MAPPING OF PORTAL VEIN IN LIVE LIVER DONORS

Shruthy KM and Rathi Sudhakaran. Department of Anatomy, ACS Medical College and Hospital, Chennai, Tamil Nadu, Department of Anatomy, Amrita School of Medicine, AIMS, Kochi, Kerala. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Aim of this study is to document the prevalence of anatomical variations of portal vein from MDCT abdomen images of live liver donors who have attended to a tertiary care hospital in Kochi. Images of 300 live liver donors are assessed and grouped according to the classification done by Cheng et al for portal vein. The portal venous anatomy was of type I in 86% of the portal phase images obtained, type II in 8% cases, type III in 5% cases, and type IV in 1% cases. Awareness of the rare Type II and Type III variants is important preoperatively and intraoperative to avoid risking the donor's life.

Introduction:-
Liver transplantation has matured from an experimental procedure to an accepted life saving operation for long time of survival in patients with advanced liver diseases who have reached the limits of medical intervention. In LDLT donor safety is paramount and donor evaluation is done to find out whether the donor is suitable for donation and also to evaluate the vascular anatomy, segmental anatomy and the bile duct anatomy. The understanding of internal anatomy of liver has greatly facilitated liver surgery 1 . Preoperative clinical and radiological evaluation of the transplant candidate is critical for appropriate patient selection. The main objective of preoperative imaging is to provide the surgeon with necessary information to plan and perform liver transplantation and exclude donors with whom surgery is not feasible. Multidetector CT proves to be valuable in the evaluation of a potential live liver donor by providing comprehensive information about the hepatic vascular anatomy 2 . Most of our knowledge is based on the data obtained from Western and East Asian studies. We endeavor to analyze the pattern of hepatic vasculature in Indian patients with similar studies in the past.

Materials and methods:-
The data required for this retrospective study is collected from the Department of Radiology, Amrita Institute of Medical Sciences, Kochi. This includes the MDCT images of the hepatic vasculature of 300 live liver donors who had undergone hepatectomy during the period 2006-2014. For imaging 64 Multidetector CT scanner (SEIMENS SENSATION CARDIA-64) is used. The pre-contrast series is taken by using a 5 mm slice thickness. An average of 80 ml of low osmolar non-ionic contrast medium (Omnipaque 350mg) is given at 5 ml/sec. The post-contrast CT images are taken at 6s, +20s and +30s for arterial, portal and delayed phase respectively. The images that had undergone three-phase, dual-enhancement are analyzed from their source images and from three-dimensional (3D) post processing images like maximum intensity projections (MIP) and reconstructed image as volume renderings

Discussion:-
Liver resection has gained importance in the field of surgery as a therapeutic means for several liver diseases. LDLT has added another dimension for liver resection. Success of liver surgeries is not only due to refinements in surgical, anaesthetical and critical care developments but also due to the precision of anatomical assessment. The precise preoperative anatomical road map helps the surgeon make a complex surgery technically feasible. In LDLT, the recipient and the donor, both will be benefitted by the information on minute details of the hepatic vasculature. The advent of MDCT has made it a single stop method preferred technically to assess the information regarding potential liver donors 2 . For assessing the results of the present study on the variants of portal vein, we use the classification done by Cheng 22 .  The strength of this study is its sample size, the results were confirmed intraoperatively and this is the first study done in liver donors in an Indian setup. However the limitation of the study is that the study group includes only the donors who underwent liver resection.

Conclusion:-
Variations in the hepatic vasculature are frequently encountered and reported in several studies. LDLT is a procedure requiring detailed evaluation of the hepatic vascular anatomy to ensure successful postoperative results. The triphasic CT protocol using 64 Multidetector permits comprehensive and accurate assessment of the detailed hepatic vascular anatomy in liver transplant potential donors, thereby preventing surgical complications arising from vascular variations.