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IC‐P‐123: Should we assess atrophy of the mammillothalamic tracts in Alzheimer's disease?: A preliminary study of their conspicuity and age‐related morphometry on axial 3T MRI
Author(s) -
Horsburgh Avril,
Massoud Tarik F.
Publication year - 2012
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2012.05.157
Subject(s) - medicine , atrophy , magnetic resonance imaging , fornix , nuclear medicine , pathology , radiology , hippocampus
Background: Defining age-related alterations in normal brain is an important prelude to earlier detection of neurodegenerative disorders. Many limbic structures show atrophy in Alzheimer’s disease (AD). Since transneuronal degeneration occursmore commonly in a ‘closed neuronal system’ such as the circuit of Papez, and despite existing evidence for atrophy of the fornix and mammillary bodies in AD, the projections from the mammillary bodies to the anterior thalamic nuclei, i.e. the mamillothalamic tracts (MTTs, bundles of Vicq d’Azyr) have not been studied in AD previously. We preliminarily studied the conspicuity and age-related changes in the MTTs on axial 3T brain MRI studies in healthy subjects prior to future evaluation in AD. Methods: We retrospectively analysed the standardized images of 147 patients. We used magnified T2-weighted images for analysis ofMTT visualization, and specifically assessed conspicuity, signal intensity, size (using electronic callipers), shape, location, and symmetry of the MTTs. We used a Student’s t-test for independent samples to statistically compare the MTT size in young and older patient groups, with significance at P<0.05. The effect of independent variables (gender and side) was also tested on the dependent variable (MTT size) using regression analysis. Results: The younger age group (<60 yr, mean age 39 yr) comprised 62 patients (M:F1⁄4 50:50), and the older age group (>60 yr, mean age 72 yr) were 85 patients (M:F1⁄4 30:70). MTTs were visualized in 85% in the young, and 72% in the older. Etat cribl e precluded detection of the MTTs in several of the over 70’s. Right MTTs in the young were a mean 1.09 mm 2, and left MTTs were 1.30 mm 2. Right MTTs in the older were a mean 0.87 mm 2, and left MTTs were 1.08 mm 2. N one of the independent variables affected variation in MTT size. There were no statistical differences in the MTT sizes between young and older age groups. Conclusions: This is the first report of baseline ageand gender-related changes in cross-sectional dimensions of the MTTs, made possible by their greater conspicuity on 3T MRI. Additional studies in AD will determine if the MTTs might be useful biomarkers in assessing response to neuroprotective agents.