Birkl Christoph, Langkammer Christian, Haybaeck Johannes, Ernst Christina, Stollberger Rudolf, Fazekas Franz, Ropele Stefan
Department of Neurology, Medical University of Graz, Austria.
Magn Reson Med. 2014 Apr;71(4):1575-80. doi: 10.1002/mrm.24799. Epub 2013 May 28.
Magnetic resonance relaxation times of most tissues are expected to depend on temperature, which can impact findings in postmortem magnetic resonance imaging or when using magnetic resonance imaging for relaxation-based thermometry. The purpose of this study was to investigate the exact temperature dependency of the relaxation times T(1), T(2), T(2) *, and the magnetization transfer ratio in different structures of the human brain.
To prevent fixation and autolysis effects, this study was performed with fresh postmortem brain tissues. Following autopsy, coronal brain slices from five deceased subjects were subjected to relaxometry at 3T in a temperature range between 4°C and 37°C. Heating of the tissue was achieved by flushing the vacuum packed brain slices with water at a predefined temperature.
T1 showed a linear dependency on temperature with the highest temperature coefficient in the cortex (17.4 ms/°C) and the lowest in the white matter (3.4 ms/°C). T(2) did not depend on temperature. T(2) * and magnetization transfer ratio scaled with temperature only in deep gray matter.
The temperature coefficient for T(1) is higher than expected from previous reports and varies across brain structures. The coefficients obtained in this study can serve as reference for thermometry or for correcting quantitative postmortem magnetic resonance imaging.
大多数组织的磁共振弛豫时间预计取决于温度，这可能会影响死后磁共振成像的结果，或在使用基于弛豫的磁共振成像进行体温测量时产生影响。本研究的目的是调查人脑不同结构中弛豫时间T(1)、T(2)、T(2)*和磁化转移率与温度的确切依赖关系。
为防止固定和自溶效应，本研究使用新鲜的死后脑组织进行。尸检后，对五名死者的冠状脑切片在3T磁场下于4°C至37°C的温度范围内进行弛豫测量。通过用预定义温度的水冲洗真空包装的脑切片来实现组织的加热。
T1显示出与温度呈线性依赖关系，在皮质中温度系数最高（17.4 ms/°C），在白质中最低（3.4 ms/°C）。T(2)不依赖于温度。T(2)*和磁化转移率仅在深部灰质中随温度变化。
T(1)的温度系数高于先前报道的预期，且在不同脑结构中有所不同。本研究中获得的系数可作为体温测量或校正死后定量磁共振成像的参考。
