MR Spectroscopy in Localized Prostate Cancer

This study is designed to investigate whether filling the rectum with high density barium prior to a magnetic resonance spectroscopy (MRS) exam of the prostate improves the quality of the acquired spectrum. It is expected that the dense substance should help prevent air from entering the rectum and thus susceptibility artifacts in the obtained MRS data should be reduced. Ten patients with localized prostate cancer will be recruited for this study. There will be no change in treatment planning based on MRS study. Patient will receive standard radiation treatment prescribed by radiation oncologist.

An MRS study of each patient's prostate will be conducted with the 3 Tesla Philips Intera NMR (Nuclear Magnetic Resonance) scanners before and after filling the rectum with barium. Patients will be requested to take a mild laxative of their choice the night before the exam, and not to eat for 2-4 hours prior to the scan. To facilitate this, that patient's exam will be booked prior to lunch. Prior to the exam, the patient will be asked to empty their bladder and 40 mg of Buscopan will be administered to the patient (i.m. of i.v.) to reduce peristalsis, the presence of which degrades the quality of NMR scans. The patient will lie on a board designed to fit on the MR scanner patient bed and that holds one of the elements of the dual element phased array radiofrequency (RF) coil in place. The patient will be positioned such that the prostate is within the coil's field of view (preferably along its central axis); that is, the patient will lie on one element of the coil and the other element will be placed on top of the patients abdomen. An abdominal restraint will be placed around the patients abdomen to reduce breathing effects. After the patient has been centered in the magnet, MRI (Magnetic Resonance Imaging) images will be acquired to identify the tumor location. The positioning of the MRS voxel with the prostate will be carefully determined with the aid of a radiation oncologist. Preparation scans for the spectroscopy acquisition will be carried out prior to applying a PRESS (Point RESolved Spectroscopy) sequence that will be employed to obtain a proton (1H) spectrum of the prostate. The entire scan duration from preparation till completion will be approximately 30 minutes (5 minutes for patient positioning, 10 minutes for imaging and voxel placement, 5 minutes for spectroscope sequence preparation scans, and 10 minutes for spectrum acquisition). Following scan completion, the patient will have about 150 mL of Barium solution administered to the rectum. After standing for 3-4 minutes, the patient will like back on the NMR scanner bed and the same NMR procedure will be repeated again. The spectra acquired without and with the presence of Barium solution in the rectum will be compared to see if the latter situation is indeed advantageous.