HEAT DEPOSITION BY MRI COILS W/ NA4HTM[DOTP]2/AGAROSE PHANTOM AT 4 0 TESLA

高场磁共振成像的优势带来了 增加输送到MRI线圈的功率的缺点。 这 迫使MR社区努力寻找一种方法来确定 在接受MRI程序的组织中的比吸收率。 为 在发射/接收表面线圈处，电场最高， 电容器. 对于鸟笼线圈，电场随着电流的增加而增加。 线圈中心向外距离的平方。 是 电场与组织的相互作用 理论上会导致局部发热 然而，目前还不清楚，在 这种加热可能是，如果有的话。 我们发现了一个依赖于温度的化学位移， Na4HTm [DOTP] 2-。 这种变化非常接近0.5 PPM每oC，无论是对于 溶液和琼脂糖中。 然后，我们构建了一个大的琼脂糖幻影， 与Na4HTm [DOTP] 2-反应并进行30分钟长的成像实验， 都有鸟笼和表面线圈。 我们监测了 化学位移在实验过程中，并发现它不改变， 所有. 此外，体模的相位图像描述了局部 加热样品。 在相位图中，我们没有发现 局部加热，无论是在表面线圈或鸟笼线圈，甚至 就在电容器上面 这些初步结果表明， 该化合物用于通过MRI确定热沉积的有用性 线圈。

The advantages of high field MR Imaging have brought with it the disadvantages of increased power delivered to MRI coils. This has forced the MR community to struggle with a method to determine specific absorption rates in tissues subjected to MRI procedures. For transmit/receive surface coils, the electric field is highest at the capacitors. For a birdcage coil, the electric field increases as the square of the distance outwards from the center of the coil. It is the interaction of the electric field with the tissue which theoretically causes local heating. However, it is unclear what, in practice this heating might be, if at all. We have found a temperature dependent chemical shift for Na4HTm[DOTP]2-. This shift is very near 0.5 PPM per oC, both for a solution and in agarose. We then constructed a large agarose phantom with Na4HTm[DOTP]2- and performed 30 minute long imaging experiments, both with the birdcage and the surface coils. We monitored the chemical shift during the experiment and found it to not change at all. In addition, phase images of the phantom describe areas of local heating in the sample. In the phase images, we found no areas of local heating, in either the surface coils or the birdcage coil, even right on top of the capacitors. These preliminary results indicate the usefulness of this compound for determining heat deposition by MRI coils.