Objectives: To evaluate image quality, radiation exposure and diagnostic accuracy of coronary CT angiography (CCTA) performed with a newest generation of cardiac-CT scanner in patients with heart rate (HR) >80 bpm and to compare this evaluation with that obtained in patients with HR suitable for conventional CCTA (<65 bpm).
Background: Despite the progressive improvement of temporal resolution in the recent scanner generation, the evaluation of coronary arteries in patients with high heart rate is still a challenging application of cardiac-CT. Moreover, CCTA performed in this conditions is associated with particularly high radiation exposure.
Materials and methods: 202 patients (111 males, mean age 66±8 years old) undergoing CCTA for suspected CAD by using a novel whole organ volumetric CT scanner (16cm z-axis coverage with 256 detector rows and 512 slices, gantry rotation time 0.28 sec), were enrolled in the study. Prospective ECG-triggering was used in all patients. In 100 patients (Group 1), the HR during the scan was ≥80 bpm; in the remaining 102 patients (Group 2), the HR during the scan was ≤65 bpm. In all patients, image quality score and coronary interpretability were evaluated and effective dose (ED) was recorded. Of the 202 patients prospectively enrolled, we evaluated the CCTA diagnostic accuracy vs. invasive coronary angiography (ICA) in the 86 patients (40 patients in group 1, 46 patients in group 2) who were referred for a clinically indicated ICA in the 6 months following CCTA.
Results: The mean HR during the scan was 93±24 bpm in Group 1 and 57±7 bpm in Group 2. The mean image quality was very high in both Groups (Likert=3.35 in Group 1 vs. 3.39 in Group 2). The overall coronary interpretability was 97.3% (1542/1584 segments) in Group 1 and 98% (1569/1600 segments) in Group 2, without statistically significant differences; The mean ED was low in the two Groups, with lower values in Group 2 (2.9±1.6 mSv in Group 1 and 1.1±0.5 mSv in Group 2). Sensitivity and specificity of CCTA for detection of >50% stenosis vs. ICA were 95.2% and 98.9% in a segment-based analysis and 100% and 81.8% in a patient-based analysis, respectively.
Conclusions: The novel whole organ high definition CT scanner allows to evaluate coronary arteries in patients with very high HR with excellent image quality and coronary interpretability and low radiation exposure.