Functional MRI (fMRI) is being increasingly used to investigate the functional integrity of brain networks in AD. In combination with other tests, the information gained from fMRI will help differentiate the diseases and determine the status of progression. Synaptic activity is measured either by the visualization of glucose metabolism of brain cells using PET or the visualization of signal changes due to changes in blood volume, blood flow, and the blood oxyhemoglobin/ deoxyhemoglobin ratio using BOLD MRI. Many fMRI studies in MCI and AD focus on the pattern of fMRI activation in the hippocampus and related structures in the medial temporal lobe. In patients with clinically diagnosed AD, the results have been quite consistent, showing decreased hippocampal activity during theencoding of new information. Furthermore, several studies report increased prefrontal cortical activity in AD patients. These results suggest that other networks may increase activity as an attempted compensatory mechanism during hippocampal failure.1 Other MRI techniques such as diffusion tensor imaging (DTI), arterial spin labeling measures of cerebral blood flow and PET tracers targeted at the cholinergic system, microglial activation and other tracers in development will also be contributing to our understanding of AD pathology in the future.
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.
1Johnson KA et al. Brain Imaging in Alzheimer Disease. Cold Spring Harb Perspect Med 2012;2:a006213