Diagnostic accuracy of sub-mSv prospective ECG-triggering cardiac CT in young infant with complex congenital heart disease

Abstract

To explore the clinical value and evaluate the diagnostic accuracy of sub-mSv low-dose prospective ECG-triggering cardiac CT (CCT) in young infants with complex congenital heart disease (CHD). A total of 102 consecutive infant patients (53 boys and 49 girls with mean age of 2.9 ± 2.4 m and weight less than 5 kg) with complex CHD were prospectively enrolled. Scans were performed on a 64-slice high definition CT scanner with low dose prospective ECG-triggering mode and reconstructed with 80 % adaptive statistical iterative reconstruction algorithm. All studies were performed during free breathing with sedation. The subjective image quality was evaluated by 5-point grading scale and interobserver variability was calculated. The objective image noise (standard deviation, SD) and contrast to noise ratio (CNR) was calculated. The effective radiation dose from the prospective ECG-triggering mode was recorded and compared with the virtual conventional retrospective ECG-gating mode. The detection rate for the origin of coronary artery was calculated. All patients also underwent echocardiography before CCT examination. 81 patients had surgery and their preoperative CCT and echocardiography findings were compared with the surgical results and sensitivity, specificity, positive and negative predictive values and accuracy were calculated for separate cardiovascular anomalies. Heart rates were 70–161 beats per minute (bpm) with mean value of 129.19 ± 14.52 bpm. The effective dose of 0.53 ± 0.15 mSv in the prospective ECG-triggering cardiac CT was lower than the calculated value in a conventional retrospective ECG-gating mode (2.00 ± 0.35 mSv) (p < 0.001). The mean CNR and SD were 28.19 ± 13.00 and 15.75 ± 3.61HU, respectively. The image quality scores were 4.31 ± 0.36 and 4.29 ± 0.41 from reviewer 1 and 2 respectively with an excellent agreement between them (Kappa = 0.85). The detection rate for the origins of the left and right coronary arteries was 96 and 90 %, respectively. The detection rates of the origins of left coronary artery and right coronary artery in all cases were 96 % (78/81) and 90 % (73/81), respectively. Twenty cases of conotruncal anomalies and ALCAPA were validated surgically and the accuracy of cardiac CT diagnosis was 95 % (19/20). The overall deformity based sensitivity, specificity, positive predictive value and negative predictive value were 94.0.1, 99.9, 98.6, 99.5 % respectively, by CCT, and 88.2, 99.9, 97.8, 99.0 %, respectively, by echocardiography. Prospective ECG-triggering CCT with sub-mSv effective dose provides excellent imaging quality and high diagnostic accuracy for young infants with complex CHD.