Limbic system structures are of central interest in many neuropsychiatric disorders. Magnetic resonance imaging (MRI) has a unique potential for imaging limbic system structures in vivo, but methodological constraints can limit the usefulness and interpretation of the collected image data. In this article, we present approaches for the acquisition and quantification of high resolution MR images of the limbic system. We used a long TR, cardiac gated, flow compensated, spin echo sequence to collect 22, 3-mm thick contiguous sections encompassing the limbic system. The sections were oriented relative to standard internal neuroanatomical landmarks. The sequence provided good gray matter/white matter/cerebrospinal fluid (CSF) and CSF/bone contrast; the latter is necessary for quantifying intracranial size and total CSF volume. Using operationalized criteria, we achieved high interrater reliability in volumetric measurement of temporal horn and hippocampus. This technique was then used to examine the effect of normal aging by comparing eight young (mean = 24 years) and seven old (mean = 73 years) healthy community members. We were able to demonstrate a significant age-related increase in temporal horn volume and a trend toward an age-related decrease in hippocampal volume.
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Acknowledgments. The authors appreciate the assistance of Chung Nim Ha and Jody M. Rawles in recruiting subjects for this study and Edith V. Sullivan, Ph.D., and Margaret J. Rosenbloom for helpful discussions. This work was supported by the National Alliance for Research on Schizophrenia and Depression, the National Institute on Alcholism and Alcohol Abuse (AA-5965) the National Institute of Mental Health (MH-30854) and the Medical Research Service of the Department of Veterans Affairs.
- Brain imaging
- temporal lobe
- ventricular volume