Magnetic resonance imaging 4-D flow-based analysis of aortic hemodynamics in Turner syndrome.

BACKGROUND: Cardiovascular surveillance is important in Turner syndrome because of the increased risk of aortic dilation and dissection with consecutively increased mortality. OBJECTIVE: To compare 4-D flow MRI for the characterization of aortic 3-D flow patterns, dimensions and vessel wall parameters in pediatric patients with Turner syndrome and age-matched controls. MATERIALS AND METHODS: We performed 4-D flow MRI measuring in vivo 3-D blood flow with coverage of the thoracic aorta in 25 patients with Turner syndrome and in 16 female healthy controls (age mean ± standard deviation were 16 ± 5 years and 17 ± 4 years, respectively). Blood flow was visualized by time-resolved 3-D path lines. Visual grading of aortic flow in terms of helices and vortices was performed by two independent observers. Quantitative analysis included measurement of aortic diameters, quantification of peak systolic wall shear stress, pulsatility index and oscillatory shear index at eight defined sites. RESULTS: Patients with Turner syndrome had significantly larger aortic diameters normalized to BSA, increased vortices in the ascending aorta and elevated helix flow in the ascending and descending aorta compared to controls (all P<0.03). Patients with abnormal helical or vortical flow in the ascending aorta had significantly larger diameters of the ascending aorta (P<0.03). Peak systolic wall shear stress, pulsatility index and oscillatory shear index were significantly lower in Turner patients compared to controls (p=0.02, p=0.002 and p=0.01 respectively). CONCLUSION: Four-dimensional flow MRI provides new insights into the altered aortic hemodynamics and wall shear stress that could have an impact on the development of aortic dissections.

Magnetic resonance tissue phase mapping demonstrates altered left ventricular diastolic function in children with chronic kidney disease.

BACKGROUND: Echocardiographic examinations have revealed functional cardiac abnormalities in children with chronic kidney disease. OBJECTIVE: To assess the feasibility of MRI tissue phase mapping in children and to assess regional left ventricular wall movements in children with chronic kidney disease. MATERIALS AND METHODS: Twenty pediatric patients with chronic kidney disease (before or after renal transplantation) and 12 healthy controls underwent tissue phase mapping (TPM) to quantify regional left ventricular function through myocardial long (Vz) and short-axis (Vr) velocities at all 3 levels of the left ventricle. RESULTS: Patients and controls (age: 8 years-20 years) were matched for age, height, weight, gender and heart rate. Patients had higher systolic blood pressure. No patient had left ventricular hypertrophy on MRI or diastolic dysfunction on echocardiography. Fifteen patients underwent tissue Doppler echocardiography, with normal z-scores for mitral early diastolic (VE), late diastolic (VA) and peak systolic (VS) velocities. Throughout all left ventricular levels, peak diastolic Vz and Vr (cm/s) were reduced in patients: Vzbase -10.6 ± 1.9 vs. -13.4 ± 2.0 (P < 0.0003), Vzmid -7.8 ± 1.6 vs. -11 ± 1.5 (P < 0.0001), Vzapex -3.8 ± 1.6 vs. -5.3 ± 1.6 (P = 0.01), Vrbase -4.2 ± 0.8 vs. -4.9 ± 0.7 (P = 0.01), Vrmid -4.7 ± 0.7 vs. -5.4 ± 0.7 (P = 0.01), Vrapex -4.7 ± 1.4 vs. -5.6 ± 1.1 (P = 0.05). CONCLUSION: Tissue phase mapping is feasible in children and adolescents. Children with chronic kidney disease show significantly reduced peak diastolic long- and short-axis left ventricular wall velocities, reflecting impaired early diastolic filling. Thus, tissue phase mapping detects chronic kidney disease-related functional myocardial changes before overt left ventricular hypertrophy or echocardiographic diastolic dysfunction occurs.

Left ventricular mass and systolic function in children with chronic kidney disease-comparing echocardiography with cardiac magnetic resonance imaging.

BACKGROUND: Increased left ventricular mass (LVM) is an important risk marker of uremic cardiovascular disease. Calculation of LVM by echocardiography (Echo) relies on geometric assumptions and in adults on hemodialysis overestimates LVM compared to cardiac magnetic resonance (CMR). We compare both techniques in children with chronic kidney disease (CKD). METHODS: Concurrent Echo and CMR was performed in 25 children with CKD (14 after kidney transplantation) aged 8-17 years. RESULTS: Compared to normal children, CMR-LVM was increased (standard deviation score (SDS) 0.39 ± 0.8 (p = 0.03)), stroke volume and cardiac output decreased (SDS -1.76 ± 1.1, p = 0.002 and -1.11 ± 2.0, p = 0.001). CMR-LVM index but not Echo-LVMI correlated to future glomerular filtration rate (GFR) decline (r = -0.52, p = 0.01). Mean Echo-LVM was higher than CMR-LVM (117 ± 40 vs. 89 ± 29 g, p < 0.0001), with wide limits of agreement (-6.2 to 62.8 g). The Echo-CMR LVM difference increased with higher Echo-LVMI (r = 0.77, p < 0.0001). Agreement of classifying left ventricular hypertrophy was poor with Cohen's kappa of 0.08. Mean Echo and CMR-ejection fraction differed by 1.42% with wide limits of agreement (-12.6 to 15.4%). CONCLUSIONS: Echo overestimates LVM compared to CMR, especially at higher LVM. Despite this, CMR confirms increased LVM in children with CKD. Only CMR-LVMI but not Echo-LVMI correlated to future GFR decline.

Postoperative pulmonary and aortic 3D haemodynamics in patients after repair of transposition of the great arteries.

OBJECTIVES: To characterise aortic and pulmonary haemodynamics and investigate the correlation with post-surgical anatomy in patients with dextro-transposition of the great arteries (d-TGA). METHODS: Four-dimensional (4D) MRI was performed in 17 patients after switch repair of TGA and 12 healthy controls (age, 11.9 ± 5.4 vs 23.3 ± 1.6 years). Patients were divided according to the pulmonary trunk (TP) position in relation to the ascending aorta (AAo): anterior (n = 10) and right/left anterior position (n = 7). Analysis included visual grading (ranking 0-2) of pulmonary and aortic vortical and helical flow, flow velocity quantification, blood-flow distribution to the right and left pulmonary arteries (flow ratio rPA:lPA), and vessel lumen areas. RESULTS: Anterior TP position was associated with increased vortices in six out of ten patients compared with right anterior TP position (one out of seven) and controls (none). Reduced systolic lPA and TP lumina in patients resulted in significantly increased peak systolic velocities (P < 0.001). Flow ratio rPA:lPA was more heterogeneous in patients (rPA:lPA = 1.56 ± 0.78 vs volunteers 1.09 ± 0.15; P < 0.05) with predominant flow to the rPA. Eleven patients presented increased helices in the AAo (grade 1.6). CONCLUSIONS: Evaluation of post-surgical haemodynamics in TGA patients revealed increased vortical flow for anterior TP position, asymmetric flow and increased systolic flow velocity in the pulmonary arteries owing to reduced vascular lumina. KEY POINTS: • 3D phase contrast MRI with velocity encoding (4D MRI) has numerous cardiovascular applications • 4D MRI demonstrates postoperative haemodynamics following surgery for transposition of the great arteries • Flow visualisation depicted enhanced pulmonary vortices in the anterior pulmonary trunk • Narrow pulmonary arterial systolic lumina resulted in increased peak systolic velocities.

Aortic wall shear stress in Marfan syndrome.

The aim of this study was to quantify changes in thoracic aortic wall shear stress (WSS) in asymptomatic patients with Marfan syndrome (MFS) compared with healthy controls. WSS in the thoracic aorta was quantified based on time-resolved 3D phase contrast MRI with three-directional velocity encoding (4D flow MRI, temporal resolution ∼44 ms, spatial resolution ∼2.5 mm) in 24 patients with confirmed MFS (age = 18 ± 12 years) and in 12 older healthy volunteers (age = 25 ± 3 years). Diameters of the thoracic aorta normalized to body surface area were similar for both groups. Peak systolic velocity, absolute WSS, time-averaged WSS, circumferential WSS, peak systolic WSS, and WSS eccentricity were calculated in eight analysis planes distributed along the thoracic aorta. Plane-wise comparison revealed significant differences between MFS patients and volunteers in the proximal ascending aorta for peak systolic velocities (1.11 ± 0.23 m/s vs. 1.34 ± 0.18 m/s, P = 0.004) and circumferential WSS (0.14 ± 0.03 N/m(2) vs. 0.11 ± 0.02 N/m(2), P = 0.007). WSS eccentricity was altered in most of the ascending aorta and proximal arch (P = 0.009-0.020). MFS patients demonstrated segmental differences in peak systolic WSS with a significantly higher WSS at the inner curvature in the proximal ascending aorta and at the anterior part in the more distal ascending aorta (P < 0.01). These findings indicate differences in WSS associated with MFS despite similar aortic dimensions compared to controls.

4-D MRI flow analysis in the course of interrupted aortic arch reveals complex morphology and quantifies amount of collateral blood flow.

We present findings in a 17-year-old with interrupted aortic arch, in whom standard imaging techniques missed functional and morphological problems. Flow-sensitive four-dimensional magnetic resonance (4-D MR) enabled assessment of the complex anatomy and blood-flow characteristics in the entire aorta and direct quantification of blood flow in collateral vessels. Our findings highlight the entire morphological and functional problem of interrupted aortic arch and illustrate the potential of flow-sensitive 4-D MR for surgical planning in congenital heart disease.

Impact of hybrid procedure on pulmonary arterial dimensions and right ventricular load after biventricular repair.

BACKGROUND: Hybrid procedure with ductal stenting and bilateral pulmonary banding offers a temporary approach in high-risk neonates with complex congenital heart defects aiming biventricular repair. This procedure may also have negative impact concerning post-banding pulmonary stenosis resulting in right ventricular pressure load. METHODS: Between 2010 and 2021 we identified 5 patients with interrupted aortic arch and complex congenital heart defect who underwent hybrid procedure and staged biventricular repair ("hybrid-group"). Other 7 cases with interrupted aortic arch were corrected in the neonatal phase without hybrid procedure ("nonhybrid-group"). Detailed intra- and extracardiac features and surgical procedures were documented as well as pulmonary interventions during follow up. Pulmonary vessel size was assessed by diameter of left and right pulmonary artery in absolute and indexed values. RV pressure was evaluated invasively via catheterization. RESULTS: Survival in cases with hybrid procedure and staged biventricular repair was 91% for a follow-up time of 40.7 months (95% CI 26-55 months) and 100% in the non-hybrid-group. Postoperative results concerning left ventricular function showed normal LV dimensions and systolic function without relevant stenosis on distal aortic arch. Hybrid procedure was associated with impaired local pulmonary arterial diameter after debanding resulting in increased right ventricular pressure and need for interventions (number intervention per patient: hybrid group 1.7 ± 0.95, non-hybrid group 0.17 ± 0.41; P 0.003). CONCLUSIONS: Hybrid procedure in high-risk cases with interrupted aortic arch and staged biventricular repair shows good postoperative results with low perioperative mortality and normal left ventricular function. Due to potential risk of relevant pulmonary stenosis and right ventricular pressure load, follow up examinations must not only focus on left but also on the right heart.

Noninvasive evaluation of 3D hemodynamics in a complex case of single ventricle physiology.

We report the comprehensive evaluation of the complex hemodynamics in a rare case of a pediatric patient after repair of congenital heart disease with multiple abnormalities including hypoplastic left heart, double outlet right ventricle, transposition of great arteries, ventricular septal defect, aortic coarctation, and total cavopulmonary connection. Based on a single measurement, whole-heart flow-sensitive 4D magnetic resonance imaging (MRI) was able to demonstrate a number of regional flow alterations such as poststenotic helix formation and asymmetric flow distributions for the double arterial outlet and to the left and right lungs. Our findings illustrate the potential role of flow-sensitive 4D MRI as a noninvasive and radiation-free technique for the frequent postinterventional follow-up in these pediatric patients.

Aortic flow patterns in patients with Marfan syndrome assessed by flow-sensitive four-dimensional MRI.

PURPOSE: To apply time-resolved three-dimensional (3D) phase contrast MRI with three-directional velocity encoding (flow-sensitive 4D MRI) for the characterization of flow pattern changes in patients with Marfan syndrome (MFS) compared with normal controls. MATERIALS AND METHODS: Flow-sensitive 4D MRI of the thoracic aorta (temporal resolution ∼45 ms, spatial resolution ∼2.4 × 2.1 × 2.8 mm(3) ) was performed in 24 MFS patients and 10 volunteers. Aortic flow patterns were visualized by 3D particle traces and streamlines. Global (affecting the complete lumen) and local (parts of the vessel lumen) helix and vortex flow in the ascending aorta (AAo), aortic arch, and descending aorta (DAo) were graded in 3 categories (blinded reading, two observers): none = 0, moderate = 1, pronounced = 2. RESULTS: Flow grading revealed similar global helix and vortex flow in the AAo and arch for MFS patients and controls. Local helix flow in the AAo was significantly (P = 0.011) increased in patients and was associated with aortic sinus dilatation. The incidence of global helix and vortex flow in the DAo was increased in patients (77% and 50% of subjects) compared with controls (none and 10%). CONCLUSION: The 4D flow analysis revealed marked differences of the aortic flow patterns between Marfan patients and controls: Local helix flow in the patients' AAo may be associated with the increased incidence of aortic root dilatation. The flow alterations in the proximal DAo could explain the occurrence of Type-B dissection originating from this site.

Surgical Treatment Following Stent Angioplasty for High-Risk Neonates With Critical Coarctation of the Aorta.

BACKGROUND: Neonatal coarctation of the aorta (CoA) is primarily treated by surgical repair. However, under certain high-risk constellations, initial stent angioplasty may be considered followed by surgical repair. We report our experience with this staged approach. Methods: All patients undergoing surgical CoA repair following prior stenting at our institution between January 2011 and December 2019 were included in this retrospective analysis. The patients were classified to be at high risk because of cardiogenic shock, associated complex cardiac malformations, neonatal infection, necrotizing enterocolitis, and extracardiac conditions, respectively. Outcomes were analyzed and compared with neonates who underwent surgical CoA repair without prior stenting in the same observation period. RESULTS: Twenty-six neonates received stent implantation at a median age of 20 days (IQR 9-33 days). Subsequent surgical repair was conducted at an age of 4.2 months (IQR 3.2-6.1 months) with a median body weight of 5.6 kg (IQR 4.5-6.5 kg). Cardiopulmonary bypass was applied in 96% of cases. Extended end-to-end anastomosis was possible in 11 patients. Extended reconstruction with patch material was necessary in the remaining patients. One fatality (3.8%) occurred 33 days postoperatively. At a median follow-up of 5.2 years after initial stenting, all remaining patients were alive; 15/25 patients (60%) were free from re-intervention. Of note, re-intervention rates were comparable in neonates (n = 76) who were operated on with native CoA (28/74 patients; 38%; P = .67). CONCLUSIONS: Neonatal stent angioplasty for CoA results in increased complexity of the subsequent surgical repair. Nevertheless, this staged approach allows to bridge high-risk neonates to later surgical repair with reduced perioperative risk and acceptable midterm outcomes.

In vivo noninvasive 4D pressure difference mapping in the human aorta: phantom comparison and application in healthy volunteers and patients.

In this work, we present a systematic phantom comparison and clinical application of noninvasive pressure difference mapping in the human aorta based on time-resolved 3D phase contrast data. Relative pressure differences were calculated based on integration and iterative refinement of pressure gradients derived from MR-based three-directional velocity vector fields (flow-sensitive 4D MRI with spatial/temporal resolution ∼ 2.1 mm(3)/40 ms) using the Navier-Stokes equation. After in vitro study using a stenosis phantom, time-resolved 3D pressure gradients were systematically evaluated in the thoracic aorta in a group of 12 healthy subjects and 6 patients after repair for aortic coarctation. Results from the phantom study showed good agreement with expected values and standard methods (Bernoulli). Data of healthy subjects showed good intersubject consistency and good agreement with the literature. In patients, pressure waveforms showed elevated peak values. Pressure gradients across the stenosis were compared with reference measurements from Doppler ultrasound. The MRI findings demonstrated a significant correlation (r = 0.96, P < 0.05) but moderate underestimation (14.7% ± 15.5%) compared with ultrasound when the maximum pressure difference for all possible paths connecting proximal and distal locations of the stenosis were used. This study demonstrates the potential of the applied approach to derive additional quantitative information such as pressure gradients from time-resolved 3D phase contrast MRI.

A family with a new elastin gene mutation: broad clinical spectrum, including sudden cardiac death.

Supravalvular aortic stenosis is associated with the Williams-Beuren syndrome, but it also occurs in a non-syndromatic congenital form. An elastin gene mutation of chromosome 7q11.23 is responsible in both cases. The vascular features are identical. These patients have a higher risk of sudden death, particularly when undergoing diagnostic or surgical procedures. We report the account of a family with a new mutation in the elastin gene. Screening over three generations revealed eight affected individuals. The cardiac and vascular malformations ranged from mild asymptomatic supravalvular aortic stenosis and isolated dysplastic atrioventricular valves to diffuse arterial hypoplasia. Two infants presented arteries affected at multiple locations, including the left coronary artery. Both died of sudden cardiac death and myocardial ischaemia, one while under general anaesthesia for cardiac catheterisation, and the other perioperatively. We discuss the pathophysiological aspects in these patients that deserve consideration before any general anaesthesia is administered.

Regional myocardial function in children with chronic aortic regurgitation.

AIM: To determine the influence of volume overload on regional myocardial function in children with aortic regurgitation (AR) using tissue Doppler echocardiography and strain rate imaging (TDE/SRI). METHODS: Thirty children with AR (median age 14 years (range 3-28 years)) were divided into three groups: mild (n = 6), moderate (n = 15), and severe AR (n = 9). Patients and 30 matched healthy controls underwent echocardiography with TDE/SRI. Cineloops were acquired from parasternal long- and short-axis and from apical four- and two-chamber views. The following parameters were extracted: peak systolic (V(S) ) and diastolic (V(E) ) velocities, peak systolic strain (S), peak systolic (SR(S) ), and early diastolic strain rate (SR(E) ). To quantify longitudinal LV function, V(S) and V(E) were obtained as peak values in the basal segments, whereas S, SR(S) , and SR(E) were expressed as mean values between basal and midwall segments. RESULTS: Compared to the control group, patients showed a significant reduction in V(E) in the longitudinal direction (-91 ± 30 mm/sec for patients vs. 119 ± 20 mm/sec for control group). In patients with severe AR, longitudinal SR(E) was significantly reduced. On the other hand, we noted no differences between patients and controls with regard to S and SR(S) values. CONCLUSION: Children with AR presented with significantly reduced longitudinal diastolic function (V(E) ). Severe AR leads to a decrease in diastolic myocardial deformation (SR(E) ). Due to the short duration of AR in this group of patients, systolic function (SR(S) ) is still preserved.

Three-dimensional flow characteristics in aortic coarctation and poststenotic dilatation.

The authors present findings from a scientific study in a 36-year-old male patient who was transferred for the evaluation of a restenosis in aortic coarctation that was initially treated by surgical repair. Contrast-enhanced magnetic resonance angiography and comprehensive flow-sensitive 4-dimensional magnetic resonance imaging for the evaluation of 3-dimensional blood flow in the entire thoracic aorta demonstrated distinct flow pattern changes associated with the disease, demonstrating a potential link between altered vascular hemodynamics and the development of vascular disease.

Multidirectional flow analysis by cardiovascular magnetic resonance in aneurysm development following repair of aortic coarctation.

Aneurysm formation is a life-threatening complication after operative therapy in coarctation. The identification of patients at risk for the development of such secondary pathologies is of high interest and requires a detailed understanding of the link between vascular malformation and altered hemodynamics. The routine morphometric follow-up by magnetic resonance angiography is a well-established technique. However, the intrinsic sensitivity of magnetic resonance (MR) towards motion offers the possibility to additionally investigate hemodynamic consequences of morphological changes of the aorta. We demonstrate two cases of aneurysm formation 13 and 35 years after coarctation surgery based on a Waldhausen repair with a subclavian patch and a Vosschulte repair with a Dacron patch, respectively. Comprehensive flow visualization by cardiovascular MR (CMR) was performed using a flow-sensitive, 3-dimensional, and 3-directional time-resolved gradient echo sequence at 3T. Subsequent analysis included the calculation of a phase contrast MR angiography and color-coded streamline and particle trace 3D visualization. Additional quantitative evaluation provided regional physiological information on blood flow and derived vessel wall parameters such as wall shear stress and oscillatory shear index. The results highlight the individual 3D blood-flow patterns associated with the different vascular pathologies following repair of aortic coarctation. In addition to known factors predisposing for aneurysm formation after surgical repair of coarctation these findings indicate the importance of flow sensitive CMR to follow up hemodynamic changes with respect to the development of vascular disease.

Tissue Doppler derived isovolumic acceleration in patients after atrial repair for dextrotransposition of the great arteries.

BACKGROUND: Ventricular dysfunction represents one of the major problems in the long-term follow-up of patients after atrial repair for dextrotransposition of the great arteries. We aimed to study the role of tissue Doppler derived isovolumic acceleration (IVA) to detect early myocardial dysfunction in these patients. METHODS: Twenty-four patients with dextrotransposition of the great arteries (D-TGA) that underwent atrial repair (Senning procedure: n = 12; Mustard procedure: n = 12) in infancy were examined at the age of 21 [12-33] years (median [range]) using tissue Doppler analysis of IVA and peak systolic myocardial velocity at rest and during exercise. 12 age-matched healthy subjects served as controls. RESULTS: At rest, IVA and peak systolic myocardial velocity were reduced in the systemic ventricle (SV) of patients. IVA correlated with peak systolic myocardial velocity (r = 0.76, P < 0.001). During exercise, IVA, but not peak systolic myocardial velocity, increased significantly in the SV of patients (rest: 1.03 +/- 0.44 cm/sec(2); 1 W/kg: 1.80 +/- 1.22 cm/sec(2); 2 W/kg: 2.85 +/- 1.26 cm/sec(2)). In the subpulmonary ventricle, IVA was significantly lower in patients compared to the controls (patients: 1.45 +/- 0.49 cm/sec(2) vs. controls: 2.31 +/- 0.43 cm/sec(2), P < 0.05). IVA but not peak systolic myocardial velocity was able to discriminate between patients and healthy subjects. CONCLUSIONS: IVA is superior to peak systolic myocardial velocity to assess a reduction in functional reserve of both ventricles in patients after atrial repair for D-TGA.

Cardiac diagnostics before oral propranolol therapy in infantile hemangioma: retrospective evaluation of 234 infants.

BACKGROUND: The indication and extent of cardiac screening before oral propranolol therapy (OPT) in patients with infantile hemangioma (IH) has been challenged. In this study, we evaluated pre-OPT cardiac diagnostics in a pediatric IH cohort in our department. METHODS: Retrospective chart review of infants ≤ 12 months old with IH undergoing OPT. The diagnostics prior to OPT, occurrence of complications, and outcome were recorded. RESULTS: A total of 234 patients were evaluated. The mean age at the onset of OPT was 4.2 ± 0.3 months, the average duration of OPT was 6.1 ± 0.1 months, and the average follow-up was 12.3 ± 0.7 months. Echocardiograms and electrocardiograms were performed prior to OPT in all patients. One hundred and three (44.0%) echocardiograms revealed pathological findings, 19 (8.1%) of which were minor (including atrial septal defects, pulmonary stenosis, and patent ductus arteriosus). Pathological findings were observed in 17 (7.3%) of electrocardiograms, only one (0.4%) of which was minor (suspected cardiac arrhythmia, subsequently excluded by long-term electrocardiogram analysis). These findings did not contraindicate OPT and no severe adverse events associated with OPT occurred during the follow-up period. CONCLUSIONS: Routine cardiac screening by electrocardiogram and echocardiogram before OPT is debatable and not routinely indicated in children with IH. Further studies are necessary to draw definite conclusions on the reasonable indication and extent of this diagnostic approach.

3D Geometric Analysis of the Pediatric Aorta in 3D MRA Follow-Up Images with Application to Aortic Coarctation.

BACKGROUND: Coarctation of the aorta is one of the most common congenital heart diseases. Despite different treatment opportunities, long-term outcome after surgical or interventional therapy is diverse. Serial morphologic follow-up of vessel growth is necessary, because vessel growth cannot be predicted by primer morphology or a therapeutic option. OBJECTIVES: For the analysis of the long-term outcome after therapy of congenital diseases such as aortic coarctation, accurate 3D geometric analysis of the aorta from follow-up 3D medical image data such as magnetic resonance angiography (MRA) is important. However, for an objective, fast, and accurate 3D geometric analysis, an automatic approach for 3D segmentation and quantification of the aorta from pediatric images is required. METHODS: We introduce a new model-based approach for the segmentation of the thoracic aorta and its main branches from follow-up pediatric 3D MRA image data. For robust segmentation of vessels even in difficult cases (e.g., neighboring structures), we propose a new extended parametric cylinder model that requires only relatively few model parameters. Moreover, we include a novel adaptive background-masking scheme used for least-squares model fitting, we use a spatial normalization scheme to align the segmentation results from follow-up examinations, and we determine relevant 3D geometric parameters of the aortic arch. RESULTS: We have evaluated our proposed approach using different 3D synthetic images. Moreover, we have successfully applied the approach to follow-up pediatric 3D MRA image data, we have normalized the 3D segmentation results of follow-up images of individual patients, and we have combined the results of all patients. We also present a quantitative evaluation of our approach for four follow-up 3D MRA images of a patient, which confirms that our approach yields accurate 3D segmentation results. An experimental comparison with two previous approaches demonstrates that our approach yields superior results. CONCLUSIONS: From the results, we found that our approach is well suited for the quantification of the 3D geometry of the aortic arch from follow-up pediatric 3D MRA image data. In future work, this will enable to investigate the long-term outcome of different surgical and interventional therapies for aortic coarctation.