Napkin-ring Sign TCFA — EECC MCQ

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HardCardiac ImagingNapkin-ring Sign TCFAEECC

A 55-year-old man with chest pain undergoes CT coronary angiography. The radiologist reports a 'napkin-ring sign' in a plaque in the proximal LAD. What does this feature indicate?

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Correct answer: E — The napkin-ring sign is a CT finding of a ring-like higher attenuation surrounding a low-attenuation plaque core — it indicates a thin-cap fibroatheroma (TCFA), the plaque type most prone to rupture and ACS

The napkin-ring sign (NRS) on CTCA represents a specific plaque morphology: a ring of higher-attenuation tissue (fibrous cap + outer rim of plaque) surrounding a central area of low attenuation (lipid-rich necrotic core). This corresponds histopathologically to a thin-cap fibroatheroma (TCFA) — the vulnerable plaque phenotype most prone to rupture. Studies (ROMICAT, ICONIC) show NRS is independently associated with future ACS events. Other high-risk plaque features on CTCA include: low-attenuation plaque (<30 HU), positive remodelling (RI >1.1), and spotty calcification. The 2024 ESC CCS Guidelines recognise these features as markers of plaque vulnerability that may guide intensification of medical therapy (aggressive LDL-C lowering, anti-inflammatory strategies) even in the absence of significant luminal stenosis.

Reference: ESC (2024): CCS Guidelines