An optimal contrast dose indicator for the determination of hepatic enhancement in abdominal multidetector computed tomography: comparison of patient attenuation indicator with total body weight and body mass index

Dual-Energy Spectral Computed Tomography With Adaptive Statistical Iterative Reconstruction for Improving Image Quality of Portal Venography

OBJECTIVE

The aim of the study was to investigate whether spectral computed tomography (CT) plus adaptive statistical iterative reconstruction (ASIR) could improve imaging quality of computed tomography portal venography (CTPV).

METHODS

Sixty-four patients underwent CTPV, with CT number of portal vein (PV) less than 150 HU in portal phase, were divided into 2 groups A (n = 31), using standard 120-kVp protocol. group B (n = 33), using spectral CT protocol. Standard 120-kVp images were reconstructed with 40% ASIR, and monochromatic images at 60 keV were reconstructed with the following 4 ASIR percentages: 0%, 20%, 40%, and 60%. The CT number, image noise, and contrast-to-noise ratio in main PV were measured. The maximum intensity projection and volume-rendering images were used for subjective evaluation. These 2 kinds of results were statistically analyzed.

RESULTS

The contrast-to-noise ratio and subjective scoring of PV increased gradually from 120-kVp images to 60% weight ASIR (3.44 ± 0.95, 4.58 ± 1. 59, 5.26 ± 1.85, 6.18 ± 2.18, and 7.39 ± 2.65 and 4.35 ± 1.17, 6.21 ± 1.29, 6.48 ± 1.35, 6.85 ± 1.28, and 7.00 ± 1.19). There were statistically different for the 5 groups (P < 0.001). The CT number of the PV in the 60-kiloelectron volt spectral images had higher than the 120-kVp images (P < 0.001). The noise of 120 kVp was significantly higher than those of 60% ASIR and significantly lower than those of 0% ASIR (both P < 0.001), and there were no significant differences between 120-kVp, 20% ASIR, and 40% ASIR (P = 0.107 and 1.000, respectively). The diagnostic acceptability was highest at 40% ASIR.

CONCLUSIONS

Forty-percent ASIR addition to the 60-kiloelectron volt monochromatic image could improve image quality of CTPV comparing with conventional 120-kVp images.

Dual Energy CT (DECT) Monochromatic Imaging: Added Value of Adaptive Statistical Iterative Reconstructions (ASIR) in Portal Venography

OBJECTIVE

To investigate the effect of the adaptive statistical iterative reconstructions (ASIR) on image quality in portal venography by dual energy CT (DECT) imaging.

MATERIALS AND METHODS

DECT scans of 45 cirrhotic patients obtained in the portal venous phase were analyzed. Monochromatic images at 70keV were reconstructed with the following 4 ASIR percentages: 0%, 30%, 50%, and 70%. The image noise (IN) (standard deviation, SD) of portal vein (PV), the contrast-to-noise-ratio (CNR), and the subjective score for the sharpness of PV boundaries, and the diagnostic acceptability (DA) were obtained. The IN, CNR, and the subjective scores were compared among the four ASIR groups.

RESULTS

The IN (in HU) of PV (10.05±3.14, 9.23±3.05, 8.44±2.95 and 7.83±2.90) decreased and CNR values of PV (8.04±3.32, 8.95±3.63, 9.80±4.12 and 10.74±4.73) increased with the increase in ASIR percentage (0%, 30%, 50%, and 70%, respectively), and were statistically different for the 4 ASIR groups (p<0.05). The subjective scores showed that the sharpness of portal vein boundaries (3.13±0.59, 2.82±0.44, 2.73±0.54 and 2.07±0.54) decreased with higher ASIR percentages (p<0.05). The subjective diagnostic acceptability was highest at 30% ASIR (p<0.05).

CONCLUSIONS

30% ASIR addition in DECT portal venography could improve the 70 keV monochromatic image quality.