Comparison of multiparametric MRI‐based and transrectal ultrasound‐based preplans with intraoperative ultrasound‐based planning for low dose rate interstitial prostate seed implantation

Abstract

Purpose Transrectal ultrasound images are routinely acquired for low dose rate (LDR) prostate brachytherapy dosimetric preplanning (pTRUS), although diagnostic multiparametric magnetic resonance imaging (mpMRI) may serve this purpose as well. We compared the predictive abilities of TRUS vs MRI relative to intraoperative TRUS (iTRUS) to assess the role of mpMRI in brachytherapy preplanning. Materials and methods Retrospective analysis was performed on 32 patients who underwent iTRUS‐guided prostate LDR brachytherapy as either mono‐ or combination therapy. 56.3% had pTRUS‐only volume studies and 43.7% had both 3T‐mpMRI and pTRUS preplanning. MRI was used for preplanning and its image fusion with iTRUS was also used for intraoperative guidance of seed placement. Differences in gland volume, seed number, and activity and procedure time were examined, as well as the identification of lesions suspicious for tumor foci. Pearson correlation coefficient and Fisher's Z test were used to estimate associations between continuous measures. Results There was good correlation of planning volumes between iTRUS and either pTRUS or MRI (r = 0.89, r = 0.77), not impacted by the addition of hormonal therapy (P = 0.65, P = 0.33). Both consistently predicted intraoperative seed number (r = 0.87, r = 0.86). MRI/TRUS fusion did not significantly increase surgical or anesthesia time (P = 0.10, P = 0.46). mpMRI revealed suspicious focal lesions in 11 of 14 cases not visible on pTRUS, that when correlated with histopathology, were incorporated into the plan. Conclusions Relative to pTRUS, MRI yielded reliable preplanning measures, supporting the role of MRI‐only LDR treatment planning. mpMRI carries numerous diagnostic, staging and preplanning advantages that facilitate better patient selection and delivery of novel dose escalation and targeted therapy, with no additional surgical or anesthesia time. Prospective studies assessing its impact on treatment planning and delivery can serve to establish mpMRI as the standard of care in LDR prostate brachytherapy planning.

A comparison of treatment planning techniques for low-dose-rate (LDR) prostate brachytherapy

“…Preplanning TRUS, MRI, and intraoperative TRUS all predicted similar numbers of seeds for implantation. The ability of MRI to consistently and accurately determine prostate volume and predict the required number of seeds equivalently to preplanning TRUS was demonstrated, and the appointment of MRI as the sole imaging modality for LDRPB preplanning was supported (14).…”

“…Some studies have found no significant difference between MRI-and TRUSbased prostate volumes (12), whereas others have (16). Some studies report MRI overestimating prostate volume relative to TRUS, whereas others report MRI underestimating prostate volume relative to TRUS (14).…”

Case Report: Role of an Iodinated Rectal Hydrogel Spacer, SpaceOAR Vue™, in the Context of Low-Dose-Rate Prostate Brachytherapy, for Enhanced Post-Operative Contouring to Aid in Accurate Implant Evaluation and Dosimetry

“…Brachytherapy preplanning was performed utilizing mpMRI ( 19 ). The mean prostate volume was 35.2 ± 8.1 cc (range, 26.6–53.1cc).…”

Detection of individual prostate cancer via multiparametric magnetic resonance imaging in own material – initial experience

“…Brachytherapy low-dose-rate (LDR) or highdose-rate (HDR) is a standard primary treatment for low-or intermediate-risk PCa [6]. TRUS-Bx is routinely acquired for LDR prostate brachytherapy preplanning (pTRUS), although diagnostic mpMRI may serve this purpose as well [7]. Fredman et al compared the predictive abilities of TRUS vs. MRI relative to intraoperative TRUS (iTRUS) to assess the role of mpMRI in brachytherapy preplanning.…”

“…Shaaer et al described the use of mp-MRI during prostate HDR brachytherapy planning [8]. These works suggest that mpMRI carries numerous diagnostic, staging and preplanning advantages that facilitate better patient selection and delivery of novel dose escalation and targeted therapy, with no additional surgical or anesthesia time [7,8].…”