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Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI.

ABSTRACT: Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry.We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan geometry.Four-dimensional flow MRI was acquired in 10 Fontan patients (age: 16?±?4 years [mean?±?standard deviation], range: 9-21 years). The Fontan connection was isolated by 3-D segmentation to evaluate flow distribution from the inferior vena cava (IVC) and superior vena cava (SVC) to the left and right pulmonary arteries (LPA, RPA) and to characterize geometry (cross-sectional area, caval offset, vessel angle).Flow distribution results indicated SVC flow tended toward the RPA while IVC flow was more evenly distributed (SVC to RPA: 78%?±?28 [9-100], IVC to LPA: 54%?±?28 [4-98]). There was a significant relationship between pulmonary artery cross-sectional area and flow distribution (IVC to RPA: R(2)=0.50, P=0.02; SVC to LPA: R(2)=0.81, P=0.0004). Good agreement was found between observers and for flow distribution when compared to net flow values.Four-dimensional flow MRI was able to detect relationships between flow distribution and vessel geometry. Future studies are warranted to investigate the potential of patient specific hemodynamic analysis to improve diagnostic capability.

SUBMITTER: Jarvis K

PROVIDER: S-EPMC5039076 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI.

Jarvis Kelly K Schnell Susanne S Barker Alex J AJ Garcia Julio J Lorenz Ramona R Rose Michael M Chowdhary Varun V Carr James J Robinson Joshua D JD Rigsby Cynthia K CK Markl Michael M

Pediatric radiology 20160627 11

<h4>Background</h4>Asymmetrical caval to pulmonary blood flow is suspected to cause complications in patients with Fontan circulation. The aim of this study was to test the feasibility of 4-D flow MRI for characterizing the relationship between 3-D blood flow distribution and vascular geometry.<h4>Objective</h4>We hypothesized that both flow distribution and geometry can be calculated with low interobserver variability and will detect a direct relationship between flow distribution and Fontan ge ...[more]

PMID: 27350377

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Project description:BackgroundPulmonary vascular disease, pulmonary endothelial dysfunction, liver fibrosis, renal disease, and exercise intolerance are common in adults with Fontan physiology. Although the pathophysiologic mechanisms linking these phenomena have been studied, certain aspects are not well understood.ObjectivesThis study hypothesized that impaired pulmonary vascular reserve (VR) plays a central role linking these abnormalities, and that patients with abnormal pulmonary VR with exercise, compared with patients with normal VR, would display poorer pulmonary endothelial function, greater liver stiffness, more renal dysfunction, and poorer exercise capacity.MethodsSymptomatic adults with the Fontan palliation (n = 29) underwent invasive cardiopulmonary exercise testing, echocardiography, and assessment of microvascular function. Abnormal pulmonary VR was defined by the slope of increase in pulmonary pressure relative to cardiac output with exercise >3 mm Hg/l/min. Pulmonary endothelial function was assessed using reactive hyperemia index. End-organ function was assessed using magnetic resonance elastography-derived liver stiffness, glomerular filtration rate, N-terminal pro-B-type natriuretic peptide, and peak oxygen consumption (Vo2).ResultsCompared with individuals with normal VR (n = 8), those with abnormal VR (n = 21) displayed higher central and pulmonary venous pressures, and more severely impaired cardiac output and stroke volume responses to exertion, but similar pulmonary vascular resistance at rest. Patients with abnormal VR displayed more severely impaired reactive hyperemia index, increased liver stiffness, lower glomerular filtration rate, higher N-terminal pro-B-type natriuretic peptide, and lower peak Vo2. As compared to pulmonary vascular resistance at rest, slope of increase in pulmonary pressure relative to cardiac output displayed stronger correlations with reactive hyperemia index (r = -0.63 vs. r = -0.31; Meng test p = 0.009), magnetic resonance elastography-derived liver stiffness (r = 0.47 vs. r = 0.29; Meng test p = 0.07), glomerular filtration rate (r = -0.52 vs. r = -0.24; Meng test p = 0.03), N-terminal pro-B-type natriuretic peptide (r = 0.56 vs. r = 0.17; Meng test p = 0.02), and peak Vo2 (r = -0.63 vs. r = -0.26; Meng test p = 0.02).ConclusionsPulmonary vascular limitations in Fontan physiology are related to pulmonary endothelial and end-organ dysfunction, suggesting a mechanistic link between these commonly observed findings, and these abnormalities are more apparent during exercise testing, with little relationship at rest.

Project description:BackgroundCerebral arteriovenous malformations (AVMs) are pathological connections between arteries and veins. Dual-venc 4D flow MRI, an extended 4D flow MRI method with improved velocity dynamic range, provides time-resolved 3D cerebral hemodynamics.PurposeTo optimize dual-venc 4D flow imaging parameters for AVM; to assess the relationship between spatial resolution, acceleration, and flow quantification accuracy; and to introduce and apply the flow distribution network graph (FDNG) paradigm for storing and analyzing complex neurovascular 4D flow data.Study typeRetrospective cohort study.Subjects/phantomScans were performed in a specialized flow phantom: 26 healthy subjects (age 41 ± 17 years) and five AVM patients (age 27-68 years).Field strength/sequenceDual-venc 4D flow with varying spatial resolution and acceleration factors were performed at 3T field strength.AssessmentQuantification accuracy was assessed in vitro by direct comparison to measured flow. FDNGs were used to quantify and compare flow, peak velocity (PV), and pulsatility index (PI) between healthy controls with various Circle of Willis (CoW) anatomy and AVM patients.Statistical testsIn vitro measurements were compared to ground truth with Student's t-test. In vivo groups were compared with Wilcoxon rank-sum test and Kruskal-Wallis test.ResultsFlow was overestimated in all in vitro experiments, by an average 7.1 ± 1.4% for all measurement conditions. Error in flow measurement was significantly correlated with number of voxels across the channel (P = 3.11 × 10-28 ) but not with acceleration factor (P = 0.74). For the venous-arterial PV and PI ratios, a significant difference was found between AVM nidal and extranidal circulation (P = 0.008 and 0.05, respectively), and between AVM nidal and healthy control circulation (P = 0.005 and 0.003, respectively).Data conclusionDual-venc 4D flow MRI and standardized FDNG analysis might be feasible in clinical applications. Venous-arterial ratios of PV and PI are proposed as network-based biomarkers characterizing AVM nidal hemodynamics.Level of evidence3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1718-1730.

Dataset Information

Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI.

Publications

Evaluation of blood flow distribution asymmetry and vascular geometry in patients with Fontan circulation using 4-D flow MRI.

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