Multiparametric MRI detection of cerebral metabolism: a tool for early differentiation between MELAS and ischemic...

The differential diagnosis of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and ischemic cerebral infarction (ICI) is challenging using conventional sequences. This study aims to investigate the magnetic resonance imaging (MRI) characteristics of MELAS revealed by multiparametric MRI and their value in the differential diagnosis from ICI.

This study included 24 MELAS and 25 ICI patients who underwent proton magnetic resonance spectroscopy (¹H-MRS), dynamic susceptibility contrast (DSC) imaging, and diffusion-weighted imaging (DWI). The image characteristics were calculated both from MRI-visible lesions (MVL) and from normal-appearing regions (NAR), and compared between MELAS and ICI as well as between MVL and NAR. We also compared these differences between the acute and the chronic phase.

(I) Compared with NAR, the MVL of MELAS demonstrated significantly higher lactate/creatine (Lac/Cr) and relative apparent diffusion coefficient (rADC) (P=0.005 and P<0.001, respectively) and significantly lower N-acetyl-aspartate /(creatine + phosphocreatine) (NAA/Cr) (P=0.002), whereas there was no difference of relative cerebral blood flow (rCBF) or relative cerebral blood volume (rCBV). The rCBF and rCBV of the acute phase were significantly higher than those in the chronic phase (P<0.05). (II) Compared with ICI, MELAS demonstrated significantly higher Lac/Cr, rCBF, and rCBV of MVL (P<0.05). (III) Presence of Lac in NAR, rCBV, and rCBF of MVL were the best 3 parameters which were able to differentiate MELAS from ICI, with area under the curves (AUCs) of 0.929, 0.886, and 0.871, respectively.

Multiparametric MRI can be helpful in the differentiation of MELAS from ICI since they demonstrate characteristic and different changes, especially on MRS and DSC.