Moving towards earlier detection
In the future, new imaging technologies and disease biomarkers may be helpful to take the clinical evaluation of AD forward from simply ruling out the disease to supporting the identification of patients who have the strong likelihood of developing AD, by identifying characteristic patterns of functional and structural cerebral alterations.
The actual guidelines for the Mild Cognitive Impairment (MCI) stage are largely for research, but they may be applied in specialized clinical settings. They supplement standard clinical tests to help determine possible causes of MCI symptoms.1 Currently, imaging is being used in research to help establish correlations between pathophysiologic manifestations, clinical status and their relation to other biomarkers, and their prognosis as well as therapeutic trials. Going forward, imaging could be valuable to identify which MCI patients might progress to a clinical diagnosis of AD and support the identification of proper disease modifying therapies.2
Combining diagnostic imaging and laboratory capabilities, Siemens is your partner in the evaluation of AD and in pushing diagnostic boundaries going forward.
Alzheimer's DiseaseNeurology Solutions for more diagnostic confidence
Imaging and Lab Tests support Alzheimer’s disease Evaluation
At the moment, there are no stand-alone tests for a definitive diagnosis of Alzheimer’s disease (AD) other than histopathological confirmation at autopsy. Complete work up of AD includes a thorough medical history, mental status testing, physical and neurological exam, brain imaging and laboratory tests.
Screening
There are a variety of types of dementia and cognitive impairment, which can have various underlying causes, ranging from Alzheimer’s disease (AD) to vascular dementia to name but a few, requiring different therapeutical approaches. Hence various risk factors need to be assessed. While imaging and laboratory tests have traditionally been used independently on a diagnostic basis to rule out other causes of dementia, they may in the future help to assess multiple different aspects of AD pathology and have immediate prognostic importance. Siemens provides technology and laboratory equipment to help effectively differentiate AD from other dementias and venture forward in AD research.
Genetic Testing
The ɛ4 allele of the apolipoprotein E (APOE) gene has been identified as a major genetic risk factor for AD. It encodes a protein that plays a key role in cholesterol metabolism and has been found to increase the risk of developing AD. APOE-ɛ4 contributes to AD pathogenesis seems to act primarily as a risk factor in brain beta-amyloid deposition.2 Hence, screening for APOE gene mutations and micro RNA pattern indicating a risk profile will become important screening tools in the future.
Laboratory testing
In patients with suspected AD, the clinical evaluation essentially includes lab tests for a number of mimicking diseases such as hypo- and hyperthyroidism, vitamin deficiencies, and infections of the central nervous system (Creutzfeldt-Jakob disease, AIDS dementia, neurosyphilis). As your partner in thyroid testing, Siemens solutions help labs keep pace with the evolving standards in thyroid disease diagnostics.
Morphological Evaluation
Brain scans are used to rule out other possible causes of dementia, including brain tumors, stroke, subdural hematomas, normal-pressure hydrocephalus, and other conditions. Non-contrast and contrast-enhanced CT imaging is a highly efficient neuro-imaging technique that provides differential and cause-related information on possible causes of dementia. The unmatched soft tissue contrast of MRI and additional information gained from dedicated sequences enables to reliably rule out differential diagnoses. With state-of-theart CT and MR scanners together with software for all your clinical and research related data handling, Siemens is the ideal partner in AD image based evaluation.
Functional Evaluation
Morphometry
3T MRI Scanners
Structural MRI in AD can assess atrophy and changes in tissue characteristics. Also, progressive cerebral atrophy can be visualized in patients, in particular, with T1-weighted volumetric sequences. MRI offers a range of different sequences that can probe different tissue characteristics, providing multiple clinical and research measures in a single session. MRI measures of atrophy reflect cumulative neuronal damage, which in turn is directly responsible for the clinical state.
Biograph mMR
The benefits of single modality MR and PET in the study of neurological diseases such as AD are well known. Combining these modalities brings the potential for a more complete imaging picture and better understanding of AD pathologies. In addition, the current research and development of new tracers offers great promise. Biograph mMR fully integrates state-of-the-art 3T MRI and cutting-edge molecular imaging. Simultaneous acquisition of the morphology, function, and metabolism of the brain are now possible. You can obtain a comprehensive diagnostic picture with just one scan, which shows MR and PET data in virtually seamless spatial alignment. In addition, the MR acquisition can be used to correct motion-related effects in PET, greatly improving image quality.
Function
Inline BOLD Imaging
- Automatic real-time calculation of z-score (t-test) maps with inline technology for variable paradigms
- Compatible with single-shot EPI with high susceptibility contrast for fast multi-slice imaging
- ART (Advanced Retrospective Technique) for fully automatic 3D retrospective motion correction for 6 degrees of freedom (3 translations and 3 rotations)
- Mosaic images for efficient storage and transfer of large data sets
- Inline calculation of t-statistics (t-maps) based on a general linear model (GLM), including the hemodynamic response function and correction for slow drifts (GLM not available for MAGNETOM ESSENZA)
- Overlay of statistical results calculated inline onto EPI images.
syngo DTI Tractography
- Multiple parameters can be derived from the diffusion tensor, including the trace, ADC (Apparent Diffusion Coefficient), relative anisotropy, and fractional anisotropy. These secondary parameters are independent of the frame of reference and are very sensitive to white matter pathology.
- syngo DTI (Diffusion Tensor Imaging) Tractography uses diffusion tensor data and allows 3D visualization of specific white matter tracts.
- syngo DTI and syngo DTI Evaluation will help you to identify anatomical substructures, and with fiber direction maps and fiber tracts (tractography) you will be able to assess the microstructural aspects of the brain lesions.
- The Siemens Multidirectional DTI with 256 directions allows a finer and more precise visualisation of fiber tracks and direction.
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Adam S. Fleisher et al: “Using Positron Emission Tomography and Florbetapir F 18 to Image Cortical Amyloid in Patients With Mild Cognitive Impairment or Dementia Due to Alzheimer Disease”, Archives of Neurology, July 12, 2011
Johnson KA et al. Brain Imaging in Alzheimer Disease. Cold Spring Harb Perspect Med 2012;2:a006213