Aortic Hemodynamics with Accelerated Dual-Venc 4D Flow MRI in Type B Aortic Dissection

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Biomedical Engineering

Background:

• Type B aortic dissection (TBAD) presents complex hemodynamic challenges.
• Accurate quantification of blood flow is crucial for managing TBAD.
• Limitations exist in current 4D flow MRI techniques for TBAD assessment.

Purpose of the Study:

• To evaluate the applicability of dual-venc (DV) 4D flow MRI for quantifying complex flow patterns in TBAD.
• To compare compressed-sensing (CS) accelerated DV 4D flow MRI with single-venc (SV) MRI for reproducibility and parameter accuracy.
• To assess the impact of high-venc (HV) data within DV acquisition on hemodynamic parameters.

Main Methods:

• Utilized GRAPPA-accelerated SV and CS-accelerated DV 4D flow MRI sequences in 12 TBAD patients and 2 volunteers.
• Performed serial scans for reproducibility assessment.
• Calculated voxelwise parameters: kinetic energy (KE), peak velocity (PV), forward/reverse flow (FF, RF), and stasis. Analyzed HV data separately.

Main Results:

• CS-accelerated DV 4D flow MRI reduced scan time by 46.4% compared to SV.
• DV acquisition showed higher velocity-to-noise ratio (VNR) than HV (p=0.000).
• False lumen (FL) reverse flow (RF) was higher in SV vs. DV (p=0.009). HV acquisition showed higher KE and lower stasis in FL compared to SV and DV (p<0.05).
• High agreement observed between acquisition types for true lumen (TL) parameters and most FL parameters, except HV RF in FL (moderate agreement).

Conclusions:

• CS-accelerated DV 4D flow MRI demonstrates clinical utility in TBAD with shortened scan times and enhanced velocity measurements.
• The technique provides high VNR, aiding in accurate hemodynamic assessment.
• While hemodynamic trends are similar, CS-accelerated HV protocols impact FL parameters, potentially due to regularization effects.