Vogl Thomas J, Huebner Frank, Naguib Nagy N N, Bauer Ralf W, Mack Martin G, Nour-Eldin Nour-Eldin A, Meister Dirk
Institute for Diagnostic and Interventional Radiology, Johann Wolfgang Goethe University Hospital, Frankfurt University, Frankfurt, Germany.
Lasers Surg Med. 2012 Mar;44(3):257-65. doi: 10.1002/lsm.22012. Epub 2012 Mar 7.
To evaluate MR-thermometry using fast MR sequences for laser induced interstitial thermotherapy (LITT) at 0.2 and 1.5 T systems.
METHODS & MATERIALS: In-vitro experiments were performed using Agarose gel mixture and lobes of porcine liver. MR-thermometry was performed by means of longitudinal relaxation time (T1) and proton resonance frequency shift (PRF) methods under acquisition of amplitude and phase shift images. Four different sequences were used for T1 thermometry: A gradient-echo (GRE), a True Fast Imaging with Steady Precession (TRUFI), a Saturation Recovery Turbo-FLASH (SRTF), and an Inversion Recovery Turbo-FLASH (IRTF) sequence (FLASH-Fast Low Angle Shot). PRF was measured with four sequences: Two fast-spoiled GRE sequences (one as WIP sequence), a Turbo-FLASH (TFL) sequence (WIP sequence), and a multiecho-TrueFISP sequence. Temperature was controlled and verified using a fiber-optic Luxtron device. The temperature was correlated with the MR measurement.
All sequences showed a good linear correlation R(2) = 0.97-0.99 between the measured temperature and the MR-thermometry measurements. The only exception was the TRUFI sequence in the Agarose phantom that showed a non-linear calibration curve R(2) = 0.39-0.67. At 1.5 T, the Agarose experiments revealed similar temperature accuracies of 4-6°C for all sequences excluding TRUFI. During experiments with the liver, the PRF sequences showed better performance than the T1, with accuracies of 5-12°C, contrary to the T1 sequences at 14-18°C. The accuracy of the Siemens PRF-FLASH sequence was 5.1°C. At 0.2 T, the Agarose experiments provided the highest accuracy of 3.3°C for PRF measurement. At the liver experiments the T1 sequences SRTF and FLASH revealed the best accuracies at 6.4 and 7.0°C.
The accuracy and speed of MR temperature measurements are sufficient for controlling the temperature-based tumor destruction. For 0.2 T systems SRTF and FLASH sequences are recommended. For 1.5 T systems SRTF and FLASH are the most accurate.
评估在0.2T和1.5T系统中使用快速磁共振序列进行激光诱导间质热疗（LITT）的磁共振测温技术。
使用琼脂糖凝胶混合物和猪肝叶进行体外实验。在采集幅度和相移图像的情况下，通过纵向弛豫时间（T1）和质子共振频率偏移（PRF）方法进行磁共振测温。四种不同序列用于T1测温：梯度回波（GRE）序列、稳态进动快速成像（TRUFI）序列、饱和恢复快速小角度激发（SRTF）序列和反转恢复快速小角度激发（IRTF）序列（快速低角度激发快速成像序列）。PRF用四种序列测量：两个快速扰相GRE序列（其中一个作为在研序列）、一个快速小角度激发（TFL）序列（在研序列）和一个多回波稳态进动快速成像（TrueFISP）序列。使用光纤Luxtron设备控制和验证温度。将温度与磁共振测量结果进行关联。
所有序列在测量温度与磁共振测温测量结果之间均显示出良好的线性相关性，R(2)=0.97 - 0.99。唯一的例外是琼脂糖模型中的TRUFI序列，其显示出非线性校准曲线，R(2)=0.39 - 0.67。在1.5T时，除TRUFI外，所有序列在琼脂糖实验中的温度精度相似，为4 - 6°C。在肝脏实验中，PRF序列的性能优于T1序列，精度为5 - 12°C，而T1序列的精度为14 - 18°C。西门子PRF - FLASH序列的精度为5.1°C。在0.2T时，琼脂糖实验中PRF测量的最高精度为3.3°C。在肝脏实验中，T1序列SRTF和快速低角度激发（FLASH）的精度最佳，分别为6.4°C和7.0°C。
磁共振温度测量的精度和速度足以控制基于温度的肿瘤破坏。对于0.2T系统，推荐使用SRTF和FLASH序列。对于1.5T系统，SRTF和FLASH序列最为准确。
