Magnetization transfer based metric for chemical exchange saturation transfer mri

A method for processing magnetic resonance imaging MRI data from a target volume in a subject, the method comprising:

• determining from the MRI data chemical exchange saturation transfer, CEST, voxel values corresponding to a transfer of saturation between a predefined pool of protons and water protons, the pool of protons having a predefined chemical shift;
• weighting the CEST values in order to distinguish CEST values of fluid-rich tissues from CEST values of solid tissues in the target volume, wherein the fluid-rich tissue comprises an amount of fluid higher than a predefined minimum amount of fluid, the MRI data being acquired using predefined MRI sequences, wherein the first MRI data comprises non-saturated data at a predefined large saturation frequency offset or without RF saturation and saturation transfer data at N saturation frequency offsets, wherein N>=2, wherein the weighting comprises:
• performing a quantitative tissue scoring using a subset of the saturation transfer data comprising N2 saturation frequency offsets and the non-saturated data in order to assess fluid content and solid tissue content at each voxel in the MRI data, generating a correction function using results of the scoring, and using the correction function to weight the CEST value of each voxel, wherein using the correction function to weight the CEST values comprises multiplying a correction factor CF=ε×MTR(+Δωc)+MTR(Δωc)) with CEST values, wherein ±Δωc are the saturation frequency offsets and c is a factor that is determined such that the application of the correction factor results in the CEST values within the fluid-rich tissues being rescaled while the CEST values remain unchanged for the solid tissues.

A computer program product comprising machine executable instructions stored on a non-transitory computer readable medium for execution by a processor, wherein execution of the machine executable instructions causes the processor to process magnetic resonance imaging MRI data from a target volume in a subject by:

• determining from the MRI data chemical exchange saturation transfer, CEST, voxel values corresponding to a transfer of saturation between a predefined pool of protons and water protons, the pool of protons having a predefined chemical shift;
• and
• weighting the CEST values in order to distinguish CEST values of fluid-rich tissues from CEST values of solid tissues in the target volume, wherein the fluid-rich tissue comprises an amount of fluid higher than a predefined minimum amount of fluid, the MRI data being acquired using predefined MRI sequences, wherein the first MRI data comprises non-saturated data at a predefined large saturation frequency offset or without RF saturation and saturation transfer data at N saturation frequency offsets, wherein N>=2, wherein the weighting comprises:
• performing a quantitative tissue scoring using a subset of the saturation transfer data comprising N2 saturation frequency offsets and the non-saturated data in order to assess fluid content and solid tissue content at each voxel in the MRI data, generating a correction function using results of the scoring, and using the correction function to weight the CEST value of each voxel, wherein using the correction function to weight the CEST values comprises multiplying a correction factor CF=ε×MTR(+Δωc)+MTR(Δωc)) with CEST values, wherein ±Δωc are the saturation frequency offsets and E is a factor that is determined such that the application of the correction factor results in the CEST values within the fluid-rich tissues being rescaled while the CEST values remain unchanged for the solid tissues.