Definitive Diagnosis And Intensive Monitor Of Prostate Diseases Based On Magnetic Resonance Spectroscopic Imaging

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It was found that the proton chemical shift of citrate has pH dependency of -0.09 ppm/pH, while that of choline or creatine has no pH dependency. The prostate metabolite measurement system based upon magnetic resonance spectroscopic imaging (MRSI) with the very high tesla (3T) magnet has been constructed. It was also found based on the phantom experiments that the intensity of the citrate signal is modulated by J-coupling and the chemical shift, and that the highest echo signal appears at the echo time of 290 ms. Density matrix simulation adopting J-modulation factor, chemical shift, pulse timing and T2 showed that the highest echo signal of citrate proton appears around 290 ms when the citrate T2 is longer than 133 ms while it is around 145 ms when the T2 is shorter than 133 ms. By fitting the volunteer data on the simulation model curve derived from the density matrix calculation, the citrate T2 value, which has not been reported so far, was estimated as approximately 80 ms.As for th … More e MR probe development; a new coil element configuration with two pairs of loop coils was developed. Although we first examined suppression of thermal noise by cooling the coil to improve signal to noise, it turned out that increasing signal intensity by minimizing the distance between prostate and the coil elements, and by finely adjusting the shapes of the elements are more significant. The new coil design improved the signal to noise 2.1 times at the peripheral zone and 1.3 times at the central zone of prostate compared with the phased array coil used with a 1.5 T scanner.Imaging sequence was optimized based on the prostate coil by adjusting the outer volume suppression pulses, water suppression pulses as well as spatial-frequency excitation pulses. High-resolution diagnostic anatomical images as well as high quality metabolite spectra were constantly obtained for twenty healthy volunteers. The spectral band width and signal to noise ratio (S/N) were smaller than 0.1 ppm and higher than 10, respectively, for citrate in the healthy prostates. Scans for patient volunteers with prostate cancers were started at the end of this annual year to examine the ability of the metabolite measurement system for the definitive diagnosis of prostate cancer and benign prostatic hyperplasia (BPH). It is our duty to continuously examine the patient volunteers to establish a practical prostate observation system based on the results obtained by this grant-in-aid.We deeply thank to the Japan Society for the Promotion of Science (JSPS) for supporting our research. Less