Three dimensional proton MR spectroscopic imaging in transition zone prostate cancer

Abstract

Objective To discuss the clinical value of three dimensional proton MR spectroscopic imaging( 3D 1HMRSI) in the detection of transition zone(TZ) prorate cancer and evaluate the feasibility of 3D 1HMRSI for determining the aggressiveness of TZ cancer by analyzing its metabolic characteristics.Methods The 3D 1HMRSI data of sixty patients suspected TZ cancer in conventional MR examinations were retrospectively analyzed.The values of (Cho + Cre)/Cit of TZ cancer and benign prostatic hyperplasia (BPH) voxels were recorded and compared using independent sample t' test,and the area under the ROC curve was used to evaluate the diagnostic accuracy.Based on Gleason scores,TZ cancer voxels were divided into three groups,including low-risk ( Gleason score ＜ 7 ),intermediate-risk ( Gleason score =7 ) and highrisk (Gleason score ＞ 7).The values of (Cho + Cre)/Cit were compared among the three groups using Kruskal-Wallis test.The correlation of the value of (Cho + Cre)/Cit and Gleason score was analyzed using rank correlation analysis.Results Among the 60 patients,histopathology confirmed TZ cancer in 25 patients and BPH in 35 patients.The inversion of Cho and Cit peak value with increased ( Cho + Cre)/Cit was detected in 160 out of 177 TZ cancer voxels.Most spectral curves of the 517 BPH voxels were similar with that of normal peripheral zone on 1HMRSI.The mean values of ( Cho + Cre)/Cit of TZ cancer and BPH voxels were 2.17 ± 1.29 and 0.77 ± 0.20,respectively,with significant difference between them( t' =14.38,P ＜ 0.01).Using (Cho + Cre)/Cit for distinguishing TZ cancer,the area under ROC curve was 0.985 (P ＜ 0.01).With the cut-off point 1.08,the sensitivity,specificity and accuracy of TZ cancer diagnosis was 92.7％,94.2％ and 93.8％,respectively.The number of low-risk,intermediate-risk and high-risk TZ cancer voxels were 57,64 and 56 respectively,and the mean values of ( Cho + Cre)/Cit of the three groups were 1.43 ( 1.16-1.87 ),1.66 ( 1.43-2.36 ) and 2.32 ( 1.86-3.30 ) respectively,with significant difference among them ( x2 =36.282,P ＜ 0.01).The value of ( Cho + Cre )/Cit of TZ cancer increased with the increasing of Gleason score with positive correlation ( r =0.555,P ＜ 0.01).Conclusions TZ caner has a different metabolic profile from BPH.The value of ( Cho + Cre)/Cit on 3D 1HMRSI could provide useful information for early detection and differentiation TZ cancer from BPH.Besides these,( Cho +Cre)/Cit is also a valuable imaging marker to evaluate the aggressiveness of TZ cancer. Key words: Prostatic neoplasms; Prostatic hyperplasia; Magnetic resonance spectroscopy