Three-T-guided prostate biopsy wins more support

August 1, 2007

MR-guided biopsies at 3T are showing great promise in prostate cancer because of their speed and high tumor detection rate in patients with rising prostate-specific antigen levels but previous negative biopsies, according to a leading research team from the Netherlands.

MR-guided biopsies at 3T are showing great promise in prostate cancer because of their speed and high tumor detection rate in patients with rising prostate-specific antigen levels but previous negative biopsies, according to a leading research team from the Netherlands. The procedures also do well in patients who have had previous radiotherapy sessions.

Overall, MRI during prostate interventions provides excellent soft-tissue contrast and resolution and enables assessment of adjacent tissues at risk of injury, the burden of disease within the gland, and the biological profile of the disease, said Dr. Gregory Bootsma of Princess Margaret Hospital in Toronto. The scans provide the ability to characterize pathology and biology through dynamic contrast-enhanced, proton spectroscopy, and diffusion-weighted imaging.

In an electronic poster presentation, Dr. Thomas Hambrock and fellow radiologists at St. Radboud University Medical Center in Nijmegen, the Netherlands, explained why these procedures are easy to perform. They use a 32-channel phased-array coil and prototype biopsy device. With the patient in prone position, the practitioner inserts a gadolinium needle guider endorectally, along with a 3D positioning device, and takes axial and sagittal T2-weighted turbo spin-echo images as the biopsy needle is guided into the tumor-suspicious region.

The 35-minute examination is well tolerated, Hambrock said.

Conversely, there is growing support for performing prostate interventions in the supine position, as noted in another electronic poster by Bootsma and colleagues. Conventional systems have good biopsy-targeting accuracy but require that the patient lie in a prone or left lateral decubitus position, which compromises stability, comfort, and safety. The Canadian group favors a dedicated table that docks to the diagnostic MR unit, integrates imaging coils, and creates perineal access. Their custom-built interventional table comes from Sentinelle Medical in Toronto, and they have adapted the company's Aegis software.