Julia Geiger

Evaluation of 3D blood flow patterns and wall shear stress in the normal and dilated thoracic aorta using flow-sensitive 4D CMR

BackgroundThe purpose of this study was to investigate 3D flow patterns and vessel wall parameters in patients with dilated ascending aorta, age-matched subjects, and healthy volunteers.MethodsThoracic time-resolved 3D phase contrast CMR with 3-directional velocity encoding was applied to 33 patients with dilated ascending aorta (diameter ≥40 mm, age=60±16 years), 15 age-matched normal controls (diameter ≤37 mm, age=68±7.5 years) and 15 young healthy volunteers (diameter ≤30 mm, age=23±2 years). 3D blood flow was visualized and flow patterns were graded regarding presence of supra-physiologic-helix and vortex flow using a semi-quantitative 3-point grading scale. Blood flow velocities, regional wall shear stress (WSS), and oscillatory shear index (OSI) were quantified.ResultsIncidence and strength of supra-physiologic-helix and vortex flow in the ascending aorta (AAo) was significantly higher in patients with dilated AAo (16/33 and 31/33, grade 0.9±1.0 and 1.5±0.6) than in controls (2/15 and 7/15, grade 0.2 ± 0.6 and 0.6 ± 0.7, P<.05) or healthy volunteers (1/15 and 0/15, grade 0.1 ± 0.3 P<.05). Greater strength of the ascending aortic helix and vortex flow were associated with significant differences in AAo diameters (P<.05). Peak systolic WSS in the ascending aorta and aortic arch was significantly lower in patients with dilated AAo (P<.0157-.0488). AAo diameter positively correlated to time to peak systolic velocities (r=0.30-0.53, P<.04), OSI (r=0.33-0.49, P<0.02) and inversely correlated to peak systolic WSS (r=0.32-0.40, P<.03). Peak systolic WSS was significantly lower in AAo aneurysms at the right and outer curvature within the AAo and proximal arch (P<.01-.05).ConclusionsIncrease in AAo diameter is significantly correlated with the presence and strength of supra-physiologic-helix and vortex formation in the AAo, as well with decrease in systolic WSS and increase in OSI.

Time-resolved three-dimensional magnetic resonance velocity mapping of cardiovascular flow paths in volunteers and patients with Fontan circulation

OBJECTIVE To apply flow-sensitive magnetic resonance imaging for the evaluation of whole-heart flow characteristics in healthy volunteers and patients with Fontan circulation. METHODS Time-resolved three-dimensional magnetic resonance velocity mapping (spatial resolution = 2.5 × 2.8 × 2.8mm(3), temporal resolution = 38.4 ms) was acquired in normal controls and in four Fontan patients with extracardiac total cavopulmonary connection. Data analysis included flow connectivity mapping and flow quantification of arterial and venous blood flow. Haemodynamics in four patients with Fontan circulation were individually evaluated in the aorta, caval veins and left and right pulmonary arteries. RESULTS In four controls, nine distinct flow features were consistently identified with good feature clarity (median = 2 in 80.6% of readings) and image quality (median = 2 in 75.0% of readings). In patients, a marked variability of flow from the caval veins towards the left and right pulmonary arteries (flow ratio = 1.7 ± 0.6, range 1.2-2.6 vs 1.1 ± 0.1 in controls) was found. Increased offset of the caval venous connection resulted in enhanced pulmonary flow asymmetry. Compared with controls, reduced pulsatility in pulmonary arteries (1.4 ± 0.6 vs 4.1 ± 0.6 in controls) and caval veins (1.2 ± 0.4 vs 2.8 ± 1.1 in controls) were observed. Peak flow was reduced in both superior (22 ± 14 mls(-1) vs 76 ± 7 mls(-1) in controls) and inferior vena cava (61 ± 28 mls(-1) vs 187 ± 42 mls(-1) in controls). CONCLUSIONS This feasibility study demonstrated the potential of whole-heart three-dimensional magnetic resonance velocity mapping to reveal overt haemodynamic differences in surgically palliated congenital heart with similar extracardiac cavopulmonary connection geometry. Future studies are warranted to evaluate its diagnostic impact for improved evaluation of the pre- and postoperative status in the individual patient.

Aortic Hemodynamics in Patients With and Without Repair of Aortic Coarctation In Vivo Analysis by 4D Flow-Sensitive Magnetic Resonance Imaging

Objectives:The purpose of this study was to characterize hemodynamic alterations and flow-derived vessel wall parameters in aortic coarctation (CoA) patients with and without operative repair by time-resolved, 3-dimensional, and 3-directional velocity sensitive, phase-contrast magnetic resonance imaging (4D PC MRI) in comparison with healthy subjects. Methods and Material:Twenty-four patients, 12.5 ± 6.4 years after CoA repair, 4 patients without treatment for CoA, and 19 healthy subjects were examined. The study was approved by the institutional review board and signature of written informed consent was obtained from the participants. Echocardiography was performed in patients before participation. MRI studies were conducted by applying flow-sensitive 4D phase-contrast MRI at either 1.5 T (n = 5 patients) or 3 T (all 19 healthy subjects, n = 23 patients). Blood flow visualization was used to evaluate overall aortic helicity, presence of pronounced or additional localized helix flow, and vortex development. Quantitative evaluation comprised the calculation of regional time-averaged absolute wall shear stress (WSSmag), peak velocities, and oscillatory shear index at 8 locations distributed along the thoracic aorta and additionally at the site of CoA. Inter- and intraobserver variabilities of calculations were determined. Results:Volunteers and patients demonstrated the same amount of overall aortic helicity. In contrast, the number of additional localized helix flow or vortex formation was significantly increased in patients (25/28 patients vs. 5/19 normal controls, Fisher exact test: P < 0.001). Vortices in the orifices of the supra-aortic branches were detected in 64.3% (18/28) of patients but in only 11.8% (2/19) of controls (P < 0.001). Quantitative analyses revealed a significant increase in overall aortic WSSmag (0.44 ± 0.17 N/m2 in patients vs. 0.27 ± 0.08 N/m2 in volunteers, P < 0.005) and a decrease in overall oscillatory shear index. Repeated quantitative analysis showed moderate interobserver and low intraobserver variability. Correlation with echocardiography showed good agreement with MRI which tended to underestimate peak velocities (r = 0.76; Bland-Altman analysis, limits of agreement = −0.57–2.16 m/s, mean = 0.79 m/s). Conclusion:Alterations in aortic hemodynamics after CoA repair are not limited to the specific region of repair, but can be found in the entire aorta. The presented findings highlight the systemic nature of the disease and the need for a systemic diagnostic approach which can be provided by flow-sensitive 4D PC MRI. Furthermore, valuable additional insights on the hemodynamic consequences of coarctation have been shown that may help understanding secondary complications such as restenosis, aneurysm formation, and arterial hypertension.

Giant Cell Arteritis: Diagnostic Accuracy of MR Imaging of Superficial Cranial Arteries in Initial Diagnosis—Results from a Multicenter Trial

PURPOSE To assess the diagnostic accuracy of contrast material-enhanced magnetic resonance (MR) imaging of superficial cranial arteries in the initial diagnosis of giant cell arteritis ( GCA giant cell arteritis ). MATERIALS AND METHODS Following institutional review board approval and informed consent, 185 patients suspected of having GCA giant cell arteritis were included in a prospective three-university medical center trial. GCA giant cell arteritis was diagnosed or excluded clinically in all patients (reference standard [final clinical diagnosis]). In 53.0% of patients (98 of 185), temporal artery biopsy ( TAB temporal artery biopsy ) was performed (diagnostic standard [ TAB temporal artery biopsy ]). Two observers independently evaluated contrast-enhanced T1-weighted MR images of superficial cranial arteries by using a four-point scale. Diagnostic accuracy, involvement pattern, and systemic corticosteroid ( sCS systemic corticosteroid ) therapy effects were assessed in comparison with the reference standard (total study cohort) and separately in comparison with the diagnostic standard TAB temporal artery biopsy ( TAB temporal artery biopsy subcohort). Statistical analysis included diagnostic accuracy parameters, interobserver agreement, and receiver operating characteristic analysis. RESULTS Sensitivity of MR imaging was 78.4% and specificity was 90.4% for the total study cohort, and sensitivity was 88.7% and specificity was 75.0% for the TAB temporal artery biopsy subcohort (first observer). Diagnostic accuracy was comparable for both observers, with good interobserver agreement ( TAB temporal artery biopsy subcohort, κ = 0.718; total study cohort, κ = 0.676). MR imaging scores were significantly higher in patients with GCA giant cell arteritis -positive results than in patients with GCA giant cell arteritis -negative results ( TAB temporal artery biopsy subcohort and total study cohort, P < .001). Diagnostic accuracy of MR imaging was high in patients without and with sCS systemic corticosteroid therapy for 5 days or fewer (area under the curve, ≥0.9) and was decreased in patients receiving sCS systemic corticosteroid therapy for 6-14 days. In 56.5% of patients with TAB temporal artery biopsy -positive results (35 of 62), MR imaging displayed symmetrical and simultaneous inflammation of arterial segments. CONCLUSION MR imaging of superficial cranial arteries is accurate in the initial diagnosis of GCA giant cell arteritis . Sensitivity probably decreases after more than 5 days of sCS systemic corticosteroid therapy; thus, imaging should not be delayed. Clinical trial registration no. DRKS00000594 .

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

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.

Involvement of the ophthalmic artery in giant cell arteritis visualized by 3T MRI

OBJECTIVES To retrospectively analyse inflammatory involvement of the ophthalmic arteries in patients with GCA utilizing high-resolution MRI. METHODS A cohort of 50 patients with GCA who had been examined by 1.5 or 3T high-field MRI was analysed retrospectively in a consensus reading for possible involvement of the ophthalmic arteries. In 43 patients, entire orbits were within the field of view. In all cases, the superficial cranial arteries displayed mural inflammation in post-contrast T1-weighted spin-echo (SE) images. MRI results were compared with ophthalmological findings, subjective visual symptoms and laboratory values, i.e. CRP and ESR. RESULTS We observed mural contrast enhancement of the ophthalmic arteries in 20/43 patients (46%). Bilateral involvement was seen in 14, unilateral enhancement in six cases. Fifteen patients had ophthalmic vascular diseases: nine had anterior ischaemic optic neuropathy (AION), one posterior ischaemic optic neuropathy (PION), four revealed central retinal artery occlusion (CRAO) and one patient presented with narrowing of the retinal arteries. Funduscopy detected no arteritis-related changes in 22 cases. Of those patients who were MRI positive, seven had ophthalmological disease. Twenty-six patients complained of visual symptoms including amaurosis fugax, vision loss, diplopia or eye pain. CONCLUSIONS High-resolution MRI detects mural contrast enhancement consistent with inflammatory changes in the superficial cranial and extracranial arteries and additionally in the ophthalmic arteries. This provides insight in vasculitic orbital involvement during one single investigation.

Early Life Stress Differentially Modulates Distinct Forms of Brain Plasticity in Young and Adult Mice

Background Early life trauma is an important risk factor for many psychiatric and somatic disorders in adulthood. As a growing body of evidence suggests that brain plasticity is disturbed in affective disorders, we examined the short-term and remote effects of early life stress on different forms of brain plasticity. Methodology/Principal Findings Mice were subjected to early deprivation by individually separating pups from their dam in the first two weeks after birth. Distinct forms of brain plasticity were assessed in the hippocampus by longitudinal MR volumetry, immunohistochemistry of neurogenesis, and whole-cell patch-clamp measurements of synaptic plasticity. Depression-related behavior was assessed by the forced swimming test in adult animals. Neuropeptides and their receptors were determined by real-time PCR and immunoassay. Early maternal deprivation caused a loss of hippocampal volume, which returned to normal in adulthood. Adult neurogenesis was unaffected by early life stress. Long-term synaptic potentiation, however, was normal immediately after the end of the stress protocol but was impaired in adult animals. In the forced swimming test, adult animals that had been subjected to early life stress showed increased immobility time. Levels of substance P were increased both in young and adult animals after early deprivation. Conclusion Hippocampal volume was affected by early life stress but recovered in adulthood which corresponded to normal adult neurogenesis. Synaptic plasticity, however, exhibited a delayed impairment. The modulation of synaptic plasticity by early life stress might contribute to affective dysfunction in adulthood.

Assessment of intracardiac flow and vorticity in the right heart of patients after repair of tetralogy of Fallot by flow-sensitive 4D MRI

ObjectivesTo comprehensively and quantitatively analyse flow and vorticity in the right heart of patients after repair of tetralogy of Fallot (rTOF) compared with healthy volunteers.MethodsTime-resolved flow-sensitive 4D MRI was acquired in 24 rTOF patients and 12 volunteers. Qualitative flow evaluation was based on consensus reading of two observers. Quantitative analysis included segmentation of the right atrium (RA) and ventricle (RV) in a four-chamber view to extract volumes and regional haemodynamic information for computation of regional mean and peak vorticity.ResultsRight heart intra-atrial, intraventricular and outflow tract flow patterns differed considerably between rTOF patients and volunteers. Peak RA and mean RV vorticity was significantly higher in patients (p = 0.02/0.05). Significant negative correlations were found between patients’ maximum and mean RV and RA vorticity and ventricular volumes (p < 0.05). The main pulmonary artery (MPA) regurgitant flow was associated with higher RA and RV vorticity, which was significant for RA maximum and RV mean vorticity (p = 0.01/0.03).ConclusionThe calculation of vorticity based on 4D flow data is an alternative approach to assess intracardiac flow changes in rTOF patients compared with qualitative flow visualization. Alterations in intracardiac vorticity could be relevant with regard to the development of RV dilation and impaired function.Key points• 4D flow MRI with vorticity calculation enables a novel approach to assess intracardiac flow.• Significantly higher intracardiac vorticity occurred in patients after repair of tetralogy of Fallot.• Regurgitant flow in the main pulmonary artery is associated with higher right heart vorticity.

High-resolution MRI for assessment of middle meningeal artery involvement in giant cell arteritis

Giant cell arteritis (GCA) typically involves the superficial cranial arteries, the aorta and its branches. It has been discussed to which extent the vasculitic changes of the cranial arteries continue into the intracranial region. Autopsy findings have indicated that the characteristic signs of arteritic inflammation of GCA end after crossing the dural border.1 In a recent review of several published cases it was concluded that intracranial/intradural involvement in GCA is rare and represents a small subset of GCA that is non-responsive to corticosteroids and has a fatal course.2 Contrast-enhanced, high-resolution MRI allows non-invasive assessment of mural inflammation in the extracranial, superficial arteries in giant cell arteritis.3 Here, we report MRI findings suggestive of intracranial vasculitic involvement in patients with GCA. High-resolution MRI of …

Comprehensive 4-Dimensional Magnetic Resonance Flow Analysis After Successful Heart Transplantation Resolves Controversial Intraoperative Findings and Reveals Complex Hemodynamic Alterations

We present findings in a 68-year-old man listed for heart transplantation (T status, which is similar to US status 1B) who suffered from long-term heart failure due to dilative cardiomyopathy. After recurrent cardiac decompensation, he was supported with a left ventricular assist device (Synergy, CircuLite, Saddle Brook, NJ).1 After 17 weeks of support, the pump had to be deactivated because of recurrent system failure and thromboembolic events. As a consequence, he was registered as a high-urgency patient and had to wait for another 16 weeks before an organ became available. Orthotopic heart transplantation using the bicaval technique combined with explantation of the left ventricular assist device was uneventful.2,3 Intraoperatively, 3 additional procedures had to be performed: (1) A patch repair of the upper right pulmonary vein was performed after explantation of the left atrial cannula of the left ventricular assist device; (2) a significant discrepancy in the diameters of the native and the transplanted ascending aorta (34 versus 24 mm) made a tapered diameter reduction in the aortic anastomosis necessary; and (3) the donor pulmonary trunk was directly connected to the branching point of the left and right pulmonary arteries. Immediately after heart transplantation and while still in the operating room, the patient was examined by transesophageal echocardiography and pulmonary artery catheterization (Swan-Ganz catheter, Edwards Lifesciences Corp, Irvine, CA). The catheter measurement revealed an elevated systolic pressure gradient in the pulmonary artery of 10 mm Hg, indicative of a pulmonary stenosis; however, this was not supported by transesophageal echocardiography or other hemodynamic data (central venous pressure, pressure in the right ventricle, and cardiac output). After a smooth intraoperative course, the patient made an uncomplicated recovery and was discharged from the hospital within 30 days after heart transplantation. All predischarge examinations, including transthoracic echocardiography, chest radiographs, laboratory …