Usefulness of constructive interference in steady-state magnetic resonance imaging in the presurgical examination for lumbosacral lipoma

Object. The aim of this study was to evaluate three-dimensional Fourier transformation constructive interference in steady-state (CISS) imaging as a preoperative investigation of anatomical structures around the lumbosacral lipoma for surgical untethering of the spinal cord and debulking of the lipoma. Methods. The CISS imaging was used to visualize neural structures around the lumbosacral lipoma in 13 cases and was compared with conventional magnetic resonance imaging. In all cases, CISS images demonstrated the fine structure of the spinal cord and nerve roots, with good contrast between subarachnoid spaces and lipomas. The CISS findings were closely correlated with microscopic observation and electrophysiological investigation during surgery. In three of eight patients whose CISS images demonstrated abundant nerve roots embedded in the lipoma, untethering of the conus medullaris was not satisfactorily achieved. These three cases had obliteration of the subarachnoid space by the lipomas at the bilateral sides of the cord. In two cases with the vertebral misalignments scoliosis and lordosis, curvilinear reconstruction of CISS images along the spinal cord clearly demonstrated a neuroanatomy around the complicated lipomas. Conclusions. Using CISS imaging is useful for establishing precise neuroanatomical information around lumbosacral lipomas and for predicting the level of surgical difficulty.