Several quantitative MRI-based protocols have been developed for measuring the volume of entorhinal (ERC), perirhinal (PRC), and posterior parahippocampal (PPHC) cortex. However, since the volume of a cortical region is a composite measure, relating directly to both thickness and surface area, it would be ideal to be able to quantify all of these morphometric measures, particularly since disease-related processes, such as Alzheimer's disease (AD), may preferentially affect thickness. This study describes a novel protocol for measuring the thickness, surface area, and volume of these three medial temporal lobe (MTL) subregions. Participants included 29 younger normal subjects (ages 18-30), 47 older normal subjects (ages 66-90), and 29 patients with mild AD (ages 56-90). Cortical surface models were reconstructed from the gray/white and gray/cerebrospinal fluid boundaries, and a hybrid visualization approach was implemented to trace the ERC, PRC, and PPHC using both orthogonal MRI slice- and cortical surface-based visualization of landmarks. Anatomic variants of the collateral sulcus (CS) were classified in all 105 participants, and the relationship between CS variants and corresponding morphometric measures was examined. One CS variant - deep, uninterrupted CS not connected with nearby sulci - was the most common configuration and was associated with thinner cortex within the ERC and PRC regions. This novel protocol enables the reliable measurement of both the thickness and surface area of ERC, PRC, and PPHC.
|Original language||English (US)|
|Number of pages||12|
|Journal||Neurobiology of Aging|
|State||Published - Mar 2009|
Bibliographical noteFunding Information:
This study was supported in part by the National Institute on Aging (K23-AG22509, P50-AG05681, P01-AG03991), the National Center for Research Resources (P41-RR14075, R01 RR16594-01A1, the NCRR BIRN Morphometric Project BIRN002, U24 RR021382 & U24-RR021382), and the Mental Illness and Neuroscience Discovery (MIND) Institute. Additional support was provided by the National Institute for Biomedical Imaging and Bioengineering (R01 EB001550), the National Institute for Neurological Disorders and Stroke (R01 NS052585-01) and the National Alliance for Medical Image Computing (NAMIC), funded by the National Institutes of Health through the NIH Roadmap for Medical Research, Grant U54 EB005149.
- Alzheimer's disease
- Entorhinal cortex
- Magnetic resonance imaging
- Parahippocampal cortex
- Perirhinal cortex