Brain Magnetic Resonance with Negative Diffusion-Weighted Imaging: Does It Preclude Acute Stroke Diagnosis?

Brain magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) sequences and correlative apparent diffusion coefficient (ADC) maps is a very sensitive way to detect acute ischemic stroke. Cases of negative MRI-DWI on acute phase of ischemic stroke are uncommon, and most of them are reported in single small-sized lesions, which in most cases are below the technical spatial resolution and in patients imaged shortly after the symptoms start. The few published cases of territorial ischemic stroke with negative DWI affect exclusively one vascular territory. We report the case of an ischemic stroke involving 2 different arteries of the posterior circulation, with a negative DWI/ADC brain MRI 18 hours after time-last-seen-well. We also suggest a possible explanation regarding the mechanism of false-negative diffusion MRI on ischemic stroke.