From the Guidelines
MRI findings in Alzheimer's disease typically show brain atrophy in specific regions, particularly starting in the medial temporal lobes, including the hippocampus and entorhinal cortex, as noted in the most recent study by 1. The characteristic findings of Alzheimer's disease on Magnetic Resonance Imaging (MRI) include:
- Brain atrophy in the medial temporal lobes, including the hippocampus and entorhinal cortex
- Widespread atrophy affecting the parietal and frontal lobes as the disease progresses
- White matter hyperintensities, which may indicate small vessel disease that often coexists with Alzheimer's
- Reduced volume of the hippocampus, a reliable MRI marker that can predict progression from mild cognitive impairment to Alzheimer's disease, as supported by 1
- Cortical thinning in temporal and parietal regions, another important finding in Alzheimer's disease While MRI cannot definitively diagnose Alzheimer's disease on its own, these structural changes, when combined with clinical symptoms and other diagnostic tests, help support the diagnosis and rule out other causes of cognitive decline, such as tumors, strokes, or normal pressure hydrocephalus, as stated in 1. Serial MRIs over time can also track disease progression and potentially evaluate treatment response, making MRI a valuable tool in the management of Alzheimer's disease, as noted in 1 and 1.
From the Research
Characteristic Findings of Alzheimer's Disease on MRI
The characteristic findings of Alzheimer's disease on Magnetic Resonance Imaging (MRI) include:
- Brain atrophy, which can be evaluated using structural MRI (sMRI) 2
- Presence of amyloid β (Aβ) plaques, although accurate assessment is currently only possible on autopsy, and in vivo MRI of plaques is limited to mouse models of AD 2
- Functional and biochemical abnormalities, which can be measured using functional MRI (fMRI) and magnetic resonance spectroscopy (MRS) 2
- Hippocampal atrophy, which is considered a marker of neuronal injury and is included in the diagnostic criteria for "mild cognitive impairment due to AD" 3
Evaluation of Hippocampal Atrophy
Hippocampal atrophy can be evaluated using T1-weighted (T1WI) or T2-weighted (T2WI) imaging, with T2WI providing better discrimination power between AD and mild cognitive impairment (MCI) groups 4
- Visual qualitative ratings of the hippocampus can be made independently by operators using the medial temporal lobe atrophy score based on T1WI or T2WI 4
- The medial temporal lobe atrophy score evaluated on T2WI exhibits better correlation with neuropsychological tests 4
Advanced Image Analysis Techniques
Advanced image analysis techniques, such as diffusion-tensor imaging and resting-state functional MRI, can provide additional measures that could contribute to the early diagnosis of AD, but require further validation 3
- Automatic and reproducible measures of atrophy can be generated using advanced image analysis techniques, both in the hippocampus and throughout the whole brain 3
- Nonlinear classification approaches can be used to discriminate between AD and control groups using T1-weighted and T2-weighted MRI images 5