Abstract 16422: 4D Flow MRI Improves Assessment of Aortic and Pulmonary Peak Velocities in Patients With D-Transposition of Great Arteries Following Arterial Switch Operation
BACKGROUND: Pulmonary artery stenosis is the most common complication seen following the arterial switch operation (ASO) for D-transposition of the great arteries (DTGA). During follow-up, it is important to accurately detect peak velocity as an indicator of vessel narrowing. The purpose of this study was to compare peak velocity measurements by 4D flow MRI (4D flow) (with full volumetric coverage of aorta and pulmonary system) to those by standard 2D phase contrast MRI (2D PC) and Doppler echo.
METHODS: 4D flow and 2D PC were performed in n=14 subjects (age = 12.4 ± 7.6, range = 1 to 25) with DTGA s/p ASO. 3D segmentation of the aorta (Ao) and pulmonary arteries (PAs) was performed to isolate 4D flow velocities for these vessels (Figure a). The location and value of peak systolic velocity was determined inside volumes of interest for the ascending aorta (AAO), main (MPA), right (RPA) and left pulmonary arteries (LPA). RPA and LPA 2D PC data were not available in one patient. Contemporary echo data were available in 11 patients (11 AAO, 8 MPA, 6 RPA, 5 LPA).
RESULTS: Peak velocity measurements by 4D flow were significantly higher than 2D PC in all regions (AAO: 1.51±0.61m/s vs. 1.15±0.24m/s, p = 0.016; MPA: 2.08±1.11m/s vs. 1.44± 0.61m/s, p = 0.004; RPA: 2.19±0.65m/s vs. 1.79±0.81m/s, p = 0.027; LPA: 2.08±0.85m/s vs. 1.74±0.70m/s, p = 0.014). Regression results indicated strong relationships between 4D flow and 2D PC (AAO: R2 = 0.46, p = 0.008; MPA: R2 = 0.69, p = 0.0002; RPA: R2 =0.50, p = 0.007; LPA: R2 = 0.74, p = 0.0001) (Figure b). No significant difference was found between peak velocities measured by 4D flow and echo (AAO: p = 0.32, MPA: p = 0.24, RPA: p = 0.91, LPA: p = 0.36) or by 2D PC and echo (AAO: p = 0.49, MPA: p = 0.62, RPA: p = 0.35, LPA: p = 0.066).
CONCLUSION: 4D flow outperformed 2D PC for detecting peak velocity in the Ao and PAs. No significant difference was found between peak velocities measured by 4D flow and echo. Further studies are warranted in a larger patient cohort to determine clinical impact.
Author Disclosures: K. Jarvis: None. S. Schnell: None. A. Barker: None. M. Vonder: None. M. Rose: None. J. Carr: None. J.D. Robinson: None. M. Markl: None. C. Rigsby: None.
This research has received full or partial funding support from the American Heart Association.
- © 2014 by American Heart Association, Inc.