硬脊膜内蛛网膜囊肿MRI诊断
作者：林曰增
单位：第一军医大学南方医院影像诊断中心, 广州，510515
关键词：硬膜内蛛网膜囊肿；脊髓；磁共振成像
第一军医大学学报990521 摘要：目的 评估硬膜内蛛网膜囊肿的MRI特征。材料和方法 6例硬膜内蛛网膜囊肿(4例男性，2例女性，年龄17～56岁不等，平均33岁)，行MRI诊断且手术病理证实。使用0.35特斯拉超导型MR成像仪，采用自旋回波和多回波技术。行矢状面、横断面T1加权成像和矢状面T2加权成像。结果 病变分布：颈段、腰段、腰骶段各1例，胸段3例。长度为1～4个椎体长度不等(平均2.2个椎体长度)。4例囊肿位于脊髓平面，将脊髓推向对侧，其上、下端蛛网膜下腔扩大。1例并发其平面下的脊髓空洞症。所有的MR序列呈现与脑脊液相同的信号。结论 MR是直接显示囊肿的大小、成分及与周围蛛网膜下腔联系的最好的手段。它还直接显示囊肿的信号和周围的结构，且无电离辐射、无损伤性、无骨伪影、多平面成像、无需椎管内注入造影剂。
, 百拇医药
中图分类号：R816.1; R730.44
MRI diagnosis of intradural arachnoid cysts
Lin Yuezeng
Imaging Diagnostic Center, Nanfang Hospital, First Military Medical University, Guangzhou, 510515
Abstract: Objective To evaluate the MRI features of intradural arachnoid cysts. Material and Methods Six cases ( 4 males and 2 females, ranging in age from 17 to 56 years, mean age 33 years) of intradural arachnoid cysts, diagnosed on MRI and confirmed surgically and pathologically. Superconductive MR unit at 0.35T was performed. Spin echo (SE) and multiple echoes were available. Sagittal, axial T1-weighted images and sagittal T2-weighted images were obtained. Results The distribution regions of the lesions: cervical (1 case ), thoracic ( 3 cases ), lumbar ( 1 case ) and lumbosacral ( 1 case ). The length was one to four vertebral height (mean 2.2 vertebral height). Four cysts which were at the levels of the spinal cord displaced the cords away from their sites and widened the subarachnoid space below and above the cysts. One case was associated with syringomyelia below its level. All MRI sequences gave the same signal as cerebrospinal fluid. Conclusion MR is the best imaging modality for directly demonstrating the size, content and communication of the cyst with the surrounding subarachnoid space. It also directly showed cyst,s signal and its surrounding structures: non-ionizing radiation, noninvasive, no bony artifacts, multiple planar imaging, and there was no need to inject agents to the spinal canal.
, 百拇医药
Key words: intradural arachnoid cyst; spinal cord; magnetic resonance image (MRI)
硬脊膜内蛛网膜囊肿为引起脊髓压迫的少见疾病。作者回顾手术病理证实的6例硬膜内蛛网膜囊肿，以期提高对该病变MRI表现的认识。
1材料和方法
6例中，男性4例，女性2例。年龄17～60岁不等，平均年龄33岁。主要临床表现为肢体无力、疼痛，腰痛，严重者双下肢瘫痪。病程2个月至6个月不等。
使用超导型MR成像仪，工作场强0.35 T。自旋回波(Spin Echo，SE)序列，多回波技术。全部病例行矢状面及横断面T1加权成像(TR/TE=500 ms/30 ms)，矢状面T2加权成像(TR/TE=2 000 ms/40～80 ms)。矢状面时层厚5.0 mm，横断面时层厚10.0 mm。
, 百拇医药
2 结果
病变节段：颈段1例，胸段3例，腰段及腰骶段各1例。病变长度1～4个椎体高度不等，平均2.2个椎体高度。位于脊髓平面者4例，均将脊髓向对侧推移，导致对侧蛛网膜下腔变窄，病变侧上下端蛛网膜下腔变宽。与正常脊髓信号比较，6例T1加权成像为低信号，T2加权呈高信号，信号强度等同于脑脊液。其中1例并发其平面以下脊髓空洞症，表现为脊髓中央低信号的管状扩张，在T2加权图像上空洞内液呈高信号。空洞内液体信号均匀一致。横断面上空洞呈圆形。
3 讨论
硬膜内蛛网膜囊肿是局限于硬脊膜腔内蛛网膜下腔扩大的憩室，仅由蛛网膜构成，常以相对狭窄的颈与蛛网膜下腔相通，但术前常常不能确定这一交通。通过脊髓的髓外硬膜下的压迫或神经根受压而引起神经症状[1,2,3]，男、女发病率无差别，多见于成人，儿童少见。其好发于胸段后侧。起源于蛛网膜小梁分布的先天性异常、增生或后隔(一种中线脊膜结构)的缺损。后隔位于背侧，与硬膜内蛛网膜囊肿常发生于脊髓背侧有关(80%)。很少发生于脊髓前侧。这些囊肿很少伴随先天性脊柱异常[2,4,5]。有些作者认为感染、出血、外伤或手术也是发病原因之一[1,3,4]。
, 百拇医药
MR成像时，位于脊髓平面的较大的硬膜内囊肿可推移脊髓向对侧移位，使对侧蛛网膜下腔变窄，病变上下侧的蛛网膜下腔扩大，T1、T2加权成像时囊肿显示与脑脊液相同的信号[4,5]。本组囊肿大小1～4个椎体不等，均可清楚显示。有1例伴随其脊髓平面以下空洞症形成，机理可能是压迫蛛网膜下腔和脊髓影响脑脊液的循环所致。
尽管MR能直接显示囊肿及其对周围结构的压迫，但有时很难确认囊肿与蛛网膜下腔的界限[3]，因为二者成分相同，信号相似。MR有时不能显示没有脊髓压迫、含有脑脊液样液体的小囊肿。这些病变可通过椎管碘水造影或造影后CT扫描确诊[3,5]。
总之，MR是显示大的硬膜内蛛网膜囊肿的最好的成像手段：无电离辐射，无损伤性，无骨伪影，多平面成像，不需椎管内注入造影剂。
作者简介：林日增，男，1964年出生；硕士，主治医师；电话85142086
, 百拇医药
参考文献
1.Kendall BE, Valentine AR, Keis B.Spinal arachnoid cysts: clinical and radiological correlation with prognosis. Neuroradiol, 1982,22:225
2.Gindre BT, Charleux F,Turjman F et al. Magnetic resonance imaging contribution to the diagnosis of spinal cord compression by a subdural arachnoid cyst. Neuroradiol, 1991,33:87
3.Fujimura M, Tominaga T, Koshu K et al. Cine mode magnetic resonance imaging of a thoracic intradural arachnoid cyst: case report. Surg Neurol, 1996,45:533
4.Slavotinek JP, Sage MR, Brophy BP. An usual spinal intradural arachnoid cyst. Neuroradiol,1996,38:152
5.Dietemann JL, Filippi de la Palavesa MM, Astler B et al. Thoracic intradural arachnoid cyst: possible pitfalls with myelo-CT and MR. Neuroradiol, l991, 33:90
(收稿日期：1998-10-17), 百拇医药
单位：第一军医大学南方医院影像诊断中心, 广州，510515
关键词：硬膜内蛛网膜囊肿；脊髓；磁共振成像
第一军医大学学报990521 摘要：目的 评估硬膜内蛛网膜囊肿的MRI特征。材料和方法 6例硬膜内蛛网膜囊肿(4例男性，2例女性，年龄17～56岁不等，平均33岁)，行MRI诊断且手术病理证实。使用0.35特斯拉超导型MR成像仪，采用自旋回波和多回波技术。行矢状面、横断面T1加权成像和矢状面T2加权成像。结果 病变分布：颈段、腰段、腰骶段各1例，胸段3例。长度为1～4个椎体长度不等(平均2.2个椎体长度)。4例囊肿位于脊髓平面，将脊髓推向对侧，其上、下端蛛网膜下腔扩大。1例并发其平面下的脊髓空洞症。所有的MR序列呈现与脑脊液相同的信号。结论 MR是直接显示囊肿的大小、成分及与周围蛛网膜下腔联系的最好的手段。它还直接显示囊肿的信号和周围的结构，且无电离辐射、无损伤性、无骨伪影、多平面成像、无需椎管内注入造影剂。
, 百拇医药
中图分类号：R816.1; R730.44
MRI diagnosis of intradural arachnoid cysts
Lin Yuezeng
Imaging Diagnostic Center, Nanfang Hospital, First Military Medical University, Guangzhou, 510515
Abstract: Objective To evaluate the MRI features of intradural arachnoid cysts. Material and Methods Six cases ( 4 males and 2 females, ranging in age from 17 to 56 years, mean age 33 years) of intradural arachnoid cysts, diagnosed on MRI and confirmed surgically and pathologically. Superconductive MR unit at 0.35T was performed. Spin echo (SE) and multiple echoes were available. Sagittal, axial T1-weighted images and sagittal T2-weighted images were obtained. Results The distribution regions of the lesions: cervical (1 case ), thoracic ( 3 cases ), lumbar ( 1 case ) and lumbosacral ( 1 case ). The length was one to four vertebral height (mean 2.2 vertebral height). Four cysts which were at the levels of the spinal cord displaced the cords away from their sites and widened the subarachnoid space below and above the cysts. One case was associated with syringomyelia below its level. All MRI sequences gave the same signal as cerebrospinal fluid. Conclusion MR is the best imaging modality for directly demonstrating the size, content and communication of the cyst with the surrounding subarachnoid space. It also directly showed cyst,s signal and its surrounding structures: non-ionizing radiation, noninvasive, no bony artifacts, multiple planar imaging, and there was no need to inject agents to the spinal canal.
, 百拇医药
Key words: intradural arachnoid cyst; spinal cord; magnetic resonance image (MRI)
硬脊膜内蛛网膜囊肿为引起脊髓压迫的少见疾病。作者回顾手术病理证实的6例硬膜内蛛网膜囊肿，以期提高对该病变MRI表现的认识。
1材料和方法
6例中，男性4例，女性2例。年龄17～60岁不等，平均年龄33岁。主要临床表现为肢体无力、疼痛，腰痛，严重者双下肢瘫痪。病程2个月至6个月不等。
使用超导型MR成像仪，工作场强0.35 T。自旋回波(Spin Echo，SE)序列，多回波技术。全部病例行矢状面及横断面T1加权成像(TR/TE=500 ms/30 ms)，矢状面T2加权成像(TR/TE=2 000 ms/40～80 ms)。矢状面时层厚5.0 mm，横断面时层厚10.0 mm。
, 百拇医药
2 结果
病变节段：颈段1例，胸段3例，腰段及腰骶段各1例。病变长度1～4个椎体高度不等，平均2.2个椎体高度。位于脊髓平面者4例，均将脊髓向对侧推移，导致对侧蛛网膜下腔变窄，病变侧上下端蛛网膜下腔变宽。与正常脊髓信号比较，6例T1加权成像为低信号，T2加权呈高信号，信号强度等同于脑脊液。其中1例并发其平面以下脊髓空洞症，表现为脊髓中央低信号的管状扩张，在T2加权图像上空洞内液呈高信号。空洞内液体信号均匀一致。横断面上空洞呈圆形。
3 讨论
硬膜内蛛网膜囊肿是局限于硬脊膜腔内蛛网膜下腔扩大的憩室，仅由蛛网膜构成，常以相对狭窄的颈与蛛网膜下腔相通，但术前常常不能确定这一交通。通过脊髓的髓外硬膜下的压迫或神经根受压而引起神经症状[1,2,3]，男、女发病率无差别，多见于成人，儿童少见。其好发于胸段后侧。起源于蛛网膜小梁分布的先天性异常、增生或后隔(一种中线脊膜结构)的缺损。后隔位于背侧，与硬膜内蛛网膜囊肿常发生于脊髓背侧有关(80%)。很少发生于脊髓前侧。这些囊肿很少伴随先天性脊柱异常[2,4,5]。有些作者认为感染、出血、外伤或手术也是发病原因之一[1,3,4]。
, 百拇医药
MR成像时，位于脊髓平面的较大的硬膜内囊肿可推移脊髓向对侧移位，使对侧蛛网膜下腔变窄，病变上下侧的蛛网膜下腔扩大，T1、T2加权成像时囊肿显示与脑脊液相同的信号[4,5]。本组囊肿大小1～4个椎体不等，均可清楚显示。有1例伴随其脊髓平面以下空洞症形成，机理可能是压迫蛛网膜下腔和脊髓影响脑脊液的循环所致。
尽管MR能直接显示囊肿及其对周围结构的压迫，但有时很难确认囊肿与蛛网膜下腔的界限[3]，因为二者成分相同，信号相似。MR有时不能显示没有脊髓压迫、含有脑脊液样液体的小囊肿。这些病变可通过椎管碘水造影或造影后CT扫描确诊[3,5]。
总之，MR是显示大的硬膜内蛛网膜囊肿的最好的成像手段：无电离辐射，无损伤性，无骨伪影，多平面成像，不需椎管内注入造影剂。
作者简介：林日增，男，1964年出生；硕士，主治医师；电话85142086
, 百拇医药
参考文献
1.Kendall BE, Valentine AR, Keis B.Spinal arachnoid cysts: clinical and radiological correlation with prognosis. Neuroradiol, 1982,22:225
2.Gindre BT, Charleux F,Turjman F et al. Magnetic resonance imaging contribution to the diagnosis of spinal cord compression by a subdural arachnoid cyst. Neuroradiol, 1991,33:87
3.Fujimura M, Tominaga T, Koshu K et al. Cine mode magnetic resonance imaging of a thoracic intradural arachnoid cyst: case report. Surg Neurol, 1996,45:533
4.Slavotinek JP, Sage MR, Brophy BP. An usual spinal intradural arachnoid cyst. Neuroradiol,1996,38:152
5.Dietemann JL, Filippi de la Palavesa MM, Astler B et al. Thoracic intradural arachnoid cyst: possible pitfalls with myelo-CT and MR. Neuroradiol, l991, 33:90
(收稿日期：1998-10-17), 百拇医药