重T2WI和间质MR淋巴管成像在下肢淋巴水肿中联合应用的价值

Value of combined application of interstitial MR lymphangiography and heavily T2WI in the lower extremity with lymphedema

目的评估MR重T2WI和间质MR淋巴管成像（MRL）联合应用显示下肢淋巴水肿患者形态改变的价值。方法回顾性分析31例原发性淋巴水肿患者40条病变下肢资料，患者行MR重T，W1和间质MRL，对淋巴管成像图像进行分析。重T2WI和间质MRL图像上显示淋巴管数目及淋巴液积聚的比较采用秩和检验，信噪比（SNR）和对比噪声比（CNR）及扩张淋巴管最大径的比较采用配对t检验。结果在重LwI上共显示498条扩张淋巴管，每条肢体显示扩张淋巴管的中位数为5（1—24）条；在MRL上共显示356条淋巴管，每条肢体显示扩张淋巴管的中位数为3（1～16）条，重T2WI显示扩张淋巴管的数目多于MRL，差异有统计学意义（Z=-2．92，P〈0．01）。在显示最大径方面，重T，WI上扩张淋巴管的最大径为（4．3±1．5）mm，间质MRL上为（3．4±1．0）mm，差异有统计学意义（t=6．90，P〈0．01）；在显示扩张淋巴管的SNR和CNR方面，间质MRL（分别为257±130和2074-113）均优于重T2wI（分别为169±91和135±82），差异均有统计学意义（t值分别为-5．95和-5．10，P值均〈0．01）。在显示淋巴液积聚方面，重T2WI（中位数为1个）优于间质MRL（中位数为0个），差异有统计学意义（Z=-5．64，P〈0．01）。结论重T2WI具有较高的敏感度，而MRL具有较高的SNR和CNR，结合两者能更好地显示出下肢淋巴水肿患者的淋巴管结构。

Objective To access the value of combined application of high-resolution interstitial MR lymphangiography （MRL） and heavily T2WI for the visualization of lymphatic vessels in patients with primary lymphedema. Methods Forty lower extremities in 31 patients with primary lymphedema were examined by heavily T2WI and interstitial MRL with a 3.0 T MR unit （ Philips Medical Systems, Best, the Netherlands）. Two experienced radiologists analyzed the images and tried to determine the differences in number of lymphatic vessels, and their maximum diameters, SNR and CNR, and accumulated lymph fluid in the tissue. Statistical analyses were conducted by using Wilcoxon test and t test. Results Dilated lymphatic vessels in 73 leg segments of 40 lower extremities were visualized on heavily T2WI （median 5, 1 to 24） , which were more than those on MRL （ median 3, 1 to 16） （ Z = - 2. 92, P 〈 0. 01 ）. The maximum diameter of lymphatic vessels was （4. 3 ±1.5） mm on heavily T2WI, whereas it was （3.4 ± 1.0） mm on MRL （t = 6. 90, P 〈 0.01）. The average SNR and CNR in the dilated lymphatic vessels were 257 ± 130, 207 ± 113 on MRL and 169 ±91, 135±82 on heavily T2WI, which was statistically significant （SNR t = -5.95, CNR t = - 5.10 ; P 〈 0. 01 ）. The visualization of regions of accumulated lymph fluid on heavily T2WI （ median 1 ） had a higher score than that on MRL （ median 0） （ Z = - 5.64, P 〈 0. 01 ）. Conclusions The heavily T2WI has greater sensitivity and the MRL image has better SNR and CNR. Combining these two MR techniques can provide adequate information for clinicians in the therapeutic planning of patients with advanced stages of lymphedema.