Baron Paul, Deckers Roel, Knuttel Floor M, Bartels Lambertus W
Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands.
Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands.
NMR Biomed. 2015 Nov;28(11):1463-70. doi: 10.1002/nbm.3410. Epub 2015 Sep 24.
The T1 and T2 temperature dependence of female breast adipose tissue was investigated at 1.5 T in order to evaluate the applicability of relaxation-based MR thermometry in fat for the monitoring of thermal therapies in the breast. Relaxation times T1 , T2 and T2TSE (the apparent T2 measured using a turbo spin echo readout sequence) were measured in seven fresh adipose breast samples for temperatures from 25 to 65 °C. Spectral water suppression was used to reduce the influence of the residual water signal. The temperature dependence of the relaxation times was characterized. The expected maximum temperature measurement errors based on average calibration lines were calculated. In addition, the heating-cooling reversibility was investigated for two samples. The T1 and T2TSE temperature (T) dependence could be fitted well with an exponential function of 1/T. A linear relationship between T2 and temperature was found. The temperature coefficients (mean ± inter-sample standard deviation) of T1 and T2TSE increased from 25 °C (dT1/dT = 5.35 ± 0.08 ms/°C, dT2TSE/dT = 3.82 ± 0.06 ms/°C) to 65 °C (dT1 /dT = 9.50 ± 0.16 ms/°C, dT2TSE/dT = 7.99 ± 0.38 ms/°C). The temperature coefficient of T2 was 0.90 ± 0.03 ms/°C. The temperature-induced changes in the relaxation times were found to be reversible after heating to 65 °C. Given the small inter-sample variation of the temperature coefficients, relaxation-based MR thermometry appears to be feasible in breast adipose tissue, and may be used as an adjunct to proton resonance frequency shift (PRFS) thermometry in aqueous tissue (glandular + tumor).
为了评估基于弛豫的磁共振测温法在脂肪组织中监测乳腺热疗的适用性，在1.5 T磁场下研究了女性乳腺脂肪组织的T1和T2弛豫时间随温度的变化。在7个新鲜乳腺脂肪组织样本中测量了温度范围为25至65°C时的弛豫时间T1、T2以及T2TSE（使用快速自旋回波读出序列测量的表观T2）。采用频谱水抑制技术来减少残留水信号的影响。对弛豫时间的温度依赖性进行了表征。计算了基于平均校准曲线的预期最大温度测量误差。此外，还对两个样本的加热-冷却可逆性进行了研究。T1和T2TSE的温度（T）依赖性可以用1/T的指数函数很好地拟合。发现T2与温度之间存在线性关系。T1和T2TSE的温度系数（平均值±样本间标准差）从25°C时（dT1/dT = 5.35±0.08 ms/°C，dT2TSE/dT = 3.82±0.06 ms/°C）增加到65°C时（dT1 /dT = 9.50±0.16 ms/°C，dT2TSE/dT = 7.99±0.38 ms/°C）。T2的温度系数为0.90±0.03 ms/°C。发现在加热到65°C后温度引起的弛豫时间变化是可逆的。鉴于温度系数的样本间差异较小，基于弛豫的磁共振测温法在乳腺脂肪组织中似乎是可行的，并且可以作为水相组织（腺体+肿瘤）中质子共振频率偏移（PRFS）测温法的辅助手段。
