Diagnostic accuracy of automated 3D volumetry of cardiac chambers by CT pulmonary angiography for identification of pulmonary hypertension due to left heart disease.

OBJECTIVES: To assess diagnostic accuracy of automated 3D volumetry of cardiac chambers based on computed tomography pulmonary angiography (CTPA) for the differentiation of pulmonary hypertension due to left heart disease (group 2 PH) from non-group 2 PH compared to manual diameter measurements. METHODS: Patients with confirmed PH undergoing right heart catheterisation and CTPA within 100 days for diagnostic workup of PH between August 2013 and February 2016 were included in this retrospective, single-centre study. Automated 3D segmentation of left atrium, left ventricle, right atrium and right ventricle (LA/LV/RA/RV) was performed by two independent and blinded radiologists using commercial software. For comparison, axial diameters were manually measured. The ability to differentiate group 2 PH from non-group 2 PH was assessed by means of logistic regression. RESULTS: Ninety-one patients (median 67.5 years, 44 women) were included, thereof 19 patients (20.9%) classified as group 2 PH. After adjustment for age, sex and mean pulmonary arterial pressure, group 2 PH was significantly associated with larger LA volume (p < 0.001), larger LV volume (p = 0.001), lower RV/LV volume ratio (p = 0.04) and lower RV/LA volume ratio (p = 0.003). LA volume demonstrated the highest discriminatory ability to identify group 2 PH (AUC, 0.908; 95% confidence interval, 0.835-0.981) and was significantly superior to LA diameter (p = 0.009). Intraobserver and interobserver agreements were excellent for all volume measurements (intraclass correlation coefficients 0.926-0.999, all p < 0.001). CONCLUSIONS: LA volume quantified by automated, CTPA-based 3D volumetry can differentiate group 2 PH from other PH groups with good diagnostic accuracy and yields significantly higher diagnostic accuracy than left atrial diameter. KEY POINTS: • Automated cardiac chamber volumetry using non-gated CT pulmonary angiography can differentiate pulmonary hypertension due to left heart disease from other causes with good diagnostic accuracy. • Left atrial volume yields significantly higher diagnostic accuracy than left atrial axial diameter for identification of pulmonary hypertension due to left heart disease without time-consuming manual processing.

Dual-Layer Spectral Detector CT in Comparison with FDG-PET/CT for the Assessment of Lymphoma Activity.

PURPOSE: In patients with malignant lymphoma, disease activity is recommended to be assessed by FDG-PET/CT and the Deauville five-point scale (5-PS). The purpose of this study was to explore the potential of iodine concentration measured in contrast-enhanced dual-layer spectral detector CT (SDCT) as an alternative surrogate parameter for lymphoma disease activity by investigating its correlation with maximum standardized uptake values (SUVmax) and 5-PS. MATERIALS AND METHODS: 25 patients were retrospectively analyzed. Contrast-enhanced SDCT and FDG-PET/CT were performed in the same treatment interval within at most 3 months. CT attenuation values (AV), absolute iodine concentrations (aIC), and normalized iodine concentrations (nIC) of lymphoma lesions were correlated with SUVmax using Spearman's rank correlation coefficient. The performance of aIC and nIC to detect lymphoma activity (defined as 5-PS > 3) was determined using ROC curves. RESULTS: 60 lesions were analyzed, and 31 lesions were considered active. AV, aIC, and nIC all correlated significantly with SUVmax. The strongest correlation (Spearman ρ = 0.71; p < 0.001) and highest area under the ROC curve (AUROC) for detecting lymphoma activity were observed for nIC normalized to inferior vena cava enhancement (AUROC = 0.866). The latter provided sensitivity, specificity, and diagnostic accuracy of 87 %, 75 %, and 80 %, respectively, at a threshold of 0.20. ROC analysis for AV (AUROC = 0.834) and aIC (AUROC = 0.853) yielded similar results. CONCLUSION: In malignant lymphomas, there is a significant correlation between metabolic activity as assessed by FDG-PET/CT and iodine concentration as assessed by SDCT. Iodine concentration shows promising diagnostic performance for detecting lymphoma activity and may represent a potential imaging biomarker. KEY POINTS: · Iodine concentration correlates significantly with SUVmax in lymphoma patients. · Iodine concentration may represent a potential imaging biomarker for detecting lymphoma activity. · Normalization of iodine concentration improves diagnostic performance of iodine concentration. CITATION FORMAT: · Gehling K, Mokry T, Do TD et al. Dual-Layer Spectral Detector CT in Comparison with FDG-PET/CT for the Assessment of Lymphoma Activity. Fortschr Röntgenstr 2022; 194: 747 - 754.

Treatment of Postoperative Lymphatic Leakage Applying Transpedal Lymphangiography - Experience in 355 Consecutive Patients.

PURPOSE: Report of experience from a single institution in treating postoperative lymphatic leakage (PLL) applying conventional transpedal lymphangiography (TL). MATERIALS AND METHODS: 453 patients with the initial diagnosis of PLL receiving TL between 03/1993 and 09/2018 were identified in the database. Only patients with confirmed PLL were included in the study. The technical success, safety, and treatment success of TL were evaluated. Independent predictors of TL treatment failure were examined using univariate and multivariate logistic regression analysis. RESULTS: 355 consecutive patients (218 men, 137 women; median age of 62 years) who underwent TL for PLL (e. g., chylothorax) after ineffective conservative treatment were included. The median time between causal surgery and TL was 27 days. The median technical success rate of TL was 88.5 %, with a median volume of Lipiodol of 10.0 ml. No complication of TL was recorded. Three groups were defined according to the different clinical courses: group A (41/355, 11.5 %) - TL with technical failure; group B (258/355, 72.7 %) - "therapeutic" TL alone with technical success; and group C (56/355, 15.8 %) - "diagnostic" TL with simultaneously invasive treatment (incl. surgical revision and percutaneous sclerotherapy). Treatment success rate and median time to treatment success were higher in group C than in group B, but without significant differences (64.3 % vs. 61.6 %, p = 0.710; six vs. five days, p = 0.065). Univariate and multivariate logistic regression analyses for group B confirmed drainage volume (> 500 ml/d) and Lipiodol extravasation as independent predictors of TL clinical failure (odds ratios [ORs] of 2.128 and 2.372 [p = 0.005 and p = 0.003, respectively]). CONCLUSION: TL is technically reliable, safe, and effective in treating PLL. When conservative treatment fails, TL can be regarded as the next treatment option. KEY POINTS: · TL is technically reliable, safe, and effective for treating PLL.. · When conservative treatment fails, TL can be regarded as the next treatment option.. · Drainage volume > 500 ml/day is an independent predictor of clinical failure after TL.. · Lipiodol extravasation is an independent predictor of clinical failure after TL.. CITATION FORMAT: · Pan F, Richter GM, Do TD et al. Treatment of Postoperative Lymphatic Leakage Applying Transpedal Lymphangiography - Experience in 355 Consecutive Patients. Fortschr Röntgenstr 2022; 194: 634 - 643.

Utility of Automated Cardiac Chamber Volumetry by Nongated CT Pulmonary Angiography for Detection of Pulmonary Hypertension Using the 2018 Updated Hemodynamic Definition.

BACKGROUND. Noninvasive tests for pulmonary hypertension (PH) are needed to help select patients for diagnostic right heart catheterization (RHC). CT pulmonary angiography (CTPA) is commonly performed for suspected PH. OBJECTIVE. The purpose of this study was to assess the utility of CTPA-based cardiac chamber volumetric measurements for the diagnosis of PH in comparison with echocardiographic and conventional CTPA parameters, with the 2018 updated hemodynamic definition used as reference. METHODS. This retrospective study included 109 patients (72 women and 37 men; median age, 68 years) who underwent nongated CTPA, transthoracic echocardiography, and RHC for the workup of suspected PH between August 2013 and February 2016. Two radiologists independently used automated 3D segmentation software to determine the volumes of the right ventricle (RV), right atrium (RA), left ventricle (LV), and left atrium (LA) and also measured the axial diameters of the cardiac chambers, main pulmonary artery, and ascending aorta. Interobserver agreement was assessed, and mean values were obtained; one observer repeated volumetric measurements to assess intraobserver agreement. ROC analysis was used to assess diagnostic performance for the detection of PH. A multivariable binary logistic regression model was established. RESULTS. A total of 60 of 109 patients had PH. Intra- and interobserver agreements were excellent for all volume measurements (intraclass correlation coefficients, 0.935-0.999). In patients with PH versus those without PH, RV volume was 172.6 versus 118.1 mL, and RA volume was 130.2 versus 77.0 mL (both p < .05). Cardiac chamber measurements with the highest AUC for PH were the RV/LV volume ratio and RA volume (both 0.791). Significant predictors of PH20 (as defined using the 2018 hemodynamic definition from the Sixth World Symposium on Pulmonary Hypertension) after adjustment for age, sex, and body surface area included RV volume per 10 mL (odds ratio [OR], 1.21), RA volume per 10 mL (OR, 1.27), RV/LV volume ratio (OR, 2.91), and RA/LA volume ratio (OR, 11.22). Regression analysis yielded a predictive model for PH that contained two independent predictors: echocardiographic pulmonary arterial systolic pressure and CTPA-based RA volume; the model had an AUC of 0.898, sensitivity of 83.3%, and specificity of 85.7%. CONCLUSION. Automated cardiac chamber volumetry using nongated CTPA, particularly of the RA, provides incremental utility relative to echocardiographic and conventional CTPA parameters for diagnosis of PH. CLINICAL IMPACT. Automated volumetry of cardiac chambers based on nongated CTPA may facilitate early noninvasive detection of PH, identifying patients who warrant further evaluation by RHC.

Insights into Clostridium tetani: From genome to bioreactors.

Tetanus vaccination is of major importance for public health in most countries in the world. The World Health Organization indicated that 15,000 tetanus cases were reported in 2018 (Organization, World Health, 2019). Currently, vaccine manufacturers use tetanus toxin produced by Clostridium tetani fermentation in complex media. The complex components, commonly derived from animal sources, introduce potential variability in cultures. To achieve replicable fermentation and to avoid toxic or allergic reactions from animal-source compounds, several studies have tried to switch from complex to chemically defined media without affecting toxin titers. The present review introduces the current knowledge on i) C. tetani strain diversity, whole-genome sequences and metabolic networks; ii) toxin regulation and synthesis; and iii) culture media, cultivation processes and growth requirements. We critically reviewed the reported data on metabolism in C. tetani and completed comparative genomic and proteomic analyses with other Clostridia species. We integrated genomic data based on whole-genome sequence annotation, supplemented with cofactor specificities determined by protein sequence identity, in a new map of C. tetani central metabolism. This is the first data review that integrates insights from omics experiments on C. tetani. The overview of C. tetani physiology described here could provide support for the design of new chemically defined media devoid of complex sources for toxin production.

Acquisition of a Dose Management System with Consideration of Medico-Legal and Economic Aspects. / Beschaffung eines Dosismanagementsystems unter mediko-legalen und ökonomischen Aspekten.

BACKGROUND: New radiation protection regulation encompassing additional obligations for monitoring, reporting and recording of radiation exposure, was enacted on December 31, 2018. As a consequence, dose management systems (DMS) are necessary to fulfill the requirements. The process of selection, acquisition and implementation of a suitable IT solution for this purpose is a challenge that all X-ray-applying facilities, including hospitals and private practices, are currently facing. METHOD: A target/actual-analysis as well as a cost-utility analysis is presented for this specific case as a foundation for the acquisition decision-making process. RESULT: An actual analysis is necessary in order to record the current status of dose documentation. An interdivisional approach is recommended to include all imaging modalities and devices. An interdisciplinary steering committee can be helpful in enabling consensus and rapid action. A target analysis includes additional criteria with respect to ease of operation, technical feasibility, process optimization and research opportunities to consider in addition to the statutory requirements. By means of a cost-benefit analysis, considerations between costs and the individually weighted advantages and disadvantages of eligible DMS result in a ranking of preference for the available solutions. CONCLUSION: Requirements of a DMS can be summarized in a specification sheet. Deploying an actual condition analysis, target state analysis and cost-utility analysis can help to identify a suitable DMS to achieve rapid commissioning and highest possible user acceptance while optimizing costs at the same time. KEY POINTS: · An actual analysis reveals optimization and standardization needs in examination protocols and technical coding of dose data that can be addressed before or during the acquisition process.. · A specification sheet covers all functional, technical, and financial aspects of a target analysis.. · A cost-utility analysis is useful for exploring an appropriate dose management system with high user acceptance, rapid implementation, and low cost.. · An interdisciplinary steering committee can be helpful to enable early consensus building and fast action.. CITATION FORMAT: · Do TD, Melzig C, Kauczor H et al. Acquisition of a Dose Management System with Consideration of Medico-Legal and Economic Aspects. Fortschr Röntgenstr 2022; 194: 363 - 372.

Single-energy versus dual-energy imaging during CT-guided biopsy using dedicated metal artifact reduction algorithm in an in vivo pig model.

PURPOSE: To evaluate dual-energy CT (DE) and dedicated metal artifact reduction algorithms (iMAR) during CT-guided biopsy in comparison to single-energy CT (SE). METHODS: A trocar was placed in the liver of six pigs. CT acquisitions were performed with SE and dose equivalent DE at four dose levels(1.7-13.5mGy). Iterative reconstructions were performed with and without iMAR. ROIs were placed in four positions e.g. at the trocar tip(TROCAR) and liver parenchyma adjacent to the trocar tip(LIVER-1) by two independent observers for quantitative analysis using CT numbers, noise, SNR and CNR. Qualitative image analysis was performed regarding overall image quality and artifacts generated by iMAR. RESULTS: There were no significant differences in CT numbers between DE and SE at TROCAR and LIVER-1 irrespective of iMAR. iMAR significantly reduced metal artifacts at LIVER-1 for all exposure settings for DE and SE(p = 0.02-0.04), but not at TROCAR. SNR, CNR and noise were comparable for DE and SE. SNR was best for high dose levels of 6.7/13.5mGy. Mean difference in the Blant-Altman analysis was -8.43 to 0.36. Cohen's kappa for qualitative interreader-agreement was 0.901. CONCLUSIONS: iMAR independently reduced metal artifacts more effectively and efficiently than CT acquisition in DE at any dose setting and its application is feasible during CT-guided liver biopsy.

Image quality evaluation of dual-layer spectral CT in comparison to single-layer CT in a reduced-dose setting.

OBJECTIVES: To quantitatively and qualitatively evaluate image quality in dual-layer CT (DLCT) compared to single-layer CT (SLCT) in the thorax, abdomen, and pelvis in a reduced-dose setting. METHODS: Intraindividual, retrospective comparisons were performed in 25 patients who received at least one acquisition of all three acquisition protocols SLCTlow (100 kVp), DLCThigh (120 kVp), and DLCTlow (120 kVp), all covering the venous-phase thorax, abdomen, and pelvis with matched CTDIvol between SLCTlow and DLCTlow. Reconstruction parameters were identical between all scans. Image quality was assessed quantitatively at 10 measurement locations in the thorax, abdomen, and pelvis by two independent observers, and subjectively with an intraindividual forced choice test between the three acquisitions. Dose-length product (DLP) and CTDIvol were extracted for dose comparison. RESULTS: Despite matched CTDIvol in acquisition protocols, CTDIvol and DLP were lower for SLCTlow compared to DLCTlow and DLCThigh (DLP 408.58, 444.68, 647.08 mGy·cm, respectively; p < 0.0004), as automated tube current modulation for DLCTlow reached the lower limit in the thorax (mean 66.1 mAs vs limit 65 mAs). Noise and CNR were comparable between SLCTlow and DLCTlow (p values, 0.29-0.51 and 0.05-0.20), but CT numbers were significantly higher for organs and vessels in the upper abdomen for SLCTlow compared to DLCTlow. DLCThigh had significantly better image quality (Noise and CNR). Subjective image quality was superior for DLCThigh, but no difference was found between SLCTlow and DLCTlow. CONCLUSIONS: DLCTlow showed comparable image quality to SLCTlow, with the additional possibility of spectral post-processing. Further dose reduction seems possible by decreasing the lower limit of the tube current for the thorax. KEY POINTS: • Clinical use of reduced-dose DLCT is feasible despite the required higher tube potential. • DLCT with reduced dose shows comparable objective and subjective image quality to reduced-dose SLCT. • Further dose reduction in the thorax might be possible by adjusting mAs thresholds.

The value of iterative metal artifact reduction algorithms during antenna positioning for CT-guided microwave ablation.

Objectives: To compare image quality between filtered back projection (FBP) and iterative reconstruction algorithm and dedicated metal artifact reduction (iMAR) algorithms during antenna positioning for computed tomography-guided microwave ablation (MWA).Materials and methods: An MWA antenna was positioned in the liver of five pigs under CT guidance. Different exposure settings (120kVp/200mAs-120kVp/50mAs) and image reconstruction techniques (FBP, iterative reconstruction with and without iMAR) were applied. Quantitative image analysis included density measurements in six positions (e.g., liver in extension of the antenna [ANTENNA] and liver >3 cm away from the antenna [LIVER-1]). Qualitative image analysis included assessment of overall quality, image noise, artifacts at the antenna tip, artifacts in liver parenchyma bordering antenna tip and newly generated artifacts. Two independent observers performed the analyses twice and interreader agreement was compared with Bland-Altman analysis.Results: For all exposure and reconstruction settings, density measurements for ANTENNA were significantly higher for the I30-1 iMAR compared with FBP and I30-1 (e.g., 8.3-17.2HU vs. -104.5 to 155.1HU; p ≤ 0.01, respectively). In contrast, for all exposure settings, density measurements for LIVER-1 were comparable between FBP and I30-1 iMAR (e.g., 49.4-50.4HU vs. 50.1-52.5U, respectively). For all exposure and reconstruction settings, subjective image quality for LIVER-1 was better for the I30-1 iMAR algorithm compared with FBP and I30-1. Bland-Altman interobserver agreement was from -0.2 to 0.2 for FBP and iMAR, and Cohen's kappa was 0.74.Conclusion: Iterative algorithms I30-1 with iMAR algorithm improves image quality during antenna positioning and placement for CT-guided MWA and is applicable over a range of exposure settings.

CT and MRI Techniques for Imaging Around Orthopedic Hardware.

Orthopedic hardware impairs image quality in cross-sectional imaging. With an increasing number of orthopedic implants in an aging population, the need to mitigate metal artifacts in computed tomography and magnetic resonance imaging is becoming increasingly relevant. This review provides an overview of the major artifacts in CT and MRI and state-of-the-art solutions to improve image quality. All steps of image acquisition from device selection, scan preparations and parameters to image post-processing influence the magnitude of metal artifacts. Technological advances like dual-energy CT with the possibility of virtual monochromatic imaging (VMI) and new materials offer opportunities to further reduce artifacts in CT and MRI. Dedicated metal artifact reduction sequences contain algorithms to reduce artifacts and improve imaging of surrounding tissue and are essential tools in orthopedic imaging to detect postoperative complications in early stages. KEY POINTS: · Tissues around orthopaedic hardware can still be well visualised despite metal artifacts.. · Artefact reduction in CT: acquisition parameters, iterative reconstruction, Dual-energy CT and VMI.. · Artefact reduction in MRI: choice of device, sequences, acquisition parameters and MARS. CITATION FORMAT: · Do TD, Sutter R, Skornitzke S et al. CT and MRI Techniques for Imaging Around Orthopedic Hardware. Fortschr Röntgenstr 2018; 190: 31 - 41.