Value of MRI and ¹H-MR spectroscopy in propionic acidemia

Objective: To determine the MR imaging characteristics of brain and assess the value of ¹H-MR spectroscopy (¹H-MRS) in propionic acidemia (PA). Methods: Nine patients (7 boys, 2 girls; age range: neonate to 2 years) with PA diagnosed by gas chromatography-mass spectrometry (GC-MS) underwent brain MRI (9) and ¹H-MRS (3) before and after treatment. Regions of interest were placed in the right basal ganglia and N-acetylaspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (MI)/Cr ratios were calculated and compared with that of six healthy children. Results: MRI showed ventricle dilation (4), myelination delay (3), supratentorial white matter edema (2), thinning of the corpus callosum (2), cerebral atrophy (2), basal ganglionic abnormalities (3) with low T₁ and high T₂ signal intensities and reduced diffusion. Compared with control group, the ratios of NAA/Cr and Cho/Cr were decreased with no change in Ml/Cr. A double lactate peak was detected in one patient. The MRI findings improved in one case and were worse in two cases at follow-up. Conclusion: MRI findings were nonspecific in PA with varying degrees of ventricle dilation, delayed myelination and basal ganglia abnormalities. The brain damage was irreversible and was more readily detected on ¹H-MRS. (authors)