Background: Timing of the onset of subarachnoid hemorrhage (SAH) is important for treatment decision-making, especially as some patients visit hospital several weeks after the onset of SAH. T2*-weighted (T2*W) magnetic resonance (MR) imaging is regarded as a sensitive method for the detection of deoxyhemoglobin or hemosiderin deposits. This study investigated the characteristics of the abnormal low intensity changes on T2*W imaging in patients with SAH, how long the abnormal low intensity persisted, and whether the day of onset could be predicted based on the T2*W imaging changes.
Methods: The study included patients treated for SAH associated with ruptured cerebral aneurysms, or who had previously suffered such SAH and were followed up at our hospital, between 2006 and 2007. MR imaging was performed using a whole-body 3.0-tesla MR scanner. All patients underwent gradient recalled echo (GRE) and echo planar (EP) T2*W imaging. The strength of the low intensity areas was evaluated as the following 5 grades: grade 0, no abnormal low intensity on both GRE and EP T2*W images; grade 1, no abnormal intensity on GRE T2*W images and low intensity on EP T2*W images; grade 2, spotty abnormal low intensity on both GRE and EP T2*W images; grade 3, medium abnormal low intensity (<5 mm) on both GRE and EP T2*W images, and grade 4, large abnormal low intensity (≥5 mm) on both GRE and EP T2*W images.
Results: A total of 50 patients with 74 MR images were included during the study period. Abnormal low intensity on T2*W imaging was observed in all patients. The T2* score gradually decreased from the onset of SAH until day 90, showing a significant negative linear correlation (R(2) = 0.25, p = 0.0002). On the other hand, the T2* score did not change after 1 year. The square correlation coefficient between the recorded and calculated days from the onset of SAH was 0.29 (p = 0.0107). The pure error was ±10 days.
Conclusion: The T2* score gradually decreased until 90 days from the onset of SAH, but persisted for 16 years after the onset. We could predict the day of onset with pure error ±10 days in patients with SAH within 90 days of onset using our grading system for T2*W images.