Imaging modalities and physics: renal cyst pseudoenhancement: practice question

A Radiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Radiology · Imaging modalities and physics: renal cyst pseudoenhancement

Sample item

A 12-mm renal lesion measures 6 HU before and 22 HU after contrast on CT. Ultrasound shows a thin-walled anechoic lesion with posterior acoustic enhancement and no internal flow. What best explains the rise in attenuation?

APseudoenhancement of a simple cyst from reconstruction and beam-hardening correctionBTrue enhancement of a cystic renal cell carcinomaCCalcification of the cyst wallDHaemorrhage into the cyst between the two scans

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Pseudoenhancement of a simple cyst from reconstruction and beam-hardening correction

Small simple renal cysts can show an apparent rise in attenuation after contrast because the beam-hardening correction in reconstruction is affected by the adjacent brightly enhancing renal parenchyma. Anechoic appearance, posterior enhancement and absent Doppler flow confirm a simple cyst. Do not label it as an enhancing mass.

Option by option

A. Pseudoenhancement of a simple cyst from reconstruction and beam-hardening correction (correct)
Correct. Pseudoenhancement is a CT reconstruction effect and does not reflect vascularity.
B. True enhancement of a cystic renal cell carcinoma
True enhancement would need internal flow on Doppler and a solid component, which are absent.
C. Calcification of the cyst wall
Calcification would be dense on the unenhanced scan and would not change with contrast.
D. Haemorrhage into the cyst between the two scans
Haemorrhage would raise the unenhanced attenuation and produce internal echoes.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is A, Pseudoenhancement of a simple cyst from reconstruction and beam-hardening correction. Small simple renal cysts can show an apparent rise in attenuation after contrast because the beam-hardening correction in reconstruction is affected by the adjacent brightly enhancing renal parenchyma.

Why is "True enhancement of a cystic renal cell carcinoma" not the answer?

True enhancement would need internal flow on Doppler and a solid component, which are absent.

Why is "Calcification of the cyst wall" not the answer?

Calcification would be dense on the unenhanced scan and would not change with contrast.

Why is "Haemorrhage into the cyst between the two scans" not the answer?

Haemorrhage would raise the unenhanced attenuation and produce internal echoes.

What concept does this question test?

It tests Imaging modalities and physics: renal cyst pseudoenhancement in Radiology. Anechoic appearance, posterior enhancement and absent Doppler flow confirm a simple cyst. Do not label it as an enhancing mass.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Imaging modalities and physics: renal cyst pseudoenhancement?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.