Comparative study of multiparametric MRI of intraprostatic lesion detection: Correlation with transrectal ultrasound-guided and template biopsies.

Abstract

e15003 Background: Multiple MRI techniques (T2W, dynamic contrast enhancement (DCE), diffusion-weighted (DW) and spectroscopic imaging (MRSI)) can detect the intraprostatic location of cancer. This study compares the diagnostic performance of each alone and in combination for detecting cancer in men with raised serum PSA levels. Methods: 20 patients (PSA 6.5ng/ml; range 4.5- 47.9ng/ml; previous negative systematic TRUS=11) underwent multifunctional MRI studies. T2W, DCE, DW and MRSI MRI findings were correlated with TRUS or template biopsies. Each prostate was divided in multiple sectors according to biopsy site. For TRUS biopsy correlations, only the posterior 1.5cm (needle length) of each gland was evaluated. A radiologist blinded to biopsy results evaluated each sequence, scoring each sector 1(definite normal)-5(definite cancer) using literature based criteria. ROC analysis was used to compare diagnostic performance of each technique alone and in combination. Results: 329 biopsies from 100 sectors were reviewed (median 3/sector; range 1-12). 15 sectors had cancers (prevalence 15%; pre-test likelihood). 2 sectors had Gleason 3+4 cancer and 13 sectors had Gleason 3+3 cancer. Only T2W (AUC 0.67, P=0.03; sen 40%, spec 94%) and DW-MRI (AUC 0.72, p=0.005; sen 67%, spec 69%) were able to detect cancer. DCE-MRI and MRSI were poor at cancer detection (p=NS). Combining T2W+DW-MRI was not better than DW-MRI alone (AUC 0.71, p=0.008; sen 60%, spec 76%). The post-test likelihood of cancer being present/sector (positive predictive value) increased by 45%, 10% & 15% for T2W, DW-MRI & T2W+DW-MRI respectively. 8 of 9 T2W/DW false negative sectors had small volume tumor (length less or equals 2mm/involved core). Negative predictive value (NPV)/sector was high for T2W/DW-MRI (increasing by 5% to 90% for both). Presumed tumor foci in non-biopsied TRUS regions were seen in 3/16 patients (diameter 8mm-20 mm). Conclusions: Only T2W and DW-MRI are useful for detecting cancers in patients with previous negative systematic TRUS prostate biopsies and persistently raised PSA levels. The high NPV/sector suggests a role for MRI in guiding biopsies. No significant financial relationships to disclose.