Measurement of coronary blood flow using MRI for the course observation after stent placement

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We developed a model simulating blood flow in the vessel for the usage in MRI units. It has three components of a rotary pomp, flow-measurement unit and closed long circuit. The circuit was filled with dilated contrast material (Gadolinium). T1 value of the dilated contrast material in the circuit was adjusted to 1200 msec to simulate the blood at 1.5 Tesla. The measurement unit was placed in the magnet bore and the long hose connected to the pump was placed outside of the MR unite and through partly opened door. The system was able to generate the pulsatile flow, using manually operated and electromagnetic valves. The pattern and cycle of the pulsatile flow were controlled using three timers t1-t3, regulating the periods, 1) between the start of the cycle and the time when valve opened, 2) during the valve opened and 3) between the time when the valve closed and the end of the cycle. The system was successfully operated to generate the pulsatile flow.Although the aim of this experiment was to observe the change of flow pattern and speed through stenotic lesion though, the outflow of the pump decreased when the pipe was compressed to simulate the stenosis of the vessel. In addition, the air bubble in the long circuit was obstacle to measure flow rate and speed with MRI.Flow measurement was not applicable in the stent due to susceptibility. The distance of one centimeter from the end of stent was necessary to enable the flow measurement with MRI.