Mechanism of burn injury during magnetic resonance imaging (MRI)--simple loops can induce heat injury.
Mechanism of burn injury during magnetic resonance imaging (MRI)--simple loops can induce heat injury.
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磁共振成像（MRI）过程中烧伤的机制——简单的循环即可引起热损伤。
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
Y. Shimizu
中科院分区：
文献类型：
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作者：
T. Nakamura;K. Fukuda;K. Hayakawa;I. Aoki;K. Matsumoto;T. Sekine;H. Ueda;Y. Shimizu
为了确定与磁共振成像 (MRI) 相关的烧伤机制，测量了导电引线回路中的感应电流。制作了七种有效面积在 100 至 12 000 cm2 范围内的环，然后将每个环置于 0.5 T 的全身 MR 系统的孔中并进行 MRI。在射频（RF）辐射期间，在其轴平行于线性偏振发射射频场放置的环路中观察到感应电压。电压具有正弦函数特性，并且在用于常规 MR 成像的 RF 脉冲序列下处于 55-235 V 范围内。当轴垂直时，观察到的电流可以忽略不计。插入 30 x 40 cm 环路的电阻器会产生火花并烧毁。简单的导电材料环路可能会导致成像系统中感应出较大且具有潜在危险的电压。这种环路的自谐振可能会增加与射频发射器的有效耦合，从而大大增加危险。此外，插入的电阻器与环路阻抗的阻抗匹配增加了电阻器处的耗散功率。
To determine the mechanism of burn injury associated with magnetic resonance imaging (MRI), the induced current in the loops of a conductive lead was measured. Seven types of loops with effective areas within the range from 100 to 12 000 cm2 were made and then each loop was placed in the bore of a whole-body MR system at 0.5 T and MRI was carried out. During radio frequency (RF) irradiation, an induced voltage was observed in loops that were placed with their axes parallel to the linearly polarized transmitting RF field. The voltage had a sincfunction characteristic and was within the range 55-235 V at the RF pulse sequence for usual MR imaging. When the axis was vertical, negligible current was observed. A resistor inserted into the circuit of a 30 x 40 cm loop sparked and burned out. Simple loops of conductive material may result in the induction of a large and potentially hazardous voltage in the imaging system. Self-resonance of such a loop may add greatly to hazards by increasing the effective coupling to the RF transmitter. Also, impedance matching of the inserted resistor with the impedance of the loop increases the dissipated power at the resistor.