《MSK RADIOLOGY骨肌小影像》——腰椎骶化还是骶椎腰化？一个小韧带帮你辨认！
并发症2:
Wrong-Level Spine Surgery
准确辨认移行椎的层面才能避免脊柱手术的定位错误。错误定位常发生于缺失平片或颈胸段定位的患者中。
如何准确定位腰骶移行椎，到底是腰5椎体骶化还是骶1椎体腰化：
方法1：借助平片，从颈2或腰1向下数，简单易得；现实困境：平片也很少拍全脊柱，少数患者可同时出现胸腰移行椎，到底是胸12或腰1又是一个难题。
方法2: 借助核磁颈胸椎矢状定位向，从颈2向下数，假定患者有7个颈椎、12个胸椎；现实困境：仍存在胸腰移行椎的漏诊，且行腰椎核磁时一般认定有L5作定位，故较少扫描颈胸定位向。
方法3:借助腰髂韧带，仅存在于腰5椎体横突，腰4横突无腰髂韧带存在，可作为定位腰5的可靠证据；
定位方式：
A.锁定移行椎（L5或S1)，将目光放在移行椎上一椎体层面；
B.若移行椎上一椎体层面存在腰髂韧带，则移行椎为S1；
C.若移行椎上一椎体层面无腰髂韧带，则移行椎为L5（同时适用于移行椎双侧横突均融合或形成假关节时，或移行椎层面可见腰髂韧带）；（若椎体为单侧横突假关节形成或融合，对侧L5椎体横突均可见腰髂韧带）
附：
Hughes and Saifuddin试验：500名患者，433例腰骶椎正常的患者中100%仅在L5椎体横突处可见腰髂韧带，其中仅1例患者为单侧可见，余均为双侧；67例腰骶移行椎患者中，均可用腰髂韧带成功定位L5，46例移行椎系L5椎体，21例为S1腰化。
方法原文：If an LSTV was present, it was numbered as a transitional L5 or transitional S1 segment based on the following method. When the ILL was identified to arise at the level above the LSTV, the vertebral level of origin of the ILL was labeled L5 and, consequently, the LSTV was numbered S1. If the ILL was not visualized, the LSTV was numbered L5. This numbering system was based on the hypothesis that in the presence of healthy lumbosacral segmentation, the ILL always arises from L5 and is therefore a marker of the L5 level. In the case of Castellvi type IIa or IIIa transitional vertebrae (with unilateral enlargement of a transverse process), the ILL was always seen to arise from the contralateral,normal transverse process and these were therefore numbered as L5 transitions .
腰髂韧带解剖及影像：起源于腰5横突，并分成两束，前束较宽、平，附着于髂骨结节，后束为梭形，附着于髂嵴；MRI轴位可很好显示腰髂韧带，呈L5横突与髂嵴后内部之间的单/双束低信号条带影
参考文献：
DOI 10.3174/ajnr.A2036
Konin, G.P., and D.M. Walz. “Lumbosacral Transitional Vertebrae: Classification, Imaging Findings, and Clinical Relevance.” American Journal of Neuroradiology 31.10 (2010): 1778-1786. Web. 06 May. 2022.
DOI:10.2214/AJR.05.0415
Numbering of Lumbosacral Transitional Vertebrae on MRI: Role of the Iliolumbar Ligaments
Richard J. Hughes and Asif Saifuddin
American Journal of Roentgenology 2006 187:1, W59-W65