Room: Karl Dean Ballroom C
Purpose: MRI is widely used in the management of body diseases. However, respiratory motion represents a critical factor limiting its image quality, spatial coverage, and acquisition efficiency. In this work, we developed a time-efficient technique aimed for multi-task quantitative imaging (MTQI) of the body during free-breathing.
Methods: The MTQI technique is based on a low-rank tensor imaging framework and a stack-of-stars acquisition. A saturation recovery (SR) preparation and length-variable T2 preparations are combined to generate T1-weighted and T2-weighted signals during magnetization evolution. Radial projections are continuously acquired during the saturation-recovery phase and T2 prepared phase, respectively, with in-plane golden angle ordering and Gaussian-density randomized partition ordering. Respiratory-resolved T1- and T2- weighted images and T1 and T2 maps can be reconstructed. The technique was tested on 3 healthy volunteers at 1.5T, with a 2D (1 minute, 2x2x5 mm3) and 3D (10 minutes, 2x2x2 mm3) coronally oriented scan. Conventional breath-hold 2D T1/T2 mapping sequences and a real-time 2D imaging sequence were performed to provide T1/T2 and motion references.
Results: T1-, T2-weighted images as well as T1, T2 maps at any respiratory phase were obtainable with consistently good image quality. The user could retrospectively select any time point during the saturation-recovery phase or T2-prepared phase to generate images with desirable tissue contrast. The obtained T1/T2 values in the liver region-of-interest were in good agreement with those from literature and reference methods. Respiratory motion resolved by MTQI was comparable to that by real-time 2D imaging.
Conclusion: MTQI is a single-scan, free-breathing MRI technique allowing qualitative and quantitative imaging of the body. This technique, owing to its flexible image contrast and quantitative nature, would potentially be valuable for early detection and severity assessment of tumors. MTQI can also serve as a viable 4D-MRI approach for radiotherapy planning with a tumor-tailored image contrast.
Funding Support, Disclosures, and Conflict of Interest: Drs. Bi and Han are employees of Siemens Healthcare
Not Applicable / None Entered.