Improved Luminal Visualization of Flow Diverters after Deployment Using Non-Contrast-Enhanced 3D-TOF-MRA: A...

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Neuroradiology

Background:

• Accurate luminal evaluation of flow diverters (FDs) is crucial for assessing treatment efficacy in cerebrovascular diseases.
• Non-contrast enhanced 3D time-of-flight MRA (3D-TOF-MRA) is a valuable tool, but its accuracy in visualizing FDs requires optimization.

Purpose of the Study:

• To enhance the accuracy of luminal evaluation for flow diverters (FDs) using non-contrast-enhanced 3D-TOF-MRA.
• To investigate the impact of varying acquisition parameters on the visualization of FDs.

Main Methods:

• Flow diverters (FRED and Pipeline) were tested in phantom vessels under steady flow conditions.
• Non-contrast-enhanced 3D-TOF-MRA images were acquired with varied echo time (TE), flip angle (FA), and Tilted Optimized Non-Saturating Excitation (TONE) ramp settings.
• Relative in-stent signal (RIS) and lumen area ratio were analyzed, alongside the saturation ratio.

Main Results:

• Relative in-stent signal (RIS) and lumen area ratio decreased with increasing echo time (TE) for both FRED and Pipeline.
• FRED generally showed higher RIS and area ratio values compared to Pipeline.
• Optimal flip angle (FA) for peak RIS was observed at 35°, and a TONE ramp setting of 30% yielded the saturation ratio closest to 100%.

Conclusions:

• Optimizing 3D-TOF-MRA acquisition parameters, specifically TE, FA, and TONE ramp settings, can significantly improve the luminal visualization of flow diverters.
• These optimized parameters enhance the accuracy of evaluating FD performance and patient outcomes.