1. © NIH National Center for Image-Guided Therapy NCIGT Project Week Fast Imaging Library W. Scott Hoge and Bruno Madore

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

8. © NIH National Center for Image-Guided Therapy App: Real-time Cardiac Tracking 3.2x acceleration, 128x128, 8 channel coil, SSFP Completely self-referenced 6 images/sec with 1 frame of latency Credit: E. Samset, R. Chu

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

10. © NIH National Center for Image-Guided Therapy 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 1x:3.2x: Credit: H.Tan, B. Kraft (WFU) note Reduced Distortion

11. © NIH National Center for Image-Guided Therapy 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. © NIH National Center for Image-Guided Therapy 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. © NIH National Center for Image-Guided Therapy 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. © NIH National Center for Image-Guided Therapy 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