Focal magnetic resonance guided focused ultrasound for prostate cancer: Initial North American experience

Abstract

The treatment of low-risk prostate cancer is a common clinical dilemma between standard curative whole gland therapy (and its associated quality of life diminishing side effects) and active surveillance (and its low, but real, risk of progression). The goal of focal therapy in low-risk prostate cancer is to achieve the best balance between cancer control and maintenance of quality of life. Magnetic resonance-guided focused ultrasound (MRgFUS) surgery is a non-invasive thermal ablation method that integrates magnetic resonance imaging for target identification, treatment planning and closed-loop control of thermal deposition and focused ultrasound for thermal ablation of the tumour target. This novel transrectal system allows for tumour localization, targeting and monitoring of tumour target ablation in real time, while simultaneously preserving adjacent normal tissue thereby minimizing the side effects of standard curative surgical or radiation therapy. We report the first North American clinical experience of treatment of localized prostate cancer with focal MR-guided transrectal focused ultrasound (clinicaltrial.gov identifier NCT01226576).

White Paper: Interventional MRI: Current Status and Potential for Development Considering Economic Perspectives, Part 2: Liver and Other Applications in Oncology

“…1 -6 hours [41,45]. A reproducible reduction of the intervention time to less than three hours would make greater use of focal therapy in the clinical routine more realistic.…”

Model‐based feasibility assessment and evaluation of prostate hyperthermia with a commercial MR‐guided endorectal HIFU ablation array

“…[41][42][43] Potentially, it can be fast tracked into the clinic for hyperthermia applications as well. Feasibility of safe hyperthermia delivery to the prostate using transrectal ultrasound arrays (∼1.5 MHz, 4-16 elements) has been reported in the past.…”

“…Based on real time MR temperature imaging (MRTI), the ERUS array can be utilized to translate (mechanical or electronic scanning) a small HIFU focal pattern in 3D and perform repetitive ablations to coagulate overlapping lesions that cumulatively cover the entire target volume. 41,42 In contrast to HIFU, hyperthermia requires more diffused energy deposition sustained over longer durations to establish uniform temperature distribution and sufficient thermal dose within the entire targeted volume. Array beamforming and phasing requirements of these sonications are very different from conventional HIFU exposures [Figs.…”

“…[1][2][3][4][5][6] Mild hyperthermia (40)(41)(42)(43)(44)(45) • C) can induce direct cytotoxicity in tumors, radiosensitize cancer cells by impairing DNA repair mechanisms, and enhance blood flow in tumor microenvironments to increase tumor oxygenation and facilitate drug delivery. 7 It may also be used to enhance localized drug delivery 8 and gene therapy 9 as reported in some recent investigations.…”

“…[41][42][43] If it can be successfully adapted for protracted hyperthermia, it can be potentially fast-tracked for clinical application. With this motivation, this initial study employed theoretical and experimental techniques to identify operational modifications, and assess the feasibility and capability of safe and reliable MRguided prostate hyperthermia with the ExAblate 2100 prostate applicator.…”