abstract:aim to study characteristics of the images and clinical features of arachnoid cyst
in the sacral canal in order to improve our ability to diagnose it.methods the imag-ing changes
including x-ray,ct,ct following myelography and mri were assessed in24patients with
operation-proved arachnoid cysts in sacral canal,and their clinical characteris-tice and
pathologies were asloanalysed.results bone erosion sometimes was observed in x-ray,but
often in ct and mri.ct after myelography demonstrated contrast fill-ing of the arachnoid cyst
in sacral canal.long t1and t2 signals of the cysts were clearly shown in mri,and the sig-nal
density was the same as that of cerebrospinal fluid.clini-cal symptoms were caused by
compression of sacral nerve.generally,there were communicating holes between cysts and
thecal sacs.conclusion mri allows us to predict better the arachnoid cyst in sacral canal,and
the cyst seems to arise as a result of congenital defect of thecal dura.