Objective: To study the anatomical characteristics of blood vessels in the lateral segment of the vertebral body through the surgical approach of oblique lumbar interbody fusion (OLIF) using MRI imaging, and evaluate its potential vascular safety zone.
Methods: The lumbar MRI data of 107 patients with low back and leg pain who met the selection criteria between October 2019 and November 2022 were retrospectively analyzed. The vascular emanation angles, vascular travel angles, and the length of vessels in the lateral segments of the left vertebral body of L 1-L 5, as well as the distance between the segmental vessels in different Moro junctions of the vertebral body and their distances from the edges of the vertebrae in the same sequence (bottom marked as I, top as S) were measured. The gap between the large abdominal vessels and the lateral vessels of the vertebral body was set as the lateral vascular safe zones of the lumbar spine, and the extent of the safe zones (namely the area between the vessels) was measured. The anterior 1/3 of the lumbar intervertebral disc was taken as the simulated puncture center, and the area with a diameter of 22 mm around it as the simulated channel area. The proportion of vessels in the channel was further counted. In addition, the proportions of segmental vessels at L 5 without a clear travel and with an emanation angel less than 90° were calculated.
Results: Except for the differences in the vascular emanation angles between L 4 and L 5, the vascular travel angles between L 1, L 2 and L 4, L 5, and the length of vessels in the lateral segments of the vertebral body among L 1-L 4 were not significant ( P>0.05), the differences in the vascular emanation angles, vascular travel angles, and the length of vessels between the rest segments were all significant ( P<0.05). There was no significant difference in the distance between vessels of L 1, L 2 and L 2, L 3 at Moro Ⅰ-Ⅳ junctions ( P>0.05), in L 3, L 4 and L 4, L 5 at Ⅱ and Ⅲ junction ( P>0.05). There was no significant difference in the vascular distance of L 2, L 3 between Ⅱ, Ⅲ junction and Ⅲ, Ⅳ junction, and the vascular distance of L 3, L 4 between Ⅰ, Ⅱ junction and Ⅲ, Ⅳ junction ( P>0.05). The vascular distance of the other adjacent vertebral bodies was significant different between different Moro junctions ( P<0.05). Except that there was no significant difference in the distance between L 2I and L 3S at Ⅰ, Ⅱ junction, L 3I and L 4S at Ⅱ, Ⅲ junction, and L 2I and L 3S at Ⅲ, Ⅳ junction ( P>0.05), there was significant difference of the vascular distance between the bottom of one segment and the top of the next in the other segments ( P<0.05). Comparison between junctions: Except for the L 3S between Ⅰ, Ⅱ junction and Ⅱ, Ⅲ junction, and L 5S between Ⅰ, Ⅱ junction and Ⅱ, Ⅲ and Ⅲ, Ⅳ junctions had no significant difference ( P>0.05), there were significant differences in the distance between the other segmental vessels and the vertebral edge of the same sequence in different Moro junctions ( P<0.05). The overall proportion of vessels in the simulated channels was 40.19% (43/107), and the proportion of vessels in L 1 (41.12%, 44/107) and L 5 (18.69%, 20/107) was higher than that in the other segments. The proportion of vessels in the channel of Moro zone Ⅰ (46.73%, 50/107) and zone Ⅱ (32.71%, 35/107) was higher than that in the zone Ⅲ, while no segmental vessels in L 1 and L 2 were found in the channel of zone Ⅲ ( χ 2=74.950, P<0.001). Moreover, 26.17% (28/107) of the segmental vessels of lateral L 5 showed no movement, and 27.10% (29/107) vascular emanation angles of lateral L 5 were less than 90°.
Conclusion: L 1 and L 5 segmental vessels are most likely to be injured in Moro zones Ⅰ and Ⅱ, and the placement of OLIF channels in L 4, 5 at Ⅲ, Ⅳ junction should be avoided. It is usually safe to place fixation pins at the vertebral body edge on the cephalic side of the intervertebral space, but it is safer to place them on the caudal side in L 1, 2 (Ⅰ, Ⅱ junction), L 3, 4 (Ⅲ, Ⅳ junction), and L 4, 5 (Ⅱ, Ⅲ, Ⅳ junctions).
目的: 通过MRI影像研究斜外侧腰椎椎间融合术（oblique lumbar interbody fusion，OLIF）手术入路椎体侧方节段血管的解剖特征，评估其潜在的血管安全区范围。.
方法: 回顾性分析2019年10月—2022年11月收治的107例符合选择标准的腰腿痛患者腰椎MRI资料。测量L 1～5左侧椎体侧方节段血管发出角度、血管走行角度、血管长度、椎体不同Moro交界区节段血管间距及其与同序列椎体边缘（尾端为I，头端为S）的距离。将腹部大血管、椎体侧方血管之间的间隙设定为腰椎侧方血管安全区，测量安全区范围（即血管间面积）；将腰椎间盘中前1/3作为模拟穿刺中心、直径22 mm区域为模拟通道区域，统计通道内发现血管的比例；并统计L 5椎体无明确节段血管走行及血管发出角度<90° 的比例。.
结果: 除L 4和L 5节段血管发出角度，L 1和L 2间、L 4和L 5间血管走行角度，以及L 1～L 4间椎体侧方节段血管长度差异无统计学意义（ P>0.05）外，其余各椎体节段血管发出角度、走行角度及长度差异均有统计学意义（ P<0.05）。在Moro Ⅰ～Ⅳ各区交界L 1、2、L 2、3血管间距差异均无统计学意义（ P>0.05），Ⅱ、Ⅲ区交界L 3、4、L 4、5血管间距差异无统计学意义（ P>0.05）；L 2、3血管间距在Ⅱ、Ⅲ区交界和Ⅲ、Ⅳ区交界间，以及L 3、4血管间距在Ⅰ、Ⅱ区交界和Ⅲ、Ⅳ区交界间差异无统计学意义（ P>0.05）；其余各相邻椎体血管间距在不同Moro交界区差异均有统计学意义（ P<0.05）。除Ⅰ、Ⅱ区交界L 2I与L 3S之间，Ⅱ、Ⅲ区交界L 3I与L 4S之间，Ⅲ、Ⅳ区交界L 2I与L 3S之间差异无统计学意义（ P>0.05）外，其他节段尾端距离与下一节段头端距离比较差异均有统计学意义（ P<0.05）。各区交界间比较：除Ⅰ、Ⅱ区交界与Ⅱ、Ⅲ区交界间L 3S，以及Ⅰ、Ⅱ区交界与Ⅱ、Ⅲ区交界和Ⅲ 、Ⅳ区交界间L 5S比较差异无统计学意义（ P>0.05）外，其他各节段血管至同序列椎体边缘间距在不同Moro交界区差异均有统计学意义（ P<0.05）。模拟通道内发现血管的总体比例为40.19%（43/107），其中L 1（41.12%，44/107）、L 5（18.69%，20/107）节段发现血管比例高于其他节段，在Moro Ⅰ区（46.73%，50/107）、Ⅱ区（32.71%，35/107）通道内发现血管比例高于Ⅲ区，而在Moro Ⅲ区通道内未发现L 1、L 2节段血管存在（ χ 2=74.950， P<0.001）。同时，26.17%（28/107）L 5椎体侧方未发现节段血管走行，且27.10%（29/107）L 5椎体侧方血管发出角度<90°。.
结论: L 1、L 5节段血管在Moro Ⅰ区、Ⅱ区最容易出现损伤，应避免在L 4、5 Ⅲ、Ⅳ区交界放置OLIF通道；通常在椎间隙头侧椎体边缘放置固定针较安全，而L 1、2（Ⅰ、Ⅱ区交界）、L 3、4 （Ⅲ、Ⅳ区交界）、L 4、5（Ⅱ、Ⅲ、Ⅳ区交界）在椎间隙尾侧椎体边缘放置固定针更安全。.
Keywords: MRI; Oblique lateral interbody fusion; radiological evaluation; segmental vessels.