Prospective comparison of a fast 1.5-T biparametric with the 3.0-T multiparametric ESUR magnetic resonance imaging protocol as a triage test for men at risk of prostate cancer.

OBJECTIVE

To compare prospectively the diagnostic performance of a biparametric (T2-weighted imaging [T2WI] and diffusion-weighted imaging [DWI]) 1.5-T fast magnetic resonance imaging (fMRI) protocol with the standard 3.0-T multiparametric MRI (mpMRI) protocol of the European Society of Urological Imaging (ESUR) in men referred for a prostate biopsy.

PATIENTS AND METHODS

Ninety patients with a prostate cancer (PCa) risk of ≥10% according to the SWOP calculator 4 underwent first fMRI and then the reference mpMRI. Patients with Prostate Imaging Reporting and Data System (PI-RADS) v.2 lesions ≥3/5 on the mpMRI were scheduled for MRI/ultrasonography (US) fusion-guided prostate biopsy. Performance of fMRI was assessed using receiver-operating characteristic curve analysis and mpMRI as reference. Calculation of inter-technique agreement on PI-RADS v.2 score by Cohen's κ.

RESULTS

The diagnostic accuracy of fMRI shown by the lesion-based analysis was excellent: area under the curve (AUC) 0.961 (P < 0.001), sensitivity 95%, specificity 97%, positive predictive value (PPV) 99%, negative predictive value (NPV) 89%. The patient-based analysis showed an AUC for fMRI of 0.975 (P < 0.001), a sensitivity of 98%, a specificity of 97%, a PPV of 98% and an NPV of 97%. Agreement on the PI-RADS score between both protocols was found to be good (κ = 0.78 [0.57; 0.99]); fMRI missing PI-RADS 4 lesions in three patients. Biopsy results showed no cancer in two patients (two cores per nodule) and Gleason 6 cancer in one patient. There was only one false-positive fMRI, with a PI-RADS score of 4, whose biopsy was negative.

CONCLUSION

In the triage of men with a high risk of PCa for prostate biopsy, an f MRI protocol (1.5-T magnet, T2WI + DWI, <15 min) may safely replace the traditional ESUR 3.0-T mpMRI protocol, saving time and contrast injection.