The overarching goal of the proposed project is to obtain high quality perfusion and permeability information for the evaluation of brain tumors using accelerated magnetic resonance imaging (MRI) techniques. Current perfusion MRI methods use an intravenous injection of gadolinium (Gd) contrast agent and examine changes in image intensity over time. However, these imaging methods are limited in coverage and resolution due to slow MRI encoding and are furthermore susceptible to errors and imaging artifacts, which can lead to problems assessing tumor physiology. Specifically, damaged blood brain barriers (BBB) of tumor patients result in contrast leakage effects that enhance in the same way a malignant tumor can, making it difficult to determine tumor progression and treatment planning. Recently, a multiple spin and gradient echo (SAGE) sequence has been shown to provide more accurate quantitative perfusion information as well as new valuable information on tumor vessel architecture. However, the added image encoding burden of SAGE severely limits the achievable resolution and coverage. This project aims to achieve quantitative, whole brain perfusion images with a high 1.8 mm isotropic resolution at a fast temporal sampling rate of 1.4s, using an efficient SAGE acquisition scheme to greatly improve the diagnosis, monitoring, and treatment of brain tumors. The enhanced spatiotemporal technology will be accomplished using synergistic acquisition and reconstruction MRI techniques to overcome current spatial encoding limits. To accomplish this high acceleration factor, a simultaneous multi-slice acquisition with a sagittal zoom imaging method will be combined with in-plane acceleration. Dual polarity GRAPPA will be incorporated into the reconstruction to ensure high imaging fidelity with minimal ghosting artifacts. The acquisition will be complemented by joint virtual coil parallel imaging reconstruction that can take advantage of phase prior and mutual information across echoes and time to reconstruct highly under-sampled data. The protocol will be able to achieve both dynamic susceptibility contrast (DSC) perfusion measures such as cerebral blood volume, as well as dynamic contrast enhanced (DCE) derived transfer coefficient Ktrans to assess tumor permeability. The technology in this proposal will result in a wealth of new detailed quantitative perfusion information that has the potential to influence clinical decision making in treatment options and planning.
Current perfusion imaging methods for diagnosing and evaluating brain tumors are limited in coverage and resolution, and are susceptible to errors. The proposed research aims to develop a highly efficient quantitative MRI perfusion protocol that enables whole brain coverage and significantly higher resolution. The proposed method has the potential to enhance the ability to assess tumor dynamics, vessel architecture, and permeability, important metrics to understanding tumor progression and response to drug treatments.
