Evaluation of semi-quantitative parameters of prostate MR spectroscopy: comparison with biopsy / 中华放射学杂志

ABSTRACT

Objective To explore convenient and practical semi-quantitative MRS indicators in diagnosis of prostate cancer.Methods One hundred patients with completer MRS data and clinical data were enrolled in the study.The following parameters were assessed to evaluate their efficacy in diagnosis of prostate cancer, (Cho + Cr)/Cit of single voxel, mean (Cho + Cr)/Cit of the whole area and (Cho + Cr)/ Cit positive voxel ratio at the sextant level.Similarly, all the parameters mentioned above and mean (Cho +Cr)/Cit positive voxel ratios of the whole gland were assessed at the whole gland level.Pearson test and Kappa test were used in the research.Results Two thousand nine hundred and forty-five voxels were assessed including 1203 in cancer positive region and 1742 in cancer negative regioa The range of the (Cho + Cr) /Cit ratio in cancer positive region was from 0.22 to 8.00 (median, 1.87), and that in cancer negative region was from 0.11 to 8.00 (median, 0.53).The (Cho + Cr)/Cit ratio in cancer positive region was higher than that in cancer negative region (Z =28.48, P<0.01) with partial overlap.On the level of sextant, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of (Cho + Cr)/Cit ratio> 0.911 to diagnose prostate cancer were 81.4% (179/220),64.2% (194/302), 62.4% (179/287) 、82.6% (194/235) 、71.5% (373/522) respectively; those of mean (Cho + Cr)/Cit ratio>0.911 were 77.3% (170/220),77.2% (233/302),71.1% (170/239),82.3% (233/283),77.2% (403/522) respectively; those of positive voxel ratio>0.519 were 73.2% (161/220),80.8% (244/302)、 73.5% (161/219),80.8% (244/302), 77.6% (405/522) respectively; the consistency between mean (Cho + Cr) /Cit ratio and positive voxel ratio was high (Kappa=0.907).On the level of the whole prostate, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of (Cho + Cr)/ Cit ratio>0.911 to diagnose prostate cancer were 94.3% (50/53),40.4% (19/47),64.1% (50/78), 86.4% (19/22),69.0% (69/100) respectively; those of mean (Cho + Cr)/Cit ratio>0.911 were73.6% (39/53),83.0% (39/47), 83.0% (39/47), 73.6% (39/53), 78.0% (78/100) respectively; those of maximum positive voxel ratio> 0.519 were 88.7% (47/53),61.7% (29/47),72.3% (47/65),82.9% (29/35),76.0% (76/100) respectively; those of mean positive voxel ratio>0.519 were 62.3% (33/53), 85.1% (40/47), 82.5% (33/40), 66.7% (40/60), 73.0% (73/100) respectively; the consistency between mean (Cho + Cr)/Cit ratio and mean positive voxel ratio was fairly high (Kappa =0.818).Conclusion Single voxel criteria were suggested to diagnose clinically suspected prostate cancer.Maximum positive voxel ratio criteria were suggested to guide localization in biopsy.