This document summarizes research into using simultaneous PET-MRI to track respiratory motion in 3D in real time. The goal is to generate a 3D motion vector field to correct PET images corrupted by breathing motion. The method uses radial 3D MRI with golden angle sampling to acquire imaging data. Image reconstruction is performed using sliding window frames and iterative compressed sensing in the 3D wavelet domain. Preliminary results show the technique generates real-time 3D images with sufficient resolution for mapping respiratory motion.

1. Real-time 3D MR Respiratory Motion
Acquisition for Simultaneous
PET / MR Imaging
Liheng Guo1, Mark Ahlman3, Tao Feng2, Michael Guttman4, Elliot McVeigh1,
David Bluemke3, Benjamin Tsui2, Daniel Herzka1
1Biomedical Engineering, Johns Hopkins University, Baltimore, MD
2Department of Radiology, Johns Hopkins University, Baltimore, MD
3Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD
4Cardiology, School of Medicine, Johns Hopkins University, Baltimore, MD
Podium Presentation. Annual Meeting of the International Society for Nuclear
Medicine and Molecular Imaging (SNMMI). St. Louis, MO. June 11, 2014.
Liheng Guo
SNMMI 2014

2. Motivation
• Breathing motion corrupts positron emission tomography (PET) images
Goerres, et al. %Respiration-induced Attenuation Artifact at PET/CT: Technical Considerations. Radiology. 2003; 226:906–910.
Liver
Lung

Time
Heart
http://www.siemens.com/press/en
/presspicture/
Positron Emission Tomography (PET)
Motion-induced false signal void

3. Objective
• To track breathing motion in 3D in real time, using simultaneous PET-MRI
• To generate 3D motion vector field to correct PET images
http://www.siemens.com/press/en/events/healthcare/2010-11-Biograph-mMR.php

4. Method: Imaging Data Acquisition
• Radial 3D MRI
Barger, et al. MRM
2002;48:297-305
• Golden Angle Sampling Pattern
500 views
1000
2000
Early Late

5. Method: Image Reconstruction
Imaging Data Acquisition
. . .
• Sliding window frames
• Iterative compressed-sensing reconstruction in 3D wavelet domain

6. Frame 1 Frame 2 Frame 3 Frame 4
Coronal View
(slice 60 of 128)
Coronal
Projection
(all slices)
Motion
Vector Field
(slice 60 of 128)
3.1×3.1×3.1mm3 voxels 2s temporal res 4D registration
Results: Real-Time 3D Images
• Sufficient Resolution for Motion Mapping