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KMID : 0372919970180030243
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Journal of Biomedical Engineering Research
1997 Volume.18 No. 3 p.243 ~ p.251
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Flow Effects on Tailored RF Gradient Echo (TRFGE) Magnetic Resonance Imaging : In-flow and In-Plane Flow Effect
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Mun Chi-Ung
Kim Sang-Tae
No Yong-Man
Im Tae-Hwan
Jo Jang-Hui
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Abstract
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In this paper, we have reported two interesting flow effects arising in the TRFGE sequence using water flow phantom. First, we have shown that the TRFGE sequence is indeed not affected by "in-flow" effect from the unsaturated spins flowing into the imaging slice. Second, the enhancement of "in-plane flow" signal in the readout gradient direction was observed when the TRFGE sequence was used without flow compensation. These two results have many interesting applications in MR imaging other than fMRI. Results obtained were also compared with the results obtained by the conventional gradient echo(CGE) imaging. Experiments were performed at 4.7T MRI/S animal system (Biospec, BRUKER, Switzerland). A cylindrical phantom was made using acryl and a vinyl tube was inserted at the center(Fig. 1). The whole cylinder was filled with water doped with and the center tube was filled with saline which flows in parallel to the main magnetic field along the tube. Tailored RF pulse was designed to have quadratic () phase distribution in slice direction(z). Imaging parameters were TR/TE = 55~85/10msec, flip angle = , slice thickness = 2mm, matrix size = 256256, and FOV= 10cm. In-flow effect : Axial images were obtained with and without flow using the CGE and TRFGE sequences, respectively. The flow direction was perpendicular to the image slice. In-plane flow : Sagittal images were obtained with and without flow using the TRGE sequence. The readout gradient was applied in parallel to the flow direction. We have observed that the "in-flow" effect did not affect the TRFGE image, while "in-plane flow" running along the readout gradient direction enhanced the signal in the TRFGE sequence when flow compensation gradient scheme was not used.
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KEYWORD
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MRI, Tailored RF, Gradient echo, In-flow effect, In-plane flow
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