Vascular and plaque imaging with ultrasmall superparamagnetic particles of iron oxide

Cardiovascular Magnetic Resonance (CMR) has become a primary tool for non-invasive assessment of cardiovascular anatomy, pathology and function. Existing contrast agents have been utilised for the identification of infarction, fibrosis, perfusion deficits and for angiography. Novel ultrasmall superparamagnetic particles of iron oxide (USPIO) contrast agents that are taken up by inflammatory cells can detect cellular inflammation non-invasively using CMR, potentially aiding the diagnosis of inflammatory medical conditions, guiding their treatment and giving insight into their pathophysiology. In this review we describe the utilization of USPIO as a novel contrast agent in vascular disease

Differential flow improvements after valve replacements in bicuspid aortic valve disease: a cardiovascular magnetic resonance assessment

Background Abnormal aortic flow patterns in bicuspid aortic valve disease (BAV) may be partly responsible for the associated aortic dilation. Aortic valve replacement (AVR) may normalize flow patterns and potentially slow the concomitant aortic dilation. We therefore sought to examine differences in flow patterns post AVR. Methods Ninety participants underwent 4D flow cardiovascular magnetic resonance: 30 BAV patients with prior AVR (11 mechanical, 10 bioprosthetic, 9 Ross procedure), 30 BAV patients with a native aortic valve and 30 healthy subjects. Results The majority of subjects with mechanical AVR or Ross showed normal flow pattern (73% and 67% respectively) with near normal rotational flow values (7.2 ± 3.9 and 10.6 ± 10.5 mm2/ms respectively vs 3.8 ± 3.1 mm2/s for healthy subjects; both p > 0.05); and reduced in-plane wall shear stress (0.19 ± 0.13 N/m2for mechanical AVR vs. 0.40 ± 0.28 N/m2 for native BAV, p  0.05), and a similar pattern for wall shear stress. Data before and after AVR (n = 16) supported these findings: mechanical AVR showed a significant reduction in rotational flow (30.4 ± 16.3 → 7.3 ± 4.1 mm2/ms; p < 0.05) and in-plane wall shear stress (0.47 ± 0.20 → 0.20 ± 0.13 N/m2; p < 0.05), whereas these parameters remained similar in the bioprosthetic AVR group. Conclusions Abnormal flow patterns in BAV disease tend to normalize after mechanical AVR or Ross procedure, in contrast to the remnant abnormal flow pattern after bioprosthetic AVR. This may in part explain different aortic growth rates post AVR in BAV observed in the literature, but requires confirmation in a prospective study

Vascular blood flow reconstruction from tomographic projections with the ajoint method and receding optimal control strategy

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Vascular blood flow reconstruction from tomographic projections with the adjoint method and receding optimal control strategy

International audienceIn this work, we study the measurement of blood velocity with contrast enhanced computed tomography. The inverse problem is formulated as an optimal control problem with the transport equation as constraint. The velocity field is reconstructed with a receding optimal control strategy and the adjoint method. The convergence of the method is fast

Vascular blood flow reconstruction with contrast-enhanced computerized tomography

International audienceIn this work, we study the measurement of blood velocity with contrast-enhanced computed tomography. The transport equation is used as a constraint to obtain stable solutions. The inverse problem is formulated as an optimal control problem. The density of the contrast agent is reconstructed together with the flow field. The existence of a minimizer of the regularization functional and a local unicity are demonstrated. The inversion scheme is tested on a simple numerical phantom

Contrast enhanced tomographic reconstruction of vascular blood flow based on the Navier-Stokes equation.

International audienceIn this work, we study the reconstruction of blood velocity with contrast enhanced computed tomography with tomographic projections perpendicular to the main flow field direction. The inverse problem is regularized with a convection-diffusion partial differential equation and with the Navier-Stokes equation. The velocity field is reconstructed together with the density field with a first-order adjoint method. The method is validated on a simple phantom. The addition of a physical constraint with a partial differential equation for the velocity field improves the reconstruction results