CT evaluation of living liver donor: Can 100-kVp plus iterative reconstruction protocol provide accurate liver volume and vascular anatomy for liver transplantation with reduced radiation and contrast dose?

Abstract

We evaluated whether donor computed tomography (CT) with a combined technique of lower tube voltage and iterative reconstruction (IR) can provide sufficient preoperative information for liver transplantation.We retrospectively reviewed CT of 113 liver donor candidates. Dynamic contrast-enhanced CT of the liver was performed on the following protocol: protocol A (n = 70), 120-kVp with filtered back projection (FBP); protocol B (n = 43), 100-kVp with IR. To equalize the background covariates, one-to-one propensity-matched analysis was used. We visually compared the score of the hepatic artery (A-score), portal vein (P-score), and hepatic vein (V-score) of the 2 protocols and quantitatively correlated the graft volume obtained by CT volumetry (graft-CTv) under the 2 protocols with the actual graft weight.In total, 39 protocol-A and protocol-B candidates showed comparable preoperative clinical characteristics with propensity matching. For protocols A and B, the A-score was 3.87 ± 0.73 and 4.51 ± 0.56 (P < .01), the P-score was 4.92 ± 0.27 and 5.0 ± 0.0 (P = .07), and the V-score was 4.23 ± 0.78 and 4.82 ± 0.39 (P < .01), respectively. Correlations between the actual graft weight and graft-CTv of protocols A and B were 0.97 and 0.96, respectively.Liver-donor CT imaging under 100-kVp plus IR protocol provides better visualization for vascular structures than that under 120-kVp plus FBP protocol with comparable accuracy for graft-CTv, while lowering radiation exposure by more than 40% and reducing contrast-medium dose by 20%.

Figure 1

Computed tomography (CT) volumetry for the liver graft. The graft is traced with the cutting line along the middle hepatic vein (arrows) on the axial CT image in the venous phase (A). Volume-rendering 3D image (B) shows the total volume of the graft (637 mL). The accurate graft weight was 590 g.

Figure 2

Thirty-year-old male donor candidate undergoing CT imaging under 100-kVp with IR (protocol B). Hepatic vein is clearly identified on the axial CT (A) and volume-rendering 3D images (B), providing helpful information for surgery. The hepatic artery and portal vein are also clearly visualized on volume-rendering 3D images (C and D, respectively). Each visual score (hepatic artery, hepatic vein, and portal vein) is excellent (score 5). CT = computed tomography, IR = iterative reconstruction.

Figure 3

A 40-year-old female donor candidate undergoing computed tomography (CT) imaging under 120-kVp with filtered back projection (protocol A). Hepatic vein is identified but partially unclear on the axial CT (A) and volume-rendering 3D images (B). The visual score for hepatic vein was fair (score 3).