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Building a Toolbox to Support Enhanced MR Imaging in Image-Guided Therapy. Lawrence Panych, Ph.D. PI: NCIGT Imaging Core. Lawrence Panych Bruno Madore Stephan Maier Robert Mulkern Gary Zientara Seung-Schik Yoo Scott Hoge. People. Investigators. Students and Fellows. Renxin Chu
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Building a Toolbox to SupportEnhanced MR Imagingin Image-Guided Therapy Lawrence Panych, Ph.D. PI: NCIGT Imaging Core
Lawrence Panych Bruno Madore Stephan Maier Robert Mulkern Gary Zientara Seung-Schik Yoo Scott Hoge People Investigators Students and Fellows • Renxin Chu • Ming-long Wu • Jing Yuan • Chang-Sheng Mei • Mohammed Al Jallad
Aim Leverage expertise of BWH investigators to develop freely available libraries of functions to support enhanced imaging in Image-Guided Therapy. Library I Library II functions to support real-time data acquisition, reconstruction and scanner control Library III functions to support fast imaging methods including parallel imaging functions to enable reduced field-of-view acquisition using 2DRF excitation
I. Real-Time Imaging • Dynamically Adaptive Real-Time System (DARTS): • a flexible platform for real-time data acquisition, reconstruction and scanner control • Supports parallel image reconstruction in multi-core computers. • ----- • Uses pipe structure to manage multiple processes with bulletin board to pass parameters between processes. • ----- • Reconstruction modules for different sequences are easily plugged into system. • -----
I. Real-Time Imaging DARTS Kernel Control Process Data Objects Bulletin Board Encode Computation Acquisition … Reconstruction … … MR machine Data Objects Display Encode Computation Acquisition Reconstruction Processing stream
II. Fast MR Imaging Fast MR Imaging Library SENSE recon SPACE RIP recon GRAPPA recon UNFOLD recon Partial Fourier recon Gradient field inhomogeneity correction Automatic Image orientation Read/edit/write DICOM headers … Approximately 12500 lines of well-debugged C code
II. Fast MR Imaging • Parallel imaging algorithms coded with multithreads, for fast recons on multiprocessor engines. • CMAKE environment used for builds, successfully tested on Linux and Windows platforms. • Regression tests in place for several key algorithms. • DOXYGEN used to generate the documentation, in html and pdf formats. • Issues about licensing now resolved, first library download was from Wake Forest.
III. 2DRF Selective Excitation • Set of functions to support implementation of 2DRF pulses • in pulse sequences on GE MR platforms • Macros and supporting function files for ease of implementation. • ----- • Incorporated into several product sequences: • 2dfast, fgre, fiesta, ssfse, epi. • ----- • Tested for reduced FOV applications: • FUS monitoring, needle tracking. • -----
Cardiac imaging with UNFOLD+SPACERIP/GRAPPA Temperature mapping with MURPS in a reduced field-of-view (rFOV) with 2DRF Fast temperature mapping in a rFOV with SENSE+UNFOLD + 2DRF excitation Line-scan diffusion imaging (LSDI) with SENSE Enhanced Applications
Cardiac MR Imaging UNFOLD + GRAPPA/SPACERIP hybrid 55 lines instead of 192 (R = 3.5) Slice 1, phase 1 vdSENSE alone Slice 1, phase 1 SPACERIP alone
Temperature Mapping with MURPS Multi-resolution thermal mapping with MURPS Slice B1 Slice A Slice B2 Focus of heating Slices B1 and B2, which are placed away from the focus of heating, are thicker than Slice A and have lower in-plane resolution. A 2DRF pulse was used for 1/2 FOV selection in the phase-encode direction.
MURPS with 2DRF in a reduced FOV Slice Slice Slice Temperature maps in 3 slices. Temperature change in ROI. Scan time for 3 rFOV MURPS slices = Scan time for 1 full FOV slice
FUS with SENSE+2DRF+UNFOLD Water tank Transducer 1/8 FOV Gel Phantom Phase direction Water tank Phantom after 2DRF Excitation 2DRF Excitation Profile Reduced FOV Before SENSE+UNFOLD After enhanced reconstruction 8 times acceleration Reconstructed phase image Heating Result (20w for 60sec)
LSDI with SENSE LSDI with 2x acceleration a b c d b-factor=750s/mm2 b-factor=5s/mm2 a,b: LSDI images before SENSE reconstruction; c,d: LSDI images after SENSE reconstruction
Real-time Imaging Fiesta Fast Imaging Library Fiesta fast gradient echo EPI 2DRF Excitation Library Fiesta gradient echo and fast gradient echo single-shot fast spin-echo EPI Sequences using Toolbox
Implementation of 3 libraries for enhanced imaging. Implementations tested using libraries for several sequences and applications. Library for fast imaging recon is well debugged and available for dissemination. Other 2 libraries may still require more hand holding. Please contact us to discuss using these libraries to build IGT applications Real-time imaging: zientara@bwh.harvard.edu Fast imaging: bruno@bwh.harvard.edu 2DRF excitation: panych@bwh.harvard.edu Summary