I-123 IMP SPECT FINDINGS IN MITOCHONDRIAL ENCEPHALOMYOPATHIES

We performed N-isopropyl-[I-123]p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) in three patients with Leigh synd rome, two patients with mitochondrial encephalomyopathy, lactic acidos is and stroke-like episodes (MELAS), and two siblings with progressive external ophthalmoplegia (PEO). The SPECT images were compared with t he findings on magnetic resonance imaging (MRI) and computed tomograph y (CT), All Leigh syndrome patients showed low accumulation areas (LAA ) bilaterally in the frontal lobes and the basal ganglia, The frontal lobe LAA was seen even in an area without abnormalities on CT/MRI. Eac h MELAS patient showed a focal LAA, SPECT could also detect an old str oke-like lesion that was no longer shown by CT/MRI. However, SPECT did not show LAA in the basal ganglia, which showed calcification on CT o r abnormal signal intensity on MRI. MRI in the 2 PEO patients showed l esions bilaterally in the basal ganglia in one, and in the internal ca psules in the other, SPECT showed LAA not only in corresponding areas, but also in the occipital lobes, where no lesions were revealed by MR I, Thus, I-123-IMP SPECT was more sensitive than CT/MRI for detecting stroke-like lesions in MELAS patients, although it did not detect smal l lesions in the basal ganglia, LAA in the frontal lobes and occipital lobes may be SPECT findings characteristic of Leigh syndrome and PEG, respectively.