Diagnostic value of multiparametric MRI in detecting residual or recurrent prostate cancer after high-intensity focused ultrasound

Purpose: To evaluate the diagnostic performance of follow-up multiparametric MRI for prediction of recurrent prostate cancer after high-intensity focused ultrasound (HIFU), and to find other, if any, clinical or radiological predictors. Materials and methods: Post-HIFU MRIs of 110 consecutive patients who underwent follow-up biopsies between August 2019 and April 2021 were retrospectively analyzed and the likelihood of recurrence was assessed on a five-point Likert scale by two board-certified uroradiologists. Diagnostic performance of the Likert scale assigned to the post-HIFU MRI was assessed using the follow-up biopsy results as a reference standard. Among the clinical and radiological variables, predictors of the recurrence were examined through logistic regression. Results: In per-patient and per-sector analyses, Likert scale on post-HIFU MRI showed a sensitivity and specificity of 0.37 and 0.97, and 0.42 and 0.87, respectively, in predicting recurrence. Two patients with high suspicion on MRI required additional treatment to regain biochemical control despite negative biopsies. High suspicion on post-HIFU MRI (odds ratio = 1.74; p< 0.01), and more cancer-positive cores on initial biopsy (odds ratio = 1.25; p= 0.03) were independent predictors of recurrence. Conclusion: Albeit with low sensitivity, high suspicion on post-HIFU MRI may be clinically important because of its high specificity, especially when considering the possibility of sampling error in biopsies. Patients with a high number of cancer-positive cores at diagnosis should avoid HIFU as they have an increased risk of recurrence.