Radiology: MRI keeps tabs on temps in focused US cancer treatment
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The authors of the pilot study, including Rajiv Chopra, PhD, of Sunnybrook Research Institute in Toronto, and colleagues, explained that while clinical experience with transrectal high-intensity focused ultrasound is growing, the inability to measure temperature distribution in the prostate gland during treatment is a major limitation. Controlling the ultrasound energy delivered based on actual temperatures would have major benefits for effectively predicting the extent of cell death.
That’s where MRI comes in. The authors noted that MR thermometry has previously been shown to be feasible, and that “coupling high-intensity focused ultrasound with MR imaging for real-time temperature feedback control could improve the accuracy of treatment.”
Chopra and colleagues tested this idea by performing the procedure in eight men with localized prostate cancer. Transurethral ultrasound therapy was performed with the patient under spinal anesthesia and with the use of a 1.5T MR unit, immediately followed by radical prostatectomy. Resected glands were examined to compare MRI temperature measurements with the pattern of thermal damage, but no evaluation of the efficacy of the treatment was conducted as part of the study.
The authors reported that the treatment was well tolerated by all patients, and that a temperature uncertainty of less than 2°C was observed. Mean temperature along the boundary of thermal coagulation was 52.3°C while the thermal dose (cumulative equivalent minutes at 43°C) was 3457. There was a reported targeting accuracy of approximately 3 mm and a mean treatment rate of 0.5 mL/min.
Prostate-specific antigen testing has resulted in an increase in the proportion of men diagnosed with low- or intermediate-risk prostate cancer, emphasizing the need for treatments with reduced morbitity, according to the authors. “This type of therapy for localized prostate cancer may be beneficial in the future once further study demonstrates utility and safety.”
Evan Godt, Writer
Evan joined TriMed in 2011, writing primarily for Health Imaging. Prior to diving into medical journalism, Evan worked for the Nine Network of Public Media in St. Louis. He also has worked in public relations and education. Evan studied journalism at the University of Missouri, with an emphasis on broadcast media.