Pathophysiologic evaluation of MELAS strokes by serially quantified MRS and CASL perfusion images.
OBJECTIVE
To clarify the roles of serial MR spectroscopy (MRS) and continuous arterial spin labeling (CASL) perfusion images for evaluating cerebral lesions in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).


METHODS
Two cases of MELAS followed up serially using MRS and CASL images in addition to routine MR imaging were enrolled.


RESULTS
Newly appeared lesions assessed by MRS revealed increased lactate doublets which correlated well with CSF lactate level, and these showed a decreasing trend after treatment, although conventional T2 weighted images revealed hyper-intensity in both phases. Spectra from normally appearing white matter depicted slight lactate peaks during clinical exacerbation periods with marked elevation of CSF lactate and showed a decreasing NAA concentration during the prolonged course. In CASL images, acute lesions of the disease were clearly visible as hyper-perfusion foci, and chronic lesions were demonstrated as hypo- or iso-perfusion regions.


CONCLUSIONS
The detection of lactate peaks in the MR spectrum from normally appearing white matter may be considered as systemic lactic acidosis or an exacerbation of MELAS, and active lesions can be distinguished from chronic inactive lesions by the increase of lactate peaks in MRS or the state of hyper-perfusion in CASL images.
Tsujikawa
Tetsuya
T
Biomedical Imaging Research Center, University of Fukui, Japan. awaji@u-fukui.ac.jp
Yoneda
Makoto
M
Shimizu
Yukio
Y
Uematsu
Hidemasa
H
Toyooka
Mariko
M
Ikawa
Masamichi
M
Kudo
Takashi
T
Okazawa
Hidehiko
H
Kuriyama
Masaru
M
Kimura
Hirohiko
H
D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D002648:Child; D003952:Diagnostic Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000134:cerebrospinal fluid; D017241:MELAS Syndrome / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D012189:Retrospective Studies; D013113:Spin Labels; D020521:Stroke / Q000209:etiology / Q000473:pathology / Q000503:physiopathology
D013113:Spin Labels; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate