Comparison of magnetic resonance spectroscopy (MRS) with arterial spin labeling (ASL) in the differentiation between mitochondrial encephalomyopathy, lactic Acidosis, plus stroke-like episodes (MELAS) and acute ischemic stroke (AIS).

•Presenting as stroke mimics, MELAS can hardly be diagnosed without delay in the absence of advanced neuroimaging evaluations.•Lactate peak detected from the stroke-like lesion could not differentiate MELAS from acute ischemic stroke.•Arterial spin labeling has high sensitivity and specificity in rapid identification of MELAS from acute ischemic stroke.