Integrating perfusion with AI-derived coronary calcium on CT attenuation scans to improve selection of low-risk studies for stress-only SPECT myocardial perfusion imaging.

Abstract

Background: In many contemporary laboratories, a completely normal stress perfusion single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) is required for rest imaging cancelation. We hypothesized that an artificial intelligence (AI)-derived coronary artery calcium (CAC) score of 0 from computed tomography attenuation correction (CTAC) scans obtained during hybrid SPECT/CT may identify additional patients at a low risk of major adverse cardiovascular events (MACEs) who could be selected for stress-only imaging.

Methods: Patients without known coronary artery disease who underwent SPECT/CT MPI and had stress total perfusion deficit (TPD) <5% were included. Stress TPD was categorized as no abnormality (stress TPD: 0%) or minimal abnormality (stress TPD: 1%-4%). CAC was automatically quantified from the CTAC scans. We evaluated associations with MACEs.

Results: In total, 6884 patients (49.4% males and median age: 63 years) were included. Of these, 9.7% experienced MACE (15% non-fatal myocardial infarction, 2.7% unstable angina, 38.5% coronary revascularization and 43.8% deaths). Compared to patients with TPD 0%, those with TPD 1%-4% and CAC 0 had lower MACE risk (hazard ratio [HR]: 0.58; 95% confidence interval [CI]: 0.45-0.76), while those with TPD 1%%-4% and CAC score>0 had a higher MACE risk (HR: 1.90; 95% CI: 1.56-2.30). Compared to canceling rest scans only in patients with normal perfusion (TPD 0%), by canceling rest scans in patients with CAC 0, more than twice as many rest scans (55% vs 25%) could potentially be canceled.

Conclusion: Using an AI-derived CAC of 0 on CT scans with hybrid SPECT/CT in patients with a stress TPD <5% can double the proportion of patients in whom stress-only procedures could be safely performed.