Improved vessel-tissue contrast and image quality in 3D radial sampling-based 4D-MRI

Area of Science:

• Medical Imaging
• Radiology
• Oncology

Background:

• 4D-MRI offers improved soft-tissue contrast for respiratory motion characterization in radiation treatment planning compared to 4D-CT.
• Current 3D radial sampling-based 4D-MRI techniques can be further optimized for enhanced image quality.

Purpose of the Study:

• To improve vessel-tissue contrast and overall image quality in 3D radial sampling-based 4D-MRI.
• To evaluate a slab-selective (SS) excitation approach for enhanced 4D-MRI in radiation treatment planning.

Main Methods:

• Implemented a 3D radial sampling with self-gating k-space sorting sequence incorporating SS excitation.
• Compared SS-4D-MRI with non-selective (NS) 4D-MRI in six cancer patients and two healthy volunteers at 3T.
• Analyzed vessel-tissue contrast ratio (CR), vessel signal-to-noise ratio (SNR), and visual image quality; assessed motion trajectories.

Main Results:

• SS-4D-MRI significantly improved vessel-tissue CR (2.60 ± 3.97 vs. 1.03 ± 1.44, P < 0.05) and SNR (63.33 ± 38.45 vs. 35.74 ± 28.59, P < 0.05) compared to NS-4D-MRI.
• Visual image quality scores were significantly higher for SS-4D-MRI (2.6 ± 0.5 vs. 1.4 ± 0.5, P = 0.02).
• Motion trajectories showed strong correlation in superior-inferior but weaker in anterior-posterior and medial-lateral directions.

Conclusions:

• The proposed slab-selective 4D-MRI technique enhances blood SNR, vessel-tissue CR, and overall image quality.
• This method shows promise for improving respiratory motion characterization in radiation treatment planning for thoracic and abdominal tumors.