Gradient-echo-train-based sub-millisecond periodic event encoded dynamic imaging with random (k, t)-space...

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging
• Cardiovascular Imaging

Background:

• Sub-millisecond Periodic Event Encoded Dynamic Imaging (get-SPEEDI) offers exceptional temporal resolution for physiological activities.
• Long scan times limit the clinical utility of conventional get-SPEEDI.
• There is a need for accelerated get-SPEEDI techniques to improve efficiency.

Purpose of the Study:

• To develop an efficient variant of get-SPEEDI to reduce scan time.
• To maintain ultrahigh temporal resolution and image quality in the accelerated sequence.
• To enable broader clinical adoption of SPEEDI techniques.

Main Methods:

• Introduced k-t get-SPEEDI, a novel pulse sequence accelerating get-SPEEDI acquisition.
• Employed semi-random undersampling of k-space phase-encoding lines.
• Reconstructed dynamic image series using joint partial separability and sparsity constraints.

Main Results:

• k-t get-SPEEDI achieved a 2-fold reduction in scan time (from ~6 to ~3 minutes).
• Comparable Signal-to-Noise Ratios (SNRs) and Contrast-to-Noise Ratios (CNRs) were maintained.
• High correlation (0.86) was observed in aortic valve area time courses between k-t get-SPEEDI and conventional get-SPEEDI.

Conclusions:

• The k-t get-SPEEDI pulse sequence effectively halves scan time.
• Image quality and ultrahigh temporal resolution are preserved.
• This acceleration facilitates potential in vivo applications of SPEEDI techniques.