Development of quantitative arterial spin labeling perfusion MRI methods dedicated to brain and heart – QASAREM

Introduction The present demand is a resubmission of project RBF4MED submitted to the ANR within the 2007 'Blanc' call for proposals, in which it was placed on the complementary list, but ultimately not financed. Taking into account the entirely positive evaluation by the reviewers and the recommendations made by the ANR committee, the project was reduced in scale, and its costs are therefore significantly diminished in terms of MRI exams. Perfusion MRI measures capillary blood flow that is actually used by the tissue. In present clinical practice, perfusion MRI protocols are used on patients with macrovascular lesions after stroke or myocardial infarction. Beyond relative perfusion assessment comparing different territories, the existing perfusion MRI methods can in theory be used to absolutely quantify regional capillary blood flow. Reliable perfusion MRI methods, however, are still under development, and post-processing is still too complicated to be used by MR technologists or clinicians without interaction with MR physicists. Reliable and easy perfusion quantification would allow diagnosis and study of pathologies that are presently inaccessible by MRI. The application field of MRI would benefit from a considerable enlargement if quantitative perfusion MRI techniques entered clinical protocols. Concerned pathologies across all organs are Alzheimer as well as diabetes with its cardiovascular implications. Using quantitative approaches, longitudinal follow-up of pathologies in patients and animals becomes possible. Research objectives Methodology -Establish an organ-dependent method comparison for quantitative perfusion MRI. This will concern pure methodological healthy volunteer studies. Comparative animal studies will precede the work on humans. -Establish an original spin-labeling method for human myocardial perfusion quantification. -Develop optimized quantitative perfusion MRI techniques by including recent hardware developments such as dedicated multi-channel coil arrays, high field strengths and fast gradient systems. -Evaluate the practical impact of high-field clinical MRI devices on the comparison of perfusion MRI methods. This will be done using the 3 Tesla facility implemented at CRMBM in june 2008. Arterial spin labeling MRI techniques are in the focus of this project and particularly benefit from higher fields. Applied research -Increase the accessibility of quantitative perfusion MRI methods with respect to clinical teams and technologists by the development of reliable and sensitive imaging techniques and highly automated post-processing software. -Strengthen small animal MRI by adding quantitative perfusion MRI techniques to already established longitudinal protocols and by extending CRMBM's experience on cardiac small animal MRI to other organs. Project outline With respect to the structure of the CRMBM, this project is transversally organized between heart and brain, and also going from animal to human studies. Every « classical » team will benefit from the experience and developments carried out transversally. Developments on animals will not only contribute to accelerate human method development but also be available for the study of animal models. The research strategy proposed in this project starts with the optimal combination of the most recent approaches to quantitative perfusion MRI including recent CRMBM developments. The specific needs of each organ will stimulate further original sequence developments. Developments and comparisons on animals -Starting point: existing original arterial spin labeling methods on the animal heart -Optimization of spin labeling methods for brain applications -Optimization, simplification and automation of post processing software developed at CRMBM -Inclusion of quantitative perfusion MRI in animal model studies on heart and brain Developments and comparisons on humans, volunteer studies -Starting point: experience from animal studies and existing post-processing software -Implementation and development of spin labeling methods for brain -Implementation and development of cardiac arterial spin labeling at 3T(Siemens Verio, march 2008) -Comparison and validation of ASL techniques -Establishment of optimized protocols in collaboration with clinical teams Expected results This project aims at strengthening MRI as a medical imaging technique by extending its modal versatility as well as its capacity to be applied to other organs than the brain. Therefore, the major result expected from this work will be the feasibility of new clinical applications regardless of the organ concerned. Taking into account the framework of this project, we expect as endpoint new diagnostic protocols to emerge along with pathophysiological research applications on animals and humans (translational research).