Ralf W Bauer

University Hospital Frankfurt, Frankfurt, Hesse, Germany

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Publications (94)186.31 Total impact

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    ABSTRACT: To evaluate quantitative dual-energy computed tomography (DECT) for phantomless analysis of cancellous bone mineral density (BMD) of vertebral pedicles and to assess the correlation with pedicle screw pull-out strength. Twenty-nine thoracic and lumbar vertebrae from cadaver specimens were examined with DECT. Using dedicated post-processing software, a pedicle screw vector was mapped (R1, intrapedicular segment of the pedicle vector; R2, intermediate segment; R3, intracorporal segment; global, all segments) and BMD was calculated. To invasively evaluate pedicle stability, pedicle screws were drilled through both pedicles and left pedicle screw pull-out strength was measured. Resulting values were correlated using the paired t test and Pearson's linear correlation. Average pedicle screw vector BMD (R1, 0.232 g/cm(3); R2, 0.166 g/cm(3); R3, 0.173 g/cm(3); global, 0.236 g/cm(3)) showed significant differences between R1-R2 (P < 0.002) and R1-R3 (P < 0.034) segments while comparison of R2-R3 did not reach significance (P > 0.668). Average screw pull-out strength (639.2 N) showed a far stronger correlation with R1 (r = 0.80; P < 0.0001) than global BMD (r = 0.42; P = 0.025), R2 (r = 0.37; P = 0.048) and R3 (r = -0.33; P = 0.078) segments. Quantitative DECT allows for phantomless BMD assessment of the vertebral pedicle. BMD of the intrapedicular segment shows a significantly stronger correlation with pedicle screw pull-out strength than other segments. • Quantitative dual-energy CT enables evaluation of pedicle bone mineral density. • Intrapedicular segments show significant differences regarding bone mineral density. • Pedicle screw pull-out strength correlated strongest with R1 values. • Dual-energy CT may improve preoperative assessment before transpedicular screw fixation.
    European Radiology 12/2014; · 4.34 Impact Factor
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    ABSTRACT: To compare non-linear and linear image-blending post-processing techniques in dual-energy CT (DECT) of primary head and neck squamous cell carcinoma (SCC) regarding subjective and objective image quality. Head and neck DECT studies from 69 patients (48 male, 21 female; mean age 62.3 years) were retrospectively evaluated. All tumour lesions were histologically confirmed SCC. Linearly blended 80/140 kVp images series with varying weighting factors of 0.3 (M_0.3), 0.6 and 0.8 were compared with non-linearly blended images. Attenuation of tumour lesion, various soft-tissue structures, the internal jugular vein, and image noise were measured, tumour signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Overall image quality, delineation of tumour lesion, image sharpness, and noise level were rated individually by three radiologists using five-point Likert scales. Interobserver agreement was calculated using intraclass correlation coefficient (ICC). Enhancement of tumour lesions (non-linear, 137.5 ± 20.1 HU; M_0.3, 92.7 ± 14.4 HU; M_0.6, 110 ± 15.4 HU; M_0.8, 123 ± 18.2 HU), CNR (non-linear, 12 ± 8; M_0.3, 4 ± 4.7; M_0.6, 7.5 ± 5.5; M_0.8, 8 ± 5.5), subjective overall image quality and tumour delineation were significantly increased (all p < 0.001) with the non-linear blending technique compared to all investigated linear blending weighting factors. Overall interobserver agreement was substantial (ICC 0.70; 95% CI: 0.66-0.73). Post-processing of DECT using a non-linear blending technique provides improved objective and subjective image quality of head and neck SCC compared to linearly blended images series. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
    Clinical radiology. 12/2014;
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    ABSTRACT: The purpose of the study was to evaluate 70 kVp dual-source computed tomography pulmonary angiography (CTPA) with reduced iodine load in comparison with single-source 70 and 100 kVp CTPA with standard iodine load regarding image quality and radiation dose. Three groups with 40 consecutive patients each underwent either standard single-source 100 kVp (120 mAs; group A), single-source 70 kVp (208 mAs; group B), or dual-source 70 kVp CTPA (416 mAs; group C). A volume of 70 mL of contrast material with 400 mg I/mL (groups A, B) or 300 mg I/mL (group C) was administered. Chest diameter, dose-length product, intravascular signal attenuation, image noise, signal to noise ratio (SNR), and contrast to noise ratio (CNR) were compared. Two observers rated subjective image quality regarding intravascular enhancement and image noise using 5-point scales. Chest diameter and age were similar (P≥0.28) for all groups. Compared with group A, the average dose-length product was 59% lower in group B (67.3±11.8 vs. 164.7±50.6 mGy cm, P<0.001) and similar between groups A and C (167.7±41.2 mGy cm, P=0.39). Average SNR and CNR were significantly higher for group C (21.5±4.7 and 19.0±4.5, respectively) compared with groups A (18.3±3.5 and 15.8±3.4, respectively) and B (17.3±5.8 and 15.6±5.5, respectively; all Ps≤0.001). Subjective image quality ratings regarding enhancement and noise were highest for group C (1.73±0.62 and 2.03±0.66, respectively). Compared with standard 100 kVp CTPA, single-source 70 kVp CTPA allows for significant radiation dose savings with comparable SNR and CNR, whereas dual-source 70 kVp CTPA results in a superior objective image quality albeit a reduction of iodine concentration.
    Journal of thoracic imaging. 11/2014;
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    ABSTRACT: A sliding gantry trauma room CT solution facilitates significantly faster polytrauma management.•Faster and more efficient resumption of regularly scheduled patients due to a two room solution is supported.•Sliding gantry CT achieves the same patient throughput as two separate conventional CT devices.
    European Journal of Radiology. 11/2014;
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    ABSTRACT: Low-tube-voltage acquisition has been shown to facilitate substantial dose savings for neck CT with similar image contrast compared with standard 120-kVp acquisition. However, its potential for the detection of neck pathologies is uncertain. Our aim was to evaluate the effects of low-tube-voltage 80-kV(peak) acquisitions for neck CT on diagnostic accuracy and interobserver agreement.
    AJNR. American journal of neuroradiology. 08/2014;
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    ABSTRACT: To intra-individually compare single-portal-phase low-tube-voltage (100-kVp) computed tomography (CT) with 120-kVp images for short-term follow-up assessment of CT severity index (CTSI) of acute pancreatitis, interobserver agreement and radiation dose.
    European Radiology 07/2014; · 4.34 Impact Factor
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    ABSTRACT: Objective To investigate the impact of automated attenuation-based tube potential selection on image quality and exposure parameters in polytrauma patients undergoing contrast-enhanced thoraco-abdominal CT. Methods One hundred patients were examined on a 16-slice device at 120 kV with 190 ref.mAs and automated mA modulation only. Another 100 patients underwent 128-slice CT with automated mA modulation and topogram-based automated tube potential selection (autokV) at 100, 120 or 140 kV. Volume CT dose index (CTDIvol), dose–length product (DLP), body diameters, noise, signal-to-noise ratio (SNR) and subjective image quality were compared. Results In the autokV group, 100 kV was automatically selected in 82 patients, 120 kV in 12 patients and 140 kV in 6 patients. Patient diameters increased with higher kV settings. The median CTDIvol (8.3 vs. 12.4 mGy; −33 %) and DLP (594 vs. 909 mGy cm; −35 %) in the entire autokV group were significantly lower than in the group with fixed 120 kV (p < 0.05 for both). Image quality remained at a constantly high level at any selected kV level. Conclusion Topogram-based automated selection of the tube potential allows for significant dose savings in thoraco-abdominal trauma CT while image quality remains at a constantly high level. Key Points • Automated kV selection in thoraco-abdominal trauma CT results in significant dose savings • Most patients benefit from a 100-kV protocol with relevant DLP reduction • Constantly good image quality is ensured • Image quality benefits from higher kV when arms are positioned downward
    European Radiology 07/2014; 24(7). · 4.34 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the effects on objective and subjective image quality of virtual monoenergetic reconstructions at various energy levels of dual-energy computed tomography (DECT) in patients with head and neck cancer.
    Investigative Radiology 05/2014; · 5.46 Impact Factor
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    ABSTRACT: To compare non-linear and linear blending of cardiac dual-energy computed tomography (DECT) for optimal visualization of late iodine enhancement (LIE) in patients with chronic myocardial infarction (CMI). LIE-DECT data from 20 patients with known CMI were retrospectively analyzed. Images were reconstructed using non-linear blending center and width settings in the range of 0-500. Linear blending was performed with weighting factors 0.8 (80 % 100 kV, 20 % 140 kV), 0.6 and 0.3. 100-/140-kV data and blended images were analyzed. Contrast and percentage signal differences between infarcted and healthy myocardium and the left ventricle blood pool were computed. Statistical analysis was performed using repeated-measures analysis of variance and post hoc t tests. Non-linear blending showed the highest signal differences for all contrasts and analyses. Repeated-measures ANOVA tests confirmed the statistical differences between the investigated blending techniques (P < 0.01). Paired-samples post hoc t tests confirmed the significance of these results (P < 0.04). The ideal non-linear blending settings for best demarcation of CMI from healthy myocardium were a center of 65.8 ± 23.2 and a width of 0.0 ± 0.0. Non-linear blending of LIE-DECT improves display of LIE in patients with CMI in comparison with linear blending and non-post-processed image data from 100-/140-kV.
    The international journal of cardiovascular imaging 05/2014; · 2.15 Impact Factor
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    ABSTRACT: To evaluate image quality and diagnostic accuracy of selective monoenergetic reconstructions of late iodine enhancement (LIE) dual-energy computed tomography (DECT) for imaging of chronic myocardial infarction (CMI). Twenty patients with a history of coronary bypass surgery underwent cardiac LIE-DECT and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI). LIE-DECT images were reconstructed as selective monoenergetic spectral images with photon energies of 40, 60, 80, and 100 keV and the standard linear blending setting (M_0.6). Images were assessed for late enhancement, transmural extent, signal characteristics and subjective image quality. Seventy-nine myocardial segments (23 %) showed LGE. LIE-DECT detected 76 lesions. Images obtained at 80 keV and M_0.6 showed a high signal-to-noise ratio (15.9; 15.1), contrast-to-noise ratio (4.2; 4.0) and sensitivity (94.9 %; 92.4 %) while specificity was identical (99.6 %). Differences between these series were not statistically significant. Transmural extent of LIE was overestimated in both series (80 keV: 40 %; M_0.6: 35 %) in comparison to MRI. However, observers preferred 80 keV in 13/20 cases (65 %, κ = 0.634) over M_0.6 (4/20 cases) regarding subjective image quality. Post-processing of LIE-DECT data with selective monoenergetic reconstructions at 80 keV significantly improves subjective image quality while objective image quality shows no significant difference compared to standard linear blending. • Late enhancement dual-energy CT allows for detection of chronic myocardial infarction. • Monoenergetic reconstructions at 80 keV significantly improve subjective image quality. • 80 keV and standard linear blending reconstructions show no significant differences. • Extent of CMI detected with LIE-DECT is overestimated compared with MRI.
    European Radiology 03/2014; · 4.34 Impact Factor
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    ABSTRACT: Purpose To evaluate the feasibility of phantomless in vivo dual-energy computed tomography (CT)-based three-dimensional (3D) bone mineral density (BMD) assessment in comparison with dual x-ray absorptiometry (DXA). Materials and Methods This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Data from clinically indicated dual-energy CT and DXA examinations within 2 months, comprising the lumbar spine of 40 patients, were included. By using automated dedicated postprocessing dual-energy CT software, the trabecular bone of lumbar vertebrae L1-L4 were analyzed and segmented. A mixed-effects model was used to assess the correlations between BMD values derived from dual-energy CT and DXA. Results One hundred sixty lumbar vertebrae were analyzed in 40 patients (mean age, 57.1 years; range, 24-85 years), 21 male (mean age, 54.3 years; range, 24-85 years) and 19 female (mean age, 58.5 years; range, 31-80 years). Mean BMD of L1-L4 determined with DXA was 0.995 g/cm(2), and 18 patients (45%) showed an osteoporotic BMD (T score less than -2.5) of at least two vertebrae. Mean dual-energy CT-based BMD of L1-L4 was 0.254 g/cm(3). Bland-Altman analysis with mixed effects demonstrated a lack of correlation between dual-energy CT-based and DXA-based BMD values, with a mean difference of 0.7441 and 95% limits of agreement of 0.7441 ± 0.4080. Conclusion Dedicated postprocessing of dual-energy CT data allows for phantomless in vivo BMD assessment of the trabecular bone of lumbar vertebrae and enables freely rotatable color-coded 3D visualization of intravertebral BMD distribution. © RSNA, 2014.
    Radiology 01/2014; · 6.34 Impact Factor
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    ABSTRACT: PURPOSE To compare the radiation exposure and image quality of coronary CT angiography (cCTA) protocols on a second generation 128-slice dual-source CT (DSCT) scanner. METHOD AND MATERIALS We prospectively included 100 patients referred for cCTA. Patients with a heart rate below 65 bpm were randomized between prospectively ECG-gated high-pitch spiral (group 1) and narrow-window sequential (group 2) acquisition. Patients with a heart rate above 65 bpm were randomly assigned to a retrospectively ECG-gated spiral acquisition protocol in either dual-source (group 3) or dual-energy (group 4) mode. CT dose index volume, dose length product, effective dose, contrast-to-noise and signal-to-noise ratio were compared. Subjective image quality was rated by two observers blinded to the used protocol. RESULTS High-pitch spiral cCTA showed a mean estimated radiation dose of 1.27±0.64 mSv, significantly (p<0.001) lower than sequential mode (2.05±1.18 mSv) and spiral acquisition with DSCT(5.95±2.56 mSv) or DECT (3.82±1.38 mSv). Image noise showed no statistical difference (p>0.05), ranging from 16.03±6.3 (group 1) to 19.3±9.5 (group 4) and 20.1±16.5 (group 2) up to 26.4±23.0 (group 3). Each protocol showed diagnostic image quality in at least 98.4% of evaluated coronary segments. CONCLUSION Prospectively ECG-gated DSCT protocols allow cCTA with significant dose reduction. High-pitch spiral mode generates less than 1/2 of the estimated radiation exposure of sequential acquisition mode. In patients with a heart rate above 65 bpm, dual-energy mode should be preferred over spiral DSCT as it significantly decreases estimated dose without compromising diagnostic image quality. CLINICAL RELEVANCE/APPLICATION Second-generation DSCT scanners allow cCTA in patients with normo- or arrhythmia that result in significant dose reduction while maintaining diagnostic image quality.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE To evaluate the effect of an anti-scatter grid on perceived image quality in adult bedside chest radiographs using both a mobile digital radiography (DR) system and a conventional computed radiography (CR) system. METHOD AND MATERIALS We included 103 intensive-care patients (mean age: 66.4 years). Patients received bedside chest radiographs using four acquisition techniques (CR and DR with and without grid). Image quality was evaluated independently by four radiologists using a 9-point visibility scale. Evaluated were: lung parenchyma, soft tissues, thoracic spine, foreign bodies and overall image quality. Inter-observer agreement and differences between systems were tested using inter-class correlation test. Mean scores were compared by analysis of variance (ANOVA) followed by post-hoc pairwise testing (Tukey test) in case of multiple group comparison and by student’s t-test in case of single group comparison (p < 0.05 = significant). RESULTS The image quality of the DR images with a grid was significantly higher than that obtained without a grid (p<0.001) for all structures. The use of a grid in CR significantly improved the overall image quality, lung parenchyma and soft tissue delineation (p<0.001). Foreign body delineation, however, was significantly better in CR images obtained without a grid (p<0.001), while the two systems showed no significant difference regarding thoracic spine delineation (p=0.554). The DR-images’ scores were significantly higher than the CR-images’ scores for all structures. The inter-observer agreement was substantial for lung parenchyma (ICC=0.77), soft tissue (ICC=0.78), thoracic spine (ICC=0.80) and overall image quality (ICC=0.78) and was almost perfect for foreign bodies (ICC=0.81). CONCLUSION The use of an anti-scatter grid significantly improved the image quality of bedside DR radiographs. A similar effect was seen with CR radiographs but only for lung parenchyma, soft tissue and overall image quality. Mobile DR outperformed CR in all structures. CLINICAL RELEVANCE/APPLICATION In both, CR and DR, the use of grid in adult bedside radiography proved to be beneficial, and significantly improved the perceived image quality.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE To investigate the impact of automated attenuation-based tube potential selection on image quality and radiation dose in patients undergoing CT of the neck. METHOD AND MATERIALS 360 patients [median age 52 years (range 4 – 89)] underwent 128-slice CT of the neck. First group (n=40) was examined with fixed 120 kV with 180 ref.mAs and automated exposure control (AEC) modulating only mA output. The second group (n=320) underwent CT with AEC and topogram-based automated tube potential selection (Care-kV) by the scanner software with either 80 kV/406 ref.mAs, 100 kV/223 ref.mAs, 120 kV/180 ref.mAs or 140 kV/125 ref.mAs. CTDIvol, DLP, BMI, organ enhancement, image noise, SNR and subjective diagnostic image quality (5-point scale, 2 readers in consensus) were compared between the groups and sub-groups using Mann-Whitney-U test and Cohen's weighted kappa analysis for inter-observer agreement. RESULTS 100 kV was automatically selected in 279 patients, 120 kV in 40 patients and 80 kV in 1 patient of the Care-kV group. Patients mean BMI (20 kg/m² at 80 kV, 24.2 kg/m² at 100 kV and 28.1 kg/m² at 120 kV) increased with higher kV settings. The average CTDIvol (9.7 vs. 12.2 mGy) and DLP (255 vs. 342 mGycm; p < 0.05) in the entire Care-kV group were 20%/25% lower than in group 1 with fixed 120 kV. This effect was even more pronounced in the patients in whom 100 kV was selected (CTDIvol 8.9 mGy, -27%; DLP 244 mGycm, -29%). Organ enhancement increased with lower kV, while image noise and SNR were at a stable level. Subjective diagnostic image quality (4.61 vs. 4.56, p>0.05) were not rated significantly different with a good interobserver agreement for all tube potential levels (κ=0.5-0.8). CONCLUSION Software-based automated selection of the tube potential allows for significant dose savings in CT of the neck while image quality is maintained or even improved. CLINICAL RELEVANCE/APPLICATION Automated selection of tube potential in CT of the neck allows significant dose reduction and preserves image quality, which is relevant for staging patients with lymphoma or head and neck cancer.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: Computed tomography (CT) is the gold standard for evaluation of pulmonary nodules and is at the same time responsible for the majority of the collective effective dose. To evaluate radiation dose and efficacy of computer-assisted detection (CAD) for solid pulmonary nodules in low dose chest CT performed at 70 kV. CAD was performed upon chest CT with 70 kV and 100 kV (gold standard) at manufacture's recommended tube current of 87 mAs (collimation, 64 × 0.6 mm). Detection rate for pulmonary nodules and size measurements of both techniques were compared to each other. Radiation dosage in terms of effective dose (E) was measured using an Alderson-Rando Phantom. Seventy-four patients with 301 solid nodules were included in the study. CAD detection rate was similar for 70 kV (94.7%) and 100 kV (92.4%). Mean transversal nodule diameter was 5.5 mm for 70 kV and 5.7 mm for 100 kV with an average volume of 0.12 mL (both techniques). Derived from the phantom measurements patient examinations resulted in an E of 0.51 mSv (70 kV) versus 2.02 mSv (100 kV). 70 kV low-dose chest CT is suitable for CAD based lung nodule analysis at a fraction of the radiation burden of the standard technique. Since the measurements are highly accurate, 70 kV CT could be used for detection of pulmonal lesions as well as follow-up studies.
    Acta Radiologica 11/2013; · 1.33 Impact Factor
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    ABSTRACT: BACKGROUND AND PURPOSE:Acute intracranial hemorrhage represents a severe and time critical pathology that requires precise and quick diagnosis, mainly by performing a CT scan. The purpose of this study was to compare image quality and intracranial hemorrhage conspicuity in brain CT with sinogram-affirmed iterative reconstruction and filtered back-projection reconstruction techniques at standard (340 mAs) and low-dose tube current levels (260 mAs).MATERIALS AND METHODS:A total of 94 consecutive patients with intracranial hemorrhage received CT scans either with standard or low-dose protocol by random assignment. Group 1 (n=54; mean age, 64 ± 20 years) received CT at 340 mAs, and group 2 (n=40; mean age, 57 ± 23 years) received CT at 260 mAs. Images of both groups were reconstructed with filtered back-projection reconstruction and 5 iterative strengths (S1-S5) and ranked blind by 2 radiologists for image quality and intracranial hemorrhage on a 5-point scale. Image noise, SNR, dose-length product (mGycm), and mean effective dose (mSv) were calculated.RESULTS:In both groups, image quality and intracranial hemorrhage conspicuity were rated subjectively with an excellent/good image quality. A higher strength of sinogram-affirmed iterative reconstruction showed an increase in image quality with a difference to filtered back-projection reconstruction (P < .05). Subjective rating showed the best score of image quality and intracranial hemorrhage conspicuity achieved through S3/S4-5. Objective analysis of image quality showed in an increase of SNR with a higher strength of sinogram-affirmed iterative reconstruction. Patients in group 2 (mean: 744 mGycm/1.71 mSv) were exposed to a significantly lower dose than those in group 1 (mean: 1045 mGycm/2.40 mSv, P < .01).CONCLUSIONS:S3 provides better image quality and visualization of intracranial hemorrhage in brain CT at 260 mAs. Dose reduction by almost one-third is possible without significant loss in diagnostic quality.
    American Journal of Neuroradiology 11/2013; · 3.17 Impact Factor
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    ABSTRACT: To evaluate whether dual-energy computed tomography (DECT)-derived iodine content and iodine overlay could differentiate between normal, inflammatory and metastatic squamous cell carcinoma (SCC) cervical lymph nodes. This study was approved by the institutional review board. Sixteen patients with normal lymph nodes, 20 patients with enlarged nodes draining deep cervical inflammations and 23 patients with pathologically proved metastatic SCC nodes who underwent contrast enhanced DECT were retrospectively identified. Iodine content and overlay of 36 normal, 43 inflammatory and 52 metastatic lymph nodes were calculated using circular regions of interest and compared among the three groups. A receiver operating characteristic (ROC) curve was used to determine the sensitivity and specificity of iodine content and overlay for diagnosis of metastatic nodes. Iodine content (mg/ml) was significantly lower for metastatic lymph nodes (2.34 ± 0.45) than for normal (2.86 ± 0.37) and inflammatory (3.53 ± 0.56) lymph nodes, P < 0.0001. Iodine overlay (HU) was also significantly lower for metastatic lymph nodes (47 ± 11.6) than normal (57.4 ± 8.2) and inflammatory nodes (69.3 ± 11.5), P < 0.0001. The areas under the ROC curve for iodine content and iodine overlay were 0.923 and 0.896. DECT-derived iodine content and overlay differ significantly among normal, inflammatory and metastatic SCC cervical lymph nodes. • Derived iodine content can be calculated from contrast-enhanced dual-energy CT. • Derived iodine content and iodine overlay could help characterise cervical lymph nodes. • Iodine parameters were significantly lower in metastatic lymph nodes than normal/inflammatory lymph nodes. • Iodine content appears more sensitive than iodine overlay for lymph node characterisation.
    European Radiology 10/2013; · 4.34 Impact Factor
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    ABSTRACT: The objective of this study was to evaluate the diagnostic performance of 2 different imaging systems in adult bedside chest radiography and the impact on the visibility of selected diagnostically relevant structures in the images acquired with these systems, with and without an antiscatter grid. We acquired bedside chest radiographs of 103 intensive-care patients (36 women, 67 men; age range, 17-90 years; mean age, 66.4 years) using 4 acquisition techniques (computed radiography [CR] and digital radiography [DR], with and without grid). Image quality was evaluated independently by 4 radiologists using a 9-point visibility scale. Evaluated were lung parenchyma, soft tissues, thoracic spine, foreign bodies, and the overall image quality. Interobserver agreement and differences between the systems were tested using an interclass correlation (ICC) test. Mean scores were compared using the analysis of variance, followed by the post hoc pairwise testing (the Tukey test) in case of multiple group comparisons and by the Student t test in case of single group comparisons (P < 0.05, significant). The image quality of the structures evaluated in the DR images with a grid was significantly higher than that obtained without a grid (P < 0.001) for all structures. The use of a grid in CR significantly improved the overall image quality, lung parenchyma, and soft tissue delineation (P < 0.001). Foreign body delineation, however, was significantly better in the CR images obtained without a grid (P < 0.001), whereas the 2 systems showed no significant difference regarding thoracic spine delineation (P = 0.554). The scores of the DR images were significantly higher than those of the CR images for all structures. The interobserver agreement was substantial for lung parenchyma (ICC, 0.77), soft tissue (ICC, 0.78), thoracic spine (ICC, 0.80), and the overall image quality (ICC, 0.78) and was almost perfect for foreign bodies (ICC, 0.81). The use of an antiscatter grid significantly improved the image quality of bedside DR radiographs. A similar effect was seen with CR radiographs but only for lung parenchyma, soft tissue, and the overall image quality. Mobile DR outperformed CR in all structures.
    Investigative radiology 09/2013; · 4.85 Impact Factor
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    ABSTRACT: The purpose of the study was to compare the performance of late iodine-enhancement (LIE) dual-energy computed tomography (DECT) linear blending and selective myocardial iodine mapping for the detection of chronic myocardial infarction (CMI) with late gadolinium-enhancement (LGE) 3-T magnetic resonance imaging. This study was approved by the institutional review board, and the patients gave informed consent. A total of 20 patients with a history of CMI underwent cardiac LIE-DECT and LGE-MRI. Images of the LIE-DECT were reconstructed as 100 kilovolt (peak) (kV[p]), 140 kV(p), and weighted-average (WA; linear blending) images from low- and high-kilovoltage peak data using 3 different weighting factors (0.8, 0.6, 0.3). Additional color-coded myocardial iodine distribution maps were calculated. The images were reviewed for the presence of late enhancement, transmural extent, signal characteristics, infarct volume, and subjective image quality. Segmental analysis of LIE-DECT data from 100 kV(p), WA of 0.8, and WA of 0.6 showed identical results for the identification of CMI (89% sensitivity, 98% specificity, 96% accuracy) and correctly identified all segments with transmural scarring detected through LGE-MRI. Weighted average of 0.6 received the best subjective image quality rating (15/20 votes) and average measured infarct size correlated best with LGE-MRI (5.7% difference). In comparison with LGE-MRI, iodine distribution maps were susceptible to false-positive and false-negative findings (52% sensitivity, 88% specificity, 81% accuracy), overestimating quantity of transmural scars by 78% while underestimating infarct volume by 55%. Late iodine enhancement cardiac dual-energy computed tomography correlates well with LGE-MRI for detecting CMI, whereas iodine distribution analysis provides inferior accuracy. Linear blending further improves image quality and enables more precise estimation of scar volume.
    Investigative Radiology 07/2013; · 5.46 Impact Factor
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    ABSTRACT: PURPOSE: To assess the influence of experience and training on the proficiency in coronary CT angiography (CCTA) interpretation of practitioners with different levels of experience. METHODS AND MATERIALS: Nine radiologist and cardiologist observers with varying prior CCTA experience ranging from novice to expert independently analyzed two case series of 50 catheter-correlated CCTA studies for coronary artery stenosis (0%, ≤49%, 50-74%, 75-99%, or 100%). Results of the first case series were unblinded and presented along with catheter angiography results to each reader before proceeding to the second series. Diagnostic accuracy on a per-segment basis was compared for all readers and both case series, respectively. RESULTS: Correlation coefficients between CCTA and catheter angiography initially ranged between good (r=0.87) and poor (r=0.26), depending on reader experience, and significantly (p<0.05) improved in the second case series (range: r=0.42 to r=0.91). Diagnostic accuracy was significantly (p<0.05) higher for more experienced readers (range: 96.5-97.8%) as compared to less experienced observers (range: 90.7-93.6%). After completion of the second case series for less experienced readers sensitivity and PPV significantly (p<0.05) improved (range: 62.7-67.8%/51.4-84.1%), but still remained significantly (p<0.05) lower as compared to more experienced observers (range: 89.8-93.3%/80.6-93.3%). CONCLUSION: The level of experience appears to be a strong determinant of proficiency in CCTA interpretation. Limited one-time training improves proficiency in novice readers, but not to clinically satisfactory levels.
    European journal of radiology 04/2013; · 2.65 Impact Factor

Publication Stats

296 Citations
186.31 Total Impact Points

Institutions

  • 2013–2014
    • University Hospital Frankfurt
      Frankfurt, Hesse, Germany
  • 2007–2014
    • Goethe-Universität Frankfurt am Main
      • Institut für Diagnostische und Interventionelle Radiologie
      Frankfurt, Hesse, Germany
  • 2009–2013
    • Medical University of South Carolina
      • Department of Radiology
      Charleston, South Carolina, United States