“…Recent advances in high-resolution ultrasound (Bonnet et al, 1999;Brackley et al, 2000;Cohen, 2001;Denkhaus et al, 1979;Hamar et al, 2006;Hecher et al, 1995;Tworetzky et al, 2001) and fetal cardiac MRI (Coakley, 2001;Fogel, 2006;Fogel et al, 2005;Hubbard et al, 1999;Liu et al, 2001) have demonstrated that aortic arch hemodynamics (Lenz et al, 2006) and great vessel anatomy (Axt-Fliedner et al, 2006;Hubbard et al, 1999) correlate with the prognosis of patients with complex CHD, However, fetal cardiac imaging modalities have practical limitations. Fetal echocardiography is often not a true 4D modality, has limited field-of-view, and is constrained by acoustic maternal and fetal windows.…”