Prostate imaging studies weigh diagnostic power of MRI methods

May 6, 2008 Prostate imaging studies weigh diagnostic power of MRI methods James Brice -------------------------------------------------------------------------------- A clinical trial presented Monday demonstrated how complicated the quantification of dynamic contrast-enhanced MRI of suspected prostate cancer can be. Investigators hold great hope for DCE-MRI for this application because of the insensitivity of contrast-enhanced T2-weighted imaging and the considerable convenience of performing DCE-MRI without the need for an endorectal coil. Presenter Guang Jia, a research student at Ohio State University, and colleagues under the direction of Dr. Michael Knopp evaluated 27 patients who were awaiting robotic prostatectomy for clinically proven prostate cancer. DCE-MRI was performed on a 3T Philips Achieva scanner using an eight-channel phased-array coil. Several semiquantitative parameters were calculated from the dynamic contrast data and compared with stained histological samples of the removed prostate and seminal vesicles. Regions of interest were drawn to identify cancerous regions, including tumor in the peripheral and transition zone, the noncancerous peripheral zone, and the central gland with benign prostate hyperplasia, muscle, and neurovascular bundle. The researchers reported the various measures and their corresponding results: Time to maximum signal enhancement. The measure of tmax in the tumor region was significantly shorter than those acquired in noncancerous peripheral zones. Wash-out score (the relative difference between maximum signal enhancement and signal intensity at the end of the dynamic scan). This measure was significantly larger in the tumor region than in the other regions. Maximum enhancement ratio. This was unable differentiate between tumor and the central gland. Three separate measures of area under the curve ROC analysis at 60, 90, and 180 seconds. All three were unable to differentiate between tumor and central gland. Jia found that all parameters could differentiate tumor from the noncancerous peripheral zone. Tumor perfusion showed faster wash-in, resulting in a short tmax and higher enhancement and producing a larger maximum enhancement ratio, and faster wash-out, leading to a larger wash-out score than noncancerous peripheral zone perfusion.

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