Fat Suppression in Distal Extremity 3-T MRI Using Spectral Heterogeneity Adaptive Radiofrequency Pulses.

Area of Science:

• Radiology
• Medical Imaging
• Magnetic Resonance Imaging

Background:

• Conventional chemical shift selective (CHESS) fat suppression is often unreliable in distal extremities due to magnetic field inhomogeneities.
• This limitation impacts diagnostic accuracy in MRI of the ankle, foot, and hand.

Purpose of the Study:

• To develop and evaluate a patient-specific fat-suppression technique, Spectral Heterogeneity Adaptive Radiofrequency Pulse (SHARP), for 3-T MRI of distal extremities.
• To compare the efficacy of SHARP against the standard CHESS technique.

Main Methods:

• SHARP utilizes the MRI calibration frequency spectrum to adapt fat-suppression pulse parameters.
• Prospective study involving numerical simulations, phantom experiments, and MRI in 15 asymptomatic participants (ankle, foot, hand).
• Comparison with CHESS and reference techniques (Dixon, short-tau inversion recovery), with reader-based homogeneity ranking.

Main Results:

• Numerical simulations showed SHARP achieved 62%-70% fat suppression with 0% water suppression, outperforming CHESS (57% fat, 2% water).
• Phantom studies indicated lower inhomogeneity with SHARP (2.4%) and Dixon (1.0%) compared to CHESS (10.7%).
• In vivo, SHARP demonstrated significantly more homogeneous fat suppression than CHESS across all evaluated distal extremity joints (P < .001).

Conclusions:

• SHARP provides more homogeneous fat suppression than CHESS in distal extremity 3-T MRI.
• The SHARP technique offers a valuable, patient-specific alternative for improving MRI quality in challenging anatomical regions.