NewsRx.com
January 27, 2005
Researchers from the University of California, San Francisco, reported study results on catheter-based ultrasound devices for the treatment of prostate cancer, with magnetic resonance thermal imaging to monitor and control therapy.
C.J. Diederich and colleagues wrote in International Journal of Hyperthermia, "High-temperature thermal therapy is emerging as a feasible treatment option for prostate cancer and benign prostatic hyperplasia.
"Previous investigations have demonstrated distinct advantages of catheter-based ultrasound technology over other heating modalities for thermal ablation therapies, with significant potential for better spatial control and faster heating times."
According to the researchers, "The purpose of this study was to develop ultrasound devices and techniques specifically for treating prostate cancer in conjunction with magnetic resonance thermal imaging (MRTI) to monitor and control treatment progression.
"Directional transurethral applicators have been designed with arrays of sectored tubular (90 degrees active acoustic sector) or with narrow planar transducer segments and integrated with a flexible delivery catheter with a cooling balloon."
"This applicator can be rotated within the prostatic urethra to target specific regions during treatment. MRI compatible catheter-cooled interstitial ultrasound applicators with 180, active acoustic sectors were developed specifically to treat the prostate.
"These applicators may be implanted through the perineum into the posterior portion of the prostate, with their heating energy directed away from the rectum. Both heating strategies were evaluated via biothermal simulations and in vivo experiments within canine prostate (n = 3)," the authors noted.
"During the in vivo studies, MRTI was used to monitor treatment temperatures, cytotoxic thermal doses (t(43)>240 min), and corresponding maximum temperature thresholds (T-max >52 degrees C) within three imaging planes simultaneously.
"Urethral and endorectal cooling was employed with both treatment strategies to provide further protection of the urethral mucosa and rectum from thermal damage," Diederich and colleagues reported.
"Results using the transurethral applicators demonstrated that narrow zones of coagulation (similar to 30 degrees sector for planar, similar to 90 degrees for tubular), extending up to 20 mm from the urethra to the periphery of the prostate gland, could be produced within 10-15 min.
"Further, rotation of the applicator during treatment could be used to destroy larger regions in the prostate," according to the authors.
"Experiments using multiple interstitial directional applicators (similar to 180 degrees active sectors), implanted within the posterior margin of the prostate with the energy directed away from the rectum, produced contiguous zones of thermal coagulation which extended from the posterior prostate toward the anterior-lateral periphery of the gland.
"Both transurethral and interstitial treatment strategies demonstrated significant potential for thermal ablation of localized prostate cancer, particularly when MRTI is used to guide and assess treatment," Diederich and colleagues concluded.
Diederich and colleagues published their study in International Journal of Hyperthermia (Catheter-based ultrasound applicators for selective thermal ablation: progress towards MRI-guided applications in prostate. Int J Hyperther, 2004;20(7):739-756).
For additional information, contact C.J. Diederich, University California San Francisco, Department Radiation Oncology, Thermal Therapy Research Group, San Francisco, CA 94143, USA.
The publisher's contact information for the International Journal of Hyperthermia is: Taylor & Francis Ltd., 4 Park Square, Milton Park, Abingdon OX14 4RN, Oxon, England.
The information in this article comes under the major subject areas of Thermal Therapy, Prostate Cancer, and Oncology. This article was prepared by Biotech Business Week editors from staff and other reports.
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