Ultrashort Echo Time Magnetization Transfer Imaging for Short T2 Tissue Quantification

The imaging sequence is segmented into multiple distinct phases: ultrashort echo time imaging phase to capture signals from short T2 tissues, followed by magnetization transfer saturation phase to selectively saturate macromolecular protons, and finally a second ultrashort echo time imaging phase to detect the saturation transfer effect. This segmentation allows each phase to be optimized independently, resolving the contradiction between detection accuracy and sequence complexity.

The magnetization transfer saturation pulse is applied as a preliminary action before the second imaging phase. This pre-saturation of macromolecular protons creates a measurable contrast in the subsequent ultrashort echo time image, enabling detection of macromolecular proton signals that would otherwise be invisible. The preliminary saturation action transforms the undetectable macromolecular signal into a detectable contrast mechanism.

The methodology employs partial sampling of the parameter space by selecting specific frequency offsets and power levels that provide sufficient discrimination of tissue properties without requiring exhaustive measurement of all possible parameters. This partial action approach achieves adequate quantification accuracy while significantly reducing scanning time compared to complete parameter mapping.

The imaging protocol uses periodic repetition of the ultrashort echo time imaging sequence with varying magnetization transfer parameters across multiple repetitions. By periodically cycling through different frequency offsets and power levels in a structured manner, the protocol efficiently collects the necessary data for quantification while minimizing total scan time through optimized repetition timing.