant cell tumour

(d) Fibrous dysplasia

(e) Adamantinoma

A

(a) Bone cysts

The underlying condition described is tuberous sclerosis. The associated bone cysts most commonly affect the small bones of the hand. Other skeletal features include sclerotic bone islands which most commonly affect the calvarium (in 45% of cases) and also the pelvis and long bones.

46
Q

@#e (GU) QUESTION 30
Which one of the following radiological findings is a recognised feature of Von Hippel Lindau (VHL) disease?

A Bilateral adrenal masses that yield a high signal on T2w sequences

B Cerebral aneurysms on CT angiography

C Evidence of calcified subependymal nodules on CT head

D Polymicrogyria and corpus callosum agenesis on MRI brain

E Unenhanced CT head demonstrating a midline, hyperdense vermian mass abutting the roof of the 4th ventricle

A

A Bilateral adrenal masses that yield a high signal on T2w sequences

Phaeochromocytomas are hyperintense on T2w sequences and iso- or hypointense to the liver on Tlw sequences.

47
Q

@#e 61) On an axial section of the brain at the level of the third ventricle, which structure lies immediately lateral to the putamen?

a. internal capsule

b. globus pallidus

c. external capsule

d. thalamus

e. insular cortex

A

c. external capsule

The lentiform nucleus is composed of a larger lateral component (the putamen) and a smaller medial component (the globus pallidus), separated by a sheet of white matter. The lentiform nucleus is bounded medially by the internal capsule. Lateral to the lentiform nucleus lies the white matter of the external capsule, and then the claustrum, a thin sheet of grey matter. The extreme capsule lies lateral to the claustrum, and separates it from the insular cortex.

48
Q

@# 11. A patient is referred to your neurointerventional team for embolization of a meningioma prior to surgical resection. The lesion is based on the tentorium. What is the likely feeding vessel (parent vessel is named in brackets)?

A. Anterior meningeal artery (vertebral).

B. Middle meningeal artery (external carotid artery (ECA)).

C. Posterior meningeal artery (variable).

D. Bernasconi–Casanari artery (Internal carotid artery (ICA)).

E. Dorsal meningeal artery (ICA).

A
  1. D. Bernasconi–Casanari artery (ICA).

The majority of meningiomas occur in the parafalcine region, along the convexity or around the sphenoid. These all derive their supply from the ECA, although parafalcine meningiomas can also receive supply from a branch of the ophthalmic artery.

Tentorial or cerebellopontine angle (CPA) tumours are classically fed by the Bernasconi–Casanari artery, a branch of the meningohypophyseal trunk of the ICA.

Lesions around the foramen magnum, clivus, and posterior fossa are fed by branches of the vertebral artery (anterior and posterior meningeal) and meningohypophyseal trunk of the ICA.

49
Q

@#e2 37 A 64-year-old lady is being consented for a diagnostic cerebral angiogram for a suspected MCA aneurysm. She asks about the risk of stroke. What is the risk due to the angiogram?

a 4.7%

b 0.2%

c 1.3%

d 10%

e 3.5%

A

37 Answer C: 1.3%

The risk of stroke due to an angiogram is approximately 1.3 %.

50
Q

@#e2 22 You are considering the utility of CT in detecting acoustic neuromas and read a study evaluating its use in 200 people of whom 10 actually had the condition. The study reports that CT was reported as abnormal in seven patients and there were 188 true negatives. What is the sensitivity of CT for detection of acoustic neuroma in this study?

a 2.5%

b 29%

c 50%

d 70%

e 99%

A

22 Answer C: 50%

Sensitivity is a measure of how well the test picks up the disease if it is present; that is, true positives/(true positives and false negatives).

Specificity is a measure of how often the test is negative when the disease is not present; that is, true negatives/(true negatives + false positives).

51
Q

@#e2 17 A 55-year-old woman is being treated for hyperthyroidism using I131. How soon after it is ingested should imaging be performed?

a Within 30 minutes

b 1-2 hours

c 6 hours

d 24 hours

e One week

A

17 Answer D: 24 hours

I131 has a half-life of eight days and is usually taken as an oral preparation for the treatment of hyperthyroidism. Patients are typically imaged 24 hours after ingesting the I131. Antithyroid drugs are stopped six weeks before treatment to ensure maximum uptake of I131. Patients can remain on symptomatic management, such as beta-blocker type drugs, to reduce symptoms. The peak energy of 1131 is 364keV and the absorbed dose is 50-100cGy (rad). 1123 has a half-life of 13 hours and is ingested orally; imaging is typically performed after six hours. The peak energy is 159 keV and the absorbed dose is 2-5 cGy (rad).

52
Q

@#e2 2. The following skull foramina transmit the named cranial nerves: (T/F)

(a) Superior orbital fissure –VIth cranial nerve.

(b) Foramen ovale – orbital division of Vth cranial nerve

(c) Inferior orbital fissure – IIIrd cranial nerve.

(d) Internal auditory meatus – VIIth cranial nerve.

(e) Foramen rotundum – maxillary division of Vth cranial nerve.

A

Answers:

(a) Correct
(b) Not correct
(c) Not correct
(d) Correct
(e) Correct

Explanation:

The inferior orbital fissure transmits the infraorbital nerve (i.e. continuation of the second division of the fifth cranial nerve) and emissary veins that drain the inferior ophthalmic vein to the pterygoid plexus.

The foramen ovale transmits the mandibular division of fifth cranial nerve and the accessory meningeal artery.

The internal auditory meatus contains the seventh and eighth cranial nerves as well as the internal auditory artery.