Robert Manka

University Hospital Zürich, Zürich, Zurich, Switzerland

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Publications (74)461.03 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose To evaluate the potential of advanced modeled iterative reconstruction (ADMIRE) for optimizing radiation dose of high-pitch coronary CT angiography (CCTA). Methods High-pitch 192-slice dual-source CCTA was performed in 25 patients (group 1) according to standard settings (ref. 100 kVp, ref. 270 mAs/rot). Images were reconstructed with filtered back projection (FBP) and ADMIRE (strength levels 1–5). In another 25 patients (group 2), high-pitch CCTA protocol parameters were adapted according to results from group 1 (ref. 160 mAs/rot), and images were reconstructed with ADMIRE level 4. In ten patients of group 1, vessel sharpness using full width at half maximum (FWHM) analysis was determined. Image quality was assessed by two independent, blinded readers. Results Interobserver agreements for attenuation and noise were excellent (r = 0.88/0.85, p p p Conclusions In a selected population, ADMIRE can be used for optimizing high-pitch CCTA to an effective dose of 0.3 mSv. Key points • Advanced modeled IR (ADMIRE) reduces image noise up to 50 % as compared to FBP. • Coronary artery vessel borders show an increasing sharpness at higher ADMIRE levels. • High-pitch CCTA with ADMIRE is possible at a radiation dose of 0.3 mSv.
    European Radiology 06/2015; DOI:10.1007/s00330-015-3862-5 · 4.34 Impact Factor
  • European Heart Journal 04/2015; DOI:10.1093/eurheartj/ehv147 · 14.72 Impact Factor
  • Circulation Cardiovascular Imaging 03/2015; DOI:10.1161/CIRCIMAGING.114 · 6.75 Impact Factor
  • European Heart Journal 02/2015; 36(16). DOI:10.1093/eurheartj/ehv020 · 14.72 Impact Factor
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    ABSTRACT: Over the past decade, cardiovascular magnetic resonance (CMR) has become an established non-invasive imaging modality in cardiology. It provides clinicians and researchers with an unparalleled versatility of diagnostic parameters such as cardiac morphology, function, myocardial texture and vascular flow. One of the most relevant applications of CMR is the assessment of patients with suspected or known coronary artery disease (CAD). In large clinical trials, CMR has proven its robustness, diagnostic performance and prognostic value in CAD. In patients with known or suspected chronic CAD, detection of ischaemia and myocardial viability for guiding therapeutic decisions is a major strength of CMR. Patients with ischaemic congestive heart failure (CHF) may benefit from CMR for planning of device implantation or monitoring intracavital thrombi. Finally, the use of CMR in the emergency department for the assessment of patients with acute chest pain is an emerging field, in which CMR's capability to characterize myocardial tissue regarding e.g. necrosis, edema or microvascular obstruction (MVO) may prove clinically useful. The CMR technology is safe, free of ionizing radiation and proved higher diagnostic accuracy and superior cost efficiency compared with other standard diagnostic modalities. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
    International Journal of Cardiology 11/2014; 193. DOI:10.1016/j.ijcard.2014.11.098 · 6.18 Impact Factor
  • International Journal of Cardiology 10/2014; 177(3). DOI:10.1016/j.ijcard.2014.09.090 · 6.18 Impact Factor
  • The Lancet 09/2014; 384(9960). DOI:10.1016/S0140-6736(14)60752-2 · 45.22 Impact Factor
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    ABSTRACT: OBJECTIVES: To describe the use of a new extracellular matrix patch as a means for atrial reconstruction in patients with cardiac tumours. METHODS: A new extracellular matrix patch was used to reconstruct atrial and neighbouring structures after tumour resections. In 1 case, it was used to reconstruct the atrial septum and the left atrial roof after excision of a huge myxoma. In a second case, it was used to reconstruct the right atrium, including the superior vena cava after excision of a primary cardiac sarcoma. In a third case, it was used to reconstruct both atria, the right-sided pulmonary venous confluence and the roof of the coronary sinus after excision of a metastasis of malignant melanoma. RESULTS: In all cases, reconstruction was successful and facilitated because of the flexible and thin character of the extracellular matrix, which also seemed to be advantageous with regards to haemostasis. CONCLUSIONS: Extracellular matrix patches are a potential alternative for pericardial patches for complex reconstructions of atrial structures because of their pliable characteristics and consecutively reduced need for haemostatic stitches.
    Interactive Cardiovascular and Thoracic Surgery 09/2014; 20(1). DOI:10.1093/icvts/ivu310 · 1.11 Impact Factor
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    ABSTRACT: Purpose In this work we present a dual-phase diffusion tensor imaging (DTI) technique that incorporates a correction scheme for the cardiac material strain, based on 3D myocardial tagging. Methods In vivo dual-phase cardiac DTI with a stimulated echo approach and 3D tagging was performed in 10 healthy volunteers. The time course of material strain was estimated from the tagging data and used to correct for strain effects in the diffusion weighted acquisition. Mean diffusivity, fractional anisotropy, helix, transverse and sheet angles were calculated and compared between systole and diastole, with and without strain correction. Data acquired at the systolic sweet spot, where the effects of strain are eliminated, served as a reference. Results The impact of strain correction on helix angle was small. However, large differences were observed in the transverse and sheet angle values, with and without strain correction. The standard deviation of systolic transverse angles was significantly reduced from 35.9±3.9° to 27.8°±3.5° (p<0.001) upon strain-correction indicating more coherent fiber tracks after correction. Myocyte aggregate structure was aligned more longitudinally in systole compared to diastole as reflected by an increased transmural range of helix angles (71.8°±3.9° systole vs. 55.6°±5.6°, p<0.001 diastole). While diastolic sheet angle histograms had dominant counts at high sheet angle values, systolic histograms showed lower sheet angle values indicating a reorientation of myocyte sheets during contraction. Conclusion An approach for dual-phase cardiac DTI with correction for material strain has been successfully implemented. This technique allows assessing dynamic changes in myofiber architecture between systole and diastole, and emphasizes the need for strain correction when sheet architecture in the heart is imaged with a stimulated echo approach.
    PLoS ONE 09/2014; 9(9):e107159. DOI:10.1371/journal.pone.0107159 · 3.53 Impact Factor
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    ABSTRACT: Fett wird seit der Entdeckung des ob-Gen-Produkts Leptin als endokrines Organ angesehen. Insbesondere dem epikardialen Fett ist in den letzten Jahren vermehrte Aufmerksamkeit geschenkt worden. Das epikardiale Fett nimmt Aufgaben im Fettmetabolismus wahr, jedoch werden ihm auch schädliche parakrine, autokrine und systemische Wirkungen zugeschrieben. Die bildmorphologische Bestimmung des epikardialen Fettvolumens gelingt mittels der Echokardiographie, der Computertomographie oder der Magnetresonanztomographie. In diesem Review sollen zunächst grundlegende Betrachtungen der Physiologie und Pathophysiologie des epikardialen Fetts skizziert werden. Der Schwerpunkt des Reviews liegt dann auf der Vorstellung der Messmethoden des epikardialen Fetts mittels der einzelnen Bildgebungsmodalitäten und einem Literaturüberblick der Assoziationen des epikardialen Fetts zu Erkrankungen des kardiovaskulären Systems wie dem metabolischen Syndrom, der Herzinsuffizienz und der koronaren Herzkrankheit. Abstract Since the discovery of the obese (ob) gene product leptin, fat has been considered an endocrine organ. Especially epicardial fat has gained increasing attention in recent years. The epicardial fat plays a major role in fat metabolism; however, harmful properties have also been reported. Echocardiography, computed tomography and cardiac magnetic resonance imaging are the non-invasive tools used to measure epicardial fat volume. This review briefly introduces the basic physiological and pathophysiological considerations concerning epicardial fat. The main issue of this review is the presentation of non-invasive measurement techniques of epicardial fat using various imaging modalities and a literature overview of associations between epicardial fat and common cardiovascular diseases.
    Herz 09/2014; DOI:10.1007/s00059-014-4146-6 · 0.91 Impact Factor
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    ABSTRACT: To investigate the use of computed tomography (CT) to measure the mitral valve annulus size before implantation of a percutaneous mitral valve annuloplasty device in an animal trial. Seven domestic pigs underwent CT before and after implantation of a Cardioband™ (a percutaneously implantable mitral valve annuloplasty device) with a second-generation 128-section dual-source CT machine. Implantation of the Cardioband™ was performed in a standard fashion according to a protocol. Animals were sacrificed afterwards and the hearts explanted. The Cardioband™ was found to be adequately implanted in all animals, with no anchor dehiscence and no damage of the circumflex artery (CX) or the coronary sinus (CS). The correct length of the band as chosen according to the length of the posterior mitral annulus measured in CT before implantation was confirmed in gross examination in all animals. The device did not result in a metal artifact-related degradation of image quality. The closest distance from the closest anchor to the CX was 2.1 ± 0.7 mm in diastole and 1.6 ± 0.5 mm systole. Mitral annulus distance to the CS was 6.4 ± 1.3 mm in diastole and 7.7 ± 1.1 mm in systole. CT visualization and measurement of the mitral valve annulus dimensions is feasible and can become the imaging method of choice for procedure planning of Cardioband™ implantations or other transcatheter mitral annuloplasty devices.
    The International Journal of Cardiovascular Imaging 08/2014; 31(1). DOI:10.1007/s10554-014-0516-7 · 2.32 Impact Factor
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    ABSTRACT: To determine the association between coronary vessel wall morphology and haemodynamic consequences to the myocardium using a combined cardiovascular magnetic resonance (CMR) imaging protocol. Non-invasive CMR profiling of coronary atherosclerotic wall changes and related myocardial blood flow impairment has not been established yet.
    European Heart Journal – Cardiovascular Imaging 08/2014; DOI:10.1093/ehjci/jeu148 · 2.65 Impact Factor
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    ABSTRACT: To investigate the accuracy of post-mortem diffusion tensor imaging (DTI) for the detection of myocardial infarction (MI) and to demonstrate the feasibility of helix angle (HA) calculation to study remodelling of myofibre architecture. Cardiac DTI was performed in 26 deceased subjects prior to autopsy for medicolegal reasons. Fractional anisotropy (FA) and mean diffusivity (MD) were determined. Accuracy was calculated on per-segment (AHA classification), per-territory, and per-patient basis, with pathology as reference standard. HAs were calculated and compared between healthy segments and those with MI. Autopsy demonstrated MI in 61/440 segments (13.9 %) in 12/26 deceased subjects. Healthy myocardial segments had significantly higher FA (p < 0.01) and lower MD (p < 0.001) compared to segments with MI. Multivariate logistic regression demonstrated that FA (p < 0.10) and MD (p = 0.01) with the covariate post-mortem time (p < 0.01) predicted MI with an accuracy of 0.73. Analysis of HA distribution demonstrated remodelling of myofibre architecture, with significant differences between healthy segments and segments with chronic (p < 0.001) but not with acute MI (p > 0.05). Post-mortem cardiac DTI enablesdifferentiation between healthy and infarcted myocardial segments by means of FA and MD. HA assessment allows for the demonstration of remodelling of myofibre architecture following chronic MI. aEuro cent DTI enables post-mortem detection of myocardial infarction with good accuracy. aEuro cent A decrease in right-handed helical fibre indicates myofibre remodelling following chronic myocardial infarction. aEuro cent DTI allows for ruling out myocardial infarction by means of FA. aEuro cent Post-mortem DTI may represent a valuable screening tool in forensic investigations.
    European Radiology 07/2014; 24(11). DOI:10.1007/s00330-014-3322-7 · 4.34 Impact Factor
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    ABSTRACT: The aim of this study was to quantify the response of the myocardial transverse relaxation times (ΔT2*) to hyperoxic respiratory challenge (HRC) at different field strengths in an intra-individual comparison of healthy volunteers and in a patient with coronary artery disease. Blood oxygenation level-dependent (BOLD) cardiovascular MR (CMR) data were acquired in 10 healthy volunteers (five women, five men; mean age, 29 ± 3 years; range, 22–35 years) at 1.5 and 3.0 T. Medical air (21% O2), pure oxygen and carbogen (95% O2, 5% CO2) were administered in a block-design temporal pattern to induce normoxia, hyperoxia and hyperoxic hypercapnia, respectively. Average T2* times were derived from measurements by two independent and blind readers in 16 standard myocardial segments on three short-axis slices per patient. Inter- and intra-reader correlations of T2* measurements were good [intra-class correlation coefficient (ICC) = 0.75 and ICC = 0.79, both p < 0.001]. During normoxia, the mean T2* times were 29.9 ± 6.1 ms at 1.5 T and 27.1 ± 6.6 ms at 3.0 T. Both hyperoxic gases induced significant (all p < 0.01) T2* increases (∆T2* hyperoxia: 1.5 T, 12.7%; 3.0 T, 11.2%; hyperoxic hypercapnia: 1.5 T, 13.1%; 3.0 T, 17.7%). Analysis of variance (ANOVA) results indicated a significant (both p < 0.001) effect of the inhaled gases on the T2* times at both 1.5 T (F = 17.74) and 3.0 T (F = 39.99). With regard to the patient imaged at 1.5 T, HRC induced significant T2* increases during hyperoxia and hyperoxic hypercapnia in normal myocardial segments, whereas the T2* response was not significant in ischemic segments (p > 0.23). The myocardial ∆T2* response to HRC can reliably be imaged and quantified with BOLD CMR at both 1.5 and 3.0 T. During HRC, hyperoxia and hyperoxic hypercapnia induce a significant increase in T2*, with ∆T2* being largest at 3.0 T and during hyperoxic hypercapnia in normal myocardial segments. Copyright © 2014 John Wiley & Sons, Ltd.
    NMR in Biomedicine 07/2014; 27(7). DOI:10.1002/nbm.3119 · 3.56 Impact Factor
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    ABSTRACT: In this study, an iterative k-t principal component analysis (PCA) algorithm with nonrigid frame-to-frame motion correction is proposed for dynamic contrast-enhanced three-dimensional perfusion imaging. An iterative k-t PCA algorithm was implemented with regularization using training data corrected for frame-to-frame motion in the x-pc domain. Motion information was extracted using shape-constrained nonrigid image registration of the composite of training and k-t undersampled data. The approach was tested for 10-fold k-t undersampling using computer simulations and in vivo data sets corrupted by respiratory motion artifacts owing to free-breathing or interrupted breath-holds. Results were compared to breath-held reference data. Motion-corrected k-t PCA image reconstruction resolved residual aliasing. Signal intensity curves extracted from the myocardium were close to those obtained from the breath-held reference. Upslopes were found to be more homogeneous in space when using the k-t PCA approach with motion correction. Iterative k-t PCA with nonrigid motion correction permits correction of respiratory motion artifacts in three-dimensional first-pass myocardial perfusion imaging. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 07/2014; 72(1). DOI:10.1002/mrm.24894 · 3.40 Impact Factor
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    ABSTRACT: -The value of standard two-dimensional transthoracic echocardiographic (TTE) parameters for risk stratification in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is controversial. -We investigated the impact of right ventricular fractional area change (FAC) and tricuspid annulus plane systolic excursion (TAPSE) for prediction of major adverse cardiovascular events (MACE) defined as the occurrence of cardiac death, heart transplantation, survived sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia or arrhythmogenic syncope. Among 70 patients who fulfilled the 2010 ARVC/D Task Force Criteria and underwent baseline TTE, 37 (53%) patients experienced a MACE during a median follow-up period of 5.3 (IQR 1.8-9.8) years. Average values for FAC, TAPSE, and TAPSE indexed to body surface area (BSA) decreased over time (p=0.03 for FAC, p=0.03 for TAPSE and p=0.01 for TAPSE/BSA, each vs. baseline). In contrast, median right ventricular end-diastolic area (RVEDA) increased (p=0.001 vs. baseline). Based on the results of Kaplan-Meier estimates, the time between baseline TTE and experiencing MACE was significantly shorter for patients with FAC <23% (p<0.001), TAPSE <17mm (p=0.02) or right atrial (RA) short axis/BSA ≥25mm/m(2) (p=0.04) at baseline. A reduced FAC constituted the strongest predictor of MACE (hazard ratio 1.08 per 1% decrease; 95% confidence interval 1.04-1.12; p<0.001) on bivariable analysis. -This long-term observational study indicates that TAPSE and dilation of right-sided cardiac chambers are associated with an increased risk for MACE in ARVC/D patients with advanced disease and a high risk for adverse events. However, FAC is the strongest echocardiographic predictor of adverse outcome in these patients. Our data advocate a role for TTE in risk stratification in patients with ARVC/D, although our results may not be generalizable to lower risk ARVC/D cohorts.
    Circulation Cardiovascular Imaging 02/2014; 7(2). DOI:10.1161/CIRCIMAGING.113.000210 · 6.75 Impact Factor
  • European Heart Journal 02/2014; 35(19). DOI:10.1093/eurheartj/ehu008 · 14.72 Impact Factor
  • Journal of Cardiovascular Magnetic Resonance 01/2014; 16(Suppl 1):P330. DOI:10.1186/1532-429X-16-S1-P330 · 5.11 Impact Factor
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    ABSTRACT: To evaluate the inter-study, inter-reader and intra-reader reproducibility of cardiac cine and scar imaging in rats using a clinical 3.0 Tesla magnetic resonance (MR) system. Thirty-three adult rats (Sprague-Dawley) were imaged 24 hours after surgical occlusion of the left anterior descending coronary artery using a 3.0 Tesla clinical MR scanner (Philips Healthcare, Best, The Netherlands) equipped with a dedicated 71 mm solenoid receive-only coil. Left-ventricular (LV) volumes, mass, ejection fraction and amount of myocardial scar tissue were measured. Intra-and inter-observer reproducibility was assessed in all animals. In addition, repeat MR exams were performed in 6 randomly chosen rats within 24 hours to assess inter-study reproducibility. The MR imaging protocol was successfully completed in 32 (97%) animals. Bland-Altman analysis demonstrated high intra-reader reproducibility (mean bias%: LV end-diastolic volume (LVEDV), -1.7%; LV end-systolic volume (LVESV), -2.2%; LV ejection fraction (LVEF), 1.0%; LV mass, -2.7%; and scar mass, -1.2%) and high inter-reader reproducibility (mean bias%: LVEDV, 3.3%; LVESV, 6.2%; LVEF, -4.8%; LV mass, -1.9%; and scar mass, -1.8%). In addition, a high inter-study reproducibility was found (mean bias%: LVEDV, 0.1%; LVESV, -1.8%; LVEF, 1.0%; LV mass, -4.6%; and scar mass, -6.2%). Cardiac MR imaging of rats yielded highly reproducible measurements of cardiac volumes/function and myocardial infarct size on a clinical 3.0 Tesla MR scanner system. Consequently, more widely available high field clinical MR scanners can be employed for small animal imaging of the heart e.g. when aiming at serial assessments during therapeutic intervention studies.
    BMC Medical Imaging 12/2013; 13(1):44. DOI:10.1186/1471-2342-13-44 · 0.98 Impact Factor
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    ABSTRACT: The purpose of our study was (1) to assess retrospectively, in healthy subjects and in patients with moderate and severe functional mitral regurgitation (FMR), the normal mitral annular dimensions, (2) to determine differences in mitral annular geometry between healthy subjects and patients with FMR, and (3) to evaluate potential errors in 2-dimensional (2D) measurements given the 3D nature of the mitral annulus. 15 patients with no cardiac abnormalities (referred to as normals), 13 with moderate and 15 with severe FMR as determined by echocardiography underwent contrast-enhanced cardiac 64-slice Computed tomography (CT) with prospective electrocardiography-gating for excluding coronary artery disease. With an advanced visualization, segmentation, and image analysis software, the area, intercommissural distance (CC), septolateral distance (SLD), and the anterior and posterior circumference of the MA were measured in diastole. We found significant (P P P P = .002) and 2D (P = .001) were significantly smaller in patients with moderate FMR as compared to those with severe FMR. In contrast, there were no significant differences between groups regarding the CC and the anterior circumference both in 3D and 2D (all, P > .05). Measurements in 3D differed significantly from those with 2D for all circumference measurements and groups (P
    The international journal of cardiovascular imaging 12/2013; 30(2). DOI:10.1007/s10554-013-0341-4 · 2.32 Impact Factor

Publication Stats

780 Citations
461.03 Total Impact Points

Institutions

  • 2013–2015
    • University Hospital Zürich
      Zürich, Zurich, Switzerland
  • 2009–2015
    • University of Zurich
      • Center for Integrative Human Physiology
      Zürich, Zurich, Switzerland
    • Deutsches Herzzentrum Berlin
      • Cardiothoracic and Vascular Surgery
      Berlín, Berlin, Germany
  • 2011–2014
    • ETH Zurich
      • Institute for Biomedical Engineering
      Zürich, Zurich, Switzerland
  • 2007–2011
    • Berlin Heart
      Berlín, Berlin, Germany