Visual identification of coronary calcifications on attenuation correction CT improves diagnostic accuracy of SPECT/CT myocardial perfusion imaging

Coronary artery calcium (cac) is a powerful cad risk marker when assessed by dedicated calcium scoring ct scan. we assessed diagnostic implications of cac visible on attenuation correction ct scans (ctac) from spect/ct myocardial perfusion imaging (mpi). visual presence or absence of cac was assessed on ctac in 1047 consecutive patients undergoing spect/ct mpi. accuracy of mpi was assessed in patients undergoing invasive coronary angiography (ica) within 1 year (n = 109). outcomes were identified by retrospective chart review. prevalence of true positive spect/ct mpi studies was greater among patients with cac on ctac (70% vs 16%; p < .001); prevalence of false positive studies was greater among those without (68% vs 15%; p < .001). ppv of mpi was 0.82 in patients with cac, but only 0.19 in those without. within median follow-up of 27.7 months, patients with cac had higher all-cause mortality (6% vs 0.4%; p < .001), more late revascularizations (8% vs 0.4%; p < .001), and more mi (5% vs 0.2%; p < .001). hazard ratio for all-cause mortality, mi, or late revascularization was 22.7 (p < .001) for patients with cac vs those without. visual assessment of cac on ctac should be performed during spect/ct mpi because it affects diagnostic certainty and improve risk stratification.