Four-Dimensional flow Magnetic Resonance Imaging for Assessment of Pediatric Coarctation of the Aorta

Cardiovascular diseases consequences of type 1, type 2 diabetes mellitus and glycemic traits: A Mendelian randomization study

OBJECTIVE

This Mendelian randomization (MR) study aimed to investigate the relationships between type 1 diabetes (T1D), type 2 diabetes (T2D), and glycemic traits, including fasting insulin, fasting glucose, and HbA1c, with cardiovascular diseases (CVDs).

METHODS

We selected genetic instruments for predisposition to T1D, T2D, fasting insulin, fasting glucose, and HbA1c based on published genome-wide association studies. Using a 2-Sample MR approach, we assessed associations with 12 common CVDs sourced from the FinnGen and UK Biobank studies, along with stroke subtypes obtained from the GIGASTROKE and MEGASTROKE Consortium.

RESULTS

T1D was associated with SVS. T2D showed associations with AIS, LAA, CES, SVS, coronary heart disease, myocardial infarction, pulmonary embolism, DVT of lower extremities, peripheral vascular diseases. Genetically predicted higher HbA1c levels were associated with eight CVDs. The results of MVMR aligned with the primary findings for T1D and T2D.

CONCLUSIONS

T1D and T2D exhibit different genetic predisposition to CVDs. BMI, LDL, and HDL play intermediary roles in connecting TID and T2D to specific types of CVDs, providing insights into the potential underlying pathways and mechanisms involved in these relationships. Strategies aimed at achieving sustained reductions in HbA1c levels may offer potential for reducing the risk of various CVDs.

Intraventricular haemodynamic changes caused by increased left ventricular afterload in re-coarctation of aorta: a case report

Background

Long-term re-coarctation of the aorta can cause aortic dilatation, hypertension, and cardiac dysfunction due to increased left ventricular (LV) afterload. It is difficult to detect changes in LV function due to increased afterload if the contractile force of the left ventricle is maintained. Herein, we have reported a case of re-coarctation of the aorta, for which four-dimensional (4D) flow magnetic resonance imaging (MRI) scan was obtained both before and after balloon dilatation for aortic re-coarctation. Ultimately, improvement in aortic helical flow and LV haemodynamics was observed.

Case summary

A 29-year-old female was diagnosed with coarctation of the aorta and a bicuspid aortic valve after birth and underwent surgery at 1 month. At 8 years of age, she underwent balloon dilatation for re-coarctation. At the age of 28 years, she was diagnosed with re-coarctation triggered by hypertension. She underwent balloon dilatation as her cardiac catheterization revealed a systolic pressure gradient of 40 mmHg. Pretreatment 4D flow MRI demonstrated helical flow in the ascending aorta and descending thoracic aorta and LV blood flow analysis revealed a decrease in LV kinetic energy during systole; these improved after treatment.

Discussion

The use of helical flow evaluation by 4D flow MRI for aortic re-coarctation is well known in clinical practice. However, our report is the first to evaluate intraventricular blood flow before and after the re-coarctation treatment. The MRI evaluation demonstrated that the helical flow and LV blood flow distribution improved after re-coarctation treatment due to the reduction of afterload.

Comparison of 2D and 4D Flow MRI in Neonates Without General Anesthesia

BACKGROUND

Neonates with critical congenital heart disease require early intervention. Four-dimensional (4D) flow may facilitate surgical planning and improve outcome, but accuracy and precision in neonates are unknown.

PURPOSE

To 1) validate two-dimensional (2D) and 4D flow MRI in a phantom and investigate the effect of spatial and temporal resolution; 2) investigate accuracy and precision of 4D flow and internal consistency of 2D and 4D flow in neonates; and 3) compare scan time of 4D flow to multiple 2D flows.

STUDY TYPE

Phantom and prospective patients.

POPULATION

A total of 17 neonates with surgically corrected aortic coarctation (age 18 days [IQR 11-20]) and a three-dimensional printed neonatal aorta phantom.

FIELD STRENGTH/SEQUENCE

1.5T, 2D flow and 4D flow.

ASSESSMENT

In the phantom, 2D and 4D flow volumes (ascending and descending aorta, and aortic arch vessels) with different resolutions were compared to high-resolution reference 2D flow. In neonates, 4D flow was compared to 2D flow volumes at each vessel. Internal consistency was computed as the flow volume in the ascending aorta minus the sum of flow volumes in the aortic arch vessels and descending aorta, divided by ascending aortic flow.

STATISTICAL TESTS

Bland-Altman plots, Pearson correlation coefficient (r), and Student's t-tests.

RESULTS

In the phantom, 2D flow differed by 0.01 ± 0.02 liter/min with 1.5 mm spatial resolution and -0.01 ± 0.02 liter/min with 0.8 mm resolution; 4D flow differed by -0.05 ± 0.02 liter/min with 2.4 mm spatial and 42 msec temporal resolution, -0.01 ± 0.02 liter/min with 1.5 mm, 42 msec resolution and -0.01 ± 0.02 liter/min with 1.5 mm, 21 msec resolution. In patients, 4D flow and 2D flow differed by -0.06 ± 0.08 liter/min. Internal consistency in patients was -11% ± 17% for 2D flow and 5% ± 13% for 4D flow. Scan time was 17.1 minutes [IQR 15.5-18.5] for 2D flow and 6.2 minutes [IQR 5.3-6.9] for 4D flow, P < 0.0001.

DATA CONCLUSION

Neonatal 4D flow MRI is time efficient and can be acquired with good internal consistency without contrast agents or general anesthesia, thus potentially expanding 4D flow use to the youngest and smallest patients.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Enhanced 4D Flow MRI-Based CFD with Adaptive Mesh Refinement for Flow Dynamics Assessment in Coarctation of the Aorta

4D Flow MRI is a diagnostic tool that can visualize and quantify patient-specific hemodynamics and help interventionalists optimize treatment strategies for repairing coarctation of the aorta (COA). Despite recent developments in 4D Flow MRI, shortcomings include phase-offset errors, limited spatiotemporal resolution, aliasing, inaccuracies due to slow aneurysmal flows, and distortion of images due to metallic artifact from vascular stents. To address these limitations, we developed a framework utilizing Computational Fluid Dynamics (CFD) with Adaptive Mesh Refinement (AMR) that enhances 4D Flow MRI visualization/quantification. We applied this framework to five pediatric patients with COA, providing in-vivo and in-silico datasets, pre- and post-intervention. These two data sets were compared and showed that CFD flow rates were within 9.6% of 4D Flow MRI, which is within a clinically acceptable range. CFD simulated slow aneurysmal flow, which MRI failed to capture due to high relative velocity encoding (Venc). CFD successfully predicted in-stent blood flow, which was not visible in the in-vivo data due to susceptibility artifact. AMR improved spatial resolution by factors of 101 to 103 and temporal resolution four-fold. This computational framework has strong potential to optimize visualization/quantification of aneurysmal and in-stent flows, improve spatiotemporal resolution, and assess hemodynamic efficiency post-COA treatment.