Differential Effects of Global and Cerebellar Normalization on Detection and Differentiation of Dementia in FDG-PET Studies

Neuroimage. 2010 Jan 15;49(2):1490-5. doi: 10.1016/j.neuroimage.2009.09.017. Epub 2009 Sep 18.

Abstract

FDG-PET ([18F]fluorodeoxyglucose positron emission tomography) is frequently used to improve the differential diagnosis of dementia. However, a fundamental methodological issue of the reference area for the intensity normalization procedure is still unsolved. Here, we systematically compared the two most commonly used normalization methods to the cerebral and to the cerebellar metabolic rate for glucose with regard to detection and differentiation of dementia syndromes. FDG-PET imaging was performed on 19 subjects with early Alzheimer's disease, 13 subjects with early frontotemporal lobar degeneration and 10 subjects complaining of memory impairment, which had not been confirmed by comprehensive clinical testing. Images were normalized to either the cerebral or the cerebellar metabolic rate for glucose. Differences in relative regional glucose metabolism were assessed by voxelwise comparison. Analysis using the two normalization procedures revealed remarkable differential effects. Whereas cerebellar normalization was superior in identifying dementia patients in comparison to control subjects, cerebral normalization showed better results for differential diagnosis between types of dementia. These effects were shown for both, Alzheimer's disease and frontotemporal lobar degeneration. Relative hypermetabolism in comparison to the control group was only detected in both kinds of dementia using global normalization. The results indicate that normalization has a decisive impact on diagnostic accuracy in dementia. While cerebellar normalization seems to be more sensitive for early diagnosis, cerebral global normalization might be superior for differential diagnostic purposes in dementia syndromes.

Publication types

  • Comparative Study

MeSH terms

  • Age Factors
  • Alzheimer Disease / diagnosis
  • Alzheimer Disease / diagnostic imaging
  • Alzheimer Disease / metabolism
  • Analysis of Variance
  • Brain / diagnostic imaging*
  • Brain / metabolism
  • Brain Mapping / methods
  • Cerebellum / diagnostic imaging*
  • Cerebellum / metabolism
  • Dementia / diagnosis*
  • Dementia / diagnostic imaging*
  • Dementia / metabolism
  • Diagnosis, Differential
  • Female
  • Fluorodeoxyglucose F18*
  • Frontotemporal Lobar Degeneration / diagnosis
  • Frontotemporal Lobar Degeneration / diagnostic imaging
  • Frontotemporal Lobar Degeneration / metabolism
  • Glucose / metabolism
  • Humans
  • Male
  • Memory Disorders / diagnosis
  • Memory Disorders / diagnostic imaging
  • Memory Disorders / metabolism
  • Middle Aged
  • Positron-Emission Tomography / methods*
  • Radiopharmaceuticals
  • Severity of Illness Index
  • Signal Processing, Computer-Assisted

Substances

  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Glucose