Issac Hsu

Background and purpose To establish a method to evaluate dosimetry at the time of primary prostate permanent implant using MRI of the shrunken prostate at the time of failure. To compare cold spot mapping with sextant-biopsy mapping at tf. Material and methods Twenty-four patients were referred for biopsy-proven local failure after pPPI. Multiparametric MRI and combined-sextant biopsy with a central review of the pathology at tf were systematically performed. A model of the shrinking pattern was defined as a Volumetric Change Factor as a function of time from time of pPPI. An isotropic expansion to both prostate volume and seed position coordinates determined at t f was performed using a validated algorithm using the VCF. Results pPPI CT-based evaluation vs. MR-based evaluation: Mean D90% was 145.23 ± 19.16 Gy [100.0-167.5] vs. 85.28 ± 27.36 Gy [39-139], respectively. Mean V100% was 91.6 ± 7.9% [70-100%] vs. 73.1 ± 13.8% [55-98%], respectively. Seventy-seven per cent of the pathologically positive sextants were classified as cold. Conclusions Patients with biopsy-proven LF had poorer implantation quality when evaluated by MRI several years after implantation. There is a strong relationship between microscopic involvement at tf and cold spots. © 2013 Elsevier Ireland Ltd. All rights reserved.

Purpose: To assess the feasibility of magnetic resonance imaging -planned partial salvage permanent prostate implant among patients with biopsy-proven local recurrence after initial PPI without evidence of distant disease. Methods and Materials: From 2003-2009, 15 patients underwent MRI/magnetic resonance spectroscopy planning for salvage brachytherapy without hormone therapy. Full dose was prescribed to areas of recurrence and underdosage, without entire prostate implantation. Limiting urethral and rectal toxicity was prioritized. Follow-up was from salvage date to prostate-specific antigen concentration failure, recurrence, distant metastases, or last follow-up PSA level. Progression-free survival was defined as no PSA failure or biopsy-proven recurrence without all-cause mortality. Toxicity was scored using Common Terminology Criteria for Adverse Events version 4.0. Results: At salvage, median age was 68 years, and PSA concentration was 3.5 ng/mL. Abnormal MRI/MRS findings were evident in 40% of patients. Biopsy-proven recurrences consisted of a single focus or 2 foci. At recurrence, Gleason score was 6 or ≥7. Median interval between initial and salvage implantation was 69 months. psPPI planning characteristics limited doses to the rectum and urethra. At median follow-up, treatment failure resulted only in localized recurrence; both patients underwent second psPPI with follow-up PSA tests at 12 and 26 months, resulting in 0.6 and 0.7 ng/mL, respectively. American Society for Radiation Oncology PFS rates at 1, 2, and 3 years were 86.7%, 78.4%, and 62.7%, respectively, with 5 patients for whom treatment failed. Phoenix PFS rates at 1, 2, and 3 years were 100%, 100%, and 71.4%. 73%, respectively; achieved PSA nadir of <0.5 ng/mL; and 47% of patients had a nadir of <0.1 ng/mL. Treatment-related toxicity was minimal, with no operative interventions, fistulas, or other grade ≥3 gastrointestinal /genitourinary toxicity. Thirteen percent had grade 1 GI and 33% had grade 2 GU toxicities. Postsalvage, 20% of patients had no erectile dysfunction, 67% of patients had medication-responsive erectile dysfunction, and 13% of patients had erectile dysfunction refractory to medication. Conclusions: Focal psPPI with MR-planning in highly selected patients is feasible with short-term control comparable to conventional salvage, with less toxicity. Longer follow-up is needed to confirm its impact on quality of life and treatment. © 2013 Elsevier Inc. All rights reserved.