Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Periodic Report Summary 1 - ABRIM (Advanced Brain Imaging with MRI)

Advanced Brain Imaging (ABRIM)

Daniel Gomez, Zahra Shams, David G. Norris

Specific Objectives
In this project we bring for the first time modern methods of cognitive neuroimaging using MRI into routine application. This will bring significant benefits both for the clinic and for neuroscience. By exploiting recent dramatic increases in scanning speed we will develop a protocol that performs an assessment of brain connectivity plus a high spatial resolution evaluation of the brain within half an hour.

The measurements described above have hitherto been too time consuming for application in a single imaging session, or the session has been too long to be tolerated by patients and the elderly. Furthermore the application of sophisticated graph theoretical analyses has remained in the domain of neuroimaging research laboratories, and has not been developed for application at the single subject level. In this project we will achieve the following:

1. Design and implement a measurement protocol capable of obtaining measures of functional and anatomical connectivity, grey matter volume, spontaneous BOLD activity, susceptibility weighted imaging, and myelinisation degree within a time frame acceptable to patients, and of the order of 30 minutes.

2. Perform a connectivity analysis on the basis of a standard anatomical atlas, and derive maps of node degree and betweenness. Visualise the outcomes of the other measurements alongside these.

3. Collect data for a data-base of healthy subjects stratified on the basis of age and gender. This will be used for neuroscientific as well as clinical purposes, and in particular to identify the normal range of values for all parameters. By distributing these values rather than the whole data base it will be possible to determine whether an individual deviates significantly from the age and gender related norm.

Work Performed
Daniel Gomez has implemented a multiband multiecho imaging sequence and brought it up to a level where it works robustly. It is now ready to be ported to a works in progress implementation at Siemens. The scientific work that he has conducted has been concerned with the development of optimised protocols for fMRI. He has examined the optimal acquisition parameters for multiband multiecho imaging, and performed comparisons of the sensitivity of different protocols, which have ranged from multiband without multiecho to full multiband multiecho protocols.

Zahrah Shams has worked on the implementation of the STIFT (structure tensor informed fibre-tracking) method at 3T. The previously published implementation of this technique utilised high resolution SWI data that had been obtained at 7T, combined with DWI data from 3T. Now all data are acquired at 3T, and use improved DWI protocols. She has also implemented methods of assessing myelin content based either on the ratio of T1w/T2w image intensities, or quantitative longitudinal relaxation rate R1 mapping. These reveal patterns in human cerebral cortex that are in close correlation with its myeloarchitectonic cortical parcellation, particularly in motorsomatosensory cortices.

Main Results
The results of the fMRI comparison using multiecho multiband and straight multiband imaging show that in many regions of the brain multiband without multiecho has the highest sensitivity, but that in regions with appreciable inhomogeneity gradients there is a benefit from multiband multiecho. Both the STIFT method and the myelin-weighted imaging methods have been successfully implemented.

Expected Final Results
The outcome of the first project will be an efficient fMRI acquisition protocol combined with an optimised data analysis pathway. We will make a graph theoretical analysis available, showing the relative strengths of provincial and connector hubs (node degree and betweenness respectively) in the brain based on a partial correlation coefficient analysis.

The outcome of the second project will be: a high resolution map indicating the degree of myelinisation in the brain; a map showing the distribution of the mean diffusivity and fractional anisotropy; a tractography based brain connectivity map; a graph theoretical analysis showing the strengths of the provincial and connector hubs using the connectivity map. We will also be able to generate maps of iron content which will be of great value in the assessment of some aetiologies, for example Parkinson’s disease.

During the last six months of the project we will scan healthy volunteers in order to obtain normative values for the connectivity parameters measured in the protocol. The mean values and distributions of the node degree, betweenness, myelin index, and vitality index will be computed.

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Life Sciences
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