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NCIGT Project Week Fast Imaging Library

NCIGT Project Week Fast Imaging Library. W. Scott Hoge and Bruno Madore. Overview. Fast Imaging: reconstruct MR images from limited data MR applications limited by time Reduce data aquired == reduce acquisition time Can be used to increase spatial resolution, temporal resolution,

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NCIGT Project Week Fast Imaging Library

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  1. NCIGT Project WeekFast Imaging Library W. Scott Hoge and Bruno Madore

  2. Overview • Fast Imaging: reconstruct MR images from limited data • MR applications limited by time • Reduce data aquired == reduce acquisition time • Can be used to increase spatial resolution, temporal resolution, or both. • Aims to ‘fill the gaps’ left by scanner manufacturers • Library currently supports: • Parallel MR Imaging (SENSE, GRAPPA, …) • Temporal Processing (UNFOLD) • plus additional utility functions (Partial Fourier, DICOM, …) • Linux, Windows, and Mac distributions available • Link from stand-alone C/C++ applications or call from Matlab scripts

  3. Library Functions: Parallel Imaging • pMRI: Parallel MR Imaging employs spatial encoding to complement Fourier encoding and reduce image data requirements. • SENSE and GRAPPA are widely known variants • Library supports: • Variable-density sampling • Sophisticated regularization • 2D and 3D acquisitions

  4. Library Functions: UNFOLD • Temporal encoding can “tag” acquisition artifacts • One can then suppress the artifacts by applying temporal filters to an image series. • Library provides both time domain and frequency domain Fermi filters for UNFOLD

  5. Library Functions: Utility Routines • Partial Fourier reconstruction (homodyne) • Basic building blocks • FFT, SVD, Conjugate Gradient, LSQR • Magnetic field corrections (GradWarp) • Basic DICOM reader/editor/writer

  6. Applications • A wide variety of applications have been supported to date: • Accelerated Cardiac Perfusion CINE • Real-time cardiac imaging • Accelerated temperature monitoring • Real-time self-calibrated EPI • Accelerated PROPELLER EPI for perfusion imaging

  7. App: Cardiac Perfusion • Utilizing library building blocks, one can mix-and-match algorithms for best image quality Credit: B. Madore UNFOLD + GRAPPA (lo) + SPACE RIP (mid) UNFOLD + SPACE RIP (lo) + SPACE RIP (mid) UNFOLD + GRAPPA (lo) + GRAPPA (mid) 3.5x acceleration, 8 channel cardiac coil, 1.5T, SSFP sequence

  8. App: Real-time Cardiac Tracking Credit: E. Samset, R. Chu • 3.2x acceleration, 128x128, 8 channel coil, SSFP • Completely self-referenced • 6 images/sec with 1 frame of latency

  9. Water tank Transducer Focus of Heating 1/8 FOV Gel Phantom Phase direction Phantom after 2DRF Excitation 2DRF Excitation Profile 4.3 msec RF pulse Reduced FOV Before SENSE+UNFOLD After enhanced reconstruction 8 times acceleration Heating Result (20w for 60sec) Reconstructed phase image App: Temperature Monitoring • 8x acceleration using 2DRF, SENSE+UNFOLD Credit: C-S Mei, J. Yuan, N. McDannold, L. Panych, B. Madore

  10. App: Real-time self-cal EPI • Phase-labeling w/ UNFOLD for Nyquist ghost correction • 3.2x acceleration, 128x128, SS-GE-EPI, 1.5T • Completely self-referenced with low latency Credit: H.Tan, B. Kraft (WFU) 1x: 3.2x: note Reduced Distortion

  11. App: PROPELLER EPI for Perfusion • 2007: before collaboration No parallel imaging Blade dimension = 32 x 128 Number of blades = 64 2009: with Fast Imaging Library Acceleration factor = 2x, GRAPPA Blade dimension = 96 x 128 Number of blades = 64 with distortion correction. Credit: H.Tan, B. Kraft (WFU)

  12. What’s in the Package? • Linkable binary library file • Documentation (via Doxygen) • Quick Start Guide • Function Reference Manual • Demos • Matlab MEX functions w/ test data • C/C++ demos: FFT, data I/O, DICOM tag editing

  13. Quick Setup Example • Download from http://www.ncigt.org/pages/Downloads “Imaging Toolkit” • Unzip into working directory • Start Matlab • Build MEX files • Run Matlab demo scripts

  14. Acknowledgements • Funding provided by NCIGT NIH U41 RR019703-01A2 (PI:Jolesz) • For more information: ncigt-imaging-toolkit@bwh.harvard.edu or shoge@bwh.harvard.edu

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