ECG-gated CT coronary angiography (CTCA) shows a plaque in the left anterior descending artery (LAD) with a CT attenuation of −40 HU within the plaque. This low-density plaque component indicates:
- A Calcified plaque
- B Lipid-rich necrotic core (lipid pool) — a feature of high-risk vulnerable plaque ✓
- C Fibrous plaque (fibrous cap)
- D Thrombus within the plaque
Correct answer: B. Lipid-rich necrotic core (lipid pool) — a feature of high-risk vulnerable plaque
Explanation
On CTCA, plaque components are characterised by HU: calcified plaque > 130 HU (bright), fibrous plaque 60–100 HU (intermediate), and lipid-rich/necrotic core < 30 HU (or negative HU) representing the lipid pool. A plaque containing a lipid-rich necrotic core (low-attenuation plaque, LAP) is a CT correlate of a 'vulnerable plaque' and is associated with increased risk of acute coronary syndrome. Thrombus measures 30–60 HU and is typically luminal.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.