Magnetic Resonance Imaging Technology Development

National Institute Of Neurological Disorders And Stroke

Investigators

Linked publications, trials & patents

Abstract

The overall goal of this project is to develop high field MRI technology to improve the study of human brain anatomy and function. This includes the development of MRI scanner hardware, peripheral equipment, MRI signal acquisition pulse sequences and image reconstruction and analysis software. The AMRI section at NINDS has been at the forefront of this development and has been applying newly developed methods to both control subjects as well as patients with neurological disorders. As part of its efforts to improve MRI methodology, the AMRI section at NINDS carries the main responsibility for the development of NIHs 11.7T human MRI scanner, a uniquely powerful system that will allow in-vivo neuroimaging with unprecedented clarity. Over the last year, AMRI has continued preparation for re-installation of the 11.7T human MRI system, which got first delayed because of the COVID-19 crisis, followed in January 2022 by the Helium crisis. In spring 2023, we finally were able to get a Helium contract in place and have ASG, the magnet manufacturer come out and cool down the superconductive magnet. As of August 2023, the magnet is at 4 Kelvin, and ready to be energized to 11.7T. This will occur starting in September, with a final completion date early October. It is anticipated that MRI scanning will commence early 2024, after final installation of the electronics has completed. In parallel with work on the 11.7T magnet, we have proceeded with safety aspects of the system with an eye on FDA and IRB approval to do human scanning. Together with the clinical trials unit at NINDS, AMRI has developed an IRB protocol that will be submitted to the FDA in order to obtain an investigational device exemption (IDE). Based on initial feedback from the FDA, we have developed a two-stage protocol in which human subjects will first be exposed to 11.7T without MRI scanning. In a second stage, MRI scanning will be performed to measure the RF B1-field distribution over the human head to validate our simulation software used to predict potential harmful tissue heating associated with MRI scanning. It is anticipated that this protocol will be submitted in January 2024. To further validate the accuracy of our heating predictions, we have improved our head mimicking phantoms to allows further improved accuracy of our MRI-based temperature mapping method. Together with EC, we have also continued developing RF transmission and detection hardware for operation at 11.7T. The improved sensitivity of high field MRI can in part be exploited to improved scan speed and reduce MRI scan time. However, with most applications such improvement is limited by the time it takes to perform the necessary contrast preparation and sequentially scan through an object. In 2023, we have developed an approach to reduce this limitation. While scanning a specific slice through the object, the method prepares the contrast for an upcoming slice. Initial implementation for diffusion weighted MRI at 3T showed scan speed improvement of at least two-fold, allowing for scan times as short as 10 seconds. A provisional patent application was submitted and a journal article has been accepted for publication in Magnetic Resonance in Medicine. Together with Jiaen Liu at UT Southwestern and Danny Reich's group at NIH, we optimized our high resolution susceptibility-weighted MRI technique for robustness against head motion as evaluated the feasibility to perform scans at 0.3 mm resolution. This work was published in Neuroimage. AMRI provided recommendations to an ISMRM study group tasked with developing a standardized protocol for susceptibility-weighted MRI and contributed to a journal article describing this protocol.