Imaging modalities and physics: side-lobe artefact: 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: side-lobe artefact

Sample item

A gallbladder ultrasound shows low-level echoes layering in the dependent part of the lumen that vanish when the patient is turned and scanned from another angle. Which artefact is likely?

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

The answer and the reasoning

D. Side-lobe artefact

Off-axis side lobes of the beam strike strong reflectors, such as bowel gas, and the echoes are plotted as if on the main beam. The result is a pseudosludge appearance that disappears when the angle of insonation changes.

Option by option

  • A. Edge shadowing

    Edge shadowing is a dark band behind the lateral border of a curved structure.

  • B. Posterior acoustic enhancement

    Posterior enhancement is brightening behind a fluid-filled structure, not echoes inside the lumen.

  • C. Ring-down artefact

    Ring-down artefact is a bright line trailing a gas bubble and not a layering echo.

  • D. Side-lobe artefact (correct)

    Correct. Echoes from off-axis beam energy are mapped into the lumen as false sludge.

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.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, Side-lobe artefact. Off-axis side lobes of the beam strike strong reflectors, such as bowel gas, and the echoes are plotted as if on the main beam.

Why is "Edge shadowing" not the answer?

Edge shadowing is a dark band behind the lateral border of a curved structure.

Why is "Posterior acoustic enhancement" not the answer?

Posterior enhancement is brightening behind a fluid-filled structure, not echoes inside the lumen.

Why is "Ring-down artefact" not the answer?

Ring-down artefact is a bright line trailing a gas bubble and not a layering echo.

What concept does this question test?

It tests Imaging modalities and physics: side-lobe artefact in Radiology. The result is a pseudosludge appearance that disappears when the angle of insonation changes.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: side-lobe artefact?

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.