Brachytherapy for Prostate Cancer: Endorectal MR Imaging of Local Treatment-related Changes

Brachytherapy for Prostate Cancer: Endorectal MR Imaging of Local Treatment-related Changes

Fergus V. Coakley, MB, BCh ; Hedvig Hricak, MD, PhD ; Antje E. Wefer, MD ; Joycelyn L. Speight, MD, PhD ; John Kurhanewicz, PhD ; Mack Roach III, MD

1 From the Department of Radiology (F.V.C., H.H.), Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021; and the Departments of Radiology (A.E.W., J.K.) and Radiation Oncology (J.L.S., M.R.), University of California San Francisco. From the 1999 RSNA scientific assembly. Received July 31, 2000; revision requested September 11; final revision received December 8; accepted December 20. Supported by National Institutes of Health grant IRGICA76423-0IRI.

PURPOSE: To determine the local treatment-related endorectal magnetic resonance (MR) imaging findings after brachytherapy for prostate cancer.

MATERIALS AND METHODS: Endorectal MR imaging was performed in 35 consecutive patients at a mean interval of 12 months (range, 1–31 months) after brachytherapy for prostate cancer. Transverse T1-weighted and high-spatial-resolution transverse and coronal T2-weighted images were acquired. Two readers reviewed MR image quality and findings, with discrepancies resolved by consensus. Posttreatment urinary symptoms in patients (n = 24) were documented by using chart review.

RESULTS: All studies were of diagnostic quality. On T2-weighted images, prostatic findings consisted of diffuse low signal intensity (n = 35) and indistinct zonal anatomy (n = 34). Intra- and extraprostatic seed locations could be distinguished. The most common extraprostatic site of seed implantation was the neurovascular bundles (n = 35, bilateral in 32). The most common extraprostatic tissue finding was increased signal intensity on T2-weighted images in the levator ani muscle (n = 34) and the genitourinary diaphragm (n = 28). Postbrachytherapy urinary symptoms showed no demonstrable correlation with periurethral or genitourinary diaphragm seed implantation or with signal intensity change in the genitourinary diaphragm.

CONCLUSION: Endorectal MR imaging can be used to evaluate seed distribution and to demonstrate treatment-related changes after brachytherapy for prostate cancer.