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Hippocampal atrophy confounds template-based functional MR imaging measures of hippocampal activation in patients with mild cognitive impairment.
AJNR Am J Neuroradiol. 2006 Sep; 27(8):1622-7.AA

Abstract

BACKGROUND AND PURPOSE

Functional MR imaging has been used to study patterns of hippocampal activation that distinguish pathologic from normal memory loss in the elderly population. Our objective was to assess whether hippocampal atrophy confounds measurements of hippocampal activation in subjects with mild cognitive impairment (MCI).

METHODS

Twenty subjects with MCI and 20 elderly control subjects with objectively normal memory were studied at 4T during a face-name paradigm designed to activate the hippocampus. Hippocampal activation was measured using 2 separate approaches: applying a preset region of interest (ROI) in standardized template space and applying a manually drawn ROI in native subject space. Pearson correlation coefficients were calculated to compare group-dependent relationships between hippocampal volume and activation. Analysis of covariance (ANCOVA) was performed to assess group differences in hippocampal activation during encoding and retrieval. Age and hippocampal volume were included as covariates, as was a term for the interaction between hippocampal volume and group.

RESULTS

When hippocampal activation was measured by the template-based method, the correlation coefficient in the right hippocampus of subjects with MCI but not control subjects during retrieval differed significantly from zero. There was a significant (P < .05) group-by-volume interaction in the ANCOVA model. No significant correlations or interactions were demonstrated when activation was measured in native subject space with manually drawn ROIs.

CONCLUSION

Our findings suggest a potential confounding relationship between hippocampal volume and activation for subjects with MCI in template-based analyses. Template-based measures of hippocampal activation that do not adequately account for hippocampal atrophy should be used with caution in patients with MCI.

Authors+Show Affiliations

Department of Radiology, Brain Imaging and Analysis Center, Duke University Medical Center, Durham, NC, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

16971599

Citation

Sandstrom, C K., et al. "Hippocampal Atrophy Confounds Template-based Functional MR Imaging Measures of Hippocampal Activation in Patients With Mild Cognitive Impairment." AJNR. American Journal of Neuroradiology, vol. 27, no. 8, 2006, pp. 1622-7.
Sandstrom CK, Krishnan S, Slavin MJ, et al. Hippocampal atrophy confounds template-based functional MR imaging measures of hippocampal activation in patients with mild cognitive impairment. AJNR Am J Neuroradiol. 2006;27(8):1622-7.
Sandstrom, C. K., Krishnan, S., Slavin, M. J., Tran, T. T., Doraiswamy, P. M., & Petrella, J. R. (2006). Hippocampal atrophy confounds template-based functional MR imaging measures of hippocampal activation in patients with mild cognitive impairment. AJNR. American Journal of Neuroradiology, 27(8), 1622-7.
Sandstrom CK, et al. Hippocampal Atrophy Confounds Template-based Functional MR Imaging Measures of Hippocampal Activation in Patients With Mild Cognitive Impairment. AJNR Am J Neuroradiol. 2006;27(8):1622-7. PubMed PMID: 16971599.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hippocampal atrophy confounds template-based functional MR imaging measures of hippocampal activation in patients with mild cognitive impairment. AU - Sandstrom,C K, AU - Krishnan,S, AU - Slavin,M J, AU - Tran,T-T T, AU - Doraiswamy,P M, AU - Petrella,J R, PY - 2006/9/15/pubmed PY - 2006/11/11/medline PY - 2006/9/15/entrez SP - 1622 EP - 7 JF - AJNR. American journal of neuroradiology JO - AJNR Am J Neuroradiol VL - 27 IS - 8 N2 - BACKGROUND AND PURPOSE: Functional MR imaging has been used to study patterns of hippocampal activation that distinguish pathologic from normal memory loss in the elderly population. Our objective was to assess whether hippocampal atrophy confounds measurements of hippocampal activation in subjects with mild cognitive impairment (MCI). METHODS: Twenty subjects with MCI and 20 elderly control subjects with objectively normal memory were studied at 4T during a face-name paradigm designed to activate the hippocampus. Hippocampal activation was measured using 2 separate approaches: applying a preset region of interest (ROI) in standardized template space and applying a manually drawn ROI in native subject space. Pearson correlation coefficients were calculated to compare group-dependent relationships between hippocampal volume and activation. Analysis of covariance (ANCOVA) was performed to assess group differences in hippocampal activation during encoding and retrieval. Age and hippocampal volume were included as covariates, as was a term for the interaction between hippocampal volume and group. RESULTS: When hippocampal activation was measured by the template-based method, the correlation coefficient in the right hippocampus of subjects with MCI but not control subjects during retrieval differed significantly from zero. There was a significant (P < .05) group-by-volume interaction in the ANCOVA model. No significant correlations or interactions were demonstrated when activation was measured in native subject space with manually drawn ROIs. CONCLUSION: Our findings suggest a potential confounding relationship between hippocampal volume and activation for subjects with MCI in template-based analyses. Template-based measures of hippocampal activation that do not adequately account for hippocampal atrophy should be used with caution in patients with MCI. SN - 0195-6108 UR - https://www.unboundmedicine.com/medline/citation/16971599/Hippocampal_atrophy_confounds_template_based_functional_MR_imaging_measures_of_hippocampal_activation_in_patients_with_mild_cognitive_impairment_ L2 - http://www.ajnr.org/cgi/pmidlookup?view=long&amp;pmid=16971599 DB - PRIME DP - Unbound Medicine ER -