Objective To investigate the depiction rate of normal cisterna chyli and thoracic duct by nonenhanced MR lymphography and to describe their appearances on MR imaging. Methods Special MR hydrography sequence was added to the MR imaging protocols of 112 patients undergoing MR examination of the thorax and upper abdomen. MR imaging sequences included: ①Respiratory-gated HASTE T2W sequence; ②Breath-hold FLASH T1W sequence; ③Respiratory-gated TSE 3D T2W sequence (3D MR hydrography sequence) in coronal plane. One hundred cases who met the inclusion criteria were included into the study for observation of the depiction rate, location and morphology of cisterna chyli and thoracic duct. Results On TSE 3D T2W imaging： ①Cisterna chyli was visualized in 71/100 (depiction rate 71.0%), morphologically including single-tube type 43.7% (31/71), bifurcation type (2-3 tubes) 23.9% (17/71), plexus type 32.4% (23/71). Average length of the cisterna chyli was 4.5 cm. ②The depiction rate of the lower segment of thoracic duct was 57.0% (57/100), average ductal diameter was 0.23 cm. ③The depiction rate of upper segment of the thoracic duct was 31.0% (31/100). Conclusion As a noninvasive method for depicting the lymphatic system, nonenhaced MR lymphography (TSE 3D T2W sequence) demonstrated a high depiction rate for cisterna chyli and lower thoracic duct. Combined with axial images of HASTE and FLASH sequences, the location and morphology of these larger lymphatic ducts can be defined.
【摘要】 目的 探讨伽玛刀治疗三叉神经痛MRI定位的最佳扫描序列。 方法 选择2004年7月-2006年3月行伽玛刀手术的原发性三叉神经痛患者60例，随机分为3组，每组各20例。伽玛刀术前上头架定位，然后对3组分别采用快速自旋回波序列（Turbo Spin Echo，TSE）、增强三维小角度激发快速梯度回波序列（enhanced three-dimensiunal fast low angle shot，enhanced 3D-FLASH）、三维结构干涉稳态序列（three-dimensional constructive interference in steady state，3D-CISS）进行扫描，观察三叉神经及周围血管的显示情况。 结果 ①TSE扫描20例三叉神经，14例显示优，血管显示一般。②增强3D-FLASH扫描三叉神经，18例显示优，2例显示良，周围血管显示优。③3D-CISS扫描三叉神经，20例均显示优，周围血管显示良。 结论 3D-CISS和增强3D-FLASH序列的融合影像能够清晰地显示三叉神经根及周围血管，有利于伽玛刀的精确定位，具有较高的临床应用价值，可以作为伽玛刀治疗原发性三叉神经痛的常规定位方法。【Abstract】 Objective To evaluate the optimal MRI localization sequences of gamma knife radiosurgery for trigeminal neuralgia. Methods From July 2004 to March 2006, sixty patients with primary trigeminal neuralgia were divided into three groups, using MR Turbo Spin Echo ( TSE), enhanced three-dimensiunal fast low angle shot 3D-FLASH and three-dimensional constructive interference in steady state ( 3D-CISS) sequence for stereotactic localization, respectively. The trigeminal nerve and surrounding vessels were observed. Results Only 14 trigeminal nerves were precisely displayed by MR TSE sequence, while 20 by 3D-CISS and 18 by 3D-FLASH. The display of surrounding vessels was excellent, good, and general by 3D-FLASH, 3D-CISS, and MR TSE, respectively. Conclusion 3D-CISS and enhanced 3D-FLASH fusion image can help achieve accurate orientation of gamma knife, which provides clear images of the trigeminal nerve and the surrounding vessels. Therefore it is of high value in clinical application, which can be used as the conventional localization method for gamma knife radiosurgery in the treatment of primary trigeminal neuralgia.