Florian Schwarz
Publications
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Reproducibility of left and right ventricular mass measurements with cardiac CT.
Journal of cardiovascular computed tomography. 08/2011; 5(5):317-24.
Cardiac CT provides volumetric data that enables characterization of the myocardium. We evaluated intraobserver, interobserver, and interstudy reproducibility of left ventricular (LV) and right ventricular (RV) mass quantification with cardiac CT. Thirty-eight patients who underwent cardiac CT twice... [more] Cardiac CT provides volumetric data that enables characterization of the myocardium. We evaluated intraobserver, interobserver, and interstudy reproducibility of left ventricular (LV) and right ventricular (RV) mass quantification with cardiac CT. Thirty-eight patients who underwent cardiac CT twice within 365 days were included in this analysis. Functional reconstructions in 10% steps throughout the R-R interval and axial 1.5-mm sections were used. Semiautomatic contour detection was used to trace epicardial and endocardial borders in all cardiac phases for calculation of LV and RV ejection fraction, end-diastolic volume, end-systolic volume, cardiac output, stroke volume, and ventricular mass. For each study 2 observers measured LV and RV mass twice. LV mass parameters derived from semiautomatic contour detection algorithm had excellent intraobserver (r = 1.00), interobserver (r = 0.99), and interstudy (r = 0.99) reproducibility (P < 0.0001). Average end-diastolic LV mass was 146.2 ± 42.9 g at the first CT study and 146.8 ± 44.4 g at the second study. For measuring RV mass, reproducibility was good on all levels (r = 0.78, r = 0.78, and r = 0.68, respectively, with an average end-diastolic mass of 25.7 ± 5.8 g at the first study and 24.4 ± 4.8 g at the second study. Quantification of LV mass at cardiac CT with the threshold-based, region-growing semiautomatic segmentation analysis software evaluated here is highly observer independent and reproducible. This largely holds true for the estimation of RV mass as well; however, further improvements are needed to optimize reproducibility for RV mass quantification.
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2.09Impact points
Relationship between coronary artery disease and epicardial adipose tissue quantification at cardiac CT: comparison between automatic volumetric measurement and manual bidimensional estimation.
Academic radiology. 04/2010; 17(6):727-34.
The aim of this study was to compare the reproducibility of bidimensional and volumetric quantification of epicardial adipose tissue (EAT) on cardiac computed tomography (CT) and evaluate their relationship with the extent of coronary artery disease (CAD). Forty-five individuals underwent cardiac du... [more] The aim of this study was to compare the reproducibility of bidimensional and volumetric quantification of epicardial adipose tissue (EAT) on cardiac computed tomography (CT) and evaluate their relationship with the extent of coronary artery disease (CAD). Forty-five individuals underwent cardiac dual-source CT and conventional coronary angiography for suspicion of CAD. Nonenhanced images acquired to assess calcium score were used to quantify EAT. Coronary stenosis grading was performed on conventional coronary angiograms using Gensini scores. Two independent observers manually measured right ventricular EAT thickness at three different levels and in two different planes (four chamber and short axis) to obtain mean values. Additionally, EAT volume was automatically determined using a commercially available software tool. Conventional coronary angiography demonstrated nonstenotic coronary arteries in 22 subjects and significant coronary artery stenosis in 23. Significant correlations were observed between volumetric estimation of EAT and body mass index, coronary artery calcification, and Gensini score. On automatic volumetry, patients with significant coronary artery stenosis had significantly greater EAT volumes (154.58 +/- 58.91 mL) than those without significant CAD (120.94 +/- 81.85 mL) (P = .016). The manual bidimensional approach based on thickness measurements failed to show a significant difference between the two groups. Reproducibility and interobserver agreement for EAT quantification were higher when the automatic volumetric method was used (concordance-correlation coefficient, 0.96) compared to manual measurements (concordance-correlation coefficients, 0.37 for four-chamber EAT, 0.53 for short-axis EAT, and 0.58 for average EAT). For the quantification of EAT on cardiac CT, automated volumetry is more reproducible and correlates better with the extent of CAD than manual bidimensional measurements.
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3.58Impact points
Comparison of dual-energy computed tomography of the heart with single photon emission computed tomography for assessment of coronary artery stenosis and of the myocardial blood supply.
The American journal of cardiology. 09/2009; 104(3):318-26.
To evaluate the performance of dual-energy computed tomography (CT) for integrative imaging of the coronary artery morphology and the myocardial blood supply, 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by... [more] To evaluate the performance of dual-energy computed tomography (CT) for integrative imaging of the coronary artery morphology and the myocardial blood supply, 36 patients (15 women, mean age 57 +/- 11 years) with equivocal or incongruous single photon emission CT (SPECT) results were investigated by a single-contrast medium-enhanced, retrospectively electrocardiographic-gated dual-energy CT (DECT) scan with simultaneous acquisition of high and low x-ray spectra. Thirteen patients subsequently underwent invasive coronary angiography (ICA). The DECT data were used to reconstruct anatomic coronary CT angiographic images and to map the myocardial iodine distribution within the left ventricular myocardium. Two independent observers analyzed all DECT studies for stenosis and myocardial iodine defects. A segmental comparison was performed between the stress/rest SPECT perfusion defects and DECT iodine defects and between the ICA and coronary CT angiographic findings for stenosis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were estimated, along with the kappa statistics. Overall, DECT had 92% sensitivity and 93% specificity, with 93% accuracy for detecting any type of myocardial perfusion defect seen on SPECT. Contrast defects at DECT correctly identified 85 (96%) of 89 fixed and 60 (88%) of 68 reversible myocardial perfusion defects. The interobserver agreement was very good (weighted kappa = 0.87). Compared with ICA, coronary CT angiography had 90% sensitivity, 94% specificity, and 93% accuracy for the detection of >50% stenosis. In conclusion, our initial experience suggests that DECT, as a single examination, might be promising for the integrative analysis of the coronary artery morphology and the myocardial blood supply and is in good agreement with ICA and SPECT.
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2.65Impact points
Dual-energy CT of the heart-Principles and protocols.
European journal of radiology. 12/2008;
The introduction of coronary CT angiography (cCTA) has reinvigorated the debate whether management of patients with suspected coronary artery disease (CAD) should be primarily based on physiological versus anatomical testing. Anatomical testing (i.e., cCTA or invasive catheterization) enables direct... [more] The introduction of coronary CT angiography (cCTA) has reinvigorated the debate whether management of patients with suspected coronary artery disease (CAD) should be primarily based on physiological versus anatomical testing. Anatomical testing (i.e., cCTA or invasive catheterization) enables direct visualization and grading of coronary artery stenoses but has shortcomings for gauging the hemodynamic significance of lesions for myocardial perfusion. Conversely, rest/stress myocardial perfusion imaging (MPI) has been extensively validated for assessing the clinical significance of CAD by demonstrating fixed or reversible perfusion defects but has only limited anatomical information. There is early evidence that contrast medium enhanced dual-energy cCTA (DECT) has potential for the comprehensive analysis of coronary artery morphology as well as changes in myocardial perfusion. DECT exploits the fact that tissues in the human body and iodine-based contrast media have unique absorption characteristics when penetrated with different X-ray energy levels, which enables mapping the iodine (and thus blood) distribution within the myocardium. The purpose of this communication is to describe the practical application of this emerging technology for the comprehensive diagnosis of coronary artery disease in the context of the currently used tomographic imaging modalities (cCTA, nuclear MPI, MR MPI).
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