Annual Report

15. The Preliminary Experiments for Clinical Multi Nuclei MRS Using a Commercial MRI System.

Hiroo Ikehira, Franck Girard, Takayuki Obata, Tetsuya Suhara, Shuji Tanada and Yasuhito Sasaki

Keywords: 19F, 7Li , magnetic resonance spectroscopy, chemical shift imaging

The study of dynamic natural abundance 19F-magnetic resonance spectroscopy (19F-MRS) on 5-FU based medicines was performed in the human liver using commercial 1.5T MRI equipment. A single tuned custom-made circular shape surface coil with a diameter of 15 cm operating at 60 MHz was used for the 19F-MRS study. Localized proton shimming with a whole body coil was performed with an adequate volume to include the observing area of the surface coil, and the line width of the water signal was less than 20 Hz. The normal clinical dose of oral fluorine anticancer medicine should be too small to detect a sufficient signal for 19F-MRS using commercial MRI equipment. But we can observe very different spectroscopic appearance patterns of 5-FU. We examined whether the pharmacokinetics in the liver of orally administered 1-hexylcarbamoyl-5-fluorouracil (HCFU) differs from that of orally administered 5'-deoxy-5-fluorouridine (5'-DFUR). This preliminary study indicated 19F-MRS technique should be very useful method to evaluate in vivo 5-FU based medicine metabolism.

In another experiment 7Li 2D-CSI (two dimensional chemical shift imaging) of human brain was also performed. Lithium salts have been widely used in the treatment of mood disorders, but their mechanism of action is still not clear. In this work, a methodology for two-dimensional lithium-7 imaging in clinical systems is presented. The data were acquired using a phosphorus volume head coil that was re-tuned for the lithium-7 frequency. A spectroscopic sequence was used to acquire the free induction decay (FID) after volume excitation using a hard pulse. The results obtained on the head of patients undergoing lithium treatment (n=7, 0.6 mEq/l average serum level) demonstrate that images of adequate signal to noise ratio (100:1) can be obtained in acceptable imaging times (55 min) using the proposed methodology. The distribution of 7Li appears uniform in the brains of the patients studied.

1) Ikehira H, Girard F, Obata T, Ito H, Yoshitomi H, Kamei H, Kanazawa Y, Tanada S, Sasaki Y, Miyazaki M, Nakajima N, Takano H, Ito H: British Journal of Radiology 72 , 584-589, 1999
2) Girard F, Suhara T, Sassa T, Okubo Y, Obata T, Ikehira H , Sudo Y, Koga M, Yoshioka H, Yoshida K: MAGMA 13 (1) , 1-7, 2001

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