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Model Answers

Case 1

Case 1 Model Answer:

Internal carotid artery occlusion with watershed infarct

Findings and interpretation:

MRI brain:

·       There are multiple, small high FLAIR signal intensity lesions in the right centrum semi-ovale, aligned in a linear configuration parallel to the lateral ventricle; they extend in some areas to the subcortical white matter and cortex of parts of the frontal and parietal lobe superiorly.

·       These lesions show high signal on diffusion weighted imaging, with corresponding low ADC signal. This indicates restricted diffusion.

·       The time of flight images show no flow in the right intracranial internal carotid artery. There is reduced flow in the right middle cerebral and anterior cerebral arteries, likely from circle of Willis collaterals.

MRI neck T1 fat-sat:

·       There is a large plaque at the origin of the right internal carotid artery, causing severe narrowing of the lumen. The lumen becomes obliterated immediately past the origin, and remains occluded up to the intracranial segments.

Pertinent negative findings:

·       There is no hyperintensity in the right internal carotid artery wall on the T1 fat-sat images to indicate dissection.

·       The left cerebral hemisphere is normal.


The findings represent multiple infarcts, the configuration and location of which corresponds to the deep internal arterial territory border zone. This indicates internal border zone watershed infarction, precipitated by chronic / acute-on-chronic right internal carotid artery occlusion and possibly an episode of systemic hypotension / impaired perfusion.   


Principal Diagnosis:

Right internal watershed cerebral infarction with chronic / acute-on-chronic right internal carotid artery occlusion.


Differential diagnosis:




Inform referring physician of findings and recommend neurological consult.

Case 1 Your Answer:

No Answer Submitted

Case 2

Case 2 Model Answer:

Usual interstitial pneumonia with unilateral lung transplant

Findings and interpretation:

·       There are prominent reticular opacities in a peripheral, subpleural distribution that extend from the apex to the base of the right lung; the bases show greater disease involvement.

·       There is honeycombing in the right lung base.

·       There is peripheral traction bronchiectasis in the right lung.

·       The volume of the right lung is reduced compared to the left lung.

·       Surgical clips are seen at the left hilum.

Pertinent negative findings:

·       The left lung is normal.

·       There are no discrete ground-glass opacities/ consolidation in the right lung.

·       No pleural plaques / esophageal dilatation/ shoulder joint arthropathy.


There is volume loss and interstitial fibrosis in the right lung, with a left sided lung transplant.


Principal diagnosis:

Usual interstitial pneumonia with left sided lung transplant.


Differential diagnosis:

·       Non-specific interstitial pneumonia (unlikely as there is no significant ground-glass opacification).



Recommend discussion at pulmonary MDT regarding further management.

Case 2 Your Answer:

No Answer Submitted

Case 3

Case 3 Model Answer:

Pulmonary sequestration with congenital pulmonary airway malformation

Findings and interpretation:

Chest radiograph:

  • There is an ill-defined, multi-cystic opacity in the right lower lung zone.

CT thorax:

  • There is a heterogeneous soft tissue mass in the right lower lobe posteriorly with multiple internal cysts of varying sizes.  
  • There is an artery supplying the mass which originates from the proximal abdominal aorta. Venous drainage of the mass is through the pulmonary veins to the left atrium.
  • The lesion is surrounded by normal lung tissue and not separated by its own pleural envelope. 

Pertinent negative findings:

·       The air spaces within the mass do not communicate with the tracheo-bronchial tree.

·       There is no fluid or air/fluid levels within the mass.


The findings represent a congenital, structural abnormality in the lung.


Principal diagnosis:

Intralobar pulmonary sequestration with an intrinsic congenital pulmonary airway malformation.


Differential diagnosis:

  • Congenital pulmonary airway malformation
  • Localized bronchiectasis



Alert referring physician of findings.

Recommend referral to cardiothoracic surgeon for surgical excision.

Case 3 Your Answer:

No Answer Submitted

Case 4

Case 4 Model Answer:


Findings and interpretation:

·       A single intervertebral disc at the mid-thoracic level shows high T2 / STIR and low T1 signal intensity.

·       There is irregularity of the adjacent vertebral endplates superior and inferior to the disc, as well as reduced height of the vertebral bodies superior and inferior to this level, indicating advanced bony destruction. This is causing a kyphotic deformity of the thoracic spine.

·       There is a heterogeneously T2 and STIR hyperintense mass at this level extending into the surrounding paravertebral space, as well as posteriorly into the spinal canal causing stenosis at this level. There is marked STIR hyperintensity (and low T1 signal) surrounding the mass, indicating oedema.

·       The mass involves the spinal epidural space, and is causing compression of the cord at this level.  

Pertinent negative findings:

·       No other spinal levels involved.

·       No surrounding paravertebral abscesses.


The findings represent an acute, aggressive spondylodiscitis with inflammatory phlegmon causing neural compromise.


Principal diagnosis:

Bacterial (staphylococcal) spondylodiscitis


Differential diagnosis:

·       Tuberculous spondylodiscitis (this is usually more indolent and involves more than one level).



Urgently contact referring physician and inform of findings.

Immediate spinal decompression surgery is indicated.

Case 4 Your Answer:

No Answer Submitted

Case 5

Case 5 Model Answer:

Glioblastoma Multiforme

Findings and interpretation:


·       There is an ill-defined mass lesion of heterogeneous density centred in the splenium of the corpus callosum and crosses the midline. It extends into the septum pellucidum, as well as the body and atrium of the left lateral ventricle.

·       There is hypo-attenuation of the periventricular and deep white matter adjacent to the left lateral ventricle posteriorly, reflecting vasogenic oedema. There is mass effect, as evidenced by effacement of the left parietal and occipital lobe sulci, and distortion of the lateral ventricles.    

·       The post-contrast sequence shows thick, irregular peripheral enhancement of the mass lesion with a non-enhancing centre.


·       The mass lesion shows heterogeneous FLAIR signal intensity, with surrounding high FLAIR signal, confirming the significant degree of surrounding vasogenic oedema.

·       There is mild hyperintensity of the periphery of the lesion on diffusion weighted imaging, with corresponding low signal on the ADC map, indicating mild diffusion restriction of the periphery. The centre of the lesion shows no diffusion restriction.

Pertinent negative findings:

·       There is no evidence of haemorrhage within the mass.

·       No other intracranial lesions.


The findings reflect an aggressive mass lesion, with a solid peripheral component and a likely necrotic centre.


Principal diagnosis:

Glioblastoma multiforme


Differential diagnosis:

·       CNS lymphoma: Typically more solid and hyperdense on CT.

·       Abscess: Unlikely; this usually shows a regular border and marked internal diffusion restriction.



Alert referring physician of findings.

Refer for discussion at neurology / neurosurgery MDT with regards to biopsy / commencement of radiotherapy / chemotherapy.

Case 5 Your Answer:

No Answer Submitted

Case 6

Case 6 Model Answer:

Trichobezoar causing small bowel obstruction

Findings and interpretation:

·       The stomach is markedly distended, with a laminated foreign body in the lumen which does not contact the stomach wall; the object shows heterogeneous density, and has a mottled appearance with air foci within.

·       There is dilatation of multiple segments of small bowel, including some duodenal segments, proximal jejunum, and distal ileum. 

·       The dilated distal ileal loops are filled with material showing the same mottled appearance with debris and gas foci.

·       There are focal segments of small bowel that show thickened and hyper-enhancing walls.

·       Both kidneys have multiple, small hypodense and non-enhancing lesions, consistent with simple cysts in both the cortex and the medulla.

Pertinent negative findings:

·       The large bowel is non-dilated and appears normal.


The findings represent mechanical small bowel obstruction caused by ingested material forming obstructing masses; this is causing focal small bowel inflammation. Given the history of psychiatric illness, this is likely to represent hair ingestion giving rise to trichobezoar formation in the stomach and bowel.

The renal cysts most likely represent lithium nephropathy in this clinical context.


Principal diagnosis:

Trichobezoar causing small bowel obstruction and inflammation; lithium nephrotoxicity.


Differential diagnosis:

·       Phytobezoar or other ingested material.

·       Renal findings: Acquired cystic disease of uraemia (unlikely as there is no history of dialysis).



Alert referring physician of findings.

Correlate with history of lithium treatment.

Case 6 Your Answer:

No Answer Submitted
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