Room: Room 205
Purpose: The T2 quantification (T2 mapping) of the abdomen is challenging due to long scantime and respiratory motion. A technique called 2D radial TSE with tiered echo-sharing and bit-reverse (BR) view ordering can potentially resolve these issues by acquiring TE data for T2 mapping in an efficient and motion robust fashion, but imposes limits on the choice of Echo Train Length (ETL) due to the construction of BR. The current work introduces a novel view ordering algorithm with "pseudo" Golden Ratio (pGR) that removes the ETL restrictions. With pGR, the current 2D radial TSE can be further generalized to support any ETL and affording scan time reduction without a compromise in image and T2Map quality.
Methods: The proposed sequence and online reconstruction were implemented on a 3T scanner. The technique was validated with healthy volunteers (n=10) under a local IRB approved protocol. Radial TSE liver MRI data was acquired with (a) breath-hold liver protocol (pGR vs. BR) and (b) free-breathing liver protocol with diaphragm navigator (vs. the CartesianTSE counterpart). The resulting data sets were compared for overall image quality and for T2 quantitative values.
Results: With the pGR, the scan time of 2D radial TSE is reduced vs. the BR (by 18% in this study) without a compromise in image quality or T2Map values. Free-breathing optimized radial TSE generates scantime-efficient motion free images, while contrast and T2Map values matched the Cartesian counterpart.
Conclusion: Liver T2 mapping with motion robust and highly efficient 2D radial TSE technique has shown a great potential in the MR evaluation of the abdomen, and has the added benefit of providing quantitative T2 information. The pGR ordering scheme provides the necessary flexibility to bring the technique to routine clinical use and will play a future role in radiation oncology (e.g. T2Map for lesion delineation in MR-SIM).
Funding Support, Disclosures, and Conflict of Interest: Yutaka Natsuaki, Bradley Bolster and Xiaoming Bi are an employee of Siemens Healthineers.
MRI, Quantitative Imaging, Pulse Sequences