AIM:To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography(CT) perfusion of rabbit VX2 tumor.METHODS:Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential(120 k Vp) protocol with 350 mg I/m L contrast medium and filtered back projection,and a low tube potential(80 k Vp) protocol with 270 mg I/m L contrast medium with iterative reconstruction.Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor.Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated.RESULTS:A 38% reduction in contrast medium dose(360.1 ± 13.3 mg I/kg vs 583.5 ± 21.5 mg I/kg,P < 0.001) and a 73% decrease in radiation dose(1898.5 m Gy·cm vs 6951.8 m Gy·cm) were observed.Interestingly,there was a strong positive correlation in hepatic arterial perfusion(r = 0.907,P < 0.001;r = 0.879,P < 0.001),hepatic portal perfusion(r = 0.819,P = 0.002;r = 0.831,P = 0.002),and hepatic blood flow(r = 0.945,P < 0.001;r = 0.930,P < 0.001) as well as a moderate correlation in hepatic perfusion index(r = 0.736,P = 0.01;r = 0.636,P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor.These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumorto-liver CNR during arterial and portal venous phases(5.63 ± 2.38 vs 6.16 ± 2.60,P = 0.814;4.60 ± 1.27 vs 5.11 ± 1.74,P = 0.587).CONCLUSION:Compared with the conventional protocol,low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.
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