The goal of this proposal is to develop technology that is both novel and disruptive in order to achieve anatomical quality, dynamic B0 corrected, whole brain, microscale (? 500 m isotropic) fMRI. Our Brain Initiative work thus far has demonstrated that, with the significant SNR gains of MR Corticography and SLIDER technologies, ultra-high 500 m resolution fMRI is feasible at 7T. However, significant barriers remain that make microscale imaging of the whole brain extremely challenging, if not impossible. Current fMRI technology relies on gradient-echo EPI which, especially at higher field strengths and resolutions, suffers from static B0 signal dropout, dynamic B0 distortions, T2* decay related blurring and large vein bias, which together limit our ability to acquire true, whole brain, microscale resolution fMRI. Furthermore, even with advanced acceleration techniques, scanning the entire brain at microscale resolution currently requires unacceptably long repetition times (TR >> 3 s). To address these limitations, we propose the development and integration of several key, novel technologies. StImulus-Locked K-Space (SILK) fMRI technology, which we recently developed, overcomes the spatial-temporal resolution tradeoff and provides anatomical quality, task-based, fMRI. By synergistically combining SILK fMRI with cutting-edge commercially available technology for prospective and passive motion mitigation (i.e. technologies offered by Kineticor and Caseforge) as well as for navigator based dynamic B0 correction (i.e. technologies offered by Siemens and MGH) we will achieve transformative advances in our ability study both the microscale structure and function across the human brain. Importantly, because SILK fMRI is based on the 3D GRE FLASH pulse sequence, SILK images can also serve as ground truth, susceptibility weighted structural images capable of differentiating laminar organization as well as sources of large vein bias. The dual anatomical/functional nature of SILK fMRI data is a disruptive paradigm shift that will enable information rich, co-registration free, study of the brain at much higher fidelity and resolution than current technology allows. An additional advantage of the proposed technologies is that they are easily integrated into currently existing 7T MRI scanners and therefore can be rapidly disseminated to both clinical and neuroscience imaging research centers. Successful execution of this project would also greatly augment our ongoing Brain Initiative studies aimed at improving localization and mapping of neuronal circuitry in the brains of both healthy and patient populations.
Current fMRI technology relies on gradient-echo EPI which suffers from dynamic B0 distortions as well as T2* decay related blurring and limits our ability to acquire true, whole brain, microscale resolution fMRI. StImulus- Locked K-Space (SILK) fMRI technology, coupled with the proposed state-of-the-art motion mitigation and dynamic B0 correction technologies, will overcome these limitations and provide over an order of magnitude higher spatial resolution than current 7T technology. As a new research tool, SILK fMRI will enable transformative studies of the microscale structure and function across the entire human brain.
