Detecting Early Alzheimer's Using MR

Overview

Alzheimer's disease (AD) is the most common cause of dementia, affecting approximately 10% of individuals aged ≥ 65. Most available treatments aim at controlling symptoms at an early stage rather than providing a cure. Therefore, an accurate and early diagnosis of AD with appropriate management will slow the progression of the condition. Reduced cerebral glucose levels have been observed in patients with early AD. Glucose hypometabolism can be assessed by administering a radioactive glucose analogue, 2-deoxy-2-(18F) fluoro-D-glucose (18FDG), and imaging with PET (positron emission tomography). The high cost and limited availability of PET-CT (PET - computed tomography) still hamper its general clinical application. Moreover, the use of radioactive tracers in combination with the additional ionizing radiation of CT is not suitable for repeated measurements. Therefore, currently, the provisional diagnosis of AD is still based on the combination of clinical history, neurological examination, cognitive testing over a period of time, and structural neuroimaging. This has major time and resource implications. A radically different and highly innovative means for imaging glucose with magnetic resonance imaging (MRI) has now been established, exploiting the interaction between hydroxyl protons in glucose and the protons in water; the method is termed glucose Chemical Exchange Saturation Transfer (glucoCEST). GlucoCEST MRI is a method that has no reliance on radiolabelled glucose analogues and could become widely implemented in clinic practice. We therefore aim to investigate the potential of glucoCEST MRI in Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of dementia, affecting approximately 10% of individuals aged ≥ 65. Most available treatments aim at controlling symptoms at an early stage rather than providing a cure. Therefore, an accurate and early diagnosis of AD with appropriate management will slow the progression of the condition. Reduced cerebral glucose levels have been observed in patients with early AD. Glucose hypometabolism can be assessed by administering a radioactive glucose analogue, 2-deoxy-2-(18F) fluoro-D-glucose (18FDG), and imaging with PET (positron emission tomography). The high cost and limited availability of PET-CT (PET - computed tomography) still hamper its general clinical application. Moreover, the use of radioactive tracers in combination with the additional ionizing radiation of CT is not suitable for repeated measurements. Therefore, currently, the provisional diagnosis of AD is still based on the combination of clinical history, neurological examination, cognitive testing over a period of time, and structural neuroimaging. This has major time and resource implications. A radically different and highly innovative means for imaging glucose with magnetic resonance imaging (MRI) has now been established, exploiting the interaction between hydroxyl protons in glucose and the protons in water; the method is termed glucose Chemical Exchange Saturation Transfer (glucoCEST). GlucoCEST MRI is a method that has no reliance on radiolabelled glucose analogues and could become widely implemented in clinic practice. We believe that glucoCEST MRI has the potential to replace FDG-PET and improve patient healthcare as part of a routine clinical pathway in very early detection of AD. The study will include 20 healthy volunteers for developing glucoCEST in the clinical 3T MRI scanner (development phase) and 20 volunteers without AD and 20 patients with clinically diagnosed AD (clinical phase). All participants will have a 3T brain MRI scan after they receive oral glucose. The participants in the clinical phase will have a 3T brain MRI scan, a brain PET scan and they will also undertake two cognitive tests. The glucose uptake and clearance rate in the brain will be measured from PET and MRI scans and compared between groups and imaging modalities. Sensitivity and specificity of glucoCEST to detect AD will be also calculated. Primary Objective: To estimate the sensitivity of glucose uptake as measured by glucoCEST MRI in patients with AD compared with age and sex matched controls. Secondary objective: To investigate if the glucose uptake as measured by glucoCEST MRI is related to the glucose uptake as measured in FDG-PET. The main aims of the study are: 1. To determine normal uptake and clearance rates of glucose in the brain as measured by dynamic glucoCEST MRI at 3T 2. To compare glucose uptake as measured by glucoCEST MRI and FDG-PET. 3. To compare glucose uptake as measured by glucoCEST MRI in patients with AD and age and sex matched controls.