Physics Just the Basics Series #10 - Making SENSE (and GRAPPA) of Parallel Imaging-Webinar

Video Transcription

Video Summary

The webinar, hosted by the Society for Cardiovascular Magnetic Resonance, introduced the basics of parallel imaging in cardiac MRI, with a focus on SENSE and GRAPPA. Dan Knight opened by explaining the purpose of the session: to make MRI physics more accessible for clinicians and trainees, especially those working with rapid cardiac imaging. He introduced Dr. Nicole Seibellich, who then delivered the lecture.<br /><br />Dr. Seibellich first reviewed essential MRI concepts such as field of view, spatial resolution, temporal resolution, k-space, and the Fourier transform. She explained why cardiac MRI is challenging: fast heart motion and the need for short breath-holds require much faster acquisition than standard MRI allows. She showed how reducing k-space sampling can speed scans but causes aliasing or loss of resolution.<br /><br />Parallel imaging was presented as the solution, using multiple receiver coils to accelerate imaging while preserving image contrast. She explained that SENSE reconstructs images in the image domain using coil sensitivity maps, while GRAPPA reconstructs missing k-space lines before the Fourier transform using calibration data. Both methods can fail if acceleration is too high or if coil sensitivity information is inaccurate, and both reduce signal-to-noise ratio through g-factor noise enhancement.<br /><br />She also discussed practical issues such as aliasing artifacts, coil placement, and the need for calibration scans. Finally, she highlighted emerging developments including non-Cartesian imaging, simultaneous multi-slice imaging, and compressed sensing, which may enable even faster, more flexible cardiac MRI in the future.

Keywords

cardiac MRI

parallel imaging

SENSE

GRAPPA

k-space

aliasing

coil sensitivity

Fourier transform

g-factor noise

compressed sensing