CT Perfusion Imaging Of Liver And Its Clinical Application

Section ITechnique Study of CT Perfusion Imaging of Liver Objective:The aim of this study was to explore a optimal CT scanning sequence,the calculation method of perfusion parameters and the technique of image reconstraction for CT perfusion imaging of liver, hope for get a reliable examination method that suits for Chinese people,so that this technique chould be widely applied clinically.Materials and Methods.Perfusion CT was performed in twenty patients without any obvious hepatic disorders and malignant tumors after clinical confirmation.First,after plain CT scanning of the whole liver,a single slice through the portal hepatis was repeatedly scanned for 45s during a single breath-holding after 7s~9s of intravenous bolus injection of 40ml~50ml nonionic contrast media at a rate of 4 ml.s-1~5ml.s-1.Second,five perfusion parameters such as HAP,PVP,TLP,HPI,PPI were obtained with maximum slope method,every perfusion parameter was calculated by non-correction and correction calculation method respectively,then the difference was compared between two calculation methods. Third, four images such as HAP,PVP,HPI,PPI were reconstracted with modified-deconvolution method,perfusion parameters were measured at the corresponding images respectively,the results were compared with the maximum slope method.Results:Firstly,Time-density curves (TDC) of portal vein,liver,spleen, aorta and/or hepatic artery were obtained and analyzed.The TDC of aorta was suddenly rise and fall,the TDC of hepatic artery was quickly rise and fall,the ratio of peak enhancement of aorta to peak enhancement of hepatic artery was 1.6429 + 0.3234.The TDC of portal vein was also quickly rise and fall,which appeared later and its amplitude was smaller than that of aorta.The TDC of normal hepatic parenchyma was slowly rise at the hepatic arterial phase,but quickly arriveded the peak at the portal venous phase,the TDC of normal spleen was quickly rise andslowly fall,its peak of which was between that of aorta and portal vein.Secondly,HAP,PVP,TLP,HPI,PPI of normal liver calculated by the non-correction calculation method were 0.2042 + 0.1025 ml.min-1.ml-1,1.0707 + 0.1816 ml.min-1.ml-1,1.2749 + 0.2174 ml.min-1.ml-1, 16.02% + 7.4%,83.98% + 7.4% respectively,the values of which calculated by the correction method were 0.3355+0.1269ml.min-1.ml-1,1.1034+0.2065ml..ml-1,1.4389 + 0.2398ml.min-1.ml-1,23.3%+10.2%,76.7%+10.2% respectively, only PVP had not obvious difference between the two calculation methods. Thirdly, normal parenchyma appeared as intermediate perfusion at the HAP image,and as high perfusion at the PVP image,the appearance of which at the HPI image and the PPI image were similar to that at the HAP image and the PVP image respectively.HAP and PVP measured at the reconstracted images were 0.3489 + 0.12ml.min-1.ml-1 and 1.2084 + 0.37ml. min-1.ml-1 respectively,TLP,HPI and PPI calculated by HAP,PVP were 1.5573 + 0.42ml.min-1.ml-1,22.41% + 8.31% and 77.59% + 8.31% respectively,the resultes had not obvious difference compared with that of maximum slope method.Conclusions :First,the method of CT scanning that a single slice through the portal hepatis is repeatedly scanned for 45s during a single breath-holding after 7s~9s of intravenous bolus injection of 40ml~50ml nonionic contrast media at a rate of 4 ml.s-1-5ml.s-1 is a optimal and practical scanning method of CT perfuion, by which the process of hemodynamic change of tissue and structure can be approximately reflected. Second,the perfusion parameters calculated by correction method is near to the physiologic state.Third,the perfusion images reconstructed by modified-deconvolution method can directly display the perfusion character of blood flow of normal liver,so this method is a simple and practical CT perfusion image reconstraction method,it is worth for further clinical application and widely spread.