Differential Diagnosis of Mitochondrial Encephalopathy With Lactic Acidosis and Stroke-Like Episodes (MELAS) and Ischemic Stroke Using 3D Pseudocontinuous Arterial Spin Labeling

Purpose: To evaluate the efficacy of 3D pseudocontinuous arterial spin labeling (3D pCASL) in the differential diagnosis between mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) and acute ischemic stroke (AIS). Materials and Methods: Conventional magnetic resonance imaging (MRI) including T-2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), and 3D pCASL perfusion data were obtained on a 3.0T MR scanner in 16 newly appearing lesions in nine patients with MELAS and 14 acute lesions in 12 patients with AIS. A postlabeling delay (PLD) time of 2025 msec was applied. The cerebral blood flow (CBF) values were measured in the central part and the peripheral part of the lesions and the CBF values were compared between MELAS and AIS patients. Results: The lesions of both MELAS and AIS showed high signal intensity on T2WI and demonstrated hyperintensity on DWI. Compared with the perfusion defects or hypoperfusion in all AIS, hyperperfusion was revealed in 16 acute MELAS lesions, especially in the peripheral part of the lesions. The CBF values of 16 lesions in MELAS were 11.20-73.11 ml/100g/min in the central part and 65.33-169.11 ml/100g/min in the peripheral part. The CBF values of 14 lesions in AIS were 12.32-19.94 ml/100g/min in the central part and 11.66-18.37 ml/100g/min in the peripheral part. The CBF value of the peripheral part (119.80 +/- 35.41) in MELAS was significantly higher than that (14.66 +/- 2.61) in AIS (P50.0001). Conclusion: The whole-brain 3D pCASL technique might be useful in differentiating MELAS from AIS.