PSMA PET May Improve the Diagnostic Accuracy of mpMRI in Localised Prostate Cancer as Confirmed by Whole-Mount Histopathology.

Positron emission tomography (PET) using ligands targeting prostate specific membrane antigen (PSMA) has recently been introduced. PET imaging wwith 68Ga-PSMA-HBED-CC has been shown to detect metastatic prostate cancer lesions with a high detection rate. This study aims to compare mpMRI and PSMA PET of prostate with whole-mount ex-vivo prostate histopathology to determine the true sensitivity and specificity of these imaging modalities for detecting and locating tumour foci within prostate.

In a prospective clinical trial setting, twenty patients with localized prostate cancer and a planned radical prostatectomy were recruited. All patients underwent mpMRI and PET prior to surgery, and whole-mount histopathology slides were directly compared to the images. European Society of Urogenital Radiology (ESUR) guidelines for reporting MRI was used as a template for regional units of analysis. Radiologists and uropathologist were blinded to individual components of the study, and the final correlation performed by visual and deformable registration analysis.

50 clinically significant lesions were identified from the whole-mount histopathological analysis. Based on regional analysis, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for mpMRI were 44%, 94%, 81% and 76% respectively. With PSMA PET, sensitivity, specificity, PPV and NPV were 49%, 95%, 85% and 88% respectively. PSMA PET yielded higher specificity and PPV.

A significant proportion of cancers are potentially missed and underestimated by both imaging modalities. PSMA PET may be used in addition to mpMRI to help improve the local staging of those undergoing retropubic radical prostatectomy.

The Journal of urology. 2016 May 21 [Epub ahead of print]

H Rhee, P Thomas, B Shepherd, S Greenslade, I Vela, P J Russell, C Nelson, E Chung, G Wood, G Malone, S Wood, P Heathcote

Department of Urology, Princess Alexandra Hospital; Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute. Electronic address: ., Department of Nuclear Medicine, Royal Brisbane and Women's Hospital., Pathology Queensland, Princess Alexandra Hospital., Department of Radiology, Princess Alexandra Hospital., Department of Urology, Princess Alexandra Hospital; Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute., Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute., Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute., Department of Urology, Princess Alexandra Hospital., Department of Urology, Greenslopes Private Hospital., Department of Urology, Princess Alexandra Hospital; Department of Urology, Greenslopes Private Hospital., Department of Urology, Princess Alexandra Hospital; Department of Urology, Greenslopes Private Hospital., Department of Urology, Princess Alexandra Hospital; Department of Urology, Greenslopes Private Hospital; Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute.