3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;47:487-498.

BackgroundBlood flow dynamics make it possible to better understand the development of aortopathy and cardiovascular events in patients with Marfan syndrome (MFS). Aortic 3D blood flow characteristics were investigated in relation to aortic geometry in children and adolescents with MFS.MethodsTwenty-five MFS patients (age 15.6 ± 4.0 years; 11 females) and 21 healthy controls (age 16.0 ± 2.6 years; 12 females) underwent magnetic resonance angiography and 4D flow CMR for assessment of thoracic aortic size and 3D blood flow velocities. Data analysis included calculation of aortic diameter and BSA-indexed aortic dimensions (Z-score) along the thoracic aorta, 3D mean systolic wall shear stress (WSSmean) in ten aortic segments and assessment of aortic blood flow patterns.ResultsAortic root (root), ascending (AAo) and descending (DAo) aortic size was significantly larger in MFS patients than healthy controls (Root Z-score: 3.56 ± 1.45 vs 0.49 ± 0.78, p < 0.001; AAo Z-score 0.21 ± 0.95 vs −0.54 ± 0.64, p = 0.004; proximal DAo Z-score 2.02 ± 1.60 vs 0.56 ± 0.66, p < 0.001). A regional variation in prevalence and severity of flow patterns (vortex and helix flow patterns) was observed, with the aortic root and the proximal DAo (pDAo) being more frequently affected in MFS. MFS patients had significantly reduced WSSmean in the proximal AAo (pAAo) outer segment (0.65 ± 0.12 vs. 0.73 ± 0.14 Pa, p = 0.029) and pDAo inner segment (0.74 ± 0.17 vs. 0.87 ± 0.21 Pa, p = 0.021), as well as higher WSSmean in the inner segment of the distal AAo (0.94 ± 0.14 vs. 0.84 ± 0.15 Pa, p = 0.036) compared to healthy subjects. An inverse relationship existed between pDAo WSSmean and both pDAo diameter (R = −0.53, p < 0.001) and % diameter change along the pDAo segment (R = −0.64, p < 0.001).ConclusionsMFS children and young adults have altered aortic flow patterns and differences in aortic WSS that were most pronounced in the pAAo and pDAo, segments where aortic dissection or rupture often originate. The presence of vortex flow patterns and abnormal WSS correlated with regional size of the pDAo and are potentially valuable additional markers of disease severity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-017-0345-7) contains supplementary material, which is available to authorized users.

PurposeTo evaluate the in‐scan and scan–rescan consistency of left ventricular (LV) in‐ and outflow assessment from 1) 2D planimetry; 2) 4D flow magnetic resonance imaging (MRI) with retrospective valve tracking, and 3) 4D flow MRI with particle tracing.Materials and MethodsTen healthy volunteers (age 27 ± 3 years) underwent multislice cine short‐axis planimetry and whole‐heart 4D flow MRI on a 3T MRI scanner twice with repositioning between the scans. LV in‐ and outflow was compared from 1) 2D planimetry; 2) 4D flow MRI with retrospective valve tracking over the mitral valve (MV) and aortic valve (AV), and 3) 4D flow MRI with particle tracing through forward and backward integration of velocity data.ResultsIn‐scan consistency between MV and AV flow volumes is excellent for both 4D flow MRI methods with r ≥ 0.95 (P ≤ 0.001). In‐scan AV and MV flow by retrospective valve tracking shows good to excellent correlations versus AV and MV flow by particle tracing (r ≥ 0.81, P ≤ 0.004). Scan–rescan SV assessment by 2D planimetry shows excellent reproducibility (intraclass correlation [ICC] = 0.98, P < 0.001, coefficient of variation [CV] = 7%). Scan–rescan MV and AV flow volume assessment by retrospective valve tracking shows strong reproducibility (ICCs ≥ 0.89, P ≤ 0.05, CVs = 12%), as well as by forward and backward particle tracing (ICCs ≥ 0.90, P ≤ 0.001, CVs ≤ 11%). Multicomponent particle tracing shows good scan–rescan reproducibility (ICCs ≥ 0.81, P ≤ 0.007, CVs ≤ 16%).ConclusionLV in‐ and outflow assessment by 2D planimetry and 4D flow MRI with retrospective valve tracking and particle tracing show good in‐scan consistency and strong scan–rescan reproducibility, which indicates that both 4D flow MRI methods are reliable and can be used clinically. Level of Evidence: 2 Technical Efficacy Stage: 2J. Magn. Reson. Imaging 2018;47:511–522.

ObjectiveTo study neo-aortic growth and the evolution of neo-aortic valve regurgitation (AR) in patients with transposition of the great arteries (TGA) after arterial switch operation (ASO) from newborn to adulthood and to identify patients at risk.MethodsNeo-aortic dimensions (annulus/root/sinotubular junction) and neo-aortic valve regurgitation were assessed serially in 345 patients with TGA who underwent ASO between 1977 and 2015. Linear mixed-effect models were used to assess increase of neo-aortic dimensions over time and to identify risk factors for dilatation. Risk factor analysis for AR by using time-dependent Cox regression models.ResultsAfter a rapid increase in the first year after ASO and proportional growth in childhood, neo-aortic dimensions continue to increase in adulthood without stabilisation. Annual diameter increase in adulthood was 0.39±0.06, 0.63±0.09 and 0.54±0.11 mm for, respectively, neo-aortic annulus, root and sinotubular junction, all significantly exceeding normal growth. AR continues to develop over time: freedom from AR ≥moderate during the first 25 years post-ASO was 69%. Risk factors for root dilatation were complex TGA anatomy (TGA-ventricular septal defect (VSD), double outlet right ventricle with subpulmonary VSD) and male gender. Risk factors for AR ≥moderate were: complex TGA anatomy and neo-aortic growth. Per millimetre increase in aortic root dimension, there was a 9% increase in the hazard of AR ≥moderate. Bicuspid pulmonary valve did not relate to the presence of root dilatation or AR.ConclusionAfter ASO, neo-aortic dilatation proceeds beyond childhood and is associated with an increase in AR incidence over time. Careful follow-up of the neo-aortic valve and root function is mandatory, especially in males and in patients with complex TGA anatomy.

ObjectiveThe aim was to investigate scan–rescan reproducibility and observer variability of segmental aortic 3D systolic wall shear stress (WSS) by phase-specific segmentation with 4D flow MRI in healthy volunteers.Materials and methodsTen healthy volunteers (age 26.5 ± 2.6 years) underwent aortic 4D flow MRI twice. Maximum 3D systolic WSS (WSSmax) and mean 3D systolic WSS (WSSmean) for five thoracic aortic segments over five systolic cardiac phases by phase-specific segmentations were calculated. Scan–rescan analysis and observer reproducibility analysis were performed.ResultsScan–rescan data showed overall good reproducibility for WSSmean (coefficient of variation, COV 10–15%) with moderate-to-strong intraclass correlation coefficient (ICC 0.63–0.89). The variability in WSSmax was high (COV 16–31%) with moderate-to-good ICC (0.55–0.79) for different aortic segments. Intra- and interobserver reproducibility was good-to-excellent for regional aortic WSSmax (ICC ≥ 0.78; COV ≤ 17%) and strong-to-excellent for WSSmean (ICC ≥ 0.86; COV ≤ 11%). In general, ascending aortic segments showed more WSSmax/WSSmean variability compared to aortic arch or descending aortic segments for scan–rescan, intraobserver and interobserver comparison.ConclusionsScan–rescan reproducibility was good for WSSmean and moderate for WSSmax for all thoracic aortic segments over multiple systolic phases in healthy volunteers. Intra/interobserver reproducibility for segmental WSS assessment was good-to-excellent. Variability of WSSmax is higher and should be taken into account in case of individual follow-up or in comparative rest–stress studies to avoid misinterpretation.Electronic supplementary materialThe online version of this article (10.1007/s10334-018-0688-6) contains supplementary material, which is available to authorized users.

Knowledge of normal and abnormal flow patterns in the human cardiovascular system increases our understanding of normal physiology and may help unravel the complex pathophysiological mechanisms leading to cardiovascular disease. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has emerged as a suitable technique that enables visualization of in vivo blood flow patterns and quantification of parameters that could potentially be of prognostic value in the disease process. In this review, current image processing tools that are used for comprehensive visualization and quantification of blood flow and energy distribution in the heart and great vessels will be discussed. Also, imaging biomarkers extracted from 4D flow CMR will be reviewed that have been shown to distinguish between normal and abnormal flow patterns. Furthermore, current applications of 4D flow CMR in the heart and great vessels will be discussed, showing its potential as an additional diagnostic modality which could aid in disease management and timing of surgical intervention.

Aims: To investigate the metabolic consequences of long-term GH treatment in young women with Turner syndrome (TS), several years after GH discontinuation. Methods: Follow-up study of a randomized GH dose-response trial, with 3 GH dosages (1.3, 2.0, and 2.7 mg/m²/day). Thirty-nine TS patients (20.0 ± 2.1 years) participated 4.8 ± 1.9 years after GH discontinuation. Mean GH treatment duration was 8.7 ± 2.0 years. Fasting glucose, insulin, and serum lipids were measured. Results: Several years after GH discontinuation, insulin sensitivity remained lower, while β-cell function and fasting insulin levels remained higher than before treatment. Only BMI influenced β-cell function. Serum total cholesterol (TC), low-density lipoprotein and high-density lipoprotein (HDL) had further increased compared to 6 months after GH, resulting in higher TC, but also higher HDL levels compared to controls. The atherogenic index remained constant, but lower than controls. Conclusions: Besides height, GH therapy in girls with TS has additional beneficial effects on serum lipids. Nearly 5 years after discontinuation of GH therapy the favorable effect of GH was still noticeable. The GH-induced decrease in insulin sensitivity, however, remained unchanged, possibly due to having TS.

Aims: To investigate whether long-term growth hormone (GH) treatment influenced blood pressure (BP), body proportions and BMI in young Turner syndrome (TS) women several years after GH discontinuation. Methods: A follow-up study of a randomized GH dose-response trial with 3 GH dosages (1.3, 2.0, and 2.7 mg/m²/day). 39 TS patients (20.0 ± 2.1 years) participated 4.8 (1.9) years after GH discontinuation. Mean GH duration was 8.7 (2.0) years. Measurements: BP, BMI and body proportions. Results: During GH treatment, DBP had decreased. At the long-term follow-up study, DBP had increased and was similar to pretreatment levels. DBP was negatively influenced by GH dose. SBP was not influenced by GH dose or duration. The BMI increased gradually during and after GH therapy. During GH therapy, shape values of sitting height had decreased to normal values, of foot had increased, and both remained constant after GH discontinuation. Conclusions: GH therapy in girls with TS has, besides height, additional beneficial effects on BP and body proportions, except foot length. Nearly 5 years after ending GH, the favorable effect of GH on BP was still noticeable. The BMI increased gradually over the years, not influenced by GH.