[18F]-DCFPyL Positron Emission Tomography/Magnetic Resonance Imaging for Localization of Dominant Intraprostatic Foci: First Experience

An ongoing prospective study is acquiring preoperative imaging data for men with prostate cancer (PCa) using the molecular imaging agent [¹⁸F]-DCFPyL targeted against prostate-specific membrane antigen (PSMA). To date, six men (of a planned accrual of 24) with clinically localized, biopsy-proven PCa have undergone preoperative [¹⁸F]-DCFPyL positron emission tomography (PET) imaging and multiparametric magnetic resonance imaging acquired using a hybrid PET/MRI system. Lesions identified by [¹⁸F]-DCFPyL uptake on PET/MRI were characterized in terms of maximum standardized uptake value (SUV_max) and volume using a boundary threshold of 40% SUV_max. Following surgery, all prostatectomy specimens were processed using a whole-mount technique for accurate deformable co-registration and correlation with PCa foci defined on digitized pathology images. Well-defined intraprostatic dominant lesions were identified by [¹⁸F]-DCFPyL PET/MRI (mean SUV_max 11.4±8.25; mean volume 2.2±2.4cm³) in all six men. Co-registered digitized whole-mount pathology for the first case revealed that intense [¹⁸F]-DCFPyL uptake (SUV_max 27±1.1cm³) and multiparametric MRI changes (Prostate Imaging Reporting and Data System score of 4) were highly correlated with a 0.5-cm³ dominant (largest) lesion with Gleason pattern 4 PCa in the right mid peripheral zone. A smaller focus (0.01cm³) of lower-grade PCa (Gleason pattern 3) had much lower uptake (SUV 2.7). These early prospective data show that dominant intraprostatic lesions could be identified in all six men using [¹⁸F]-DCFPyL as an imaging probe. Trial accrual will continue to quantify in terms of spatial concordance the ability of [¹⁸F]-DCFPyL to identify the location and characterize the grade of intraprostatic cancer foci in clinically localized PCa. PATIENT SUMMARY: Positron emission tomography using a novel probe called [¹⁸F]-DCFPyL directed against the prostate-specific membrane antigen protein was able to identify locations of prostate cancer in the prostate glands of men undergoing imaging before surgery. In the future, such imaging may allow better targeting of treatment to the portion of the prostate containing the most aggressive components of cancer rather than treating the whole prostate in a uniform fashion.