Evaluation of regional blood flow dynamics of the liver by hepatic blood flow imaging using ultrafast MR imaging

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TrueFISP MR imaging of the portal flow using a selective inversion recovery tagging pulse was performed to evaluate the intraportal venous flow distribution from the superior mesenteric vein and the splenic vein. Tagged blood flow into the portal vein was shown as areas of decreased signal intensity in the portal vein. Especially, trueFISP images obtained perpendicular to the portal vein allows three-dimensional observation of intraportal venous flow distribution. In the study of normal subjects, the blood flow from the superior mesenteric vein and the splenic vein formed streamlined flow in the half of the subjects, but it showed whirled flow in the portal vein in the remaining subjects on the trueFISP MR images obtained perpendicular to the portal vein. TrueFISP MR imaging perpendicular to the portal vein achieved high spatial and high contrast resolution imaging and allowed detailed evaluation of the intraportal venous flow distribution. In patients with cirrhosis or chronic hepatit … More is, the whirled flow in the portal vein was often observed probably due to the increased splenic venous flow. The whirled flow may also be associated with the anatomical variations of confluent patterns between the splenic vein and the superior mesenteric vein.In evaluating the influence of fasting and food intake for the portal flow dynamics, we revealed that the portal vein was predominantly perfused by the splenic venous flow before meal while it was predominantly perfused by the superior mesenteric venous flow after meal. Additionally, the superior mesenteric venous flow dramatically increased after meal compared with the fasting state while the splenic venous flow decreased in 41%, increased in 31% and showed no change in 28% of the subjects.In hepatic perfusion MR imaging using multi-arterial and multi-portal phase contrast-enhanced dynamic MR imaging of the whole liver, we found useful appearances of hemodynamic patterns of focal hepatic lesions. Rapid central washout following the early enhancement of the lesion and coronal enhancement surrounding the lesion are highly specific and diagnostic findings of small hypervascular HCCs if present. Hypervascular pseudolesions tend to show prolonged enhancement during the arterial phase, compared with hypervascular HCCs. Subtraction images obtained from multi-arterial phase images were helpful for the detection of faint enhancement of the fecal hepatic lesions. Less