3D simultaneous cine and T1 mapping using dual-excitation flip-angle stack-of-spiral acquisition with spiral-navigated respiratory and cardiac self-gating (RF_FR_354)

Friday, January 31, 2025

11:50 AM – 12:00 PM East Coast USA Time

Location: Blue Room PreFunction

Presenting Author(s)

XW

Xitong Wang, MSc

PhD Student
Stanford University

Primary Author(s)

XW

Xitong Wang, MSc

PhD Student
Stanford University

Co-Author(s)

SZ

Shen Zhao, PhD

postdoc
Stanford University
QC

Quan Chen, PhD

postdoc
Stanford University
RZ

Ruixi Zhou, PhD

Lecturer
Beijing University of Posts and Telecommunications, China (People's Republic)
Junyu Wang, PhD

Postdoctoral Scholar
Stanford University
SL

Sizhuo Liu, PhD

Postdoctoral Scholar
Stanford University
YY

Yang Yang, PhD

Associate Professor
University of California, San Francisco
Michael Salerno, MD, PhD

Cardiology Professor
Stanford University

Background: Cardiac MR (CMR) imaging is a widely used technique that provides important diagnostic and prognostic information in cardiac diseases. T1 maps and LGE can provide additional information on myocardial viability and fibrosis by detecting changes in myocardial tissue. Our group has developed a simultaneous acquisition for T1 map and CINE images for 2D acquisition [1]. This work is to extend the acquisition to 3D simultaneous cine and T1 mapping in a single free-run randomized stack of spiral sequence about 3 minutes, which beneficially shortens clinical scan time.

Methods:

2 volunteers and 5 patients were imaged on a 3T Siemens scanner pre and post contrast. A 3D variable stack of spirals is acquired consisting of a continuous acquisition with an inversion-recovery RF pulse applied every 4.6 seconds, using one excitation flip angle (FA1) for the first half of the inversion pulses and another excitation flip angle (FA2) for the second half of the inversion pulses (Figure 1) [1,2]. For resolving cardiac motion, we exploit a 500-point fixed spiral navigator of the kz=0 partition (shown in black) to extract the self-gating signal by PCA, then bin the data into different cardiac phases. The spiral navigator is acquired every 6^th interleaf.

For T1 mapping (Figure 2), in each R-R interval every stack of spirals volume was combined into a diastolic acquisition window of 30% of RR interval. A dictionary was generated using the acquisition parameters and ranging T1 from 100 to 3000 ms, IR efficiency from 0.9 to 1. For T1 fitting, we generate the dictionary based on two flip angles by K-singular value decomposition from the Bloch simulation time courses with the acquisition parameters. By fitting the three-parameter model of equation using the dictionary learning–reconstructed images, two apparent T1* maps for two flip angles can be obtained and the fitting scheme can also provide a flip-angle scale (β) map. Dictionary learning [3,4] was performed by using OMP and an LSQR solver.

For cine images, we use the last 37.1 ms where the signal in the myocardium has reached the steady-state portion of the inversion recover curve for FA2 = 15 degree (green box in figure 2) post contrast and reconstructed with the 3D DESIRE SPARCS technique, a deep learning reconstruction for 3D cine images.[5]

Results: Figure 3 (a) shows a diastolic frame from the 3D whole heart coverage cine images using the proposed technique. (b) shows the T1* mapping corresponding to 3 degrees and 15 degrees. (c) shows the T1 mapping for this technique for 3D whole heart coverage

Conclusion:

We proposed a strategy to acquire 3D simultaneous cine and T1 mapping using dual-excitation flip-angle stack-of-spiral acquisition with respiratory and cardiac self-gating in 3-minute scan.