The performance of non-ECG gated chest CT for cardiac assessment: The cardiac pathologies in chest CT (CaPaCT) study

Purpose: Evaluating the prevalence of CAD on non-ECG gated chest CTs, image quality (IQ) and the clinical performance of the CAD-RADS classification for predicting cardiovascular events (CVE).

Methods: 215 consecutive patients referred for chest CTs between May 2016 and March 2018 were included (3rd-generation DSCT) using non-ECG gated acquisitions with automated tube voltage selection (110kV(qual.ref)/40mAs(qual.ref)), pitch 2.65-3.0 and individualized contrast media injection protocols. Dedicated cardiac post-processing reconstructions (0.6 mm/0.4 mm/Kernel Bv36) were added to standard chest reconstructions.

Two independent cardiac radiologists performed a 3-step analysis. In case of discrepancy, a third reader gave the final decision. Step 1: visual presence of calcifications; 2: scans with calcifications assessed for IQ using a 5-point Likert scale (poor/sufficient/moderate/good/excellent); 3: stenosis severity was analysed in detail (if Likert sufficient-excellent using CAD-RADS). Electronic patient files were checked to see if pathology was previously mentioned (incidental) and whether patients developed an CVE during follow-up.

Results: 1: Calcifications were present in 156/215 cases (72.6 %), 74 of these were incidental. 2: In 68/156 (43.6 %) patients with calcifications IQ was rated sufficient-excellent. 3: CAD-RADS >= 3 was seen in 39/68 patients (57.4 %), 12 times (30.8 %) findings were incidental. During follow-up (median 16 [0-35] months), 7/39 (18 %) patients with CAD-RADS >= 3 developed a CVE. 17 patients died during follow-up.

Conclusion: Coronary calcification on non ECG-gated chest CTs was detected in 72.6 % of patients, cardiac assessment was feasible in nearly half of these patients. Only patients with a CAD-RADS >= 3 developed CVE, therefore the CAD-RADS may help identify and guide patients at risk of future CVE.