极外侧型腰椎间盘突出症的CT、MRI表现

Characteristics of CT scan and MRI in far lateral lumbar disc herniation

目的探讨极外侧型腰椎间盘突出症(far lateral lumbar disc herniation,FLLDH)的CT、MRI影像表现,提高对该病的影像诊断水平。方法回顾性研究我院2000年3月至2005年5月经手术证实的FLLDH病人共15例,分析其CT、MRI影像表现。结果15例FLLDH中,根据椎间盘突出物的位置与椎弓根的关系可分为3种类型:椎间孔内侧型3例,占20%;椎间孔外侧型6例,占40%;混合型6例,占40%,包括椎间孔内外侧突出。CT显示FLLDH的特征为突入椎间孔内和椎间孔外的软组织块影,形态多呈丘状、圆形、不规则形或三角形。MRI显示同位节段脊神经受压、移位、增粗;T1加权像突出髓核的信号比脑脊液高,比硬膜外脂肪信号低,界限分明;T2加权像突出髓核可表现为高或低信号,信号强度比脑脊液低,比脊髓高。结论CT及MRI对极外侧型腰椎间盘突出症具有重要的诊断价值,并为外科医师手术入路提供指导。

Objective To investigate the characteristics of far lateral lumbar disc herniation （FLLDH） with CT scan and MRI, and to improve our diagnostic level of FLLDH. Methods Fifteen consecutive cases confirmed by operation with FLLDH underwent CT scans and MRI were studied retrospectively in our hospital from March.2000 to May 2005. Results There were 3 types according to relationship of FLLDH with intervertebral foramina among 15 cases, The herniation involved the intervertebral foramina in 3 cases （20%）, external intervertebral foramina in 6 cases （40%）, both intervertebral and external intervertebral foramina in 6 cases （40%）. They were demonstrated on CT scan as shapes of hillock, circular, irregular or trigonal soft-tissue density mass in or outside of intervertebral foramen. MRI showed nerve root of same level compressed, displaced, and swelled. TIWI showed signals of nucleus pulposus of disc herniation higher than cerebrospinal fluid, and lower than epidural fat. T2WI showed nucleus pulposus of disc herniation with high or low signals, which was lower than cerebrospinal fluid, higher than spinal cord. Conclusion CT scan and MRI are useful to diagnose ELLDH, and useful for surgeons to determine operative approach.