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

Abstract

Background: 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).

Methods: 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.

Results: 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.

Conclusions: Visual assessment of CAC on CTAC should be performed during SPECT/CT MPI because it affects diagnostic certainty and may improve risk stratification.

Keywords: Myocardial perfusion imaging: SPECT; computed tomography (CT); coronary artery disease; diagnostic and prognostic application.