摘要Objective:To clarify the length and volume reduction of seminal vesicles(SVs)after neo-adjuvant hormonal therapy(NHT),in order to help contour the optimal SV included into high-dose clinical target volume(CTV)for radiotherapy in intermediate-and high-risk patients.Methods:MR images both before and after NHT(5.3±2.2 months)were collected from thirty-one patients with cT2-4N0M0 prostate cancer.SV volume was measured in axial T1WI,while SV length was obtained in a recon-structed oblique coronary plane through its long axial from a 3D sequence.Results:SVs showed evident reduction both in length and volume(length:median 12.1％,range 4.0％-28.0％;volume:median 39.9％,range 9.4％-66.2％).For SVs with and without MR detected involvement,length short-ening were(16.7±4.8)％and(11.1±4.4)％(P＜0.001);for involved SVs and lesions,volume reduction were(41.0±16.0)％and(66.3±14.4)％,respectively(P＜0.001),both indicating a more sensitive response to NHT of the involved portion than normal SV.Conclusions:Both volume and length of the SV will be reduced after receiving NHT.Besides,the invaded segments shrink more than normal SV tissue,indicating that SV portion included within the CTV can be reduced.