Added Value of Stroke Protocol MRI Following Negative Initial CT in the Acute Stroke Setting

The aim of the study was to determine the added value of stroke protocol MRI following negative initial CT brain in the acute stroke setting. A retrospective study was performed over a 6 month period in a tertiary referral stroke centre. Patients were selected from the stroke and radiology databases. Inclusion criteria: clinical stroke syndrome, negative initial CT with subsequent MRI study with diffusion weighted sequences. Ninety two patients were reviewed and 73 (M:F of 39:34, mean age 62.1 ± 14.0 years) met the inclusion criteria. Twenty MRI studies (27.4%) were positive for acute/subacute ischaemia in the setting of a normal initial CT. The average time interval between initial CT and MRI brain imaging was 4.7 ± 2.6 days. Whilst CT continues to be the first line imaging investigation for acute stroke, MRI has substantial added value following negative initial CT in the diagnosis of stroke.