Multi-parametric MRI findings of transitional zone prostate cancers: correlation with 3-dimensional transperineal mapping biopsy

Purpose A preliminary project to correlate MR findings with mapping prostate biopsy to help differentiate malignant transitional zone lesions form benign prostatic hyperplasia (BPH) nodules. Materials and Methods Institutional IRB approved retrospective study with 14 patients suspected of having prostate cancer who underwent both prostate 3T MRI using endorectal coil and 3D transperineal mapping prostate biopsy. MR exams were independently reviewed by two abdominal radiologists blinded to pathology with disagreement resolved by consensus. An MRI lesion was defined as having hypointense T2 signal subjectively without corresponding T1 high signal intensity and low signal on ADC maps in the central gland. Mapping biopsy consisted of systematic transperineal US guided biopsy with 55-108 cores per patient. Results Twenty-nine lesions were detected on MRI. Of these, 13 correlated with Gleason 6 or higher biopsy samples. 16 were biopsy negative. Among the various MRI characteristics assessed, lack of T2 hypointense rim demonstrated the highest specificity (93%) and positive predictive value (89%). Highest sensitivity (85%) and negative predictive value (78%) were seen with ill-defined nodules. When suspicious MR characteristics were combined, the specificity and PPV rose to 100% while sensitivity decreased to 45% and NPV decreased to 73%. Conclusions Preliminary study indicates MR findings which can help differentiate a BPH nodule from transitional zone prostate cancers which could help direct biopsy in the large and growing number of people suspected of having prostate cancer. Further work will be needed for validation.