title: Pathophysiologic evaluation of MELAS strokes by serially quantified MRS and CASL perfusion images.
abstract: 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.
authors.affiliation: Biomedical Imaging Research Center, University of Fukui, Japan. awaji@u-fukui.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tsujikawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoneda
authors.forename: Yukio
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Uematsu
authors.forename: Mariko
authors.initials: M
authors.lastname: Toyooka
authors.forename: Masamichi
authors.initials: M
authors.lastname: Ikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kudo
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Okazawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Kuriyama
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kimura
mesh_terms: 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
chemical_list: D013113:Spin Labels; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate