CSF flow studies of intracranial cysts and cyst-like lesions achieved using reversed fast imaging with steady-state precession MR sequences

BACKGROUND AND PURPOSE: Differentiating between intracranial cysts or cyst- like structures and communicating or noncommunicating cysts is often not po ssible with cranial CT or nonfunctional MR imaging. We evaluated a retrospe ctive EGG-gated fast imaging with steady-state precession (PSIF) MR sequenc e with optional cine mode to differentiate cystic masses from enlarged CSF spaces and to determine the accuracy of detecting communication between cys ts and neighboring CSF spaces. METHODS: Fourteen patients with intracranial cystic masses underwent CSF fl ow studies with an ungated and a retrospective ECG-gated cine-mode PSIF seq uence in addition to spin-echo imaging, Findings were evaluated retrospecti vely by using a five-point rating scale and without knowledge of clinical o r other imaging findings, Results were compared with intraoperative finding s or with results of intrathecal contrast studies. RESULTS: Eighteen arachnoid cysts and one enlarged cisterna magna were diag nosed. Improved differentiation between cysts and enlarged CSF spaces was o btained with cine-mode PSIF imaging in six lesions (six patients), Increase d diagnostic certainty as to communication between cysts and CSF spaces was obtained in 18 cysts (13 patients). Diagnoses were verified by membranecto my in five lesions, by CT cisternography in five lesions, and indirectly by shunting in one cystic lesion. In one case, MR diagnosis was not confirmed by CT cisternography, CONCLUSION: Cine-mode MR imaging with a retrospective EGG-gated flow-sensit ive PSIF sequence contributed to the certainty of communication between ara chnoid cysts and neighboring CSF spaces with an accuracy of 90%, using surg ical findings or intrathecal contrast studies as reference, Differentiation between intracranial cysts and enlargement of CSF spaces and other cystic masses was improved in 25% of cases.