APTw-MRI with additional suppression of fluid compartments (necrosis) and noise reduction using rescaled MT-correcting CEST metrics

Motivation: APTw-MRI evolves for brain tumor diagnosis and treatment monitoring, while metrics/visualization are still debated. MTR-asymmetry under/overestimates chemical exchange at high/low MT, but MT-correction enhances background-noise. Fluid-suppression simplifies diagnosis in necrosis (cysts). While partly addressed, a combined method is needed. Goal(s): Define an MT-correction with extra fluid suppression and noise reduction. Evaluate in glioblastoma patients. Approach: MT-correction with MTRrex for solid tumors, rescaled for extra fluid suppression (necrosis) and a noise limit (NAWM), is compared to previous proposals on 12 glioblastoma patients with 2D FSE, 2μT/2s saturation on 3.0T-MRI. Results: MT-correction in solid tumors is shown with high CNR and efficient suppression of necrosis. Impact: The rescaled metric may provide a standard for displaying APTw contrast in tumor diagnosis and response assessment, combining MT-corrected and low noise quantitative assessment of chemical exchange in solid tumor areas with extra fluid suppression for efficient clinical reading.