Image quality evaluation of iterative model reconstruction on low tube voltage (80 kVp) coronary CT angiography in an animal study

Abstract

Iterative model reconstruction (IMR) is a newer generation iterative reconstruction method, but its value on coronary computed tomography (CT) angiography requires investigation. To evaluate coronary image quality using IMR at a low-tube voltage of 80 kVp on coronary CT angiography in miniature pigs. Five healthy miniature pigs underwent prospective electrocardiogram-gated coronary 256-slice CT angiography at 120 kVp and 80 kVp tube voltages, respectively. Filtered back projection (FBP) was used to reconstruct the 120 kVp standard-dose (SD) image sets (SD-FBP group), while iDose(4) and IMR were used to reconstruct the 80 kVp low-dose (LD) image sets (LD-iDose(4) and LD-IMR groups). Objective and subjective image qualities were compared among three groups. There were no significant differences in mean CT values of the ascending aorta, left main coronary artery, and right coronary artery between the LD-IMR and LD-iDose(4) groups (P > 0.05), but the values were significantly lower in the SD-FBP group than in those two groups (P < 0.05). The image noise in the LD-IMR group (21.5 ± 3.9 HU) was significantly lower than in the LD-iDose(4) (63.7 ± 9.8 HU) and SD-FBP (50.6 ± 4.6 HU) groups (P < 0.05). The signal-to-noise and contrast-to-noise ratios were significantly higher in the LD-IMR group than in the LD-iDose(4) and SD-FBP groups, respectively (P < 0.05). Subjective scoring of image noise, streak artifacts, and overall image quality indicated that the LD-IMR group was consistently superior to the LD-iDose(4) and SD-FBP groups (P < 0.05). IMR can significantly improve image quality at a low-tube voltage (80 kVp) with a 66% radiation dose reduction on coronary 256-slice CT angiography in miniature pigs.