Recurrent Prostate Cancer in Seminal Vesicles in a Patient with Brachytherapy: mpMRI and PSMA PET Findings Baris Turkbey M.D. Molecular Imaging Program, National Cancer Institute, NIH, Bethesda, MD, USA 75-year-old man with serum PSA=4.6ng/ml (S/P brachytherapy) There is no focal lesion in the Axial T2W MRI ADC map prostate suggesting residual or recurrent prostate cancer Restaging CT and bone scan are negative b1500 DW MRI DCE MRI 75-year-old man with serum PSA=4.6ng/ml (S/P brachytherapy) There is a focal lesion in the right Focal tracer seminal uptake within vesicles right seminal (hypointense vesicle lesion on T2W MRI with early Axial T2W MRI ADC map enhancement on DCE MRI; 18F-DCFpYL PET/CT ADC map and b1500 DW MRI are not contributing TRUS/MRI due to fusion guided artifacts) biopsy=prostate cancer b1500 DW MRI DCE MRI Teaching Points • Although seed artifacts are commonly observed, multiparametric MRI (mpMRI) can still be performed and may provide useful information for biochemical recurrence (BCR) following brachytherapy. • PSMA PET/CT can be quite useful to detect residual/recurrent prostate cancers in BCR after brachytherapy due to its specificity. • Residual/recurrent prostate cancers can be located at seminal vesicles in brachytherapy patients. • Please carefully check not only the prostate but also the seminal vesicles at mpMRI and PSMA PET in brachytherapy patients with BCR. References • Valle LF, Greer MD, Shih JH, Barrett T, Law YM, Rosenkrantz AB, et al. Multiparametric MRI for the detection of local recurrence of prostate cancer in the setting of biochemical recurrence after low dose rate brachytherapy. Diagn Interv Radiol. 2018;24(1):46-53. • Gaur S, Turkbey B. Prostate MR Imaging for Posttreatment Evaluation and Recurrence. Urol Clin North Am. 2018;45(3):467-79. • Liu W, Zukotynski K, Emmett L, Chung HT, Chung P, Wolfson R, et al. A Prospective Study of 18F-DCFPyL PSMA PET/CT Restaging in Recurrent Prostate Cancer following Primary External Beam Radiotherapy or Brachytherapy. International journal of radiation oncology, biology, physics. 2020;106(3):546- 55. • Mena E, Lindenberg ML, Turkbey B, Shih JH, Harmon SA, Lim I, et al. (18)F- DCFPyL PET/CT Imaging in Patients with Biochemical Recurrence Prostate Cancer after Primary Local Therapy. J Nucl Med. 2019:jnumed.119.234799..