Non-physiological Aortic Flow and Aortopathy in Adult Patients with Transposition of the Great Arteries after the Jatene Procedure: A Pilot Study Using Echo Planar 4D Flow MRI

Abstract

Purpose Dilated aortic root and ascending aorta (AAO) with progressive aortic regurgitation is a well-known sequela after arterial switch operation (ASO) in adults with transposition of the great arteries (TGA). We aimed to quantitatively assess aortic flow profiles in adults with TGA after ASO (Jatene procedure with LeCompte maneuver) using echo planar imaging (EPI) 4D flow MRI. Methods Prospectively, 9 consecutive adults (30.2 ± 6.6 years) after ASO (Jatene operation with LeCompte technique), 13 consecutive adults (34.3 ± 7.2 years) after the atrial switch operation with Senning procedure, and 8 age-matched control patients, who underwent turbo field echo (TFE) EPI 4D flow MRI (average scan time of approximately 4 min), were enrolled. Results TGA after ASO showed a markedly dilated sinus of Valsalva, compared to TGA after atrial switch operation (26.6. ± 4.9 vs. 18.6. ± 1.5 mm/cm 2 ). Vorticity, helicity, wall share stress (WSS), and energy loss (EL) in the aortic root and the AAO in TGA were greater than in the controls. Vorticity, helicity, WSS, and EL in the aortic root and the AAO were also greater in TGA after ASO than after atrial switch operation. More acute aortic arch angle correlated with greater vorticity of the aortic root, and the significant diameter ratio of the sinus of Valsalva and the AAO was relevant to greater vorticity, helicity, and EL in TGA after ASO. Conclusion A non-physiological blood flow pattern of the aortic root was identified in TGA adults after the ASO (Jatene procedure with LeCompte maneuver). Missing spiral looping of the great arteries and the unique structure after the Jatene procedure may play an adjunctive role in promoting aortopathy. The evaluation of aortic flow profile using EPI 4D flow MRI may be useful for risk stratification for aortopathy in this population.

Clinical Applications of 4D Flow MR Imaging in Aortic Valvular and Congenital Heart Disease

“…6 In contrast, 4D flow MRI utilizes longer acquisition times, which requires respiratory gating. Due to recent advances such as faster acquisition and reconstruction with compressed sensing, echo planar imaging (EPI) or k-t acceleration method, [7][8][9] 4D flow MRI can now be used in more clinical settings. 10 techniques based on compressed sensing have helped to decrease the 4D flow scan time in the thoracic aorta by up to approximately 5 min.…”

“…40,41 In patients with transposition of the great arteries adults after the Jatene procedure with LeCompte maneuver, the evaluation of non-physiological blood flow pattern of the aortic root with 4D flow MRI may be useful for risk stratification for aprotic root dilatation. 8…”

Technical Background for 4D Flow MR Imaging

“…EPI reduces imaging time and may ensure quality by reducing motion-related artifacts, such as breathing, due to the fast data sampling. [38][39][40] However, when using large EPI factors, caution should be exercised as phase shifts during data acquisition may cause velocity shifts and resolution loss. 41…”

Why 4D Flow MRI? Real Advantages

“…With the advent of 4D Flow MRI, the imaging time was significantly shortened to around 10 min; however, the current clinical environment requires an even shorter imaging time. The imaging time can be further shortened to a few minutes by using recent cutting-edge technologies such as echoplanar imaging 22,23 and sparse imaging. 24,25 Optimization of velocity encoding Currently, there is only one velocity encoding (VENC) that can be applied in a single session of the scan; hence, the actual flow velocity may often exceed this value.…”