Prospective Comparison of Ultra-high-resolution Photon-counting-detector CT Coronary Angiography versus Conventional CT.

OBJECTIVES

Determine differences in quantitative stenosis severity measurements for ultra-high-resolution (UHR) photon-counting-detector (PCD) coronary CT angiography (cCTA) relative to energy-integrating-detector (EID) cCTA in a large patient cohort.

METHODS

Adult participants seen between November 2022 and March 2023 underwent a clinical dual-source EID-CT cCTA and a research dual-source PCD-CT cCTA on the same day. Percent diameter stenosis (PDS) was measured, and stenosis severity was assigned based on the PDS of the most severe lesion per patient to determine a coronary-artery-disease reporting and data system (CAD-RADS) score. Agreement between EID-CT and PCD-CT for PDS and CAD-RADS was determined.

RESULTS

A total of 112 participants were enrolled, yielding 82 subjects with at least 1 stenosis at PCD-CT (mean age, 68.0 ± 10.8 years; 69.5% (57/82) males). A total of 177 paired stenoses were quantified. The percent decrease in mean PDS from PCD-CT (24.3%) to EID-CT (29.4%) was 17.3% (median difference in PDS: -5.0%, 95% CI: -5.7% to -4.0%). The assigned CAD-RADS score changed 31/82 times. In 11/31 subjects, the most severe stenosis was missed at EID-CT due to partial volume averaging of a small calcification, yet PCD clearly identified stenosis at those locations. In 20/31 subjects, the CAD-RADS score decreased at PCD-CT due to the decreased calcium blooming resulting from the improved spatial resolution.

CONCLUSIONS

UHR PCD cCTA decreases quantitative measures of stenosis severity when a stenosis is identified at EID, leading to decreases in CAD-RADS assignments.

ADVANCES IN KNOWLEDGE

With its improved spatial resolution, PCD-CT identifies stenoses missed on EID-CT.