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Single-LIne DrivEn Real-Time (SLIDER) MR Multi-Contrast Imaging Using Pre-Learned Spatial Subspace

P Han*, F Han, Z Hu, D Li, A Christodoulou, Z Fan, Cedars-Sinai Medical Center, Los Angeles, CA


(Monday, 7/13/2020) 1:00 PM - 3:00 PM [Eastern Time (GMT-4)]

Room: Track 1

Real-time monitoring is critically important for MR guided radiation therapy (MRgRT) at periodically moving sites. However, it is technically challenging to generate real-time 3D images with both high image quality and spatio-temporal resolution. In this work, we developed a novel Single-LIne DrivEn Real-time (SLIDER) multi-contrast imaging scheme to address this problem.

The SLIDER scheme is based on low-rank spatiotemporal decomposition. It consists of a “Prep” scan and a “Live” scan. From the “Prep” scan are learned a high-quality spatial subspace and a linear transformation which maps the k-space navigator data to corresponding subspace coordinates. In the subsequent “Live” scan, successive real-time images are generated by applying a fast matrix multiplication procedure to every single instance of the k-space navigator readout that can be acquired at a high temporal rate. By projecting onto subspaces of different contrasts (T1w/T2w/PDw), contrast-variated real-time images can be transferred onto multiple contrast-frozen images simultaneously while maintaining their motion state.
The scheme was tested on 3 healthy volunteers at 3.0T with a 3D (1.7x1.7x5 mm3) transverse-oriented scan, using an 11-min T1/T2 abdominal Multitasking sequence. The first 8-min part was used as the “Prep” scan, and the last 2-min part was used (navigator lines only) as the “Live” scan. The reconstruction result of the entire 11-min scan using regular Multitasking algorithm was used as the motion and contrast reference.

With a pre-learned high-quality spatial subspace, T1-, T2-, and proton-density weighted high-resolution 3D images can be generated simultaneously on-the-fly with an average latency of ~45ms. At arbitrarily chosen time points, their corresponding motion states and regenerated contrast weightings were highly comparable between SLIDER and the reference.

SLIDER provides multi-contrast 3D images with high spatial and temporal resolution. The scheme can potentially serve as a viable real-time monitoring approach with tumor-tailored image contrast during MRgRT.


Not Applicable / None Entered.


IM/TH- MRI in Radiation Therapy: MRI/Linear accelerator combined- IGRT and tracking

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