| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2009: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2008: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Research Abstract |
In case that strictures are caused in the hollow viscera such as coronary artery, biliary tact, and esophagus, metallic cylinders consisting mesh pattern (called as stent) are inserted in the strictures in order to expand the narrowed portions. It is required to diagnose the presence of re-stricture in the stent after treatment, but we cannot diagnose the stent lumen using the MRI device.
We found out the causes of the above phenomenon in the MRI diagnosis using the simulation with the finite element method, as follows: The eddy currents are induced in the stent by the RF magnetic fields, B_1, applied for exciting the protons in the human body, and the eddy currents induce the associated magnetic fields. The induced magnetic fields arise so as to counterbalance the applied RF magnetic fields, B_1. As a result, the RF magnetic fields in the stent are decreased, and the flip angle of the protons becomes small.
This considerations led us to the valuable idea for visualizing the stent lumen, that is, the stent must be fabricated so as to have a solenoid-pattern structure, and the solenoidal stent must be placed in the MRI device so as to the central axis of the stent being perpendicular to the direction of the applied RF magnetic fields, B_1.
In the experiment, the lumen in the solenoidal stent was visualized by placing the central axis of the stent being perpendicular to the direction of the applied RF magnetic fields, B_1
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