OUR CONTRIBUTION TO CLINICAL IMAGING
Functional Magnetic Resonance Imaging
Functional magnetic resonance imaging (fMRI) enables the localization of areas in the brain that are involved in e.g. speech activity or motor function. During ongoing measurement, the subject performs a task which is tailored to the brain function to be examined. For speech activity, it consists of recognizing displayed word pairs and signaling synonyms by pressing a button. This way, both speech comprehension and speech generation are induced. The combination of known paradigm, subject response-signals and time-synchronized MR data allows speech-activating areas to be determined through suitable post-processing routines.
Regions of interest (ROIs) selected for speech activity are Broca's (turquoise) and Wernicke's (green) areas, analyzed activations are shown in red. This subject has a pronounced speech dominance on the left side.
Pyramidal tracts (green), visual tracts (red) and Fasciculus Arcuatus (yellow). The individual structures can be localized and their extent evaluated in both hemispheres.
Diffusion Tensor Imaging
Diffusivity of water molecules provides a measure which allows to localize structure patterns and connectivities in the brain. Similarly, abnormal diffusivity can indicate loss of connectivity or pathological cerebral states. This diffusivity of water molecules is used to generate an image contrast in diffusion-weighted MRI.
White matter shows a characteristic fiber structure leading to directional diffusivity. These fiber tracts can be measured by diffusion tensor imaging (DTI), which is a functional, diffusion-weighted MRI technique
Epileptogenic Lesions, such as focal cortical dysplasia (FCD), are often very subtile in raw MR images. We use a specialized post-processing pipeline, „Morphometric Analysis Program“ (MAP18) that combines statistical analysis of features such as junction, extention and thickness to support detection of FCDs.
Single-Photon Emission CT coregistered to MRI
Metabolism of brain tissue is prone to alterations during epileptic seizures. This alteration can be quantified by applying nucleotid tracers to patients and recording the Single-Photon Emission CT (SPECT) in ictal and interictal conditions. While the previous is performed by the Nuclear Medicine Department, we perform registration of ictal and interictal SPECT to structural MR images (SISCOM). Further statistical analyses of the combined images allow us to localize brain regions with significant alteration of metabolism which are suspect to epileptogenic lesions.
SPECT-cluster with significant hypermetabolism located in the right temporal lobe.