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CTCA Calcification Limitation — EECC MCQ

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ModerateCoronary Artery DiseaseCTCA Calcification LimitationEECC

A 72-year-old man with prior CABG and recurrent angina has a CT coronary angiogram showing patent LIMA-LAD but new severe native LCx stenosis. The radiology report notes a calcium score of 1,850 Agatston units. What limitation does severe coronary calcification impose on CTCA interpretation?

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Correct answer: E — Heavy calcification causes blooming artefact on CTCA, leading to overestimation of stenosis severity and reduced diagnostic accuracy; invasive angiography with physiological assessment may be needed for definitive assessment

Severe coronary calcification is the main limitation of CTCA interpretation. Dense calcium causes 'blooming artefact' — high-attenuation calcium appears larger than its true size on CT due to partial volume effects, obscuring the coronary lumen and leading to overestimation of stenosis severity (reduced specificity). The 2024 ESC CCS Guidelines note that CTCA diagnostic accuracy decreases in patients with very high calcium scores (>400-1000 AU). In severely calcified vessels, options include: (1) functional testing (stress imaging) to assess for ischaemia; (2) invasive coronary angiography with FFR/iFR for definitive assessment; (3) CT-FFR may partially overcome blooming artefact by using computational modelling. CTCA remains excellent for its negative predictive value even in moderate calcification.

Reference: ESC (2024): CCS Guidelines