title: Single photon emission computed tomography perfusion differences in mild cognitive impairment.
abstract: OBJECTIVE
  To relate cerebral perfusion abnormalities to subsequent changes in clinical status among patients with mild cognitive impairment (MCI).
  
  
  METHODS
  Perfusion single photon emission computed tomography (SPECT) images were acquired in 105 elderly patients without dementia with MCI, using 99mTc-HMPAO. Clinical outcome after a 5-year follow-up period was heterogeneous.
  
  
  RESULTS
  Baseline SPECT data differed in those patients with MCI who were later diagnosed with Alzheimer's disease (the converter group) from those patients with MCI who experienced clinically evident decline but did not progress to a diagnosis of Alzheimer's disease within the follow-up period (the decliner group), from patients with MCI who had no clinical evidence of progression (the stable group), and from a group of 19 normal subjects (the control group). The most consistent decreases in relative perfusion in converters compared with the normal, stable and decliner groups were observed in the caudal anterior cingulate, and in the posterior cingulate. In addition, converters showed increased relative perfusion in the rostral anterior cingulate in comparison to the stable and decliner groups. A group of patients with Alzheimer's disease were also included for purposes of comparison. The group of patients with Alzheimer's disease at baseline differed from each of the other groups, with temporoparietal regions showing the most significant reductions in perfusion.
  
  
  CONCLUSIONS
  These results suggest that clinical heterogeneity in MCI is reflected in SPECT perfusion differences, and that the pattern of perfusion abnormalities evolves with increasing clinical severity.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Fruit Street, Boston, MA 02114, USA. kajohnson@partners.org
authors.forename: K A
authors.initials: KA
authors.lastname: Johnson
authors.forename: E K
authors.initials: EK
authors.lastname: Moran
authors.forename: J A
authors.initials: JA
authors.lastname: Becker
authors.forename: D
authors.initials: D
authors.lastname: Blacker
authors.forename: A J
authors.initials: AJ
authors.lastname: Fischman
authors.forename: M S
authors.initials: MS
authors.lastname: Albert
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D001921:Brain / Q000098:blood supply; D003072:Cognition Disorders / Q000000981:diagnostic imaging*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D019275:Radiopharmaceuticals; D012039:Regional Blood Flow; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime