Elisabeth Arnoldi

Publications of Elisabeth Arnoldi

• CT detection of myocardial blood volume deficits: dual-energy CT compared with single-energy CT spectra.

  Authors: Elisabeth Arnoldi, Yeong Shyan Lee, Balazs Ruzsics, Markus Weininger, J Reid Spears, Christopher P Rowley, Salvatore A Chiaramida, Philip Costello, Maximilian F Reiser, U Joseph Schoepf

  Journal of cardiovascular computed tomography. 11/2011; 5(6):421-9.

  The performance of dual-energy CT (DECT) for the detection of myocardial blood volume deficits has not systematically been compared with single-energy CT (SCT) spectra. We evaluated the accuracy forThe performance of dual-energy CT (DECT) for the detection of myocardial blood volume deficits has not systematically been compared with single-energy CT (SCT) spectra. We evaluated the accuracy for detection of myocardial blood volume deficits in DECT and SCT compared with 99m-Tc-Sestamibi-SPECT (single-photon emission CT) during rest and stress. 47 patients underwent rest/stress SPECT myocardial perfusion imaging and cardiac DECT on a dual-source CT scanner. The A- and B-tubes were operated with 140 kV and 80 kV/100 kV, respectively. DECT raw data were reconstructed by (1) only using high-energy (140 kV) CT spectra, (2) only using low-energy (80 kV/100 kV) CT spectra, (3) merging data (30% low- and 70% high-energy CT spectra), and (4) DECT-based iodine maps. Two independent, blinded observers analyzed all CT data according to each of the 4 reconstruction strategies for myocardial blood volume deficits. Specificity and positive predictive values were relatively similar between the 4 reconstruction strategies, with highest specificity (98%) of SCT datasets based on 140 kV for mixed perfusion deficits seen on SPECT. DECT iodine maps showed highest sensitivity, negative predictive value, and accuracy of 91%, 97%, and 93%, respectively, for mixed perfusion deficits. Analysis with receiver operating characteristics showed highest area under the curve values (0.84-0.93) with the use of DECT iodine maps in the detection of purely fixed and mixed perfusion deficits. DECT iodine maps show superior performance for the detection of fixed and mixed perfusion deficits compared with SCT spectra.

• Practical strategies for low radiation dose cardiac computed tomography.

  Authors: Thomas Henzler, Michael Hanley, Elisabeth Arnoldi, Gorka Bastarrika, U Joseph Schoepf, Hans-Christoph Becker

  Journal of thoracic imaging. 08/2010; 25(3):213-20.

  Concerns have been raised regarding the increasing radiation exposure associated with cardiac computed tomography (CT). Traditional cardiac CT imaging techniques comprise simultaneous recording ofConcerns have been raised regarding the increasing radiation exposure associated with cardiac computed tomography (CT). Traditional cardiac CT imaging techniques comprise simultaneous recording of the electrocardiogram signal combined with continuous slow-pitch spiral/helical scan acquisition with a relatively high incident radiation dose. Because of the increasing number of cardiac CT studies and further anticipated growth, the contribution of cardiac CT to radiation exposure of the population is not negligible. With growing radiation dose awareness, a variety of strategies have been developed aimed at improving the dose efficiency of electrocardiogram-synchronized cardiac CT acquisition techniques. Recent innovations have demonstrated that the radiation dose at cardiac CT can be substantially reduced without detrimental effects on diagnostic image quality. This study reviews currently available strategies for successfully reducing radiation dose in cardiac CT.

• Evaluation of plaques and stenosis.

  Authors: Elisabeth Arnoldi, Thomas Henzler, Gorka Bastarrika, Christian Thilo, Konstantin Nikolaou, U Joseph Schoepf

  Radiologic clinics of North America. 07/2010; 48(4):729-44.

  Cardiac CT scan has emerged from a research tool to a widely used clinical modality in the diagnostic management of coronary artery disease. Based on evidence of numerous clinical studies coronary CTCardiac CT scan has emerged from a research tool to a widely used clinical modality in the diagnostic management of coronary artery disease. Based on evidence of numerous clinical studies coronary CT angiography (cCTA) has emerged as a fast, accurate, and noninvasive alternative to conventional angiography in selected patient populations. A major strength of cCTA is its ability to combine information on the coronary artery anatomy, the vessel lumen, and atherosclerotic lesions. Recent investigations on the application of cCTA in myocardial perfusion imaging suggest that cCTA may allow analysis of the hemodynamic relevance of detected stenosis. Data is accumulating that supports its relevance for patient management and outcome. This article examines the role of cCTA for the evaluation of plaques and stenosis.

• Automated computer-aided stenosis detection at coronary CT angiography: initial experience.

  Authors: Elisabeth Arnoldi, Mulugeta Gebregziabher, U Schoepf, Roman Goldenberg, Luis Ramos-Duran, Peter Zwerner, Konstantin Nikolaou, Maximilian Reiser, Philip Costello, Christian Thilo

  European radiology. 11/2009;

  OBJECTIVE: To evaluate the performance of a computer-aided algorithm for automated stenosis detection at coronary CT angiography (cCTA). METHODS: We investigated 59 patients (38 men, mean age 58 +/-OBJECTIVE: To evaluate the performance of a computer-aided algorithm for automated stenosis detection at coronary CT angiography (cCTA). METHODS: We investigated 59 patients (38 men, mean age 58 +/- 12 years) who underwent cCTA and quantitative coronary angiography (QCA). All cCTA data sets were analyzed using a software algorithm for automated, without human interaction, detection of coronary artery stenosis. The performance of the algorithm for detection of stenosis of 50% or more was compared with QCA. RESULTS: QCA revealed a total of 38 stenoses of 50% or more of which the algorithm correctly identified 28 (74%). Overall, the automated detection algorithm had 74%/100% sensitivity, 83%/65% specificity, 46%/58% positive predictive value, and 94%/100% negative predictive value for diagnosing stenosis of 50% or more on per-vessel/per-patient analysis, respectively. There were 33 false positive detection marks (average 0.56/patient), of which 19 were associated with stenotic lesions of less than 50% on QCA and 14 were not associated with an atherosclerotic surrogate. CONCLUSION: Compared with QCA, the automated detection algorithm evaluated has relatively high accuracy for diagnosing significant coronary artery stenosis at cCTA. If used as a second reader, the high negative predictive value may further enhance the confidence of excluding significant stenosis based on a normal or near-normal cCTA study.

• Adequate image quality with reduced radiation dose in prospectively triggered coronary CTA compared with retrospective techniques.

  Authors: Elisabeth Arnoldi, Thorsten Johnson, Carsten Rist, Bernd Wintersperger, Wieland Sommer, Alexander Becker, Christoph Becker, Maximilian Reiser, Konstantin Nikolaou

  European radiology. 05/2009;

  The goal of our study was to compare a prospective triggering (PT) CT technique with retrospectively gated (RG) CT techniques in coronary computed tomographic angiograms (CCTA) with respect to imageThe goal of our study was to compare a prospective triggering (PT) CT technique with retrospectively gated (RG) CT techniques in coronary computed tomographic angiograms (CCTA) with respect to image quality and radiation dose. Sixty consecutive patients were enrolled. CCTAs using the RG technique were obtained with a dual-source 64-slice CT system in 40 patients, using ECG-triggered tube current modulation, with either a broad pulsing window at 30-80% of the RR interval (group RGb, 20 patients, heart rate > 70 bpm) or a small pulsing window at 70% (group RGs, 20 patients, heart rate < 70 bpm). The other 20 patients underwent CCTA using the PT technique on a 128-slice CT system (group PT, heart rate < 70 bpm). All images were evaluated by two observers for quality on a three-point scale, with 1 being excellent and 3 being insufficient. The effective radiation dose was calculated for each patient. The average image quality score was 1.5 +/- 0.6 for PT, 1.35 +/- 0.5 for RGs and 1.65 +/- 0.5 for RGb. The mean effective dose for RGb was 9 +/- 4 mSv, for RGs 7 +/- 3 mSv and for PT 3 +/- 1 mSv. This represents a 57% dose reduction for PT compared with RGs and a 67% dose reduction for PT compared with RGb. In conclusion, in selected patients CCTA with the PT technique offers adequate image quality with a significantly lower radiation dose compared with CCTA using RG techniques.

• The Value of Dual-Energy Bone Removal in Maximum Intensity Projections of Lower Extremity Computed Tomography Angiography.

  Authors: Wieland Sommer, Thorsten Johnson, Christoph Becker, Elisabeth Arnoldi, Harald Kramer, Maximilian Reiser, Konstantin Nikolaou

  Investigative radiology. 04/2009;

  OBJECTIVE:: Dual-energy computed tomography (CT) makes it possible to remove bones and intraluminal plaques from angiography datasets on the basis of spectral differentiation separating iodine fromOBJECTIVE:: Dual-energy computed tomography (CT) makes it possible to remove bones and intraluminal plaques from angiography datasets on the basis of spectral differentiation separating iodine from calcium. The objective of this study was to evaluate the feasibility and efficiency of this technique by comparing maximum intensity projections (MIP) created with different bone removal techniques: (a) dual-energy bone removal (DEBR); (b) purely software-based bone removal without manual corrections (SBBR - MC); and (c) manually corrected software-based bone removal (SBBR + MC). A further aim was to evaluate the dual-energy-based plaque removal tool. MATERIALS AND METHODS:: Fifty-one patients underwent dual-energy CT angiography of the lower-extremity arteries on a dual-source CT scanner. CT parameters were tube potentials, 140 and 80 kVp; exposure, 80 and 340 mAs/rot; and collimation, 14 x 1.2 mm. Bolus tracking was used in the descending aorta for timing (Ultravist 370). Bones were removed from the datasets using the 3 techniques and MIP datasets were generated. Two experienced radiologists assessed image quality ((1) correct removal of bones and preservation of vessels without artificial truncation, stenoses or occlusions of arteries; (2) minor errors with residual bone in the dataset or removal of side branches; (3) significant errors impeding diagnostic evaluation), number of vessel segmentation errors, and number of nonremoved bones. Additionally, time for MIP-generation was measured. The plaque removal tool was applied to DEBR MIPs and the outcome was rated as positive, neutral, or negative. RESULTS:: DEBR showed better image quality than SBBR (P < 0.05; median image quality DEBR: 1; SBBR - MC: 3; SBBR + MC: 2). Less vessel segmentation errors occurred in DEBR (P < 0.05; median DEBR: 0; SBBR - MC: 5; SBBR + MC: 1). The number of nonremoved bones was not significantly different between DEBR and SBBR + MC, but significantly higher in SBBR - MC (median DEBR: 1; SBBR - MC: 2; SBBR + MC: 0). Time for generation of MIPs was lowest for SBBR - MC (P < 0.05), but also DEBR was significantly faster than manually corrected SBBR (DEBR: 160 +/- 16 seconds; SBBR - MC: 95 +/- 12 seconds; SBBR + MC: 373 +/- 69 seconds). The plaque removal tool lead to an improvement of image quality of the MIPs and a better depiction of the residual lumen in 43%. CONCLUSION:: DEBR provides significant advantages, even over manually corrected SBBR. As it works completely automatically, it can effectively help to cope with the data load of CT angiography exams. Furthermore, it enables the removal of intraluminal plaques, which provides a benefit for the estimation of the residual lumen.

• Noninvasive Coronary Angiography Using Dual-Source Computed Tomography in Patients With Atrial Fibrillation.

  Authors: Carsten Rist, Thorsten Johnson, Jens Müller-Starck, Elisabeth Arnoldi, Tobias Saam, Alexander Becker, Alexander Leber, Bernd Wintersperger, Christoph Becker, Maximilian Reiser, Konstantin Nikolaou

  Investigative radiology. 01/2009;

  OBJECTIVES:: Despite constant improvements in scanner technology, reliable visualization of the coronary arteries with multislice spiral CT angiography (CTA) remains a major challenge in patientsOBJECTIVES:: Despite constant improvements in scanner technology, reliable visualization of the coronary arteries with multislice spiral CT angiography (CTA) remains a major challenge in patients with atrial fibrillation (AF). The purpose of this study was to assess the image quality of coronary CT angiograms with coronary angiography, using a dual-source CT scanner (DSCT), comparing systolic and diastolic reconstruction techniques. Additionally, we sought to evaluate the diagnostic accuracy of DSCT with coronary angiography as the standard of reference. MATERIALS AND METHODS:: Sixty-eight patients with permanent AF were imaged on a DSCT system, with a temporal resolution of 82 milliseconds. The volume and flow rate of the contrast medium were adapted to the patient's body weight. The patients were not receiving any drugs for heart rate regulation. Each dataset was reconstructed at an absolute delay determined from the R wave at 300 milliseconds (ie, systolic reconstruction), as well as at 70% of the RR-cycle (diastolic reconstruction). Twenty-one patients underwent both DSCT and coronary angiography. Two blinded independent readers assessed significant stenoses (>/=50%), and image quality in terms of visibility and artifacts (4-point rating scale: 1 = excellent, 2 = good, 3 = poor, 4 = insufficient) on a per-patient- and a per-segment-based analysis (15-segment AHA model) for both the systolic and diastolic datasets. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. RESULTS:: During 68 DSCT examinations, the mean heart rate ranged between 26 and 181 beats per minute (77 +/- 25). In the patient-based analysis, the image qualities of 64 of 68 CT angiograms (94%) were high enough to permit diagnosis, ie, 4 of 68 (6%) datasets were considered nonevaluable. Segment-based, a total of 898 of 979 coronary artery segments were rated as diagnostically evaluable (92%).In 57 of 68 evaluable patients (84%) the reconstructions in stole had fewer motion artifacts and thus showed superior image quality. The median image quality of all CT datasets was 2. In 21 patients undergoing both coronary angiography and DSCT, the overall sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of significant stenoses were 89% (16 of 18), 98% (260 of 265), 76% (16 of 21), and 99% (260 of 262), respectively, in the per-segment analysis (including 283 vessel segments) and 90% (9 of 10), 82% (9 of 11), 82% (9 of 11), and 90% (9 of 10), respectively, in the patient-based analysis. CONCLUSIONS:: The image quality of coronary CT angiograms obtained with a DSCT is satisfactory in most patients with AF. In the majority of patients with high and irregular heart rate, the absolute forward approach with end-systolic reconstruction 300 milliseconds after the R-peak yield a higher image quality than diastolic reconstructions. As a result of a significant improvement in temporal resolution, DSCT coronary angiography is feasible in patients with AF and can be used to exclude coronary artery disease in this patient cohort.

• Functional profiling of human atrial and ventricular gene expression.

  Authors: Andreas S Barth, Sylvia Merk, Elisabeth Arnoldi, Ludwig Zwermann, Patrick Kloos, Mathias Gebauer, Klaus Steinmeyer, Markus Bleich, Stefan Kääb, Arne Pfeufer, Peter Uberfuhr, Martin Dugas, Gerhard Steinbeck, Michael Nabauer

  Pflügers Archiv : European journal of physiology. 08/2005; 450(4):201-8.

  The purpose of our investigation was to identify the transcriptional basis for ultrastructural and functional specialization of human atria and ventricles. Using exploratory microarray analysisThe purpose of our investigation was to identify the transcriptional basis for ultrastructural and functional specialization of human atria and ventricles. Using exploratory microarray analysis (Affymetrix U133A+B), we detected 11,740 transcripts expressed in human heart, representing the most comprehensive report of the human myocardial transcriptome to date. Variation in gene expression between atria and ventricles accounted for the largest differences in this data set, as 3.300 and 2.974 transcripts showed higher expression in atria and ventricles, respectively. Functional classification based on Gene Ontology identified chamber-specific patterns of gene expression and provided molecular insights into the regional specialization of cardiomyocytes, correlating important functional pathways to transcriptional activity: Ventricular myocytes preferentially express genes satisfying contractile and energetic requirements, while atrial myocytes exhibit specific transcriptional activities related to neurohumoral function. In addition, several pro-fibrotic and apoptotic pathways were concentrated in atrial myocardium, substantiating the higher susceptibility of atria to programmed cell death and extracellular matrix remodelling observed in human and experimental animal models of heart failure. Differences in transcriptional profiles of atrial and ventricular myocardium thus provide molecular insights into myocardial cell diversity and distinct region-specific adaptations to physiological and pathophysiological conditions. Moreover, as major functional classes of atrial- and ventricular-specific transcripts were common to human and murine myocardium, an evolutionarily conserved chamber-specific expression pattern in mammalian myocardium is suggested.

• Reprogramming of the human atrial transcriptome in permanent atrial fibrillation: expression of a ventricular-like genomic signature.

  Authors: Andreas S Barth, Sylvia Merk, Elisabeth Arnoldi, Ludwig Zwermann, Patrick Kloos, Mathias Gebauer, Klaus Steinmeyer, Markus Bleich, Stefan Kääb, Martin Hinterseer, Heike Kartmann, Eckart Kreuzer, Martin Dugas, Gerhard Steinbeck, Michael Nabauer

  Circulation research. 06/2005; 96(9):1022-9.

  Atrial fibrillation is associated with increased expression of ventricular myosin isoforms in atrial myocardium, regarded as part of a dedifferentiation process. Whether reexpression of ventricularAtrial fibrillation is associated with increased expression of ventricular myosin isoforms in atrial myocardium, regarded as part of a dedifferentiation process. Whether reexpression of ventricular isoforms in atrial fibrillation is restricted to transcripts encoding for contractile proteins is unknown. Therefore, this study compares atrial mRNA expression in patients with permanent atrial fibrillation to atrial mRNA expression in patients with sinus rhythm and to ventricular gene expression using Affymetrix U133 arrays. In atrial myocardium, we identified 1434 genes deregulated in atrial fibrillation, the majority of which, including key elements of calcium-dependent signaling pathways, displayed downregulation. Functional classification based on Gene Ontology provided the specific gene sets of the interdependent processes of structural, contractile, and electrophysiological remodeling. In addition, we demonstrate for the first time a prominent upregulation of transcripts involved in metabolic activities, suggesting an adaptive response to increased metabolic demand in fibrillating atrial myocardium. Ventricular-predominant genes were 5 times more likely to be upregulated in atrial fibrillation (174 genes upregulated, 35 genes downregulated), whereas atrial-specific transcripts were predominantly downregulated (56 genes upregulated, 564 genes downregulated). Overall, in fibrillating atrial myocardium, functional classes of genes characteristic of ventricular myocardium were found to be upregulated (eg, metabolic processes), whereas functional classes predominantly expressed in atrial myocardium were downregulated (eg, signal transduction and cell communication). Therefore, dedifferentiation with adoption of a ventricular-like signature is a general feature of the fibrillating atrium.