Technologist Track Session 1: CMR Technical Methods (2019)-Parallel Imaging

Video Transcription

Video Summary

The speaker explains parallel imaging in cardiac MRI, focusing on how SENSE and GRAPPA accelerate scans by undersampling k-space. Because the heart moves quickly and MRI is slow, skipping lines of data helps shorten acquisition time, but causes wraparound artifacts. SENSE removes aliasing in image space using a coil sensitivity map acquired at the start of the exam, then solves equations to unwrap folded anatomy. GRAPPA removes aliasing in k-space by using a fully sampled autocalibration region to estimate missing data before Fourier transforming. Both methods rely on phased array coils and their differing sensitivities. The talk also discusses common artifacts, such as noise amplification and motion-related errors, especially when coil maps or calibration data no longer match the patient’s position. In cardiac imaging, GRAPPA is often preferred because it is more tolerant of motion and small fields of view. Parallel imaging is contrasted with compressed sensing, which uses random undersampling and different reconstruction methods.

Keywords

parallel imaging

cardiac MRI

SENSE

GRAPPA

undersampling k-space