Purpose: Left ventricular outflow tract (LVOT) dimensions are important for calculation of aortic valve areas and planning of valve repair. Mostly, LVOT areas are calculated from echocardiographic longitudinal measurements with the assumption of a round shape. Here, orthogonal phase contrast (PC) MRI with dynamic assessment of LVOT was compared to standard longitudinal tine MRI and 2D echocardiography. Methods: In 19 patients with aortic stenosis (5 female; 69 10 years), LVOT areas were determined on orthogonal PC images, either by planimetry (A(plan)) or by two-diameter measurement (A(ellip)). Data were analyzed in early, middle and late systole (tl/t2/t3). Additionally, standard diameter-based calculation (A(3cv)) of LVOT on longitudinal three-chamber view (3CV) MRI images and 2D echocardiography was performed. Results: Calculated PC LVOT areas strongly correlated to planimetry (r = 0.95; p < 0.001) with almost identical areas (A(plan),1 5.1 +/- 1.1 cm(2) vs. A(ellip) 5.3 +/- 1.0 cm(2)). In PC changes of LVOT-eccentricity during systole were most pronounced in late systole (t1 vs. t3(plan) - 7.4 +/- 18%). Cine 3CV calculation resulted in lower LVOT areas compared to A(plan) (A(3cv) 3.7 +/- 0.9 cm(2); p < 0.001), yet correlating to A(plan) (r = 0.66; p = 0.002). 3CV LVOT areas correlated to echocardiography (r = 0.56; p = 0.014). Conclusions: Calculated LVOT areas seem to be sufficient for daily routine. Compared to the orthogonal view, standard long-axis 3CV underestimates the LVOT size and overestimates the systolic reduction of LVOT-size. Systolic changes are most pronounced in late systole.

OBJECTIVE:The objective of our study was to evaluate the reproducibility of noncalcified coronary artery plaque burden quantification from coronary CT angiography (CTA) across different commercial analysis platforms. MATERIALS AND METHODS:For this study, 47 patients (36 men, 11 women; mean age ± SD, 62 ± 13 years) with noncalcified plaques on coronary CTA were included. Automated quantification of noncalcified coronary artery plaque volume was performed on identical datasets using three commercially available image analysis software platforms (software platforms 1-3). Identical tissue attenuation ranges between 0 and 50 HU for low-attenuation plaques and 50-130 HU for medium-attenuation plaques were consistently applied. Log volume data were compared with the Pearson correlation coefficient and Bland-Altman analysis. RESULTS:Differences in plaque volume measurements on intraplatform repeat measurements were statistically insignificant (p = 0.923). At the low-attenuation threshold, software platform 3 had significantly higher log volumes (p < 0.001) than both software platforms 1 and 2 and software platform 1 had significantly higher log volumes than software platform 2 (p < 0.001). The results at the medium-attenuation level were identical except that the log volumes for software platforms 1 and 2 were not significantly different (p > 0.05) in the left anterior descending artery and left circumflex artery. The Pearson correlation coefficient was found to be 0.677 (p < 0.001; 95% CI, 0.608-0.735) between software platforms 1 and 2, 0.672 (p < 0.001; 95% CI, 0.603-0.732) between software platforms 1 and 3, and 0.550 (p < 0.001; 95% CI, 0.463-0.627) between software platforms 2 and 3. CONCLUSION:Currently available noncalcified plaque quantification software provides good intraplatform reproducibility but poor interplatform reproducibility. Serial or comparative assessments require evaluation using the same software. Industry standards should be developed to enable reproducible assessments across manufacturers.

OBJECTIVE Lumbar facet joint block is generally performed under fluoroscopic guidance. The purpose of this study was to assess the technical success rate of facet joint block under CT guidance. The CT scanner was operated tableside with a step-and-shoot mode for intermittent needle visualization, and the amount of radiation used to perform the procedures was estimated. CONCLUSION CT-guided facet joint block is safe and rapid. Use of CT ensures reliable needle guidance with extremely high procedural accuracy at an effective radiation dose comparable to that of a procedure performed with 1 minute of fluoroscopic guidance.

Rationale and Objectives: To investigate the impact of iterative reconstruction in image space (IRIS) on image noise, image quality (10), and postprocessing at coronary computed tomography angiography (cCTA) compared to traditional filtered back-projection (FBP).Materials and Methods: The cCTA results of 50 patients (26 men; 58 +/- 15 years, body mass index 31.5 +/- 6.7 kg/m(2)) were investigated using a second-generation dual-source computed tomography system. Scan data were reconstructed with the use of IRIS and FBP algorithms. Two radiologists independently evaluated the reconstructions using automated-coronary tree analysis software. Image noise was measured and IQ was rated on a 5-point Likert scale. The number of manual corrections after automated vessel Segmentation, the time required to complete segmentation, and the number of,missed segments were-assessed in both IRIS and FBP reconstructions. Results were compared using paired t-test.Results: IRIS significantly reduced image noise compared. to FBP (23.3 +/- 8.8 vs. 33.5 +/- 13.5 Hounsfield units, P < .001). Subjective IQ improved with IRIS.(IRIS 3.2 +/- 1.0 vs. FBP 3.0 +/- 1.0; P < .05). IRIS decreased the time needed for coronary segmentation from 111:9 +/- 40.5 seconds to 95.2 +/- 38.2 seconds with FBP P < .01) and required fewer manual corrections (5.7 +/- 3.0 vs. 6.8 +/- 3.6, P < .01). The number of missed vessel segments was not significantly different (3..6 +/- 1.8 vs. 3.8 +/- 1.9, P > .05) between IRIS and FBP, respectively.Conclusions: During cCTA postprocessing, IRIS significantly decreases the time and the number of manual corrections for a complete coronary segmentation compared to FBP. This effect is likely attributable to suppression of image noise by IRIS, which improves the performance of automated vessel segmentation and positively impacts cCTA analysis.

PURPOSE:Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain.METHODS AND MATERIALS:Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel "shuttle" mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT.RESULTS:In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments.CONCLUSION:Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.

PURPOSE:To investigate whether coronary artery calcium (CAC) scoring performed on three different workstations generates comparable and thus vendor-independent results.MATERIALS AND METHODS:Institutional review board and Federal Office for Radiation Protection approval were received, as was each patient's written informed consent. Fifty-nine patients (37 men, 22 women; mean age, 57 years±3 [standard deviation]) underwent CAC scoring with use of 64-section multidetector computed tomography (CT) with retrospective electrocardiographic gating (one examination per patient). Data sets were created at 10% increments of the R-R interval from 40%-80%. Two experienced observers in consensus calculated Agatston and volume scores for all data sets by using the calcium scoring software of three different workstations. Comparative analysis of CAC scores between the workstations was performed by using regression analysis, Spearman rank correlation (rs), and the Kruskal-Wallis test.RESULTS:Each workstation produced different absolute numeric results for Agatston and volume scores. However, statistical analysis revealed excellent correlation between the workstations, with highest correlation at 60% of the R-R interval (minimal rs=0.998; maximal rs=0.999) for both scoring methods. No significant differences were detected for Agatston and volume score results between the software platforms. At analysis of individual reconstruction intervals, each workstation demonstrated the same score variability, with the consequence that 12 of 59 patients were assigned to divergent cardiac risk groups by using at least one of the workstations.CONCLUSION:While mere numeric values might be different, commercially available software platforms produce comparable CAC scoring results, which suggests a vendor-independence of the method; however, none of the analyzed software platforms appears to provide a distinct advantage for risk stratification, as the variability of CAC scores depending on the reconstruction interval persists across platforms.

Myocardial perfusion Is an important prognostic marker in the management of patients with suspected coronary artery disease as it demonstrates the hemodynamic con-sequences of coronary artery stenosis. The traditional diagnostic algorithm is based on a combination of physiological and anatomical testing using different modalities. Physiological testing, such as nuclear imaging, has been extensively validated for determining the effect of stenoses on the myocardial perfusion but provides only limited anatomical information. Conversely, anatomical testing, such as invasive coronary angiography, can directly visualize and grade coronary artery stenosis but has limitations for gauging their hemodynamic effect on the myocardial perfusion.Accordingly, a single test allowing the comprehensive evaluation of all aspects of coronary artery disease is clinically desirable. There is early evidence that cardiac computed tomography (CT) performed in single- or dual-energy mode has the potential for an integrative evaluation of both, coronary artery anatomy as well as changes in the myocardial blood supply. Cardiac dual-energy CT is based on the more recent technology of dual-source CT, and exploits the fact that iodine-based contrast medium has unique spectral characteristics when penetrated with different X-ray energy levels, enabling mapping of the iodine (and thus blood) distribution within the myocardium.This chapter provides an overview about the role and current state of dual-energy CT in the evaluation of the myocardial perfusion.

BACKGROUND: 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.OBJECTIVE: 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.METHODS: 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.RESULTS: 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.CONCLUSION: DECT iodine maps show superior performance for the detection of fixed and mixed perfusion deficits compared with SCT spectra. (C) 2011 Society of Cardiovascular Computed Tomography. All rights reserved.

Purpose: We compared cost-effectiveness and potential lifetime benefits of using dual-energy computed tomography (DECT) for myocardial perfusion assessment instead of single photon emission computed tomography (SPECT) for the workup of coronary artery disease (CAD).Materials and methods: A decision and simulation model was developed to estimate cost and health effects of using DECT myocardial perfusion imaging instead of SPECT for identifying patients in need of invasive imaging and possible revascularization. The model was based on the performance indices of stress/rest DECT compared with stress/rest SPECT for detecting myocardial perfusion deficits in 50 patients (mean age 61 +/- 10 years) with CAD. Stress/rest perfusion and delayed enhancement cardiac MRI served as reference standard. For DECT a reimbursement of US$1700 was assumed but costs of cardiac MRI were not included in the model. All other actual healthcare costs in these patients were derived from MUSC's hospital billing system.Results: Compared with cardiac MRI, DECT (versus SPECT) had 90% (85%) sensitivity and 71% (58%) specificity for identifying patients with obstructive CAD. Compared with the no imaging and no treatment strategy, routine SPECT gained 13.49 quality-adjusted life-years (QALYs) with an incremental cost-effectiveness ratio (ICER) of US$3557 (in 2010) per QALY. In comparison, DECT ICER was lower (US$3.191 per QALY, p = 0.0002) and an additional 0.64 QALYs was obtained (total of 14.13 QALYs) if compared with the SPECT strategy as well as the no imaging and no treatment strategy.Conclusion: Using DECT as the first-line imaging test for myocardial perfusion for the workup of patients with CAD has the potential to provide gains in QALYs, while lowering costs if compared to routine myocardial perfusion SPECT. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Rapid technological evolution in multislice computed tomography (CT) over the last decade with improved spatial and temporal resolution has enabled cardiac CT to become a viable and effective alternative in the diagnosis of coronary artery disease. Within recent years CT coronary angiography has demonstrated high sensitivity and specificity, and in particular a very high negative-predictive value, making it a valuable imaging modality for ruling out suspected coronary artery disease. In addition, CT angiography demonstrates accuracy in the detection and characterization of coronary plaques, and it has been reported to play an important role in predicting disease progression and cardiac events. The goal of this article is to provide an overview on the role and current clinical applications of cardiac CT in the evaluation of coronary artery disease. Emerging areas of cardiac CT, including dual-energy CT and CT myocardial perfusion are also discussed, as well as the limitations and future directions of cardiac CT.

OBJECTIVE:Over the last decade, rapid technologic evolution in CT has resulted in improved spatial and temporal resolution and acquisition speed, enabling cardiothoracic CT angiography to become a viable and effective noninvasive alternative in the diagnostic algorithm. These new technologic advances have imposed new challenges for the optimization of contrast medium delivery and image acquisition strategies.CONCLUSION:Thorough understanding of contrast medium dynamics is essential for the design of effective acquisition and injection protocols. This article provides an overview of the fundamentals affecting contrast enhancement, emphasizing the modifications to contrast material delivery protocols required to optimize cardiothoracic CT angiography.

Poster: ECR 2011 / C-1644 / Comparison of iterative and filtered back-projection image reconstruction techniques: evaluation of heavily calcified vessels with coronary CT angiography by: Renker1, U. J. Schoepf1, M. Weininger1, J. M. Kerl2, R. Bauer2, T. J. Vogl2, T. Henzler1; 1Charleston, SC/US, 2Frankfurt a. Main/DE

Introduction: Heavy calcifications remain a limitation of coronary CT angiography (cCTA) and decrease the accuracy of this test for stenosis detection. Hypothesis We assessed the hypothesis that the novel iterative image reconstruction technique allows for more precise delineation of calcified plaques at cCTA in comparison to traditional filtered back projection (FBP). Methods: Dual source cCTA studies of 30 patients (18men; 57±11 years) with Agatston scores of >400 were included prospectively. Image reconstruction was performed with FBP and with iterative reconstruction in image space (IRIS) using corresponding vascular algorithms. Image noise was evaluated in a region of interest in the aortic root. To compare the two reconstruction techniques regarding calcified plaque delineation, the volume of heavy coronary artery calcifications was measured using a threshold based volumetry tool. Two experienced, blinded observers subjectively rated image quality on a 5-point scale and interpreted both, FBP and IRI...

Purpose:Direct magnetic resonance imaging (MRI) planimetry of the maximal systolic aortic valve area does not consider temporal variations of the opening area during the ejection period. We evaluated an MRI-based methodology for the assessment of valvular dynamics in patients with severe aortic stenosis by measuring the systolic variability of the valvular blood stream, that is, the “vena contracta.” Materials and Methods:With institutional review board approval, we examined 22 patients (13 male, 9 female; mean age, 68 ±10 years) with severe aortic stenosis using 1.5 T MRI and a standardized scanning protocol consisting of gradient-echo phase-contrast velocity imaging and steady-state free precession-cine MRI before and after valve replacement therapy. Temporal changes of the aortic valve area, represented by systolic variations of the area of poststenotic turbulent flow at its smallest convergence, that is, the proximal vena contracta, were determined by MRI and quantified by a calculated parameter of temporal valve dynamics (T). T was defined as the period which the aortic valve spent over its maximal opening area (>85%) during systole. MRI was also used to determine left ventricular hypertrophy before (LVMI) and its regression (LVMR) after valve replacement. Findings were compared with transthoracic echocardiography and cardiac catheterization. Results:All patients had an echocardiographic effective orifice area, EOATTE, of <1.0 cm2. The comparison of T to LVMI and LVMR revealed significant correlations (LVMI: r = −0.62; P = 0.002; LVMR: r = 0.62; P = 0.002). Further significant correlations with aortic stenosis severity were observed in the comparison with manual planimetry, invasive measurements, and echocardiographic valve areas, as well as with pressure gradients. Conclusions:MRI can measure systolic variations of the aortic valve area. Quantitative parameters of the hemodynamic relevance of valve dynamics obtained by this method correlate with established parameters of aortic stenosis severity and LVMR.

A 47-year-old man presented with symptoms typical of infective endocarditis and history of streptococcal meningitis 8 months previously. Echocardiography showed a large aortic valve vegetation that was interpreted as disruption of the noncoronary cusp. This was ruled out by 64-slice cardiac computed tomography. Valve replacement was performed successfully.

Purpose: To investigate dynamic contrast-enhanced MRI (DCE-MRI) for quantification of pulmonary blood flow (PBF) and blood volume (PBV) using the prebolus approach and to compare the results to the global lung perfusion (GLP).Materials and Methods: Eleven volunteers were examined by applying different contrast agent doses (0.5, 1.0, 2.0. and 3.0 mL gadolinium diethylene triamine pentaacetic acid [Gd-DTPA]). using a saturation-recovery (SR) true fast imaging with steady precession (TrueFISP) sequence. PBF and PBV were determined for single bolus and prebolus. Region of interest (ROI) evaluation was performed and parameter maps were calculated. Additionally, cardiac output (CO) and lung volume were determined and GLP was calculated as a contrast agent-independent reference value.Results: The prebolus results showed good agreement with low-dose single-bolus and GLP: PBF (mean +/- SD in units of mL/minute/100 mL) = single bolus 190 +/- 73 (0.5-mL dose) and 193 +/- 63 (1.0-mL dose): prebolus 192 +/- 70 (1.0-2.0-mL dose) and 165 +/- 52 (1.0-3.0-mL dose); GLP (mL/minute/100 mL) = 187 +/- 34. Higher single-bolus resulted in overestimated values due to arterial input function (AIF) saturation.Conclusion: The prebolus approach enables independent determination of appropriate doses for AIF and tissue signal. Using this technique, the signal-to-noise ratio (SNR) from lung parenchyma can be increased, resulting in improved PBF and PBV quantification, which is especially useful for the generation of parameter maps.

Christian O Ritter, MD Tel: þ49 931 201 34225 Fax: þ49 931 201 61855 Email: ritter@roentgen.uni-wuerzburg.de Institut fuer Roentgendiagnostik, ZOM, Oberduerrbacherstrasse 6, 97080 Wuerzburg, Germany. Figure 1. Postoperative chest radiograph demonstrating lung herniation at the left chest wall (arrow), and displacement of the lateral portions of several left ribs (arrow heads). Slight blunting of the left costophrenic angle (*) is consistent with pleural thickening.

Abstract  A 49‐year‐old male patient suffering from end‐stage ischemic cardiomyopathy with a left ventricular ejection fraction below 15% was presented to redo coronary artery bypass grafting (CABG). Coronary angiogram demonstrated an occluded left anterior descending artery and occluded right coronary artery, perfused retrogradely from the circumflex artery. Since positron emission tomography did not demonstrate viable left ventricular myocardium except for the basis of the left ventricle, CABG was considered futile. Cardiac transplantation was contra‐indicated due to pharmacologically unresponsive pulmonary artery hypertension. The patient successfully underwent left ventricular assist device implantation in combination with right coronary artery revascularization. The article reflects the regimen of right ventricular preservation in this patient. (J Card Surg 2010;25:116‐119)

For reprint information contact: Markus Weininger, MD Tel: 49 931 201 34201 Fax: 49 931 201 61860 email: weininger@roentgen.uni-wuerzburg.de University Hospital of Wuerzburg, Department of Radiology, Oberduerrbacher Strasse 6, 97080 Wuerzburg, Germany. A 70-year-old man who had undergone triple aortocoronary bypass grafting 9 years earlier was referred for oncology follow-up because of rectal carcinoma. Current complaints included moderate chest pain and recent hypertensive crisis. Chest radiography (Figure 1) showed widening of Figure 1. Chest radiograph in posteroanterior projection, revealing widening of the lower mediastinal silhouette to the right (white arrows).

Purpose To evaluate the influence of retrospective sorting on image quality in four-dimensional respiratory correlated CT. Materials and methods Twelve patients with intrapulmonary tumors were examined using a 24-slice CT-scanner in helical mode. Images were reconstructed after retrospective sorting based on five algorithms: amplitude-based sorting with definition of peak-exhalation and peak-inhalation separately/locally for all breathing cycles (LAS) and globally for the time of image acquisition (GAS). Drifts of the breathing signal were corrected in dc-GAS. In phase-based (PS) and cycle-based (CS) algorithm the projections were sorted relative to time. Motion artifacts were scored by a radiologist. The tumor volumes were measured using automatic image segmentation. Results Averaged over all breathing phases, LAS and PS achieved significantly improved image quality and lowest tumor volume variability compared to GAS, dc-GAS and CS. Imaging redundancy of 5 s was not sufficient for GAS and dc-GAS: missing corresponding amplitude positions in one or several breathing cycles resulted in incomplete reconstruction of peak-ventilation images in 11/12 and 10/12 patients with GAS and dc-GAS, respectively. Limiting the analysis to mid-ventilation phases showed GAS and dc-GAS as the most reliable algorithms. Conclusions LAS and PS are suggested as a compromise between image quality and radiation dose.