Subarachnoid hemosiderin deposition after subarachnoid hemorrhage on T2*-weighted MRI correlates with the location of disturbed cerebrospinal fluid flow on computed tomography cisternography

A 72-year-old male was admitted with subarachnoid hemorrhage associated with a ruptured cerebral aneurysm. The aneurysm was treated with clipping soon after radiological examination. Eight weeks after the treatment, the patient suffered from secondary hydrocephalus resulting from blockage of the subarachnoid space due to subarachnoid granulation. Previous pathological examination revealed the granulation was associated with hemosiderin deposition. We investigated subarachnoid hemosiderin deposition in this patient using T2*-weighted (T2*-w) magnetic resonance image (MRI), a sensitive method for hemosiderin detection. computed tomography (CT) cisternography demonstrated that cerebrospinal fluid (CSF) flow was disturbed adjacent to sites of subarachnoid hemosiderin deposition on T2*-w MRI. Placement of a ventriculo-peritoneal shunt contributed to neurological improvement. In this case, T2*-w MRI was an effective means of diagnosing the location of disturbed CSF flow associated with subarachnoid hemosiderin deposition.