椎管内皮样囊肿破裂的MRI诊断（附13例报告）

目的 探讨椎管内皮样囊肿破裂（RDIC）的MRI诊断价值。材料与方法 13例RDIC原发灶均经手术和病理证实，皮样囊肿均位于T12以下椎管内，其中9例位于脊髓内，4例位于髓外硬膜下，均行脑和全脊柱MRISE序列T1WI、T2WI，7例有脊柱脂肪抑制序列。5例行脑CT检查，结果 4例髓外硬膜下皮样囊肿破裂MRI与CT均表现在脑池、脑沟或脑室内有脂肪滴，9例脊髓内皮样囊肿破裂者均见脊髓中央管内分布有脂肪滴，其中4例脑室内见脂肪滴，5例脑MRI发现脑底及后颅窝脂肪滴者，CT仅显示2例。脂肪滴MIE SE序列T1WI呈显著高信号，T2WI其信号略有衰减，脂肪抑制序列则呈极低信号；CT上脂肪滴则呈低密度，CT值-20--150HU。结论 MRI是诊断RDIC的最佳影像学方法，其显示RDIC脂肪滴在脑室、蛛网膜下腔和脊髓中央管内分布优于CT。CT与MRI联合应用能有效地鉴别RDIC脂肪滴抑或积气、碘化油滞留和血块。

MRI Diagnosis of Ruptured Dermoid Cyst in Intraspinal Canal

Objective　To evaluate MRI in the diagnosis of ruptured dermoid cyst in the intraspinal canal (RDCIC).　Materials and Methods　Thirteen patients with surgico-pathologically proved RDCIC, located below T12, were collected. Nine lesions were intramedullary, and four were extramedullary and intradural. Cranial and full spinal MRI scanning with SE T1WI and T2WI were performed in all cases, additional fat-suppression sequences of the spine were done in 7 cases. Cranial CT scanning was made in 5 cases. 　Results　Lipid droplets in cerebral subarachnoid space or ventricles were seen in all extramedullary intradural RDCIC on both CT and MRI. Lipid droplets within central canal of spinal cord were seen in all 9 cases of intramedullary RDCIC on MRI, in 4 of them intraventricular lipid droplets were found. On MRI lipid droplets at cerebral bottom and posterior fossa were displayed in 5 cases, while on CT lipid droplets could be revealed only in 2 cases. The lipid droplets showed hyperintensity on SE T1WI, a little lower signal intensity on T2WI, and hypointensity on fat-suppression sequence. The lipid droplets showed fatty density on CT scan with a value of -150～-20 Hu. 　Conclusion　MRI is the most effective means for the diagnosis of RDCIC, it is superior to CT in demonstrating the lipid droplets distributing in the subarachnoid space, ventricles and central canal of the spinal cord, and in distinguishing the lipid droplets from gas, iodized oil or blood clot.