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Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders.

Publication ,  Journal Article
Krishnan, S; Slavin, MJ; Tran, T-TT; Doraiswamy, PM; Petrella, JR
Published in: Neuroimage
June 2006

Functional magnetic resonance imaging (fMRI) studies in memory impairment have detected functional alterations in medial temporal lobe (MTL) structures, notably the hippocampus. Many of these studies employ spatial normalization to place subjects in a standardized template space prior to analysis; however, little is known about the effects of local atrophy on the normalization process in structures such as the hippocampus. The purpose of this study was to compare the accuracy of spatial normalization of the hippocampus between memory-impaired patients and controls. Twenty clinically-defined mild cognitive impairment (MCI) subjects and twenty elderly controls were studied at 4T with structural and functional MRI during a memory encoding-retrieval task. Bilateral hippocampal regions-of-interest (ROIs) were manually drawn for all subjects and further divided into anterior/posterior subregions. To assess normalization accuracy to the Montreal Neurological Institute template, the percentage of each template-defined hippocampal ROI originating from true hippocampal tissue was determined for all subjects. To assess the ability of spatial normalization to equalize group differences in hippocampal volume, pre- and post-normalization hippocampal volumes were compared. Finally, fMRI measures from template and non-template analyses were compared. Poorer normalization accuracy of the bilateral hippocampi, particularly the posterior portions, was found for MCI subjects. Significant group differences were found in left hippocampal and bilateral posterior hippocampal volumes, and these differences were not corrected with normalization. Hippocampal volumes were significantly correlated with normalization accuracy across MCI and control groups, but some significant differences in normalization accuracy persisted independent of these volume differences. Template and non-template fMRI analyses were significantly correlated in controls, but not MCI subjects, during memory retrieval. These findings suggest decreased normalization accuracy in memory-impaired subjects is a potentially important confounder of template-based fMRI analyses in the hippocampus and MTL.

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Published In

Neuroimage

DOI

ISSN

1053-8119

Publication Date

June 2006

Volume

31

Issue

2

Start / End Page

560 / 571

Location

United States

Related Subject Headings

  • Reproducibility of Results
  • Reference Values
  • Patient Selection
  • Neurology & Neurosurgery
  • Memory Disorders
  • Magnetic Resonance Imaging
  • Humans
  • Hippocampus
  • Functional Laterality
  • Adult
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Krishnan, S., Slavin, M. J., Tran, T.-T., Doraiswamy, P. M., & Petrella, J. R. (2006). Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders. Neuroimage, 31(2), 560–571. https://doi.org/10.1016/j.neuroimage.2005.12.061
Krishnan, Sriyesh, Melissa J. Slavin, Thanh-Thu T. Tran, P Murali Doraiswamy, and Jeffrey R. Petrella. “Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders.Neuroimage 31, no. 2 (June 2006): 560–71. https://doi.org/10.1016/j.neuroimage.2005.12.061.
Krishnan S, Slavin MJ, Tran T-TT, Doraiswamy PM, Petrella JR. Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders. Neuroimage. 2006 Jun;31(2):560–71.
Krishnan, Sriyesh, et al. “Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders.Neuroimage, vol. 31, no. 2, June 2006, pp. 560–71. Pubmed, doi:10.1016/j.neuroimage.2005.12.061.
Krishnan S, Slavin MJ, Tran T-TT, Doraiswamy PM, Petrella JR. Accuracy of spatial normalization of the hippocampus: implications for fMRI research in memory disorders. Neuroimage. 2006 Jun;31(2):560–571.
Journal cover image

Published In

Neuroimage

DOI

ISSN

1053-8119

Publication Date

June 2006

Volume

31

Issue

2

Start / End Page

560 / 571

Location

United States

Related Subject Headings

  • Reproducibility of Results
  • Reference Values
  • Patient Selection
  • Neurology & Neurosurgery
  • Memory Disorders
  • Magnetic Resonance Imaging
  • Humans
  • Hippocampus
  • Functional Laterality
  • Adult