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  • 1
    Article
    Article
    Compound analysis of gallstones using dual energy computed tomography—Results in a phantom model (2010)
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    Language: English
    In: European Journal of Radiology, 2010, Vol.75(1), pp.e74-e80
    Description: The potential of dual energy computed tomography (DECT) for the analysis of gallstone compounds was investigated. The main goal was to find parameters, that can reliably define high percentage (〉70%) cholesterol stones without calcium components. 35 gallstones were analyzed with DECT using a phantom model. Stone samples were put into specimen containers filled with formalin. Containers were put into a water-filled cylindrical acrylic glass phantom. DECT scans were performed using a tube voltage/current of 140 kV/83 mAs (tube A) and 80 kV/340 mAs (tube B). ROI-measurements to determine CT attenuation of each sector of the stones that had different appearance on the CT images were performed. Finally, semi-quantitative infrared spectroscopy (FTIR) of these sectors was performed for chemical analysis. ROI-measurements were performed in 45 different sectors in 35 gallstones. Sectors containing 〉70% of cholesterol and no calcium component ( = 20) on FTIR could be identified with 95% sensitivity and 100% specificity on DECT. These sectors showed typical attenuation of −8 ± 4 HU at 80 kV and +22 ± 3 HU at 140 kV. Even the presence of a small calcium component (〈10%) hindered the reliable identification of cholesterol components as such. Dual energy CT allows for reliable identification of gallstones containing a high percentage of cholesterol and no calcium component in this pre-clinical phantom model. Results from or anthropomorphic phantom trials will have to confirm these results. This may enable the identification of patients eligible for non-surgical treatment options in the future.
    Keywords: Dual Energy Computed Tomography ; Compound Analysis ; Tissue Differentiation ; Gallstones ; Cholesterol ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2009.08.004
    URL: View record in ScienceDirect (Access to full text may be restricted)
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  • 2
    Article
    Article
    Dose and image quality of high-pitch dual source computed tomography for the evaluation of cervical lymph node status – Comparison to regular 128-slice single source computed tomography (2013)
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    Language: English
    In: European Journal of Radiology, June 2013, Vol.82(6), pp.e281-e285
    Description: A high-pitch dual-source CT (DSCT) was compared to a standard single-source CT protocol in terms of dose and image quality for malignant lymphoma staging. Data from 43 patients who underwent DSCT (group 1) of the neck for staging of malignant lymphoma and 40 patients who underwent regular single source CT (group 2) were investigated retrospectively. Volume CT dose index (CTDIvol), dose length product (DLP), background noise (BN), attenuation values, signal-to-noise-ratio (SNR), scan time, effective tube current-time product (eff. mAs), subjective diagnostic image quality and artifact burden were compared. CTDIvol (5.5 ± 0.8 mGy vs. 12.4 ± 1.4 mGy), DLP (172 ± 27 mGycm vs. 344 ± 60 mGycm, 〈 0.0001), eff. mAs (98 ± 15 mAs vs. 183 ± 20 mAs, 〈 0.0001) and scan time (0.64 ± 0.05 s vs. 8.21 ± 0.72 s) were lower for group 1. BN was higher ( 〈 0.001) for group 1 with a mean difference of 2.6 HU. SNR for sternocleidomastoid and pectoral muscle was lower (6.6–12.3 vs. 7.8–19.1) for group 1. Subjective image quality (1.55 ± 0.6 vs. 1.42 ± 0.5) and artifact burden (1.62 ± 1.0 vs. 1.57 ± 0.9) were not rated significantly different ( = 0.47 and = 0.80) with a good inter-observer agreement ( = 0.59–0.90). High-pitch DSCT allows reduction of patient dose for cervical lymphoma staging while diagnostic image quality is preserved.
    Keywords: High-Pitch ; Dual Source ; Computed Tomography ; Cervical Lymph Node ; Lymphoma ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2013.01.003
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  • 3
    Article
    Article
    Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications (2012)
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    Language: English
    In: European Journal of Radiology, December 2012, Vol.81(12), pp.4138-4142
    Description: To evaluate the radiation exposure for operating personel associated with rotational flat-panel angiography and C-arm cone beam CT. Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8 s/rotation, 20 s/rotation and 5 s/2 rotations), and 47 cm × 18 cm (16 s/2 rotations) and standard 2D angiography (10 s, FOV 24 cm × 18 cm). Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8 s/rotation: 28.0 μSv, 20 s/rotation: 79.3 μSv, 5 s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20 s/rotation). Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.
    Keywords: Flat-Panel Computed Tomography ; Angiography ; Interventional CT ; Cone-Beam CT ; Radiation Exposure ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2012.01.010
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  • 4
    Article
    Article
    Low-dose abdominal computed tomography for detection of urinary stone disease − Impact of additional spectral shaping of the X-ray beam on image quality and dose parameters (2016)
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    Language: English
    In: European Journal of Radiology, June 2016, Vol.85(6), pp.1058-1062
    Description: To evaluate a novel tin filter-based abdominal CT protocol for urolithiasis in terms of image quality and CT dose parameters. 130 consecutive patients with suspected urolithiasis underwent CT with three different protocols: 48 patients (group 1) were examined at tin-filtered 150 kV (150 kV Sn) on a third-generation dual-source-CT, 33 patients were examined with automated kV-selection (110–140 kV) based on the scout view on the same CT-device (group 2), and 49 patients were examined on a second-generation dual-source-CT (group 3) with automated kV-selection (100–140 kV). Automated exposure control was active in all groups. Image quality was subjectively evaluated on a 5-point-likert-scale by two radiologists and interobserver agreement as well as signal-to-noise-ratio (SNR) was calculated. Dose-length-product (DLP) and volume CT dose index (CTDIvol) were compared. Image quality was rated in favour for the tin filter protocol with excellent interobserver agreement (ICC = 0.86–0.91) and the difference reached statistical significance (p 〈 0.001). SNR was significantly higher in group 1 and 2 compared to second-generation DSCT ( ). On third-generation dual-source CT, there was no significant difference in SNR between the 150 kV Sn and the automated kV selection protocol (p = 0.5). The DLP of group 1 was 23% and 21% (p 〈 0.002) lower in comparison to group 2 and 3, respectively. So was the CTDIvol of group 1 compared to group 2 (−36%) and 3 (−32%) (p 〈 0.001). Additional shaping of a 150 kV source spectrum by a tin filter substantially lowers patient exposure while improving image quality on un-enhanced abdominal computed tomography for urinary stone disease.
    Keywords: Low-Dose Abdominal CT ; Urinary Stone Disease ; Spectral Shaping ; Tin Filter ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2016.03.016
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  • 5
    Article
    Article
    Bolus timing in high-pitch CT angiography of the aorta (2013)
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    Language: English
    In: European Journal of Radiology, June 2013, Vol.82(6), pp.1028-1033
    Description: To investigate the bolus geometry in high-pitch CT angiography (CTA) of the aorta without ECG synchronisation in comparison to single-source CT. Overall 160 consecutive patients underwent CTA either in conventional single-source mode with a pitch of 1.2 (group 1), or in dual-source mode with a pitch of 3.0 (groups 2, 3 and 4) using different contrast media timings with bolus triggering at 140 HU (5 s, group 1; 10 s, group 2; 12 s, group 3; 14 s, group 4). Contrast material, saline flush, flow rate and kV/mAs settings were kept equal for optimum comparability. Aortic attenuation was measured along the -axis of the patient at different anatomic landmarks and subjective image quality was compared. The most homogeneous enhancement of the aorta was reached with a delay of 10 s after reaching the trigger threshold. The imaging length was not significantly different, but the examination time was significantly ( 〈 0.001) shorter in the high-pitch group (7.7 s vs. 1.7 s for group 1 vs. 2, 3 and 4). In high-pitch CT angiography using a start delay of 10 s after a trigger threshold of 140 HU in the descending aorta is reached, a homogenous contrast along the -axis is accomplished.
    Keywords: CT Angiography ; Aorta ; High-Pitch CT ; Dual-Source CT ; Bolus Geometry ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2013.01.004
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  • 6
    Article
    Article
    Dual-energy CT of the pancreas: improved carcinoma-to-pancreas contrast with a noise-optimized monoenergetic reconstruction algorithm (2015)
    Details
    Language: English
    In: European Journal of Radiology, November 2015, Vol.84(11), pp.2052-2058
    Description: To evaluate a novel monoenergetic reconstruction algorithm (nMERA) with improved noise reduction for dual-energy CT (DECT) of pancreatic adenocarcinoma. Sixty patients with suspected pancreatic carcinoma underwent dual-source dual-energy CT with arterial phase. Images were reconstructed as linearly-blended 120-kV series (M_0.6) and with the standard monoenergetic (sMERA) and the novel monoenergetic algorithm (nMERA) with photon energies of 40, 55, 70 and 80 keV. Objective image quality was compared regarding image noise, pancreas attenuation, signal-to-noise ratio (SNR) and pancreas-to-lesion contrast. Subjective image quality was assessed by two observers. Thirty pancreatic adenocarcinomas were detected. nMERA showed significantly reduced image noise at low keV levels compared with sMERA images (55 keV: 7.19 ± 2.75 vs. 20.68 ± 7.01HU; 40 keV: 7.33 ± 3.20 vs. 37.22 ± 14.66HU) and M_0.6 (10.69 ± 3.57HU). nMERA pancreatic SNR was significantly superior to standard monoenergetic at 40 (47.02 ± 23.41 vs. 9.37 ± 5.83) and 55 keV (28.29 ± 16.86 vs. 9.88 ± 7.01), and M_0.6 series (11.42 ± 6.00). Pancreas-to-lesion contrast peaked in the nMERA 40 keV series (26.39 ± 16.83) and was significantly higher than in all other series ( 〈 0.001). nMERA 55 keV images series were consistently preferred by both observers over all other series ( 〈 0.01). nMERA DECT can significantly improve image quality and pancreas-to-lesion contrast in the diagnosis of pancreatic adenocarcinoma.
    Keywords: Dual-Energy CT ; Monoenergetic Reconstruction ; Pancreatic Adenocarcinoma ; Tumor Contrast ; Lesion Conspicuity ; Medicine
    ISSN: 0720-048X
    E-ISSN: 1872-7727
    DOI: 10.1016/j.ejrad.2015.07.020
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