Bernhard Krauss

Publications of Bernhard Krauss

• Virtual Nonenhanced Dual-Energy CT Urography with Tin-Filter Technology: Determinants of Detection of Urinary Calculi in the Renal Collecting System.

  Authors: Stefanie Mangold, Christoph Thomas, Michael Fenchel, Morten Vuust, Bernhard Krauss, Dominik Ketelsen, Ilias Tsiflikas, Claus D Claussen, Martin Heuschmid

  Radiology. 05/2012;

  Purpose:To retrospectively determine which features of urinary calculi are associated with their detection after virtual elimination of contrast medium at dual-energy computed tomographic (CT)Purpose:To retrospectively determine which features of urinary calculi are associated with their detection after virtual elimination of contrast medium at dual-energy computed tomographic (CT) urography by using a novel tin filter.Materials and Methods:The institutional ethics committee approved this retrospective study, with waiver of informed consent. A total of 152 patients were examined with single-energy nonenhanced CT and dual-energy CT urography in the excretory phase (either 140 and 80 kV [n = 44] or 140 and 100 kV [n = 108], with tin filtration at 140 kV). The contrast medium in the renal pelvis and ureters was virtually removed from excretory phase images by using postprocessing software, resulting in virtual nonenhanced (VNE) images. The sensitivity regarding the detection of calculi on VNE images compared with true nonenhanced (TNE) images was determined, and interrater agreement was evaluated by using the Cohen k test. By using logistic regression, the influences of image noise, attenuation, and stone size, as well as attenuation of the contrast medium, on the stone detection rate were assessed. Threshold values with maximal sensitivity and specificity were calculated by means of receiver operating characteristic analyses.Results:Eighty-seven stones were detected on TNE images; 46 calculi were identified on VNE images (sensitivity, 52.9%). Interrater agreement revealed a k value of 0.95 with TNE images and 0.91 with VNE data. Size (long-axis diameter, P = .005; short-axis diameter, P = .041) and attenuation (P = .0005) of the calculi and image noise (P = .0031) were significantly associated with the detection rate on VNE images. As threshold values, size larger than 2.9 mm, maximum attenuation of the calculi greater than 387 HU, and image noise less than 20 HU were found.Conclusion:After virtual elimination of contrast medium, large (>2.9 mm) and high-attenuation (>387 HU) calculi can be detected with good reliability; smaller and lower attenuation calculi might be erased from images, especially with increased image noise.© RSNA, 2012.

• Imaging of ventilation with dual-energy CT during breath hold after single vital-capacity inspiration of stable xenon.

  Authors: Norinari Honda, Hisato Osada, Wataru Watanabe, Mitsuo Nakayama, Keiichiro Nishimura, Bernhard Krauss, Katharina Otani

  Radiology. 01/2012; 262(1):262-8.

  To assess single-breath-hold technique for ventilation mapping by using dual-energy computed tomography (CT) in phantom experiments and volunteers. Institutional review board approved this study, andTo assess single-breath-hold technique for ventilation mapping by using dual-energy computed tomography (CT) in phantom experiments and volunteers. Institutional review board approved this study, and written informed consent was obtained from all volunteers. A rubber bag filled with a mixture of xenon (0%-35.4%) and oxygen was scanned with dual-source dual-energy CT (80 kV and 140 kV with tin [Sn] filter [Sn/140 kV] and 100 kV and Sn/140 kV). A cylinder containing six tubes of identical sizes with different apertures was ventilated once with a mixture of 35% xenon and 65% oxygen and was scanned in dual-energy mode (80 kV and Sn/140 kV). Xenon-enhanced images were derived by using three-material decomposition technique. Four volunteers were scanned twice in dual-energy mode (80 kV and Sn/140 kV) during breath hold after a single vital-capacity inspiration of air (nonenhanced) and of 35% xenon. Xenon-enhanced images were obtained by using two methods: three-material decomposition and subtraction of nonenhanced from xenon-enhanced images. Regression analysis with t and F tests was applied to the data of the rubber bag scans, with the significance level set at .05. Mean pixel values of gas in the bag were linearly related to xenon concentration for all x-ray tube voltages (r(2) = 1.00, P < .00001). Pixel values of the xenon-enhanced images of the tubes were related to their aperture size. Nearly homogeneous (coefficient of variation: 0.22, 0.23, and 0.34) pixel values were found in the lungs of healthy volunteers, with higher pixel values in the trachea and lower pixel values in the bullae. Xenon-enhanced images calculated by using three-material decomposition had better image quality on visual comparison than those calculated by using subtraction. Xenon-enhanced dual-energy CT with the single-breath-hold technique could depict ventilation in phantoms and in four volunteers.

• Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.

  Authors: Jijo Paul, Rosemarie Banckwitz, Bernhard Krauss, Thomas J Vogl, Werner Maentele, Ralf W Bauer

  European journal of radiology. 06/2011;

  PURPOSE: To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch andPURPOSE: To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. MATERIALS AND METHODS: Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. RESULTS: DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv. CONCLUSION: Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv.

• Dual-energy computed tomography characterization of solitary pulmonary nodules.

  Authors: Eun Jin Chae, Jae-Woo Song, Bernhard Krauss, Koun-Sik Song, Choong Wook Lee, Hyun Joo Lee, Joon Beom Seo

  Journal of thoracic imaging. 11/2010; 25(4):301-10.

  For the assessment of solitary pulmonary nodules (SPNs), a chest computed tomography (CT) is often performed as a combination of a nonenhanced and an enhanced scan. A nonenhanced scan is used for theFor the assessment of solitary pulmonary nodules (SPNs), a chest computed tomography (CT) is often performed as a combination of a nonenhanced and an enhanced scan. A nonenhanced scan is used for the detection of calcification in the SPN or lymph node, as the presence of calcification is one of the important determinants of benignity. An enhanced scan is informative in providing the degree and pattern of enhancement. In particular, the degree of enhancement of an SPN after iodine injection has been shown to be helpful in distinguishing malignant from benign nodules. Recently introduced dual-energy applications of dual-source CT simultaneously provide a virtual nonenhanced and an iodine-enhanced image from a single scan, after the administration of iodine contrast material. Therefore, a single enhanced dual-energy CT scan allows both measurement of the degree of enhancement and detection of calcifications. It may reduce radiation exposure to patients by avoiding baseline nonenhanced scans and may also reduce measurement error due to different regions of interest during the subtraction of a nonenhanced image from an enhanced image. This technique may have applications in contrast-enhanced dynamic CT and perfusion CT for the differentiation between benign and malignant lesions and the assessment of tumor angiogenesis. In this review article, we sought to address the usefulness of dual-energy CT for the assessment of SPN. In addition, we briefly review the physical principles of dual-energy CT and discuss potential future applications in patients with lung nodules.

• Dual energy computed tomography of lung nodules: differentiation of iodine and calcium in artificial pulmonary nodules in vitro.

  Authors: Naomi Knöss, Beata Hoffmann, Bernhard Krauss, Martin Heller, Jürgen Biederer

  European journal of radiology. 11/2010; 80(3):e516-9.

  Iodine enhancement is a marker for malignancy in pulmonary nodules. The purpose of this in vitro study was to assess whether dual energy computed tomography (DECT) can be used to detect iodine and toIodine enhancement is a marker for malignancy in pulmonary nodules. The purpose of this in vitro study was to assess whether dual energy computed tomography (DECT) can be used to detect iodine and to distinguish iodine from disperse calcifications in artificial pulmonary nodules. Small, medium, and large artificial nodules (n=54), with increasing concentrations of iodine or calcium corresponding to an increase in Hounsfield Units (HU) of 15, 30, 45, and 90 at 120 kV, were scanned in a chest phantom with DECT at 80 and 140 kV. Attenuation values of each nodule were measured using semi-automated volumetric analysis. The mean DE ratio with 95% confidence intervals (CI) was calculated for each nodule. The mean maximum diameter of the 18 small nodules was 12 mm (standard deviation: 0.4), 16 mm (0.4) for the 18 medium nodules, and 30 mm (1.1) for the 18 large nodules. There was no overlap of 95% CI of DE ratios of iodine and calcium in nodules≥16 mm. In nodules<16 mm, there was an overlap of DE ratios in low contrast lesions. DECT can distinguish iodine from calcium in artificial nodules≥16 mm in vitro. In smaller lesions, a clear differentiation is not possible.

• Xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans: correlation of xenon and CT density values with pulmonary function test results.

  Authors: Hyun Woo Goo, Dong Hyun Yang, Soo-Jong Hong, Jinho Yu, Byoung-Ju Kim, Joon Beom Seo, Eun Jin Chae, Jeongjin Lee, Bernhard Krauss

  Pediatric radiology. 09/2010; 40(9):1490-7.

  Xenon ventilation CT using dual-source and dual-energy technique is a recently introduced, promising functional lung imaging method. To expand its clinical applications evidence of additionalXenon ventilation CT using dual-source and dual-energy technique is a recently introduced, promising functional lung imaging method. To expand its clinical applications evidence of additional diagnostic value of xenon ventilation CT over conventional chest CT is required. To evaluate the usefulness of xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans (BO). Seventeen children (age 7-18 years; 11 boys) with BO underwent xenon ventilation CT using dual-source and dual-energy technique. Xenon and CT density values were measured in normal and hyperlucent lung regions on CT and were compared between the two regions. Volumes of hyperlucent regions and ventilation defects were calculated with thresholds determined by visual and histogram-based analysis. Indexed volumes of hyperlucent lung regions and ventilation defects were correlated with pulmonary function test results. Effective doses of xenon CT were calculated. Xenon (14.6 +/- 6.4 HU vs 26.1 +/- 6.5 HU; P < 0.001) and CT density (-892.8 +/- 25.4 HU vs -812.3 +/- 38.7 HU; P < 0.001) values were significantly lower in hyperlucent regions than in normal lung regions. Xenon and CT density values showed significant positive correlation for the entire lung in 16 children (gamma = 0.55 +/- 0.17, P < 0.001 or =0.017) and for hyperlucent regions in 13 children (gamma = 0.44 +/- 0.16, P < 0.001 or =0.001-0.019). Indexed volumes and volume percentages of hyperlucent lung regions and ventilation defects showed strong negative correlations with forced expiratory volume [FEV1, (gamma = -0.64--0.85, P <or= 0.006)], FEV1/forced vital capacity [FVC, (gamma = -0.63--0.84, P <or= 0.008), and forced midexpiratory flow rate [FEF(25-75), (gamma = -0.68--0.88, P <or= 0.002). Volume percentages of xenon ventilation defects (35.0 +/- 16.4%) were not significantly different from those of hyperlucent lung regions (38.2 +/- 18.6%). However, mismatches between the volume percentages were variable up to 21.4-33.3%. Mean effective dose of xenon CT was 1.9 +/- 0.5 mSv. In addition to high-resolution anatomic information, xenon ventilation CT using dual-source and dual-energy technique demonstrates impaired regional ventilation and its heterogeneity accurately in children with BO without additional radiation exposure.

• Dual-energy CT virtual noncalcium technique: detecting posttraumatic bone marrow lesions--feasibility study.

  Authors: Gregor Pache, Bernhard Krauss, Peter Strohm, Ulrich Saueressig, Philipp Blanke, Stefan Bulla, Oliver Schäfer, Peter Helwig, Elmar Kotter, Mathias Langer, Tobias Baumann

  Radiology. 08/2010; 256(2):617-24.

  To evaluate traumatized bone marrow with a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique. In this prospective institutional review board-approved study, 21 patients with anTo evaluate traumatized bone marrow with a dual-energy (DE) computed tomographic (CT) virtual noncalcium technique. In this prospective institutional review board-approved study, 21 patients with an acute knee trauma underwent DE CT and magnetic resonance (MR) imaging. A software application was used to virtually subtract calcium from the images. Presence of fractures was noted, and presence of bone bruise was rated on a four-point scale for six femoral and tibial regions by two radiologists. CT numbers were obtained in the same regions. Consensus reading of independently read MR images served as the reference standard. Image ratings and CT numbers were subjected to receiver operating characteristic curve analysis. After exclusion of 16 regions owing to artifacts, MR imaging revealed 59 bone bruises in the remaining 236 regions (19 of 114 femoral, 40 of 122 tibial). Fractures were present in eight patients. Visual rating revealed areas under the curve of 0.886 and 0.897 in the femur and 0.974 and 0.953 in the tibia for observers 1 and 2, respectively. For CT numbers, the respective areas under the curve were 0.922 and 0.974. If scores of 1 and 2 (strong or mild bone bruise) were counted as positive, sensitivities were 86.4% and 86.4% and specificities were 94.4% and 95.5% for observers 1 and 2, respectively. The kappa statistic demonstrated good to excellent agreement (femur, kappa = 0.78; tibia, kappa = 0.87). This DE CT virtual noncalcium technique can subtract calcium from cancellous bone, allowing bone marrow assessment and potentially making posttraumatic bone bruises of the knee detectable with CT.

• Differentiation of urinary calculi with dual energy CT: effect of spectral shaping by high energy tin filtration.

  Authors: Christoph Thomas, Bernhard Krauss, Dominik Ketelsen, Ilias Tsiflikas, Anja Reimann, Matthias Werner, David Schilling, Jörg Hennenlotter, Claus D Claussen, Heinz-Peter Schlemmer, Martin Heuschmid

  Investigative radiology. 07/2010; 45(7):393-8.

  In dual energy (DE) computed tomography (CT), spectral shaping by additional filtration of the high energy spectrum can theoretically improve dual energy contrast. The aim of this in vitro study wasIn dual energy (DE) computed tomography (CT), spectral shaping by additional filtration of the high energy spectrum can theoretically improve dual energy contrast. The aim of this in vitro study was to examine the influence of an additional tin filter for the differentiation of human urinary calculi by dual energy CT. A total of 36 pure human urinary calculi (uric acid, cystine, calciumoxalate monohydrate, calciumoxalate dihydrate, carbonatapatite, brushite, average diameter 10.5 mm) were placed in a phantom and imaged with 2 dual source CT scanners. One scanner was equipped with an additional tin (Sn) filter. Different combinations of tube voltages (140/80 kV, 140/100 kV, Sn140/100 kV, Sn140/80 kV, with Sn140 referring to 140 kV with the tin filter) were applied. Tube currents were adapted to yield comparable dose indices. Low- and high energy images were reconstructed. The calculi were segmented semiautomatically in the datasets and DE ratios (attenuation@low_kV/attenuation@high_kV) and were calculated for each calculus. DE contrasts (DE-ratio_material1/DE-ratio_material2) were computed for uric acid, cystine and calcified calculi and compared between the combinations of tube voltages. Using exclusively DE ratios, all uric acid, cystine and calcified calculi (as a group) could be differentiated in all protocols; the calcified calculi could not be differentiated among each other in any examination protocol. The highest DE ratios and DE contrasts were measured for the Sn140/80 protocol (53%-62% higher DE contrast than in the 140/80 kV protocol without additional filtration). The DE ratios and DE contrasts of the 80/140 kV and 100/Sn140 kV protocols were comparable. Uric acid, cystine and calcified calculi could be reliably differentiated by any of the protocols. A dose-neutral gain of DE contrast was found in the Sn-filter protocols, which might improve the differentiation of smaller calculi (Sn140/80 kV) and improve image quality and calculi differentiation in larger patients (Sn140/100 kV). However, even with the improved spectral separation of the Sn-filter protocols, the DE ratios of calcified calculi are not sufficiently distinct to allow a differentiation within this group.

• Enhanced visualization of lung vessels for diagnosis of pulmonary embolism using dual energy CT angiography.

  Authors: Radko Krissak, Thomas Henzler, Miriam Reichert, Bernhard Krauss, Stefan O Schoenberg, Christian Fink

  Investigative radiology. 06/2010; 45(6):341-6.

  To evaluate a software algorithm highlighting vascular iodine distribution in dual energy (DE) computed tomography angiography (CTA) for the diagnosis of pulmonary embolism (PE). Pulmonary DE-CTA ofTo evaluate a software algorithm highlighting vascular iodine distribution in dual energy (DE) computed tomography angiography (CTA) for the diagnosis of pulmonary embolism (PE). Pulmonary DE-CTA of 16 patients with PE and 16 patients without PE were analyzed using a software algorithm highlighting vascular iodine distribution. The algorithm color-codes lung vessels depending on their local iodine distribution on a 2-color scale. The diagnostic performance of the software for the detection of PE was assessed on patient and segmental basis by consensus reading of 2 blinded radiologists. The reading of the standard CTA data by an independent third radiologist and clinical follow-up served as the standard of reference for the diagnosis of PE. Of 576 analyzed segments CTA revealed 88 diseased lung segments with 1 or more emboli. The software correctly highlighted 62 segments as positive. Twenty-six segments with PE were not highlighted. Seventy-five segments were highlighted false positive. All 16 patients with PE were identified as positive, but 1 of these patients had no true positive finding on a segmental basis and was therefore classified as false negative. Twenty-three segments in 8 patients without PE were highlighted as positive. Sensitivity, specificity, positive predictive value, and negative predictive value of the software algorithm were 93.8%, 50%, 65.2%, 88.9% per patient and 70.5%, 84.6%, 45.3%, 94.1% per segment, respectively. Additional review of the DE-CTA with a dedicated software algorithm highlighting the vascular iodine distribution has a high negative predictive value important for exclusion of segmental PE.

• Dual-energy CT for assessment of the severity of acute pulmonary embolism: pulmonary perfusion defect score compared with CT angiographic obstruction score and right ventricular/left ventricular diameter ratio.

  Authors: Eun Jin Chae, Joon Beom Seo, Yu Mi Jang, Bernhard Krauss, Choong Wook Lee, Hyun Joo Lee, Koun-Sik Song

  AJR. American journal of roentgenology. 03/2010; 194(3):604-10.

  The purpose of this study was to prospectively evaluate the usefulness of scoring perfusion defects on perfusion images at dual-energy CT for assessment of the severity of pulmonary embolism. ThirtyThe purpose of this study was to prospectively evaluate the usefulness of scoring perfusion defects on perfusion images at dual-energy CT for assessment of the severity of pulmonary embolism. Thirty patients (13 men, 17 women; mean age, 55 +/- 15 [SD] years; range, 26-81 years) with pulmonary thromboembolism underwent dual-source CT at two voltages (140 and 80 kV). The weighted average image of two acquisitions was used for CT angiograms, and a color-coded iodine image was used for perfusion images. Two thoracic radiologists with 15 and 6 years of clinical experience independently assigned perfusion defect scores to perfusion images and both a CT angiographic (CTA) obstruction score and right ventricular-to-left ventricular (RV/LV) diameter ratio to CT angiograms. The CTA obstruction score was based on the Qanadli method. The perfusion defect score was defined as Sigma (n . d) / 40 x 100, where n is the number of segments and d is the degree of perfusion from 0 to 2. Correlations between perfusion defect score, CTA obstruction score, and RV/LV diameter ratio were evaluated. Agreement between perfusion defect score and CTA score was assessed per patient and per segment. Interobserver agreement regarding perfusion defect and CTA obstruction scores was analyzed. Perfusion defect and CTA obstruction scores had good correlation with RV/LV diameter ratio (r = 0.69, r = 0.66; all p < 0.001). Per patient, correlation between perfusion defect score and CTA obstruction score also was good (reader 1, r = 0.87; reader 2, r = 0.85; all p < 0.001). Per segment, moderate agreement was found between perfusion defect score and CTA obstruction score (reader 1, kappa = 0.56; reader 2, kappa = 0.51; all p < 0.05). Both readers were in strong agreement on perfusion defect score and CTA obstruction score. The proposed perfusion defect score had good correlation with RV/LV diameter ratio and CTA obstruction score. Therefore, acquisition of perfusion images at dual-energy CT may be helpful for assessing the severity of acute pulmonary embolism.

• Technical principles of dual source CT.

  Authors: Martin Petersilka, Herbert Bruder, Bernhard Krauss, Karl Stierstorfer, Thomas G Flohr

  European journal of radiology. 11/2008;

  During the past years, multi-detector row CT (MDCT) has evolved into clinical practice with a rapid increase of the number of detector slices. Today's 64 slice CT systems allow whole-bodyDuring the past years, multi-detector row CT (MDCT) has evolved into clinical practice with a rapid increase of the number of detector slices. Today's 64 slice CT systems allow whole-body examinations with sub-millimeter resolution in short scan times. As an alternative to adding even more detector slices, we describe the system concept and design of a CT scanner with two X-ray tubes and two detectors (mounted on a CT gantry with a mechanical offset of 90 degrees ) that has the potential to overcome limitations of conventional MDCT systems, such as temporal resolution for cardiac imaging. A dual source CT (DSCT) scanner provides temporal resolution equivalent to a quarter of the gantry rotation time, independent of the patient's heart rate (83ms at 0.33s rotation time). In addition to the benefits for cardiac scanning, it allows to go beyond conventional CT imaging by obtaining dual energy information if the two tubes are operated at different voltages. Furthermore, we discuss how both acquisition systems can be used to add the power reserve of two X-ray tubes for long scan ranges and obese patients. Finally, future advances of DSCT are highlighted.

• Clinical Utility of Dual-Energy CT in the Evaluation of Solitary Pulmonary Nodules: Initial Experience.

  Authors: Eun Jin Chae, Jae-Woo Song, Joon Beom Seo, Bernhard Krauss, Yu Mi Jang, Koun-Sik Song

  Radiology. 10/2008;

  Purpose: To determine the clinical utility of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules (SPNs). Materials and Methods: This study was approved by the institutionalPurpose: To determine the clinical utility of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules (SPNs). Materials and Methods: This study was approved by the institutional review board, and informed consent was obtained. CT scans were obtained before and 3 minutes after contrast material injection in 49 patients (26 men, 23 women; mean age, 60.39 years +/- 12.24 [standard deviation]) by using a scanner with a dual-energy technique. Image sets that included nonenhanced weighted average, enhanced weighted average, virtual nonenhanced, and iodine-enhanced images were reconstructed. CT numbers of SPNs on virtual nonenhanced and nonenhanced weighted average images were compared, and CT numbers on iodine-enhanced image and the degree of enhancement were compared. Diagnostic accuracy for malignancy by using CT number on iodine-enhanced image and the degree of enhancement were compared. On the virtual nonenhanced image, the number and size of calcifications were compared with those on the nonenhanced weighted average image. Radiation dose was compared with that of single-energy CT. Results: CT numbers on virtual nonenhanced and nonenhanced weighted average images and CT numbers on the iodine-enhanced image and the degree of enhancement showed good agreements (intraclass correlation coefficients: 0.83 and 0.91, respectively). Diagnostic accuracy for malignancy by using CT numbers on iodine-enhanced image was comparable to that by using the degree of enhancement (sensitivity, 92% and 72%; specificity, 70% and 70%; accuracy, 82.2% and 71.1%, respectively). On virtual nonenhanced image, 85.0% (17 of 20) of calcifications in the SPN and 97.8% (44 of 45) of calcifications in the lymph nodes were detected, and the apparent sizes were smaller than those on the nonenhanced weighted average image. Radiation dose (average dose-length product, 240.77 mGy . cm) was not significantly different from that of single-energy CT (P = .67). Conclusion: Dual-energy CT allows measurement of the degree of enhancement and detection of calcifications without additional radiation dose. (c) RSNA, 2008.

• Xenon ventilation CT with a dual-energy technique of dual-source CT: initial experience.

  Authors: Eun Jin Chae, Joon Beom Seo, Hyun Woo Goo, Namkug Kim, Koun-Sik Song, Sang Do Lee, Soo-Jong Hong, Bernhard Krauss

  Radiology. 08/2008; 248(2):615-24.

  Institutional review board approval and written informed consent were obtained. Although xenon (Xe) ventilation CT has been introduced as a potential method with which to depict regional ventilation,Institutional review board approval and written informed consent were obtained. Although xenon (Xe) ventilation CT has been introduced as a potential method with which to depict regional ventilation, quantification of Xe enhancement has been limited by the variability of lung attenuation caused by different lung volumes between scans. The purpose of this study was to assess the feasibility of Xe ventilation CT with a dual-energy technique. Dual-energy CT was performed in 12 subjects after Xe inhalation. With use of a dual-energy technique, the Xe component could be extracted without any influence from lung volume. Dynamic and static regional ventilation function can be displayed with an exact match to the thin-section CT image.

• Material differentiation by dual energy CT: initial experience.

  Authors: Thorsten R C Johnson, Bernhard Krauss, Martin Sedlmair, Michael Grasruck, Herbert Bruder, Dominik Morhard, Christian Fink, Sabine Weckbach, Miriam Lenhard, Bernhard Schmidt, Thomas Flohr, Maximilian F Reiser, Christoph R Becker

  European radiology. 07/2007; 17(6):1510-7.

  The aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOMThe aim of this study was to assess the feasibility of a differentiation of iodine from other materials and of different body tissues using dual energy CT. Ten patients were scanned on a SOMATOM Definition Dual Source CT (DSCT; Siemens, Forchheim, Germany) system in dual energy mode at tube voltages of 140 and 80 kVp and a ratio of 1:3 between tube currents. Weighted CT Dose Index ranged between 7 and 8 mGy, remaining markedly below reference dose values for the respective body regions. Image post-processing with three-material decomposition was applied to differentiate iodine or collagen from other tissue. The results showed that a differentiation and depiction of contrast material distribution is possible in the brain, the lung, the liver and the kidneys with or without the underlying tissue of the organ. In angiographies, bone structures can be removed from the dataset to ease the evaluation of the vessels. The differentiation of collagen makes it possible to depict tendons and ligaments. Dual energy CT offers a more specific tissue characterization in CT and can improve the assessment of vascular disease. Further studies are required to draw conclusions on the diagnostic value of the individual applications.

• First performance evaluation of a dual-source CT (DSCT) system.

  Authors: Thomas G Flohr, Cynthia H McCollough, Herbert Bruder, Martin Petersilka, Klaus Gruber, Christoph Süss, Michael Grasruck, Karl Stierstorfer, Bernhard Krauss, Rainer Raupach, Andrew N Primak, Axel Küttner, Stefan Achenbach, Christoph Becker, Andreas Kopp, Bernd M Ohnesorge

  European radiology. 03/2006; 16(2):256-68.

  We present a performance evaluation of a recently introduced dual-source computed tomography (DSCT) system equipped with two X-ray tubes and two corresponding detectors, mounted onto the rotatingWe present a performance evaluation of a recently introduced dual-source computed tomography (DSCT) system equipped with two X-ray tubes and two corresponding detectors, mounted onto the rotating gantry with an angular offset of 90 degrees . We introduce the system concept and derive its consequences and potential benefits for electrocardiograph [corrected] (ECG)-controlled cardiac CT and for general radiology applications. We evaluate both temporal and spatial resolution by means of phantom scans. We present first patient scans to illustrate the performance of DSCT for ECG-gated cardiac imaging, and we demonstrate first results using a dual-energy acquisition mode. Using ECG-gated single-segment reconstruction, the DSCT system provides 83 ms temporal resolution independent of the patient's heart rate for coronary CT angiography (CTA) and evaluation of basic functional parameters. With dual-segment reconstruction, the mean temporal resolution is 60 ms (minimum temporal resolution 42 ms) for advanced functional evaluation. The z-flying focal spot technique implemented in the evaluated DSCT system allows 0.4 mm cylinders to be resolved at all heart rates. First clinical experience shows a considerably increased robustness for the imaging of patients with high heart rates. As a potential application of the dual-energy acquisition mode, the automatic separation of bones and iodine-filled vessels is demonstrated.