A Comparative Analysis of Structural Brain MRI in the Diagnosis of Alzheimer’s Disease

Abstract

Abstract. Dementia is a debilitating and life-altering disease which leads to both memory impairment and decline of normal executive functioning. While causes of dementia are numerous and varied, the leading cause among patients 60 years and older is Alzheimer's disease. The gold standard for Alzheimer's diagnosis remains histological identification of amyloid plaques and neurofibrillary tangles within the medial temporal lobe, more specifically the entorhinal cortex and hippocampus. Although no definitive cure for Alzheimer's disease currently exists, there are treatments targeted at preserving cognition and memory while delaying continued loss of function. Alzheimer's disease exists along a spectrum of cognitive decline and is often preceded by Mild Cognitive Impairment (MCI). Patients with MCI demonstrate memory loss and cognitive impairment while still continuing normal activities of daily living, and are considered to be at increased risk for developing Alzheimer's Dementia. Identifying patients with prodromal states of Alzheimer's dementia such as MCI may allow initiation of appropriate treatment planning and delay of cognitive decline. Therefore, the need for a non-invasive early biomarker for the detection of Alzheimer's disease has never been greater. Multiple neuroimaging methods utilizing visual rating scales, volumetric measurements, and automated methods have been developed to identify, quantify, and track anatomic sequelae of Alzheimer's Disease.

Plasma biomarkers for mild cognitive impairment and Alzheimer's disease

“…are among the earliest sites of pathologic involvement in AD [32]. Neuroimaging studies have repeatedly shown decreased hippocampal and ERC volumes in patients with AD compared with age-matched control subjects [33]. MRI studies of MCI have shown that hippocampal volumes and cortical volumes in the parietal and lateral temporal regions are able to predict the likelihood of progression [34].…”

Functional and Structural MR Imaging in Neuropsychiatric Disorders, Part 1: Imaging Techniques and Their Application in Mild Cognitive Impairment and Alzheimer Disease

“…49 Manual volumetry of the hippocampus discriminates AD and healthy control groups with high accuracy 50 and displays a multicenter variability of Ͻ5%. 51,52 It is, therefore, considered the best established imaging biomarker of AD to date.…”

Degeneration of the Human Nervous System and Magnetic Resonance Neuroimaging

“…Structural CT and MRI scans are mainly used to assess volumetric changes in dementias with decreases in gyral and increases in sulcal size secondary to decrease in synaptic density, neuronal loss, and cell shrinkage (Tartaglia et al, 2010). The medial temporal lobes, especially the hippocampus and entorhinal cortex (ERC), are among the earliest sites of pathologic involvement in AD (Braak & Braak, 1991), and studies have repeatedly shown decreased hippocampal and ERC volumes in patients with AD compared with age-matched controls (Appel et al, 2009). Other severely affected areas include the lateral parietal and posterior superior temporal regions and medial posterior portion of the cingulate gyrus (Jones et al, 2006), but atrophy is also evident in the frontal, temporal, and occipital lobes (Rusinek et al, 1991).…”