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SPECT findings in mitochondrial encephalomyopathy
Y Watanabe1, K Hashikawa, H Moriwaki
1Department of Radiology, National Toneyama Hospital, Osaka University Medical School, Suita, Japan.
Summary
Mitochondrial encephalomyopathy with lactic acidosis and strokelike episodes (MELAS) shows specific regional cerebral blood flow (rCBF) alterations. Brain perfusion SPECT is useful for diagnosing MELAS, with decreased perfusion reserve potentially linked to strokelike episodes.
Area of Science:
- Neurology
- Nuclear Medicine
- Medical Imaging
Background:
- Mitochondrial encephalomyopathy (MEM) encompasses various genetic disorders affecting energy metabolism.
- Regional cerebral blood flow (rCBF) alterations may indicate specific pathophysiological changes in MEM subtypes.
Purpose of the Study:
- To investigate rCBF changes in different types of mitochondrial encephalomyopathy using SPECT.
- To assess the diagnostic utility of brain perfusion SPECT in MEM patients, particularly MELAS.
Main Methods:
- 10 MEM patients (MELAS, KSS, MERRF, CCOD) underwent SPECT imaging with [123I]N-isopropyl-p-iodoamphetamine (IMP) or 99mTc-hexamethyl propyleneamine oxime.
- Cerebral perfusion reserve was evaluated in 6 patients using a split-dose IMP SPECT method before and after acetazolamide challenge.
Main Results:
- MELAS patients exhibited focal hypoperfusion in parietal/occipital lobes, correlating with CT/MRI findings.
- SPECT findings were normal in MERRF, KSS, and CCOD patients, despite some having abnormal imaging.
- Decreased cerebral perfusion reserve was significantly observed in MELAS patients (7.4%) compared to other MEM types (33.8%).
Conclusions:
- Regional cerebral blood flow alterations are specific to MELAS, highlighting brain perfusion SPECT's diagnostic value.
- Reduced cerebral perfusion reserve in MELAS may be a key factor in the pathogenesis of strokelike episodes.
- SPECT imaging showed normal perfusion patterns in MERRF, KSS, and CCOD, differentiating them from MELAS.