Background Orthotopic liver transplantation (OLT) has become the therapeutic option of choice for end-stage liver disease.The aim of this study was to investigate the changes of splenic morphology,signal-to-noise ratio (SNR),contrastto-noise ratio (CNR),apparent diffusion coefficient (ADC) values and explore their value in evaluating the therapeutic effects of orthotopic liver transplantation (OLT) on portal hypertension at 1.5 Tesla MRI.Methods Twenty patients with portal hypertension undergoing OLT were included in this study.Conventional MRI and diffusion-weighted image (DWI) (b value=600 s/mm2) sequences were applied on each patient before and after OLT,and these patients were referred to as the preoperative and postoperative groups.Twenty healthy individuals were selected as the normal group.After image acquisition,the splenic width (W),thickness (T),length (L),the diameter of the portal vein (PD) and splenic vein (SD) were measured and the splenic volume (V) was calculated.The SNR and CNR were measured on T2WI.The ADC maps were calculated using the b600 in DWls and the ADC values were measured.Results Compared with the preoperative group,the splenic V,PD and SD decreased significantly in the postoperative group (P ＜0.05).All splenic morphological values were significantly different between preoperative and normal groups (P ＜0.05).The splenic L and V were significantly different (P ＜0.05) between postoperative and normal groups.The SNR and CNR values were 17.66±4.62 and 13.18±3.12,11.50±1.64 and 7.44±4.32,4.24±1.24 and 3.03±2.41 in the preoperative,postoperative and normal groups,respectively.Both SNR and CNR decreased after OLT,but they was still higher than the normal values.The SNR was significantly different between any two groups (P ＜0.05).The CNR was significantly different (P ＜0.05) between the preoperative and postoperative groups,preoperative and normal groups.The splenic ADC values were (1.339±0.482)×103 mm2/s,(1.120±0.254)x10-3 mm2/s and (0.997±0.447)×10-3 mm2/s in the preoperative,postoperative and normal groups,respectively.The difference of ADC values were significant (P ＜0.05) between the preoperative and postoperative groups,and the preoperative and normal groups.Conclusions OLT is an effective method of treatment for portal hypertension.In addition to dramatically decreasing the splenic V,it can also decrease the splenic SNR,CNR and ADC values in patients with portal hypertension.The changes of splenic SNR,CNR and ADC after OLT may be helpful in providing noninvasive supplementary information in assessing the therapeutic effect of OLT on portal hypertension.