A simulation-based phantom model for generating synthetic mitral valve image data-application to MRI acquisition planning

PURPOSE

Numerical phantom methods are widely used in the development of medical imaging methods. They enable quantitative evaluation and direct comparison with controlled and known ground truth information. Cardiac magnetic resonance has the potential for a comprehensive evaluation of the mitral valve (MV). The goal of this work is the development of a numerical simulation framework that supports the investigation of MRI imaging strategies for the mitral valve.

METHODS

We present a pipeline for synthetic image generation based on the combination of individual anatomical 3D models with a position-based dynamics simulation of the mitral valve closure. The corresponding images are generated using modality-specific intensity models and spatiotemporal sampling concepts. We test the applicability in the context of MRI imaging strategies for the assessment of the mitral valve. Synthetic images are generated with different strategies regarding image orientation (SAX and rLAX) and spatial sampling density.

RESULTS

The suitability of the imaging strategy is evaluated by comparing MV segmentations against ground truth annotations. The generated synthetic images were compared to ones acquired with similar parameters, and the result is promising. The quantitative analysis of annotation results suggests that the rLAX sampling strategy is preferable for MV assessment, reaching accuracy values that are comparable to or even outperform literature values.

CONCLUSION

The proposed approach provides a valuable tool for the evaluation and optimization of cardiac valve image acquisition. Its application to the use case identifies the radial image sampling strategy as the most suitable for MV assessment through MRI.

Noninvasive evaluation of pulmonary artery stiffness in heart failure patients via cardiovascular magnetic resonance

Heart failure (HF) presents manifestations in both cardiac and vascular abnormalities. Pulmonary hypertension (PH) is prevalent in up 50% of HF patients. While pulmonary arterial hypertension (PAH) is closely associated with pulmonary artery (PA) stiffness, the association of HF caused, post-capillary PH and PA stiffness is unknown. We aimed to assess and compare PA stiffness and blood flow hemodynamics noninvasively across HF entities and control subjects without HF using CMR. We analyzed data of a prospectively conducted study with 74 adults, including 55 patients with HF across the spectrum (20 HF with preserved ejection fraction [HFpEF], 18 HF with mildly-reduced ejection fraction [HFmrEF] and 17 HF with reduced ejection fraction [HFrEF]) as well as 19 control subjects without HF. PA stiffness was defined as reduced vascular compliance, indicated primarily by the relative area change (RAC), altered flow hemodynamics were detected by increased flow velocities, mainly by pulse wave velocity (PWV). Correlations between the variables were explored using correlation and linear regression analysis. PA stiffness was significantly increased in HF patients compared to controls (RAC 30.92 ± 8.47 vs. 50.08 ± 9.08%, p < 0.001). PA blood flow parameters were significantly altered in HF patients (PWV 3.03 ± 0.53 vs. 2.11 ± 0.48, p < 0.001). These results were consistent in all three HF groups (HFrEF, HFmrEF and HFpEF) compared to the control group. Furthermore, PA stiffness was associated with higher NT-proBNP levels and a reduced functional status. PA stiffness can be assessed non-invasively by CMR. PA stiffness is increased in HFrEF, HFmrEF and HFpEF patients when compared to control subjects.Trial registration The study was registered at the German Clinical Trials Register (DRKS, registration number: DRKS00015615).

VEGF-B hypertrophy predisposes to transition from diastolic to systolic heart failure in hypertensive rats

AIMS

Cardiac energy metabolism is centrally involved in heart failure (HF), although the direction of the metabolic alterations is complex and likely dependent on the particular stage of HF progression. Vascular endothelial growth factor B (VEGF-B) has been shown to modulate metabolic processes and to induce physiological cardiac hypertrophy; thus, it could be cardioprotective in the failing myocardium. This study investigates the role of VEGF-B in cardiac proteomic and metabolic adaptation in HF during aldosterone and high-salt hypertensive challenges.

METHODS AND RESULTS

Male rats overexpressing the cardiac-specific VEGF-B transgene (VEGF-B TG) were treated for 3 or 6 weeks with deoxycorticosterone-acetate combined with a high-salt (HS) diet (DOCA + HS) to induce hypertension and cardiac damage. Extensive longitudinal echocardiographic studies of HF progression were conducted, starting at baseline. Sham-treated rats served as controls. To evaluate the metabolic alterations associated with HF, cardiac proteomics by mass spectrometry was performed. Hypertrophic non-treated VEGF-B TG hearts demonstrated high oxygen and adenosine triphosphate (ATP) demand with early onset of diastolic dysfunction. Administration of DOCA + HS to VEGF-B TG rats for 6 weeks amplified the progression from cardiac hypertrophy to HF, with a drastic drop in heart ATP concentration. Dobutamine stress echocardiographic analyses uncovered a significantly impaired systolic reserve. Mechanistically, the hallmark of the failing TG heart was an abnormal energy metabolism with decreased mitochondrial ATP, preceding the attenuated cardiac performance and leading to systolic HF.

CONCLUSIONS

This study shows that the VEGF-B TG accelerates metabolic maladaptation which precedes structural cardiomyopathy in experimental hypertension and ultimately leads to systolic HF.

Comparison of hemodynamics in biological surgical aortic valve replacement and transcatheter aortic valve implantation: An in-silico study

OBJECTIVES

In aortic valve replacement (AVR), the treatment strategy as well as the model and size of the implanted prosthesis have a major impact on the postoperative hemodynamics and thus on the clinical outcome. Preinterventional prediction of the hemodynamics could support the treatment decision. Therefore, we performed paired virtual treatment with transcatheter AVR (TAVI) and biological surgical AVR (SAVR) and compared hemodynamic outcomes using numerical simulations.

METHODS

10 patients with severe aortic stenosis (AS) undergoing TAVI were virtually treated with both biological SAVR and TAVI to compare post-interventional hemodynamics using numerical simulations of peak-systolic flow. Virtual treatment procedure was done using an in-house developed tool based on position-based dynamics methodology, which was applied to the patient's anatomy including LVOT, aortic root and aorta. Geometries were automatically segmented from dynamic CT-scans and patient-specific flow rates were calculated by volumetric analysis of the left ventricle. Hemodynamics were assessed using the STAR CCM+ software by solving the RANS equations.

RESULTS

Virtual treatment with TAVI resulted in realistic hemodynamics comparable to echocardiographic measurements (median difference in transvalvular pressure gradient [TPG]: -0.33 mm Hg). Virtual TAVI and SAVR showed similar hemodynamic functions with a mean TPG with standard deviation of 8.45 ± 4.60 mm Hg in TAVI and 6.66 ± 3.79 mm Hg in SAVR (p = 0.03) while max. Wall shear stress being 12.6 ± 4.59 vs. 10.2 ± 4.42 Pa (p = 0.001).

CONCLUSIONS

Using the presented method for virtual treatment of AS, we were able to reliably predict post-interventional hemodynamics. TAVI and SAVR show similar hemodynamics in a pairwise comparison.

CMR findings after COVID-19 and after COVID-19-vaccination-same but different?

Cardiac involvement has been described in varying proportions of patients recovered from COVID-19 and proposed as a potential cause of prolonged symptoms, often described as post-COVID or long COVID syndrome. Recently, cardiac complications have been reported from COVID-19 vaccines as well. We aimed to compare CMR-findings in patients with clinical cardiac symptoms after COVID-19 and after vaccination. From May 2020 to May 2021, we included 104 patients with suspected cardiac involvement after COVID-19 who received a clinically indicated cardiac magnetic resonance (CMR) examination at a high-volume center. The mean time from first positive PCR to CMR was 112  ± 76 days. During their COVID-19 disease, 21% of patients required hospitalization, 17% supplemental oxygen and 7% mechanical ventilation. In 34 (32.7%) of patients, CMR provided a clinically relevant diagnosis: Isolated pericarditis in 10 (9.6%), %), acute myocarditis (both LLC) in 7 (6.7%), possible myocarditis (one LLC) in 5 (4.8%), ischemia in 4 (3.8%), recent infarction in 2 (1.9%), old infarction in 4 (3.8%), dilated cardiomyopathy in 3 (2.9%), hypertrophic cardiomyopathy in 2 (1.9%), aortic stenosis, pleural tumor and mitral valve prolapse each in 1 (1.0%). Between May 2021 and August 2021, we examined an additional 27 patients with suspected cardiac disease after COVID-19 vaccination. Of these, CMR provided at least one diagnosis in 22 (81.5%): Isolated pericarditis in 4 (14.8%), acute myocarditis in 9 (33.3%), possible myocarditis (acute or subsided) in 6 (22.2%), ischemia in 3 (37.5% out of 8 patients with stress test), isolated pericardial effusion (> 10 mm) and non-compaction-cardiomyopathy each in 1 (3.7%). The number of myocarditis diagnoses after COVID-19 was highly dependent on the stringency of the myocarditis criteria applied. When including only cases of matching edema and LGE and excluding findings in the right ventricular insertion site, the number of cases dropped from 7 to 2 while the number of cases after COVID-19 vaccination remained unchanged at 9. While myocarditis is an overall rare side effect after COVID-19 vaccination, it is currently the leading cause of myocarditis in our institution due to the large number of vaccinations applied over the last months. Contrary to myocarditis after vaccination, LGE and edema in myocarditis after COVID-19 often did not match or were confined to the RV-insertion site. Whether these cases truly represent myocarditis or a different pathological entity is to be determined in further studies.

Brief Research Report: Quantitative Analysis of Potential Coronary Microvascular Disease in Suspected Long-COVID Syndrome

Background

Case series have reported persistent cardiopulmonary symptoms, often termed long-COVID or post-COVID syndrome, in more than half of patients recovering from Coronavirus Disease 19 (COVID-19). Recently, alterations in microvascular perfusion have been proposed as a possible pathomechanism in long-COVID syndrome. We examined whether microvascular perfusion, measured by quantitative stress perfusion cardiac magnetic resonance (CMR), is impaired in patients with persistent cardiac symptoms post-COVID-19.

Methods

Our population consisted of 33 patients post-COVID-19 examined in Berlin and London, 11 (33%) of which complained of persistent chest pain and 13 (39%) of dyspnea. The scan protocol included standard cardiac imaging and dual-sequence quantitative stress perfusion. Standard parameters were compared to 17 healthy controls from our institution. Quantitative perfusion was compared to published values of healthy controls.

Results

The stress myocardial blood flow (MBF) was significantly lower [31.8 ± 5.1 vs. 37.8 ± 6.0 (μl/g/beat), P < 0.001] and the T2 relaxation time was significantly higher (46.2 ± 3.6 vs. 42.7 ± 2.8 ms, P = 0.002) post-COVID-19 compared to healthy controls. Stress MBF and T1 and T2 relaxation times were not correlated to the COVID-19 severity (Spearman r = −0.302, −0.070, and −0.297, respectively) or the presence of symptoms. The stress MBF showed a U-shaped relation to time from PCR to CMR, no correlation to T1 relaxation time, and a negative correlation to T2 relaxation time (Pearson r = −0.446, P = 0.029).

Conclusion

While we found a significantly reduced microvascular perfusion post-COVID-19 compared to healthy controls, this reduction was not related to symptoms or COVID-19 severity.

Impact of Right Ventricular Pressure Load After Repair of Tetralogy of Fallot

Background Right ventricular outflow tract (RVOT) stenosis after repair of tetralogy of Fallot has been linked with favorable right ventricular remodeling but adverse outcomes. The aim of our study was to assess the hemodynamic impact and prognostic relevance of right ventricular pressure load in this population. Methods and Results A total of 296 patients with repaired tetralogy of Fallot (mean age, 17.8±7.9 years) were included in a prospective cardiovascular magnetic resonance multicenter study. Myocardial strain was quantified by feature tracking technique at study entry. Follow-up, including the need for pulmonary valve replacement, was assessed. The combined end point consisted of ventricular tachycardia and cardiac death. A higher echocardiographic RVOT peak gradient was significantly associated with smaller right ventricular volumes and less pulmonary regurgitation, but lower biventricular longitudinal strain. During a follow-up of 10.1 (0.1-12.9) years, the primary end point was reached in 19 of 296 patients (cardiac death, n=6; sustained ventricular tachycardia, n=2; and nonsustained ventricular tachycardia, n=11). A higher RVOT gradient was associated with the combined outcome (hazard ratio [HR], 1.03; 95% CI, 1.00-1.06; P=0.026), and a cutoff gradient of ≥25 mm Hg was predictive for cardiovascular events (HR, 3.69; 95% CI, 1.47-9.27; P=0.005). In patients with pulmonary regurgitation ≥25%, a mild residual RVOT gradient (15-30 mm Hg) was not associated with a lower risk for pulmonary valve replacement. Conclusions Higher RVOT gradients were associated with less pulmonary regurgitation and smaller right ventricular dimensions but were related to reduced biventricular strain and emerged as univariate predictors of adverse events. Mild residual pressure gradients did not protect from pulmonary valve replacement. These results may have implications for the indication for RVOT reintervention in this population.

COVID-19 vs. Classical Myocarditis Associated Myocardial Injury Evaluated by Cardiac Magnetic Resonance and Endomyocardial Biopsy

Background: Despite the ongoing global pandemic, the impact of COVID-19 on cardiac structure and function is still not completely understood. Myocarditis is a rare but potentially serious complication of other viral infections with variable recovery, and is, in some cases, associated with long-term cardiac remodeling and functional impairment.

Aim: To assess myocardial injury in patients who recently recovered from an acute SARS-CoV-2 infection with advanced cardiac magnetic resonance imaging (CMR) and endomyocardial biopsy (EMB).

Methods: In total, 32 patients with persistent cardiac symptoms after a COVID-19 infection, 22 patients with acute classic myocarditis not related to COVID-19, and 16 healthy volunteers were included in this study and underwent a comprehensive baseline CMR scan. Of these, 10 patients post COVID-19 and 13 with non-COVID-19 myocarditis underwent a follow-up scan. In 10 of the post-COVID-19 and 15 of the non-COVID-19 patients with myocarditis endomyocardial biopsy (EMB) with histological, immunohistological, and molecular analysis was performed.

Results: In total, 10 (31%) patients with COVID-19 showed evidence of myocardial injury, eight (25%) presented with myocardial oedema, eight (25%) exhibited global or regional systolic left ventricular (LV) dysfunction, and nine (28%) exhibited impaired right ventricular (RV) function. However, only three (9%) of COVID-19 patients fulfilled updated CMR–Lake Louise criteria (LLC) for acute myocarditis. Regarding EMB, none of the COVID-19 patients but 87% of the non-COVID-19 patients with myocarditis presented histological findings in keeping with acute or chronic inflammation. COVID-19 patients with severe disease on the WHO scale presented with reduced biventricular longitudinal function, increased RV mass, and longer native T1 times compared with those with only mild or moderate disease.

Conclusions: In our cohort, CMR and EMB findings revealed that SARS-CoV-2 infection was associated with relatively mild but variable cardiac involvement. More symptomatic COVID-19 patients and those with higher clinical care demands were more likely to exhibit chronic inflammation and impaired cardiac function compared to patients with milder forms of the disease.

Hemodynamic Modeling of Biological Aortic Valve Replacement Using Preoperative Data Only

Objectives: Prediction of aortic hemodynamics after aortic valve replacement (AVR) could help optimize treatment planning and improve outcomes. This study aims to demonstrate an approach to predict postoperative maximum velocity, maximum pressure gradient, secondary flow degree (SFD), and normalized flow displacement (NFD) in patients receiving biological AVR.

Methods: Virtual AVR was performed for 10 patients, who received actual AVR with a biological prosthesis. The virtual AVRs used only preoperative anatomical and 4D flow MRI data. Subsequently, computational fluid dynamics (CFD) simulations were performed and the abovementioned hemodynamic parameters compared between postoperative 4D flow MRI data and CFD results.

Results: For maximum velocities and pressure gradients, postoperative 4D flow MRI data and CFD results were strongly correlated (R² = 0.75 and R² = 0.81) with low root mean square error (0.21 m/s and 3.8 mmHg). SFD and NFD were moderately and weakly correlated at R² = 0.44 and R² = 0.20, respectively. Flow visualization through streamlines indicates good qualitative agreement between 4D flow MRI data and CFD results in most cases.

Conclusion: The approach presented here seems suitable to estimate postoperative maximum velocity and pressure gradient in patients receiving biological AVR, using only preoperative MRI data. The workflow can be performed in a reasonable time frame and offers a method to estimate postoperative valve prosthesis performance and to identify patients at risk of patient-prosthesis mismatch preoperatively. Novel parameters, such as SFD and NFD, appear to be more sensitive, and estimation seems harder. Further workflow optimization and validation of results seems warranted.

Deep-learning-based real-time prediction of acute kidney injury outperforms human predictive performance

Acute kidney injury (AKI) is a major complication after cardiothoracic surgery. Early prediction of AKI could prompt preventive measures, but is challenging in the clinical routine. One important reason is that the amount of postoperative data is too massive and too high-dimensional to be effectively processed by the human operator. We therefore sought to develop a deep-learning-based algorithm that is able to predict postoperative AKI prior to the onset of symptoms and complications. Based on 96 routinely collected parameters we built a recurrent neural network (RNN) for real-time prediction of AKI after cardiothoracic surgery. From the data of 15,564 admissions we constructed a balanced training set (2224 admissions) for the development of the RNN. The model was then evaluated on an independent test set (350 admissions) and yielded an area under curve (AUC) (95% confidence interval) of 0.893 (0.862-0.924). We compared the performance of our model against that of experienced clinicians. The RNN significantly outperformed clinicians (AUC = 0.901 vs. 0.745, p < 0.001) and was overall well calibrated. This was not the case for the physicians, who systematically underestimated the risk (p < 0.001). In conclusion, the RNN was superior to physicians in the prediction of AKI after cardiothoracic surgery. It could potentially be integrated into hospitals' electronic health records for real-time patient monitoring and may help to detect early AKI and hence modify the treatment in perioperative care.

Sensitivity analysis of FDA´s benchmark nozzle regarding in vitro imperfections - Do we need asymmetric CFD benchmarks?

Modern technologies and methods such as computer simulation, so-called in silico methods, foster the development of medical devices. For accelerating the uptake of computer simulations and to increase credibility and reliability the U.S. Food and Drug Administration organized an inter-laboratory round robin study of a generic nozzle geometry. In preparation of own bench testing experiment using Particle Image Velocimetry, a custom made silicone nozzle was manufactured. By using in silico computational fluid dynamics method the influence of in vitro imperfections, such as inflow variations and geometrical deviations, on the flow field were evaluated. Based on literature the throat Reynolds number was varied Rethroat = 500 ± 50. It could be shown that the flow field errors resulted from variations of inlet conditions can be largely eliminated by normalizing if the Reynolds number is known. Furthermore, a symmetric imperfection of the silicone model within manufacturing tolerance does not affect the flow as much as an asymmetric failure such as an unintended curvature of the nozzle. In brief, we can conclude that geometrical imperfection of the reference experiment should be considered accordingly to in silico modelling. The question arises, if an asymmetric benchmark for biofluid analysis needs to be established. An eccentric nozzle benchmark could be a suitable case and will be further investigated.

Abstract P180: Effect Of Sunitinib Treatment On Skin Sodium Accumulation In Patients With Metastatic Renal Cancer: A Pilot Study

Angiogenesis is required for invasive tumor growth and metastasis which is controlled mainly by vascular endothelial growth factors (VEGF). Novel strategies for cancer treatment target VEGF signaling. These agents are featured by adverse events including hypertension. New concepts suggest that besides the kidneys, the skin also plays a role in body sodium homeostasis and blood pressure regulation by a VEGF-C–dependent buffering mechanism. Here, we tested the hypothesis that changes in blood pressure correspond to tissue sodium accumulation during sunitinib treatment of metastatic renal cell carcinoma patients (https://clinicaltrials.gov/identifier: NCT04368546; Charité ethical approval EA1/044/15).Male patients (n=4) took sunitinib according to the standard treatment protocol, 50 mg once daily, taken for 4 weeks followed by a 2-weeks off treatment period. Measurements were performed at baseline (before sunitinib treatment), and over a complete on-off-on period. Tissue sodium content was measured using non-invasive 23Na-MRI; skin sodium was measured in a group (n=5) of age-matched healthy subjects, as well. Blood pressure was measured according to AHA guidelines. Blood withdrawal followed after ca. 45 minutes of sitting to measure VEGF-A, VEGF-C, endothelin-1, renin and aldosterone levels.Elevated systolic blood pressure under sunitinib treatment decreased to the baseline level in the off-treatment phase (130.5 mmHg vs 117.5 mmHg, respectively, p<0.05). Plasma endothelin-1 levels mirrored directly and VEGF-A levels inversely the blood pressure changes. Baseline skin sodium content was similar to the skin sodium level of healthy controls. Skin sodium content was elevated after the first on-treatment phase and stayed high in all the following measurements in comparison to control subjects. Patients had high baseline VEGF-C levels that decreased after the first treatment with sunitinib and stayed low independently of further treatment phase.In conclusion, sunitinib treatment suppresses VEGF-C levels permanently which is associated with sustained elevated skin sodium levels. Furthermore, we confirmed the association between plasma endothelin-1 levels and blood pressure changes during sunitinib treatment protocol.

Variability of Myocardial Strain During Isometric Exercise in Subjects With and Without Heart Failure

Background: Fast strain-encoded cardiac magnetic resonance imaging (cMRI, fast-SENC) is a novel technology potentially improving characterization of heart failure (HF) patients by quantifying cardiac strain. We sought to describe the impact of isometric handgrip exercise (HG) on cardiac strain assessed by fast-SENC in HF patients and controls. Methods: Patients with stable HF and controls were examined using cMRI at rest and during HG. Left ventricular (LV) global longitudinal strain (GLS) and global circumferential (GCS) were derived from image analysis software using fast-SENC. Strain change < -0.5 and > +0.5 was classified as increase and decrease, respectively. Results: The study population comprised 72 subjects, including HF with reduced, mid-range and preserved ejection fraction and controls (HFrEF n = 18 HFmrEF n = 18, HFpEF n = 17, controls: n = 19). In controls, LV GLS remained stable in 36.8%, increased in 36.8% and decreased in 26.3% of subjects during HG. In HF subgroups, similar patterns of LV GLS response were observed (HFpEF: stable 41.2%, increase 35.3%, decrease: 23.5%; HFmrEF: stable 50.0%, increase 16.7%, decrease: 33.3%; HFrEF: stable 33.3%, increase 22.2%, decrease: 44.4%, p = 0.668). Mean change between LV GLS at rest and during HG ranged close to zero with broad standard deviation in all subgroups and was not significantly different between subgroups (+1.2 ± 5.4%, -0.6 ± 8.3%, -1.7 ± 10.7%, and -3.1 ± 19.4%, p = 0.746 in controls, HFpEF, HFmrEF and HFrEF, respectively). However, the absolute value of LV GLS change-irrespective of increase or decrease-was significantly different between subgroups with 4.4 ± 3.2% in controls, 5.9 ± 5.7% in HFpEF, 6.8 ± 8.3% in HFmrEF and 14.1 ± 13.3% in HFrEF (p = 0.005). The absolute value of LV GLS change significantly correlated with resting LVEF, NTproBNP and Minnesota Living with Heart Failure questionnaire scores. Conclusion: The response to isometric exercise in LV GLS is heterogeneous in all HF subgroups and in controls. The absolute value of LV GLS change during HG exercise is elevated in HF patients and associated with measures of HF severity. The diagnostic utility of fast-SENC strain assessment in conjunction with HG appears to be limited. Trial Registration: URL: https://www.drks.de; Unique Identifier: DRKS00015615.

Virtual downsizing for decision support in mitral valve repair

PURPOSE

Various options are available for the treatment of mitral valve insufficiency, including reconstructive approaches such as annulus correction through ring implants. The correct choice of general therapy and implant is relevant for an optimal outcome. Additional to guidelines, decision support systems (DSS) can provide decision aid by means of virtual intervention planning and predictive simulations. Our approach on virtual downsizing is one of the virtual intervention tools that are part of the DSS workflow. It allows for emulating a ring implantation based on patient-specific lumen geometry and vendor-specific implants.

METHODS

Our approach is fully automatic and relies on a lumen mask and an annulus contour as inputs. Both are acquired from previous DSS workflow steps. A virtual surface- and contour-based model of a vendor-specific ring design (26-40 mm) is generated. For each case, the ring geometry is positioned with respect to the original, patient-specific annulus and additional anatomical landmarks. The lumen mesh is parameterized to allow for a vertex-based deformation with respect to the user-defined annulus. Derived from post-interventional observations, specific deformation schemes are applied to atrium and ventricle and the lumen mesh is altered with respect to the ring location.

RESULTS

For quantitative evaluation, the surface distance between the deformed lumen mesh and segmented post-operative echo lumen close to the annulus was computed for 11 datasets. The results indicate a good agreement. An arbitrary subset of six datasets was used for a qualitative evaluation of the complete lumen. Two domain experts compared the deformed lumen mesh with post-interventional echo images. All deformations were deemed plausible.

CONCLUSION

Our approach on virtual downsizing allows for an automatic creation of plausible lumen deformations. As it takes only a few seconds to generate results, it can be added to a virtual intervention toolset without unnecessarily increasing the pipeline complexity.

Abstract P236: Sodium Accumulates in the Skin of Patients and Mice With Psoriasis

Sodium can be buffered in the skin, which mechanism is altered during aging and in certain diseases such as hypertension. High salt environment can promote autoimmunity by expanding pathogenic IL-17 producing T helper (Th17) cells. Psoriasis is a relapsing and remitting inflammatory autoimmune disease affecting the skin and joints and involves proinflammatory Th17 cells. Here we tested the hypothesis if psoriatic skin has a higher sodium content in mice and humans. We used two psoriasis mouse models; the K14-IL-17A ind/+ mice overexpressing IL-17A in K14-positive keratinocytes and the imiquimod (IMQ) mouse model by applying 62.5 mg IMQ cream (5%) on the shaved back and ears of FVB/N mice for 5 days daily. End of the study skins of mice were collected, weighted, dried and ashed to measure water and sodium content. Additionally, skin sodium and water content were measured in psoriasis patients and aged matched healthy controls by non-invasive 23 Na-MRI on non-affected flexor site of the lower leg and by 23 Na-spectroscopy to compare affected and non-affected sites of the leg. K14-IL-17A ind/+ mice had significantly higher sodium content compared to control IL-17A ind/+ mice (0.191±0.021 vs. 0.137±0.023 mg/g dry weight) together with an elevated water content. IMQ-treated back skin had significantly higher sodium content compared to untreated ventral skin of the same mice (0.175±0.023 vs. 0.143±0.014 mg/g dry weight), whereas sham mice had a significantly lower content in both regions (0.116±0.010 vs. 0.107±0.005 mg/g dry weight). IMQ treatment led to significant expansion of IL-17 producing γδT cells in the skin, regional lymph nodes and in the spleen with typical skin lesions. Patients with psoriasis area and severity index (PASI) >5 had significantly higher sodium content in the skin compared to those with lower PASI or with healthy controls (17.73±1.52 vs. 14.32±1.54 vs. 14.30±2.59 AU, respectively); this elevation was water coupled. PASI significantly correlated with skin sodium content (Pearson’s r=0.598, P<0.001). Additionally, patients with PASI>5 has higher sodium content in the affected skin compared to non-affected skin of the same patient. Data from animal models and humans argue for higher sodium accumulation in the inflamed skin.

An ultra-high vacuum scanning tunneling microscope operating at sub-Kelvin temperatures and high magnetic fields for spin-resolved measurements

We present the construction and performance of an ultra-low-temperature scanning tunneling microscope (STM), working in ultra-high vacuum (UHV) conditions and in high magnetic fields up to 9 T. The cryogenic environment of the STM is generated by a single-shot ³He magnet cryostat in combination with a ⁴He dewar system. At a base temperature (300 mK), the cryostat has an operation time of approximately 80 h. The special design of the microscope allows the transfer of the STM head from the cryostat to a UHV chamber system, where samples and STM tips can be easily exchanged. The UHV chambers are equipped with specific surface science treatment tools for the functionalization of samples and tips, including high-temperature treatments and thin film deposition. This, in particular, enables spin-resolved tunneling measurements. We present test measurements using well-known samples and tips based on superconductors and metallic materials such as LiFeAs, Nb, Fe, and W. The measurements demonstrate the outstanding performance of the STM with high spatial and energy resolution as well as the spin-resolved capability.

Non-invasive assessment of patient-specific aortic haemodynamics from four-dimensional flow MRI data

We introduce a parameter estimation framework for automatically and robustly personalizing aortic haemodynamic computations from four-dimensional magnetic resonance imaging data. The framework is based on a reduced-order multiscale fluid-structure interaction blood flow model, and on two calibration procedures. First, Windkessel parameters of the outlet boundary conditions are personalized by solving a system of nonlinear equations. Second, the regional mechanical wall properties of the aorta are personalized by employing a nonlinear least-squares minimization method. The two calibration procedures are run sequentially and iteratively until both procedures have converged. The parameter estimation framework was successfully evaluated on 15 datasets from patients with aortic valve disease. On average, only 1.27 ± 0.96 and 7.07 ± 1.44 iterations were required to personalize the outlet boundary conditions and the regional mechanical wall properties, respectively. Overall, the computational model was in close agreement with the clinical measurements used as objectives (pressures, flow rates, cross-sectional areas), with a maximum error of less than 1%. Given its level of automation, robustness and the short execution time (6.2 ± 1.2 min on a standard hardware configuration), the framework is potentially well suited for a clinical setting.

Impact of Single Center Treatment on Ewing Sarcoma 10-Year Long Term Survival Rates

PURPOSE OF THE STUDY Ewing sarcomas (ES) are the second most common solid malignant bone tumors in both, children and adolescents, and systemic chemotherapy protocols were established during the last 3 decades which proved to be a successful approach in addition to local treatment. The purpose of the present study is (i) to provide survival rates and prognostic factors for patients with ES which received treatment in a single center and (ii) to compare data with results of multicenter studies. MATERIALS AND METHODS Patients (n = 38) were treated by the same surgeon whereas surgery was combined with radiotherapy in 55.3% of the patients (n = 21). Median age at diagnosis was 17.5 years (4.7-60) and the median follow-up time for all patients was 8.2 years (9.8 years for survivors, 3.2 years for non-survivors). RESULTS The survival rate for metastasis free sarcoma decreases from 90.5% to 50% for patients diagnosed with disseminated disease stage. Patients with a good response to chemotherapy survived in 83.3% of the cases. In addition, a higher OS was found for patients younger than 15 years (82.4%) when compared to patients older than 15 years (73.3%). In contrast, multicenter studies reported lower survival rates for metastasis free (~60%) and metastasis stages (< 40%). DISCUSSION The survival rates in the present single center study are higher than the rates reported from multi-center studies although same chemotherapy protocols were used and no substantially difference are apparent for patient population. CONCLUSIONS Based on the present data we re-emphasize that patients with Ewing sarcoma receive appropriate treatment in a large and qualified center particularly considering the survival rates. In addition, our data underline that a close collaboration between the oncological team and the experienced surgeon is crucial for patient's care. Key words: Ewing sarcoma, survival rate, single center, prognostic factors, chemotherapy, surgery, multi center, single center.

Myocardial deformation parameters predict outcome in patients with repaired tetralogy of Fallot

BACKGROUND

Parameters of myocardial deformation have been suggested to be superior to conventional measures of ventricular function and to predict outcome in repaired tetralogy of Fallot (ToF). We aimed to test the hypothesis that parameters of myocardial deformation on cardiac MRI (CMR) relate to symptoms and provide prognostic information in patients with repaired ToF.

METHODS AND RESULTS

We included 372 patients with ToF (median age 16 years; 55% male), recruited within a nationwide, prospective study. Longitudinal (LS), circumferential (CS) and radial global strain (RS) were analysed by CMR-based feature tracking (FT). A combined endpoint of death, successful resuscitation or documented ventricular tachycardia was employed. Parameters of global strain were associated with New York Heart Association (NYHA) class and symptomatic deterioration. During a median follow-up of 7.4 years, 20 events occurred. Left ventricular (LV) CS and right ventricular (RV) LS emerged as predictors of outcome, independent of QRS duration, LV/RV ejection fraction and volumes, NYHA class and peak oxygen uptake. In combination, these parameters also identified a subgroup of patients at significantly increased risk of adverse of outcomes (HR 3.3, p=0.002). Furthermore, LV LS, RS, CS and RV LS were related to the risk of death and nearly missed death (p<0.05 for all).

CONCLUSIONS

FT-CMR provides myocardial deformation parameters, easily derived from standard CMR studies. They relate to symptoms and clinical deterioration in patients with ToF. More importantly, they predict adverse outcome independent of established risk markers, and should be considered as a useful adjunct to established outcome predictors, especially in younger patients with ToF.

CLINICAL TRIAL REGISTRATION NUMBER

http://www.clinicaltrials.gov: NCT00266188; Results.

Effects of incremental beta-blocker dosing on myocardial mechanics of the human left ventricle: MRI 3D-tagging insight into pharmacodynamics supports theory of inner antagonism

Beta-blockers contribute to treatment of heart failure. Their mechanism of action, however, is incompletely understood. Gradients in beta-blocker sensitivity of helically aligned cardiomyocytes compared with counteracting transversely intruding cardiomyocytes seem crucial. We hypothesize that selective blockade of transversely intruding cardiomyocytes by low-dose beta-blockade unloads ventricular performance. Cardiac magnetic resonance imaging (MRI) 3D tagging delivers parameters of myocardial performance. We studied 13 healthy volunteers by MRI 3D tagging during escalated intravenous administration of esmolol. The circumferential, longitudinal, and radial myocardial shortening was determined for each dose. The curves were analyzed for peak value, time-to-peak, upslope, and area-under-the-curve. At low doses, from 5 to 25 μg·kg−1·min−1, peak contraction increased while time-to-peak decreased yielding a steeper upslope. Combining the values revealed a left shift of the curves at low doses compared with baseline without esmolol. At doses of 50 to 150 μg·kg−1·min−1, a right shift with flattening occurred. In healthy volunteers we found more pronounced myocardial shortening at low compared with clinical dosage of beta-blockers. In patients with ventricular hypertrophy and higher prevalence of transversely intruding cardiomyocytes selective low-dose beta-blockade could be even more effective. MRI 3D tagging could help to determine optimal individual beta-blocker dosing avoiding undesirable side effects.

The impact of T-cell depletion techniques on the outcome after haploidentical hematopoietic SCT

Several T-cell depletion (TCD) techniques are used for haploidentical hematopoietic SCT (HSCT), but direct comparisons are rare. We therefore studied the effect of in vitro TCD with graft engineering (CD34 selection or CD3/CD19 depletion, 74%) or in vivo TCD using alemtuzumab (26%) on outcome, immune reconstitution and infections after haploidentical HSCT. We performed a retrospective multicenter analysis of 72 haploidentical HSCT in Switzerland. Sixty-seven patients (93%) had neutrophil engraftment. The 1-year OS, TRM and relapse incidence were 48 (36-60)%, 20 (11-33)% and 42 (31-57)%, respectively, without differences among the TCD groups. In vivo TCD caused more profound lymphocyte suppression early after HSCT, whereas immune recovery beyond the second month was comparable between the two groups. Despite anti-infective prophylaxis, most patients experienced post-transplant infectious complications (94%). Patients with in vivo TCD had a higher incidence of CMV reactivations (54% vs 28%, P=0.015), but this did not result in a higher TRM. In conclusion, TCD by graft engineering or alemtuzumab are equally effective for haploidentical HSCT.

Management of children and adolescents with primary immune thrombocytopenia: controversies and solutions

The management including diagnostic procedures, prophylaxis, treatment and follow-up of patients with primary immune thrombocytopenia (ITP) in childhood is controversial due to limited clinical data, difficulties in the estimation of individual bleeding risk and heterogeneity of pathophysiology potentially causing various treatment responses. Advances in the management of children include increased international collaborations, improved quality of diagnosis and treatment, increased clinical data, refinement of consensus statements where clinical evidence is absent, new drugs and last but not least establishment of watch-and-wait strategies. The Intercontinental Cooperative ITP Study Group promotes international collaboration since more than 10 years based on a worldwide network and experience in registries. Future considerations include concentration of available resources, strengthening international collaboration, focusing on most important scientific and clinical questions, such as identification of the subgroup of patients that benefits most from prophylactic platelet-enhancing treatments and investigation of treatment endpoints other than concepts solely based on the platelet count, including bleeding symptoms, health-related quality of life and economical aspects of treatments.

[Consensus recommendations of the German Radiology Society (DRG), the German Cardiac Society (DGK) and the German Society for Pediatric Cardiology (DGPK) on the use of cardiac imaging with computed tomography and magnetic resonance imaging]

Cardiac magnetic resonance imaging (MRI) and computed tomography (CT) have been developed rapidly in the last decade. Technical improvements and broad availability of modern CT and MRI scanners have led to an increasing and regular use of both diagnostic methods in clinical routine. Therefore, this German consensus document has been developed in collaboration by the German Cardiac Society, German Radiology Society, and the German Society for Pediatric Cardiology. It is not oriented on modalities and methods, but rather on disease entities. This consensus document deals with coronary artery disease, cardiomyopathies, arrhythmias, valvular diseases, pericardial diseases and structural changes, as well as with congenital heart defects. For different clinical scenarios both imaging modalities CT and MRI are compared and evaluated in the specific context.

Hereditary angioedema (HAE) in children and adolescents--a consensus on therapeutic strategies

Hereditary angioedema due to C1 inhibitor (C1 esterase inhibitor) deficiency (types I and II HAE-C1-INH) is a rare disease that usually presents during childhood or adolescence with intermittent episodes of potentially life-threatening angioedema. Diagnosis as early as possible is important to avoid ineffective therapies and to properly treat swelling attacks. At a consensus meeting in June 2011, pediatricians and dermatologists from Germany, Austria, and Switzerland reviewed the currently available literature, including published international consensus recommendations for HAE therapy across all age groups. Published recommendations cannot be unconditionally adopted for pediatric patients in German-speaking countries given the current approval status of HAE drugs. This article provides an overview and discusses drugs available for HAE therapy, their approval status, and study results obtained in adult and pediatric patients. Recommendations for developing appropriate treatment strategies in the management of HAE in pediatric patients in German-speaking countries are provided.Conclusion Currently, plasma-derived C1 inhibitor concentrate is considered the best available option for the treatment of acute HAE-C1-INH attacks in pediatric patients in German-speaking countries, as well as for short-term and long-term prophylaxis.

The influence of tumor- and treatment-related factors on the development of local recurrence in osteosarcoma after adequate surgery. An analysis of 1355 patients treated on neoadjuvant Cooperative Osteosarcoma Study Group protocols

BACKGROUND

Local recurrence (LR) in osteosarcoma is associated with very poor prognosis. We sought to evaluate which factors correlate with LR in patients who achieved complete surgical remission with adequate margins.

PATIENTS AND METHODS

We analyzed 1355 patients with previously untreated high-grade central osteosarcoma of the extremities, the shoulder and the pelvis registered in neoadjuvant Cooperative Osteosarcoma Study Group trials between 1986 and 2005. Seventy-six patients developed LR.

RESULTS

Median follow-up was 5.56 years. No participation in a study, pelvic tumor site, limb-sparing surgery, soft tissue infiltration beyond the periosteum, poor response to neoadjuvant chemotherapy, failure to complete the planned chemotherapy protocol and biopsy at a center other than the one performing the tumor resection were significantly associated with a higher LR rate. No differences were found for varying surgical margin widths. Surgical treatment at centers with small patient volume and additional surgery in the primary tumor area, other than biopsy and tumor resection, were significantly associated with a higher rate of ablative surgery.

CONCLUSIONS

Patient enrollment in clinical trials and performing the biopsy at experienced institutions capable of undertaking the tumor resection without compromising the oncological and functional outcome should be pursued in the future.

An open-source software tool for the generation of relaxation time maps in magnetic resonance imaging

BACKGROUND

In magnetic resonance (MR) imaging, T1, T2 and T2* relaxation times represent characteristic tissue properties that can be quantified with the help of specific imaging strategies. While there are basic software tools for specific pulse sequences, until now there is no universal software program available to automate pixel-wise mapping of relaxation times from various types of images or MR systems. Such a software program would allow researchers to test and compare new imaging strategies and thus would significantly facilitate research in the area of quantitative tissue characterization.

RESULTS

After defining requirements for a universal MR mapping tool, a software program named MRmap was created using a high-level graphics language. Additional features include a manual registration tool for source images with motion artifacts and a tabular DICOM viewer to examine pulse sequence parameters. MRmap was successfully tested on three different computer platforms with image data from three different MR system manufacturers and five different sorts of pulse sequences: multi-image inversion recovery T1; Look-Locker/TOMROP T1; modified Look-Locker (MOLLI) T1; single-echo T2/T2*; and multi-echo T2/T2*. Computing times varied between 2 and 113 seconds. Estimates of relaxation times compared favorably to those obtained from non-automated curve fitting. Completed maps were exported in DICOM format and could be read in standard software packages used for analysis of clinical and research MR data.

CONCLUSIONS

MRmap is a flexible cross-platform research tool that enables accurate mapping of relaxation times from various pulse sequences. The software allows researchers to optimize quantitative MR strategies in a manufacturer-independent fashion. The program and its source code were made available as open-source software on the internet.

Intravenous immunoglobulins induce potentially synergistic immunomodulations in autoimmune disorders

The increase in platelets in patients with immune thrombocytopenia (ITP) by intravenous administration of human immunoglobulin concentrates (IVIG) reflects a therapeutic immunomodulatory intervention targeted at the disturbed immune response in many inflammatory and autoimmune disorders. These immunoglobulin concentrates contain large numbers of antibodies as well as trace levels of various other immunologically active molecules. Clinical and laboratory studies have documented various mechanisms of action of IVIG. The complex network of immunological reactions resulting from the infusion of IVIG includes changes in several cytokines, interactions with dendritic cells, T- and B- lymphocyte effects, macrophage effects, mediated by distinct Fc-gamma receptors. In addition, effects on complement components and apoptosis have also been observed. Synergism between the different elements of the immune response characterizes the beneficial effects of IVIG in inflammatory and autoimmune disorders. They have immunopathogeneses and clinical manifestations which are difficult to define and therefore IVIG treatment indications remain heterogeneous. Dose finding studies are missing for most of the indications of the drug. In future research, defining the appropriate subgroups of patients should be undertaken. This may be accomplished by prospective registries collecting data on large numbers of patients with long-term follow-up. Controlled clinical and laboratory studies may follow based on new, validated patient selection criteria and focused on mechanisms of action, leading to more evidence-based indications.

Physical models aiding in complex congenital heart surgery

PURPOSE

Our aim was to improve spatial imagination of complex congenital cardiac abnormalities for subsequent surgical intervention.

DESCRIPTION

Magnetic resonance imaging data of a patient with complex congenital heart malformations was post-processed with software developed at our institution. The resulting virtual surface data sets were printed out three-dimensionally by rapid prototyping techniques.

EVALUATION

We present the first patient operated on with intraoperative use of physical models representing the intracardiac volumes (RepliCast) or muscle and vessel walls (RepliCardio). The courses of the coronary arteries were visible on the RepliCast, whereas the RepliCardio showed intracardiac views a surgeon could never obtain intraoperatively in the relaxed heart. Other than on virtual reconstructions presented on computer screens, physical models vastly improve the spatial imagination and give precise information regarding localization and actual size of abnormal structures. The self-explanatory utility of these models shortened preparation and expedited orientation on the open heart.

CONCLUSIONS

The additional spatial information provided by RepliCast and RepliCardio models may enable even high-risk correction procedures in patients with complex congenital heart disease.

Ecotoxicological characterization of hazardous wastes

In Europe hazardous wastes are classified by 14 criteria including ecotoxicity (H 14). Standardized methods originally developed for chemical and soil testing were adapted for the ecotoxicological characterization of wastes including leachate and solid phase tests. A consensus on which tests should be recommended as mandatory is still missing. Up to now, only a guidance on how to proceed with the preparation of waste materials has been standardized by CEN as EN 14735. In this study, tests including higher plants, earthworms, collembolans, microorganisms, duckweed and luminescent bacteria were selected to characterize the ecotoxicological potential of a boiler slag, a dried sewage sludge, a thin sludge and a waste petrol. In general, the instructions given in EN 14735 were suitable for all wastes used. The evaluation of the different test systems by determining the LC/EC(50) or NOEC-values revealed that the collembolan reproduction and the duckweed frond numbers were the most sensitive endpoints. For a final classification and ranking of wastes the Toxicity Classification System (TCS) using EC/LC(50) values seems to be appropriate.

Evaluation of new software for angiographic determination of right ventricular volumes

OBJECTIVES

The scope of the study was to evaluate a recent software for angiographic volume determination as compared to cardiovascular magnetic resonance imaging.

BACKGROUND

A new right ventricular analysis software closes a diagnostic gap in quantitative angiography. Cardiovascular magnetic resonance imaging short axis multi slice summation is a validated reference standard.

METHODS

Right ventricular angiograms were acquired in frontal and lateral projection in 15 pediatric and 17 adult patients. Additional angiograms were acquired in RAO30 degrees /LAO60 degrees projections in 10 adult patients. The tested models comprised area length with different regressions, multi-slice with different regressions, Boak, and pyramid method. Original regressions were used to calculate angiographic right ventricular volume. Right ventricular reference volumes were determined by multi-slice summation from cardiac magnetic resonance short-axis images.

RESULTS

Mean inter-observer difference was -1 ml (95% confidence: -35-34 ml) and mean intra-observer difference was 0 ml (95% confidence: -22-22 ml). There was no significant difference (4 ml, 95% confidence: -22-30 ml) between geometric calibration and calibration by a sphere. The area length and multi-slice models demonstrated the best agreement with the cardiac magnetic resonance reference. Performance was best for the Onnasch Lange models.

CONCLUSION

The evaluated software provides acceptably accurate volume estimates for the majority of ventricles. In a few cases larger errors may occur, however. The area length and multi-slice models preferably with Onnasch Lange regressions may be recommended. Inter- and intra-observer agreement were excellent. Geometric calibration using data from DICOM header files may be used.

Combination of broad molecular screening and cytogenetic analysis for genetic risk assignment and diagnosis in patients with acute leukemia

We evaluated the impact of genetic analysis combining cytogenetics and broad molecular screening on leukemia diagnosis according to World Health Organization (WHO) and on genetic risk assignment. A two-step nested multiplex RT-PCR assay was used that allowed the detection of 29 fusion transcripts. A total of 186 patients (104 males (56%), 174 adults (94%), 12 children (6%), 155 AML (83%), 31 ALL (17%)) characterized by morphology and immunophenotyping were included. Of these 186 patients, 120 (65%) had a genetic abnormality. Molecular typing revealed a fusion transcript in 49 (26%) patients and cytogenetic analysis revealed an abnormal karyotype in 119 (64%). A total of 27 (14%) cases were genetically classified as favorable, 107 (58%) intermediate and 52 (28%) unfavorable. For 38 (20%) patients, there was a discrepancy in the genetic risk assignments obtained from broad molecular screening and cytogenetics. Cryptic fusion transcripts in nine (5%) patients changed the genetic risk assignment in four and the WHO classification in four patients. In 34 patients (18%), cytogenetics defined the risk assignment by revealing structural and numerical chromosomal abnormalities not detected by molecular screening. Broad molecular screening and cytogenetics are complementary in the diagnosis and genetic risk assignment of acute leukemia.

Childhood ITP: 12 months follow-up data from the prospective registry I of the Intercontinental Childhood ITP Study Group (ICIS)

BACKGROUND

Acute and chronic idiopathic thrombocytopenic purpura (ITP) is traditionally based on the duration of thrombocytopenia at the cut-off point of 6 months after diagnosis. Registry I evaluated the diagnosis, definition, management, and follow-up of childhood ITP. This report focuses on children with thrombocytopenia persisting more than 6 months.

PROCEDURE

Data were collected by questionnaires to the physicians caring for children with ITP, at diagnosis, 6, and 12 months later. Data were compared regarding initial features and follow-up with emphasis on children with persistent thrombocytopenia, and those with ITP who recovered their platelet counts between 7 and 12 months from diagnosis.

RESULTS

At 12 months from diagnosis, 79 of 308 (25.6%) evaluable children recovered from ITP and 229 had ongoing ITP. Children with recovered ITP were younger than children with ongoing ITP (P = 0.043) and exhibited a lower frequency of bleeding symptoms during the first 6 months after diagnosis (P = 0.018). Frequency of hospitalization, bone marrow aspiration, and drug treatment differed regionally.

CONCLUSIONS

The high rate of recovery from ITP between 7 to 12 months demonstrates, that the cut-off point of 6 months for the definition of chronic ITP does not adequately differentiate chronic from acute ITP. The majority of children with ITP have variable time to recovery with gradual improvement of platelet counts and disappearance of bleeding signs. ITP is a heterogeneous disorder with a diverse natural history and diverse pattern of treatment response.

Characterisation of epitopes on barley mild mosaic virus coat protein recognised by a panel of novel monoclonal antibodies

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dot-blot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6PDPI9 and 96ITDDEK101, respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44LPEPKM49, which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology.

Purified donor NK-lymphocyte infusion to consolidate engraftment after haploidentical stem cell transplantation

This pilot study tested feasibility of natural killer cell purification and infusion (NK-DLI) in patients after haploidentical hematopoietic stem cell transplantation (HSCT). The aim was to obtain >or=1.0 x 10(7)/kg CD56+/CD3- NK cells and <1.0 x 10(5)/kg CD3+ T cells. Mononuclear cells were collected by 10 l leukapheresis. A two-step ex vivo procedure was used to purify NK cells, using an immunomagnetic T-cell depletion, followed by NK-cell enrichment. Five patients with high-risk myeloid malignancies were included, presenting 3-12 months after a haploidentical HSCT with mixed chimerism (3), impending graft failure (1) or early relapse (1). The purified product contained a median of 1.61 x 10(7)/kg (range 0.21-2.2) NK cells and 0.29 x 10(5)/kg (0.11-1.1) T cells. A purity of NK cells of 97% (78-99), a recovery of 35.5% (13-75), and a T-cell depletion of 3.55 log (2.9-4.5) was achieved. Infusions were well tolerated and none of the patients developed graft-versus-host disease. We observed an increase in donor chimerism in 2/5, stable mixed chimerism, decreasing chimerism and relapse of AML in one patient each. Selection of NK-DLI is technically feasible. NK cells are well tolerated when used as adoptive immunotherapy in recipients of haploidentical HSCT.

Ein Verfahren zur sicheren Visualisierung und Lokalisierung von Kathetern für MR-geführte intravaskuläre Prozeduren

The present paper describes a method for the visualization and localization of a catheter during real-time imaging on a clinical magnetic resonance tomograph (MRT). This method includes the use of an apposite catheter hardware equipped with an optically tunable resonant marker on its tip (OptiMa-Catheter). In the tuned state, the marker produces an intense signal spot in the MR image. The signal is modulated by optical detuning controlled by the MRT system, which results in improved visualization of the catheter tip due to flashing. During real-time imaging, additionally, the localization of the tip is precisely detected and the slice tracking automatically performed. Experiments demonstrate that the OptiMa-Catheter does not generate relevant resonance heating during imaging. Consequently, it combines the visualization and localization known from active techniques with the safety of passive techniques.

[MRI in postoperative assessment of univentricular heart disease: correlation with echocardiography and angiography]

PURPOSE

To determine the value of MRI in the postoperative evaluation of a singular ventricle compared to echocardiography and cardiac catheterization.

MATERIALS AND METHODS

Thirty-one patients (range: 6 months to 30 years) with a functional single ventricle following palliative corrective operations. Five patients had a Blalock-Taussig-Shunt, 8 patients a Glenn-Anastomosis and 18 a cavopulmonary shunt (6 with classic Fontan-Circulation, 12 with modified cavopulmonary anastomosis). The results in terms of postoperative morphologic changes were compared to percutaneous echocardiography (31/31) and cardiac catheterization (6/31).

RESULTS

Echocardiography, which was performed on all patients, could not visualize the entire length of the tunnel, the Glenn-Anastomosis or the central pulmonary arteries in 70 % of the patients due to an inadequate acoustic window. MRI was able to show the entire tunnel in 11/12 patients and the central pulmonary arteries in 30/31 patients. The exact anatomy was seen in all 6 patients undergoing cardiac catheterization.

CONCLUSION

MRI is useful in the postoperative evaluation of a functionally single ventricle. It is superior to echocardiography. Cardiac catheterization should be reserved for patients with inconclusive MRI findings.

[MR contrast media for cardiovascular imaging]

MR contrast media improve the diagnostic capability of MRI and MRA. They are used in the discrimination of viable and non-viable myocardium, transmural and non-transmural infarction, occlusive and reperfused infarction and for measurement of myocardial perfusion. Currently, clinical studies are almost completely restricted to the use of extracellular non-specific MR contrast media (i. e., Gd-DTPA, Gd-DTPA,-BMA, Gd-BOPTA, Gd-D03A). However, the feasibility of using intravascular, necrosis specific or intracellular MR contrast media or endogeneous substrates as specific MR contrast media in cardiovascular imaging has been demonstrated in experimental and a few clinical studies. Intravascular contrast media (i. e., MS-325 or NC100150 Injection) allow assessment of microvascular integrity and performance of MR angiography. Necrosis specific contrast media (i. e., Gadophrin-2) have been used for sizing the extent of infarcted myocardium while intracellular contrast media (i. e., Mn-DPDP) delineate viable myocardium. Endogenous contrast media (i. e., Deoxyhemoglobin, Na (+) or K (+)) have been tested for detecting the alterations in concentrations of these ions in infarcted myocardium and for perfusion measurements. Furthermore, intravascular MR contrast media may be useful for MRA and MRI guided cardiovascular interventions.