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Updated: Jul 2, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Magnetization transfer ratio in Alzheimer disease: comparison with volumetric measurements
B H Ridha1, M R Symms, D J Tozer
1Dementia Research Centre, Institute of Neurology, University College London, London, UK. bridha@dementia.ion.ucl.ac.uk
Background And Purpose:
Alzheimer disease (AD) is accompanied by macroscopic atrophy on volumetric MR imaging. A few studies have also demonstrated reduction in magnetization transfer ratio (MTR), suggesting microstructural changes in remaining brain tissue. This study assessed the value of measuring MTR in addition to volumetric MR in differentiating patients with AD from control subjects.
Materials And Methods:
Volumetric T1-weighted images and 3D MTR maps were obtained from 18 patients with AD and 18 age-matched control subjects. Whole-brain (WB) and total hippocampal (Hc) volumes were measured using semiautomated techniques and adjusted for total intracranial volume. Mean MTR was obtained for WB and in the Hc region. Histogram analysis was performed for WB MTR. Among patients, associations between volumetric and MTR parameters and the Mini-Mental State Examination (MMSE) were explored.
Results:
Patients with AD had significantly reduced WB volume (P<.0001) and mean WB MTR (P=.002) and Hc volume (P<.0001) and Hc mean MTR (P<.0001) compared with control subjects. Histogram analysis of WB MTR revealed significant reduction in the 25th percentile point in patients with AD (P=.03). Both WB volume and mean MTR were independently associated with case-control status after adjusting for the other using linear regression models. However, measuring Hc mean MTR added no statistically significant discriminatory value over and above Hc volume measurement alone. Of all MR imaging parameters, only WB volume was significantly correlated with MMSE (r=0.47, P=.048).
Conclusions:
This study demonstrates the independent reduction of WB volume and mean MTR in AD. This suggests that the 2 parameters reflect complementary aspects of the AD pathologic lesion at macrostructural and microstructural levels.
Insights
Alzheimer disease (AD) shows reduced whole-brain (WB) volume and magnetization transfer ratio (MTR), indicating macrostructural and microstructural brain changes. These MRI measures independently differentiate AD patients from controls.
Area of Science:
- Neurology
- Radiology
- Biomedical Imaging
Background:
- Alzheimer disease (AD) is characterized by brain atrophy visible on MRI.
- Magnetization transfer ratio (MTR) may reveal microstructural changes in AD.
Purpose of the Study:
- To evaluate if MTR measurements, alongside volumetric MRI, can distinguish AD patients from healthy controls.
- To explore the relationship between MRI parameters and cognitive function in AD.
Main Methods:
- Volumetric T1-weighted MRI and 3D MTR maps were acquired from 18 AD patients and 18 controls.
- Whole-brain (WB) and hippocampal (Hc) volumes were measured. Mean MTR for WB and Hc was calculated.
- WB MTR histogram analysis and correlations with Mini-Mental State Examination (MMSE) scores were performed.
Main Results:
- AD patients exhibited significantly reduced WB volume, WB MTR, Hc volume, and Hc MTR compared to controls.
- WB volume and mean MTR independently predicted AD status.
- Hc MTR did not add significant discriminatory value beyond Hc volume.
Conclusions:
- Both WB volume and mean MTR are independently reduced in AD, reflecting macrostructural and microstructural damage.
- These complementary MRI parameters offer insights into AD pathology.
