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Metastatic pulmonary calcification is an underdiagnosed metabolic lung disease characterized by diffuse calcium deposition in the lungs, often associated with secondary hyperparathyroidism due to chronic renal failure. A 31-year-old man with chronic renal failure initially presented with diffuse pain symptoms, deterioration of general condition, and respiratory insufficiency. Noncontrast-enhanced computed tomography of the chest was performed using a spectral-detector-based dual-energy CT. It showed multiple, centrilobular, ground-glass opacities, and nodules, ultimately leading to the diagnosis. Calcium suppression proved to be highly useful to classify the pulmonary alterations.

To determine if anemia can be predicted on enhanced computed tomography (CT) examinations of the thorax using virtual non-contrast (VNC) images, in order to support clinicians especially in diagnosing primary asymptomatic patients in daily routine.In this monocentric study, 100 consecutive patients (50 with proven anemia), who underwent a contrast-enhanced CT examination of the thorax due to various indications were included. Attenuation was measured in the descending thoracic aorta, the intraventricular septum, and the left ventricle cavity both in the conventional contrast-enhanced and in the VNC images.Two experienced radiologists annotated the delineation of a dense interventricular septum or a hyperattenuating aortic wall sign for all patients.Hemoglobin levels were then correlated with the measured attenuation values, as well as the visualization of the aortic wall or interventricular septum.Good correlation was shown between hemoglobin levels and CT attenuation values of the left ventricular cavity (r = .59), aorta (r = .56), and ratio between left ventricular cavity and the intraventricular septum (r = .57). Receiver operating characteristic curve revealed ≤ 36.5 hounsfield units (left ventricular cavity) as the threshold for diagnosing anemia. Predicting anemia by visualization of a hyperattenuating aortic wall or a dense interventricular septum yielded a specificity of 98% and 92%, respectively.Predicting anemia on enhanced CT examinations using VNC is feasible. A threshold value of ≤ 36.5 hounsfield units (left ventricular cavity) best defines anemia. Aortic wall or interventricular septum visualization on VNC is a specific anemia indicator.

BACKGROUND AND PURPOSE: CTA provides a noninvasive alternative technique to DSA in the follow-up after endovascular aneurysm treatment to evaluate aneurysm occlusion and exclude intraluminal narrowing after stent or flow-diverter implantation; however, assessability may be impeded by stent material artifacts. The objective of this in vitro study was to compare the visual assessability of different conventional stents and flow diverters as well as different reconstructions of dual-layer CT images. MATERIALS AND METHODS: Four conventional intracranial stents and 4 flow diverters were implanted in identical aneurysm phantoms. Conventional and monoenergetic images (40, 50, 60, 90, 120, 180 keV) were acquired to evaluate attenuation alteration, visible lumen diameter, and SNR. Image quality was rated subjectively by 2 independent radiologists using a 4-point Likert scale. RESULTS: Low kiloelectron volt (40–60 keV) monoenergetic reconstructions showed an improved SNR and an improved lumen density ratio compared with high kiloelectron volt reconstructions (90–180 keV) and conventional reconstructions, however without reaching significance compared with the latter. Assessment of the adjacent aneurysm and subjective evaluation was not affected by the imaging technique and stent type. Artifact susceptibility varied with the device used and increased among flow diverters. CONCLUSIONS: Low kiloelectron volt reconstructions improved the assessment of the stent lumen in comparison with high kiloelectron volt reconstructions. No significant improvement in image quality could be shown compared with conventional images. For some devices, iodine-specific reconstructions led to severe artifacts and are therefore not recommended. There was no relevant improvement in the assessability of the adjacent aneurysm.

Objectives: To investigate if low-keV virtual monoenergetic images (VMI40keV) from abdominal spectral detector CT (SDCT) with reduced intravenous contrast media application (RCM) provide abdominal assessment similar to conventional images with standard contrast media (SCM) dose. Methods: 78 patients with abdominal SDCT were retrospectively included: 41 patients at risk for adverse reactions who received 44 RCM examinations with 50 ml and 37 patients who underwent 44 SCM examinations with 100 ml of contrast media (CM) and who were matched for effective body diameters. RCM, SCM images and RCM-VMI40keV were reconstructed. Attenuation and signal-to-noise ratio (SNR) of liver, pancreas, kidneys, lymph nodes, psoas muscle, aorta and portal vein were assessed ROIs-based. Contrast-to-noise ratios (CNR) of lymph nodes vs aorta/portal vein were calculated. Two readers evaluated organ/vessel contrast, lymph node delineation, image noise and overall assessability using 4-point Likert scales. Results: RCM were inferior to SCM images in all quantitative/qualitative criteria. RCM-VMI40keV and SCM images showed similar lymph node and muscle attenuation (p = 0.83,0.17), while for all other ROIs, RCM-VMI40keV showed higher attenuation (p ≤ 0.05). SNR was comparable between RCM-VMI40keV and SCM images (p range: 0.23–0.99). CNR of lymph nodes was highest in RCM-VMI40keV (p ≤ 0.05). RCM-VMI40keV received equivalent or higher scores than SCM in all criteria except for organ contrast, overall assessability and image noise, where SCM were superior (p ≤ 0.05). However, RCM-VMI40keV received proper or excellent scores in 88.6/94.2/95.4% of the referring cases. Conclusions: VMI40keV counteract contrast deterioration in CM reduced abdominal SDCT, facilitating diagnostic assessment. Advances in knowledge: SDCT-derived VMI40keV provide adequate depiction of vessels, organs and lymph nodes even at notable CM reduction.

To compare a novel Compressed SENSE accelerated ECG- and respiratory-triggered flow-independent 3D isotropic Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT) with standard non-ECG-triggered 3D contrast-enhanced magnetic resonance angiography (CE-MRA) for imaging of the thoracic aorta in patients with connective tissue diseases (CTD) or other aortic diseases using manual and semiautomatic measurement approaches. This retrospective, single-center analysis of 30 patients (June–December 2018) was conducted by two radiologists, who independently measured aortic diameters on modified REACT and CE-MRA using manual (Multiplanar-Reconstruction) and semiautomatic (Advanced Vessel Analysis) measurement tools on seven levels (inner edge): Aortic annulus and sinus, sinotubular junction, mid- and high-ascending aorta, aortic isthmus, and descending aorta. Bland–Altman analysis was conducted to evaluate differences between the mean values of aortic width and ICCs were calculated to assess interobserver agreement. For each level, image quality was evaluated on a four-point scale in consensus with Wilcoxon matched-pair test used to evaluate for differences between both MRA techniques. Additionally, evaluation time for each measurement technique was noted, which was compared applying one-way ANOVA. When comparing both imaging and measurement methods, CE-MRA (mean difference 0.24 ± 0.27 mm) and the AVA-tool (− 0.21 ± 0.15 mm) yielded higher differences compared to modified REACT (− 0.11 ± 0.11 mm) and the MPR-tool (0.07 ± 0.21 mm) for all measurement levels combined without yielding clinical significance. There was an excellent interobserver agreement between modified REACT and CE-MRA using both tools of measurement (ICC > 0.9). Modified REACT (average acquisition time 06:34 ± 01:36 min) provided better image quality from aortic annulus to mid-ascending aorta (p

Background Non-invasive coronary imaging after stent placement remains challenging. Favorable results for dual-energy computed tomography (DECT) derived monoenergetic (MonoE) images have been reported for this purpose. Nowadays, there are different dual-energy techniques available, each with specific advantages and disadvantages. However, for the evaluation of coronaries after stent implantation there is no systematic comparison between different dual-energy techniques. Therefore, the aim of our study was to compare two widely used DECT systems using an in-stent restenosis (ISR) phantom setup. Methods Soft-plaque-like stenoses (~50% of lumen) were inserted into ten coronary stents embedded in contrast-filled vessel phantoms. A dual-source CT (DSCT) and a dual-layer CT (DLCT) with comparable acquisition and reconstruction parameters were used. Conventional polyenergetic (PolyE) and MonoE images with 9 different levels (40-120 keV) were calculated. ISR assessability was evaluated by subjective scoring using a 5-point scale and by the following quantitative parameters: image noise, visible lumen diameter (VLD) and ISR contrast-to-noise ratio (CNR). Results A non-significant trend towards larger VLD in DLCT images was observed. Highest noise was found in low-keV MonoE with significantly higher values for DSCT than for DLCT. Conversely, noise was significantly lower for DSCT at higher-keV MonoE. Peak ISR CNR values were found at low-keV MonoE with no significant difference between both systems. However, for PolyE and mid-energy MonoE, CNRs were significantly higher for DSCT. Subjective image quality was significantly better for PolyE and low-keV MonoE than for high-keV MonoE, also without significant difference between both systems. Conclusions Conspicuity of ISR benefits from DECT. Peak CNRs were comparable for both DECT systems and low-keV MonoE offered the highest CNR values and best subjective image quality. In contrast, high-keV MonoE cannot be recommended for stent evaluation due to poor CNR values and therefore significantly limited visualization of stenoses.

Purpose To evaluate the correlation between left atrial diverticula (LAD) and left-sided septal pouches (LSSP) with ischemic brain alterations in MRI. Methods A retrospective analysis of 174 patients who received both, a dedicated cardiac CT angiography (CCTA) and a brain MRI examination was performed. Two radiologists independently reviewed all examinations for the presence of LAD and LSSP as well as ischemic alterations of the brain. Subsequently, the correlation between these cardiac and cerebral findings as well as to other potentially related risk factors was assessed. Results 71 LAD (total prevalence 41%) and 65 LSSP (total prevalence 37%) were identified in 174 patients. Combined prevalence was 10%. Ischemic brain alterations were found in patients with a LAD in 42.3% (30/71) and with a LSSP in 64.6% (42/65). Patients without any anatomical variant in the left atrium showed ischemic brain alterations in 39.4% (26/66). The presence of a LSSP was associated with an increased risk for ischemic brain alterations in multivariate logistic regression analysis after adjusting for other risk factors (OR = 3.57, 95% CI = 0.51–2.09, p Conclusion In our study cohort LAD and LSSP are highly prevalent anatomical structures within the left atrium. Patients with LSSP showed an approximated 3.5-fold higher probability for ischemic brain alterations. Therefore, LSSP should be considered as a potential risk factor for cardioembolic strokes and its presence should be stated in cardiac CT reports.

Patients with Congenital heart disease (CHD) require repetitive imaging of the pulmonary vasculature throughout their life. In this study, we compared a novel Compressed SENSE accelerated (factor 9) electrocardiogram (ECG)- and respiratory-triggered 3D modified Relaxation-Enhanced Angiography without Contrast and Triggering (modified REACT-non-contrast-enhanced magnetic resonance angiography (modified REACT-non-CE-MRA)) with standard non-ECG-triggered time-resolved 4D CE-MRA for imaging of the pulmonary arteries and veins in patients with CHD.This retrospective analysis of 25 patients (June 2018-April 2019) with known or suspected CHD was independently conducted by two radiologists executing measurements on modified REACT-non-CE-MRA and 4D CE-MRA on seven dedicated points (inner edge): Main pulmonary artery (MPA), right and left pulmonary artery, right superior and inferior pulmonary vein, left superior (LSPV) and inferior pulmonary vein. Image quality for arteries and veins was evaluated on a four-point scale in consensus.Twenty-three of the 25 included patients presented a CHD. There was a high interobserver agreement for both methods of imaging at the pulmonary arteries (ICC ≥ 0.96); at the pulmonary veins, modified REACT-non-CE-MRA showed a slightly higher agreement, pronounced at LSPV (ICC 0.946 vs. 0.895). Measurements in 4D CE-MRA showed higher diameter values compared to modified REACT-non-CE-MRA, at the pulmonary arteries reaching significant difference (e.g. MPA: mean 0.408 mm, p = 0.002). Modified REACT-non-CE-MRA (average acquisition time 07:01 ± 02:44 min) showed significant better image quality than 4D CE-MRA at the pulmonary arteries (3.84 vs. 3.32, p 0.001) and veins (3.32 vs. 2.72, p = 0.015).Compressed SENSE accelerated (factor 9) ECG- and respiratory-triggered 3D modified REACT-non-CE-MRA allows for reliable and fast imaging of the pulmonary arteries and veins with higher image quality and slightly higher interobserver agreement than 4D CE-MRA without contrast agent and associated disadvantages. Therefore, it represents a clinically suitable technique for patients requiring repetitive imaging of the pulmonary vasculature, e.g. patients with CHD.

Background Advanced knowledge-based iterative model reconstructions (IMR) became recently available for routine computed tomography (CT). Using more realistic physical models it promises improved image quality and potential radiation dose reductions, both possibly beneficial for non-invasive assessment of coronary stents. Purpose To evaluate the influence of different IMR settings at different radiation doses on stent lumen visualization in comparison to filtered back projection (FBP) and first-generation (hybrid) iterative reconstruction (HIR). Material and Methods Ten coronary stents in a coronary phantom were examined at four different dose settings (120 kV/125 mAs, 120 kV/75 mAs, 100 kV/125 mAs, 100 kV/75 mAs). Images were reconstructed with stent-specific FBP and HIR kernels and with IMR using CardiacRoutine (CR) and CardiacSharp (CS) settings at three different iteration levels. Image quality was evaluated using established parameters: image noise; in-stent attenuation difference; and visible lumen diameter. Results Image noise was significantly lower in IMR than in corresponding HIR and FBP images. At lower radiation doses, image noise increased significantly except with IMR CR3 and IMR CS3. Visible lumen diameters were significantly larger with IMR CS than with FBP, HIR, and IMR CR. IMR CR showed the smallest attenuation difference, while attenuation was artificially decreased extensively with IMR CS. FBP and HIR showed moderately increased in-stent attenuations. No relevant influence of used radiation doses on visible lumen diameters or attenuation differences was found. Conclusion IMR CR reduces image noise significantly while offering comparable stent-specific image quality in comparison to FBP and HIR and therefore potentially facilitates stent lumen delineation. Utilization of IMR CS for stent evaluation seems unfavorable due to artificial image alterations.

Objectives To investigate the utilization of virtual mono-energetic images (MonoE) at low kiloelectron volt (keV) levels derived from a dual-layer spectral detector CT (SDCT) for the assessment of abdominal arteries in venous contrast phase scans using arterial phase imaging as an internal reference standard. Materials and methods A total of 50 patients who received arterial and venous phase imaging of the abdomen on a SDCT system were included in this study. Absolute attenuation, noise, signal- and contrast to noise ratios (SNR; CNR) as well as arterial diameters in defined landmarks were assessed. In arterial phase, conventional reconstructions (CRART) as well as MonoEART at 40 keV and in venous phase, conventional reconstructions (CRVEN) as well as MonoEVEN at 70 and 40 keV were investigated and intra-individual comparisons were performed. If an artery stenosis (10 patients) was present, the degree of stenosis was assessed according to the system of the North American Symptomatic Carotid Endarterectomy Trial (NASCET). Results MonoE 40 keV yielded significantly higher attenuation values (in arterial as well as in venous phase) compared to CRART (p Luminal diameters were significantly smaller in MonoE 40 keV in both contrast phases compared to CRART (p Conclusion MonoE at low keV of venous contrast phase scans derived from a novel SDCT are suitable for the assessment of arteries in the abdomen and subsequent stenosis assessment. However, MonoE at 40 keV constantly showed significant smaller luminal diameters than the corresponding conventional reconstructions (including the reference standard). This is possibly due to an improved differentiation of the vessel lumen from the wall and raises the question, which imaging technique should be used as an appropriate reference standard for vascular SDCT imaging studies.

Background Non-invasive evaluation of coronary stent patency by coronary computed tomography angiography (cCTA) remains challenging. Multiple studies showed that CT technology but also individual stent design strongly influence the assessability of coronary stents by cCTA. Purpose To expand the available data on cCTA characteristics of coronary stents by 24 novel types to help interpreting examinations of patients after stent placement and selecting which stents are suitable for assessment by cCTA. Material and Methods Twenty-four novel coronary stents (17 cobalt–chromium, six stainless-steel, one platinum–chromium) were examined in a coronary phantom. Standard cCTA parameters with stent-specific algorithms were used. Image quality was quantified for each stent using established parameters (in-stent attenuation alteration and visible lumen diameter). Results Most stents (n = 14) showed lumen visibilities of 45–55%. No severe restriction of lumen visibility (>60%) was found. The majority of stents (n = 13) caused only small intraluminal attenuation deviations and no severe alterations (>20%) were found. When grouped by manufacturing material, no significant differences were found between cobalt–chromium and stainless-steel with identical mean visible diameters (1.52 ± 0.17 mm vs. 1.52 ± 0.13 mm) and comparable attenuation alterations (35.04 ± 16.56 HU vs. 21.25 ± 14.60 HU). The only platinum–chromium stent showed a smaller visible diameter (1.23 mm) and higher attenuation alteration (41.70 HU), but was also deemed to be assessable by cCTA. Conclusion All 24 novel evaluated stents are eligible for non-invasive evaluation by cCTA without significant differences between cobalt–chromium and stainless-steel stents. This updated catalogue of CT appearances of current coronary stents may serve as reference when taking care of patients with stents in need of coronary imaging.

Objective To evaluate the influence of monoenergetic reconstructions using a spectral detector CT (SDCT) on the computer aided detection (CAD) of pulmonary artery embolism (PAE) on CT pulmonary angiography (CTPA) and CT in venous contrast phase (CTV). Material and Methods A retrospective data base search identified 15 patients with CTPA and 18 patients with CTV and diagnosis of PAE. For these patients, monoenergetic (monoE) images at different energy levels or with a fixed attenuation in the pulmonary artery were generated and independently analyzed using a commercially available computer aided detection (CAD) tool. Attenuation in the pulmonary artery and in the embolus was measured. Results For CTPA and CTV, in monoenergetic images the difference in attenuation between vessel and embolus was significantly higher than in conventional images. In CTPA the detection rate was highest in the >500 HU monoE images with 67,9% detected emboli and 93,3% of patients correctly identified as having PAE. At the same time the false positive rate could be significantly reduced by using monoE images compared to conventional images. Detection rates for CTV were lower than in CTPA but were raised significantly by monoE reconstructions. Conclusions The combination of SDCT and CAD improves the diagnostic accuracy of CAD and enables CAD interpretation of CTV.

Objectives To evaluate image quality parameters of virtual mono-energetic (MonoE) and conventional (CR) imaging derived from a dual-layer spectral detector CT (DLCT) in oncological follow-up venous phase imaging of the chest and comparison with conventional multi-detector CT (CRMDCT) imaging. Materials and methods A total of 55 patients who had oncologic staging with conventional CT and DLCT of the chest in venous phase were included in this study. Established image quality parameters were derived from all datasets in defined thoracic landmarks. Attenuation, image noise, and signal-/contrast- to noise ratios (SNR, CNR) were compared between CRDLCT and MonoE as well as CRMDCT imaging. Two readers performed subjective image analysis. Results CRMDCT showed significant lower attenuation values compared to CRDLCT and MonoE at 40–70 keV (p ≤ 0.05). Moreover, MonoE at 40–70 keV revealed significantly higher attenuations values compared to CRDLCT (p 0.99). SNR values were significantly increased for MonoE at 40–80 keV compared to CRMDCT and CRDLCT (p Conclusion In dual-layer spectral detector CT, MonoE at low keV showed superior image quality compared to conventional images derived from the same system and may therefore be added to clinical routine imaging protocols. Whether MonoE reconstructions yield additional diagnostic information is still unknown.

Accurate assessment of coronary stents using non-invasive CT imaging remains challenging despite new stent materials and improvements in CT technology. Virtual monoenergetic (monoE) images reconstructed from dual energy CT acquisitions potentially decrease artifacts caused by coronary stents. A novel spectral detector technology provides monoE and conventional images simultaneously for all conducted scans. The purpose of our study was to systematically investigate the influence of different monoE reconstructions on the visualization of coronary stent lumen in comparison to conventional images.Ten different coronary stents (diameter 3.0 mm) embedded in plastic tubes filled with contrast agent (500 HU) were scanned with a 128-row spectral detector CT (IQon, Philips, 120 kV, 125 mAs). Images were reconstructed (0.67 mm slice thickness, 0.35 mm increment) with a stent-specific conventional reconstruction kernel and 6 different monoE settings (60, 70, 80, 90, 100, 150 keV). Image quality for each stent and reconstruction was quantified using established parameters: image noise (standard deviation (SD) within a standardized ROI), in-stent attenuation difference (mean attenuation difference between stented and non-stented lumen) and visible lumen diameter (mean visible diameter of the stented tube).Image noise was significantly lower in all monoE data dets compared to conventional images (conventional: 13.41, 60 keV: 11.62, 70 keV: 11.67, 80 keV: 11.69, 90 keV: 11.71, 100 keV: 11.75, 150 keV: 11.80 HU SD; p 0.01). The in-stent attenuation difference was significantly smaller in monoE data with higher keV levels than in conventional images (conventional: 148.18, 60 keV: 154.13 p = 0.036, 70 keV: 143.43 p = 0.109, 80 keV: 137.25 p = 0.052, 90 keV: 133.02 p = 0.043, 100 keV: 130.12 p = 0.039, 150 keV: 123.99 HU p = 0.035). The visible lumen diameter was significantly greater in monoE data with higher keV levels than in conventional images (conventional: 0.65, 60 keV: 0.68 p = 0.542, 70 keV: 0.71 p = 0.053, 80 keV: 0.74 p 0.01, 90 keV: 0.77 p 0.01, 100 keV: 0.82 p 0.01, 150 keV: 0.87 mm p 0.01).In comparison to conventional CT images, well-established parameters for objective assessment of CT image quality for coronary stents are significantly improved by utilization of monoE reconstructions with adequate keV levels derived from data acquired on a novel spectral detector CT platform.

In-stent restenosis (ISR) is one of the main long-term complications after coronary stent placement, and the ability to evaluate ISR noninvasively using coronary computed tomography (CT) angiography remains challenging. For this application, spectral photon-counting CT (SPCCT) has the potential to increase image quality and reduce artifacts due to its advanced detector technology.Our study aimed to verify the technical and clinical potential of a novel SPCCT prototype using an ISR phantom setup.Soft plaque-like restenosis (45 HU; approximately 50% of the stent lumen) were inserted into 10 different coronary stents (3 mm diameter), which were placed in a vessel phantom and filled with a contrast agent (400 HU). A research prototype SPCCT and a clinical dual-layer CT (DLCT; IQon; Philips) with comparable acquisition and reconstruction parameters were used to scan the phantoms. Conventional polyenergetic (PolyE) and monoenergetic (MonoE) images with 4 different energy levels (40, 60, 90, 120 keV) were reconstructed. Qualitative (delineation of the stenosis and adjacent residual lumen using a 5-point Likert scale) and quantitative (image noise, visible lumen diameter, lumen diameter adjacent to the stenosis, contrast-to-noise ratio of the restenosis) parameters were evaluated for both systems.The qualitative results averaged over all reconstructions were significantly superior for SPCCT compared with DLCT (eg, subjective rating of the best reconstruction of each scanner: DLCT PolyE: 2.80 ± 0.42 vs SPCCT MonoE 40 keV: 4.25 ± 1.03). Stenosis could be clearly detected in 9 and suspected in 10 of the 10 stents with both SPCCT and DLCT. The residual lumen next to the stenosis was clearly delineable in 7 of 10 stents (0.64 ± 0.11 mm or 34.97% of the measured stent lumen) with SPCCT, while it was not possible to delineate the residual lumen for all stents using DLCT. The measured diameter of the lumen within the stent was significantly higher for SPCCT compared with DLCT in all reconstructions with the best results for the MonoE 40 keV images (SPCCT: 1.80 ± 0.17 mm; DLCT: 1.50 ± 0.31 mm). The image noise and the contrast-to-noise ratio were better for DLCT than for SPCCT (contrast-to-noise ratio: DLCT MonoE 40: 31.58 ± 12.54; SPCCT MonoE 40: 4.64 ± 1.30).Spectral photon-counting CT allowed for the noninvasive evaluation of ISR with reliable results regarding the residual lumen for most tested stents and the clear identification or suspicion of stenosis for all stents. In contrast, the residual lumen could not be detected for a single stent using DLCT.

ObjectivesPostoperative chylothorax is a serious complication after transthoracic esophagectomy, and is associated with major morbidity due to dehydration and malnutrition. For patients with high-output fistula, re-thoracotomy with ligation of the thoracic duct is the treatment of choice. Radiologic interventional management is an innovative procedure that has the potential to replace surgery in the treatment algorithm.MethodsFour patients with high-output chylous leaks following esophagectomy are presented. Ultrasound-guided lymphangiography with embolization of the thoracic duct and/or disruption of the cisterna chyli was performed to occlude the leakage site. Radiologic interventions and procedure-related outcomes are described in detail.ResultsIn all four patients, ultrasound-guided lymphangiography of the groin with injection of Lipiodol was able to detect and visualize the leakage site in the lower mediastinum. In three patients, the leak could be successfully occluded by Lipiodol embolization. In one patient, embolization failed and the disruption technique was successfully performed. No procedure-related complications were observed.ConclusionsIn case of a postoperative chylothorax, radiologic intervention is feasible and safe. The procedure is indicated for high-output chylous fistulas after esophagectomy, and should be applied early after the diagnosis of this postoperative complication.

Intravenous contrast administration is crucial in many CT examinations but also poses a potential risk to the patient. Monoenergetic images (MonoE) of dual-energy CT systems can virtually increase iodine attenuation and might improve image quality (IQ) if contrast dose is reduced. In this study, we investigated the influence of MonoE on lymph node (LN) delineation and IQ in chest CT examinations with significantly reduced contrast dose (50 %) of a novel dual-layer CT (DLCT).30 patients with clinically indicated reduced contrast dose underwent venous-phase chest DLCT scans. Conventional polyenergetic (PolyE) and MonoE images at 40 keV were calculated. The contrast difference of hilar lymph nodes (LN-CD) to the adjacent right pulmonary artery, their signal-to-noise (SNR) and contrast-to-noise-ratio (CNR) were determined. Subjective IQ was evaluated by 2 readers with respect to LN delineation and overall contrast enhancement (CE) using a 5-point-Likert-scale.LN-CD, SNR and CNR were significantly higher in MonoE than in PolyE images (LN-CD 92.3 ± 37.9 vs. 33.1 ± 14.5 HU, SNR 8.4 ± 3.4 vs. 4.0 ± 1.2, CNR 9.2 ± 6.3 vs. 2.6 ± 1.5; all p 0.01). The LN delineation (3.7 ± 0.9 vs.1.8 ± 0.7; p 0.01) and the CE (3.9 ± 0.7 vs. 2.3 ± 0.7; p 0.01) were rated significantly better for MonoE than for PolyE images. There was no MonoE examination classified as non-diagnostic.Subjective and objective IQ parameters can be significantly improved for venous-phase chest CT examinations with reduced contrast doses by utilization of low-keV MonoE reconstructions. All MonoE images provided sufficient overall CE and therefore reduced contrast doses might be considered in a wider range of DLCT examinations and patients.

Tilman Hickethier,1,* Kamal Mammadov,1,* Bettina Baeßler,1 Thorsten Lichtenstein,1 Jochen Hinkelbein,2 Lucy Smith,3 Patrick Sven Plum,4 Seung-Hun Chon,4 David Maintz,1 De-Hua Chang1 1Department of Radiology, University Hospital of Cologne, Cologne, Germany; 2Department of Anesthesiology and Intensive Care Medicine, University Hospital of Cologne, Cologne, Germany; 3Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada; 4Department of General, Visceral and Cancer Surgery, University Hospital of Cologne, Cologne, Germany *These authors contributed equally to this work Background: The study was conducted to compare examination time and artifact vulnerability of whole-body computed tomographies (wbCTs) for trauma patients using conventional or optimized patient positioning. Patients and methods: Examination time was measured in 100 patients scanned with conventional protocol (Group A: arms positioned alongside the body for head and neck imaging and over the head for trunk imaging) and 100 patients scanned with optimized protocol (Group B: arms flexed on a chest pillow without repositioning). Additionally, influence of two different scanning protocols on image quality in the most relevant body regions was assessed by two blinded readers. Results: Total wbCT duration was about 35% or 3:46 min shorter in B than in A. Artifacts in aorta (27 vs 6%), liver (40 vs 8%) and spleen (27 vs 5%) occurred significantly more often in B than in A. No incident of non-diagnostic image quality was reported, and no significant differences for lungs and spine were found. Conclusion: An optimized wbCT positioning protocol for trauma patients allows a significant reduction of examination time while still maintaining diagnostic image quality. Keywords: CT scan, polytrauma, acute care, time requirement, positioning

OBJECTIVE We aimed to determine optimal window settings for conventional polyenergetic (PolyE) and virtual monoenergetic images (MonoE) derived from abdominal portal venous phase computed tomography (CT) examinations on a novel dual-layer spectral-detector CT (SDCT). METHODS From 50 patients, SDCT data sets MonoE at 40 kiloelectron volt as well as PolyE were reconstructed and best individual window width and level values manually were assessed separately for evaluation of abdominal arteries as well as for liver lesions. Via regression analysis, optimized individual values were mathematically calculated. Subjective image quality parameters, vessel, and liver lesion diameters were measured to determine influences of different W/L settings. RESULTS Attenuation and contrast-to-noise values were significantly higher in MonoE compared with PolyE. Compared with standard settings, almost all adjusted W/L settings varied significantly and yielded higher subjective scoring. No differences were found between manually adjusted and mathematically calculated W/L settings. CONCLUSIONS PolyE and MonoE from abdominal portal venous phase SDCT examinations require appropriate W/L settings depending on reconstruction technique and assessment focus.

Sympathovagal imbalance plays a major role in the progression of heart failure with reduced ejection fraction. Baroreflex activation therapy (BAT) by electrical stimulation of baroreceptors located at the carotid sinus can reduce sympathetic and increase parasympathetic tone. This review provides an overview on the concept of BAT in heart failure with reduced ejection fraction and available preclinical and clinical data. Animal studies of BAT in heart failure with reduced ejection fraction have demonstrated a decline in plasma norepinephrine, an improved left ventricular ejection fraction, a reduced susceptibility to induced ventricular arrhythmias and a survival benefit. First clinical data from uncontrolled studies suggest a relevant improvement in muscle sympathetic nerve activity, ejection fraction, 6-min walk distance, New York Heart Association (NYHA) class and hospitalization rate. BAT appears to be safe in this severely ill patient population.

PURPOSE: The aim of this study was to investigate computed tomography (CT) imaging characteristics of coronary stents using a novel photon-counting detector (PCD) in comparison with a conventional energy-integrating detector (EID). MATERIALS AND METHODS: In this in vitro study, 18 different coronary stents were expanded in plastic tubes of 3 mm diameter, were filled with contrast agent (diluted to an attenuation of 250 Hounsfield units [HU] at 120 kVp), and were sealed. Stents were placed in an oil-filled custom phantom calibrated to an attenuation of -100 HU at 120 kVp for resembling pericardial fat. The phantom was positioned in the gantry at 2 different angles at 0 degree and 90 degrees relative to the z axis, and was imaged in a research dual-source PCD-CT scanner. Detector subsystem "A" used a standard 64-row EID, while detector subsystem "B" used a PCD, allowing high-resolution scanning (detector pixel-size 0.250 × 0.250 mm in the isocenter). Images were obtained from both detector systems at identical tube voltage (100 kVp) and tube current-time product (100 mA), and were both reconstructed using a typical convolution kernel for stent imaging (B46f) and using the same reconstruction parameters. Two independent, blinded readers evaluated in-stent visibility and measured noise, intraluminal stent diameter, and in-stent attenuation for each detector subsystem. Differences in noise, intraluminal stent diameter, and in-stent attenuation where tested using a paired t test; differences in subjective in-stent visibility were evaluated using a Wilcoxon signed-rank test. RESULTS: Best results for in-stent visibility, noise, intraluminal stent diameter, and in-stent attenuation in EID and PCD were observed at 0-degree phantom position along the z axis, suggesting higher in-plane compared with through-plane resolution. Subjective in-stent visibility was superior in coronary stent images obtained from PCD compared with EID (P < 0.001). Mean in-stent diameter was 28.8% and 8.4% greater in PCD (0.85 ± 0.24 mm; 0.83 ± 0.14 mm) as compared with EID acquisitions (0.66 ± 0.21 mm; 0.76 ± 0.13 mm) for both 0-degree and 90-degree phantom positions, respectively. Average noise was significantly lower (P < 0.001) for PCD (5 ± 0.2 HU) compared with EID (8.3 ± 0.2 HU). The increase in in-stent attenuation (0 degree: Δ 245 ± 163 HU vs Δ 156.5 ± 126 HU; P = 0.006; 90 degrees: Δ 194 ± 141 HU vs Δ 126 ± 78 HU; P = 0.001) was significantly lower for PCD compared with EID acquisitions. CONCLUSIONS: At matched CT scan protocol settings and identical image reconstruction parameters, the PCD yields superior in-stent lumen delineation of coronary artery stents as compared with conventional EID arrays.

We aimed to determine optimal window settings for poly-energetic (PolyE) and virtual mono-energetic images (MonoE) derived from abdominal angiographic studies on a novel dual-layer spectral detector CT (SDCT) system. From 50 patients, SDCT datasets PolyE and MonoE at 70 and 40 keV levels were reconstructed and best individual window width and level (BI-W/L) manually assessed. Through regression analysis, the so-called optimized individual (OI-W/L) values were obtained. Subjective image quality parameters and vessel diameters were measured to determine influences of different W/L settings. Image noise was lower and attenuation and contrast-to-noise ratio were higher in MonoE compared to PolyE (all p ≤ 0.002). Mean BI-W/L values for PolyE, 70, and 40 keV were 637/284, 647/291, and 1568/691, respectively. Mean OI-W/L values were 631/276, 628/286, and 1516/667, respectively. Compared to standard settings, all adjusted W/L settings varied significantly and yielded higher subjective scoring. No between-group differences were found between manually adjusted and mathematically calculated W/L settings. PolyE and MonoE from abdominal angiographic SDCT studies require appropriate W/L settings especially at low energy reconstruction levels. Individual adjustment reaches the best image quality but is time consuming. From our data, predefined W/L settings of 640/280 (PolyE/MonoE 70 keV) and 1570/690 (MonoE 40 keV) as a non-individualized starting point for abdominal angiographic studies from the novel SDCT system are suggested.

De-Hua Chang,1 Kamal Mammadov,1 Tilman Hickethier,1 Jan Borggrefe,1 Martin Hellmich,2 David Maintz,1 Christoph Kabbasch1 1Department of Diagnostic and Interventional Radiology, University Hospital of Cologne, NRW, Germany; 2Institute of Medical Statistics, Informatics and Epidemiology, University Hospital of Cologne, NRW, Germany Purpose: Evaluation of the efficacy of single-shot, low-dose urokinase administration for the treatment of port catheter-associated fibrin sheaths. Methods: Forty-six patients were retrospectively evaluated for 54 episodes of port catheter dysfunction. The presence of a fibrin sheath was detected by angiographic contrast examinations. On an outpatient basis, patients subsequently received thrombolysis consisting of a single injection of urokinase (15.000 IU in 1.5 mL normal saline) through the port system. A second attempt was made in cases of treatment failure. Patients were followed up for technical success, complications and long-term outcome. Results: Port dysfunction occurred at a median of 117 days after implantation (range: 7–825 days). The technical success after first port dysfunction by thrombolysis was 87% (40/46); thereof, initial thrombolysis was effective in 78% (36/46). Nine patients (20%) received a second dose of urokinase after previous treatment failure. Follow-up was available for 26 of 40 patients after successful thrombolysis. In 8 of these, rethrombosis occurred after a median of 98 days (range: 21–354 days), whereby rethrombolysis was effective in 5 of 7 (63%) patients. The overall success of all thrombolyses performed was 70% (45/64). No procedure-related technical or clinical complications occurred. After first favorable thrombolysis, a Kaplan–Meier analysis yielded a 30-, 90- and 180-day probability of patency of 96%, 87% and 81%. Conclusion: Thrombolytic therapy on an outpatient basis appears to be a safe and efficient. Three-month patency rates are comparable to more invasive treatment options, including catheter exchange over a guide wire and percutaneous fibrin sheath stripping. Keywords: central venous port catheter, thrombolysis, urokinase, angiography, port dysfunction, catheter occlusion

OBJECTIVES To quantitatively and qualitatively assess abdominal arterial and venous phase contrast-enhanced spectral detector computed tomography (SDCT) virtual mono-energetic (MonoE) datasets in comparison to conventional CT reconstructions provided by the same system. MATERIALS AND METHODS Conventional and MonoE images at 40-120 kilo-electron volt (keV) levels with a 10 keV increment as well as 160 and 200 keV were reconstructed in abdominal SDCT datasets of 55 patients. Attenuation, image noise, and contrast- / signal-to-noise ratios (CNR, SNR) of vessels and solid organs were compared between MonoE and conventional reconstructions. Two readers assessed contrast conditions, detail visualization, overall image quality and subjective image noise with both, fixed and adjustable window settings. RESULTS Attenuation, CNR and SNR of vessels and solid organs showed a stepwise increase from high to low keV reconstructions in both contrast phases while image noise stayed stable at low keV MonoE reconstruction levels. Highest levels were found at 40 keV MonoE reconstruction (p

BACKGROUND The effect of cold ischemia (CI) in vascularized composite allotransplantation is unknown. We herein assess tissue-specific damage, acceptable CI time, and the effect of preservation solutions in a syngenic rat hindlimb transplant model. METHODS Lewis rat limbs were flushed and stored for 2, 10, or 30 hr CI in saline, histidine-tryptophan-ketoglutarate or University of Wisconsin preservation solution before transplantation. Morphologic alterations, inflammation, and damage of the individual tissues were analyzed on day 10 using histomorphology, confocal, light, and transmission-electron microscopy. RESULTS Two-hour CI led to mild inflammation of tissues on day 10, whereas 10-hr and 30-hr CI resulted in massive inflammation and tissue damage. Although muscle was mainly affected after prolonged CI (≥10 hr), nerve was affected in all CI groups. A perineural cell infiltrate, hypercellular appearance, pronounced vacuolization, and mucoid degeneration, appearing as Wallerian degeneration, were observed. Staining with propidium iodide and Syto 16 revealed a decrease in viable muscle cell nuclei in the anterior tibial muscle on day 10 in all groups, which was most pronounced in 10-hr and 30-hr CI animals. Transmission-electron microscopy indicated that a large number of mitochondria were degenerated in the 10-hr and 30-hr CI groups. Histidine-tryptophan-ketoglutarate preservation solution slightly decreased inflammation and tissue damage compared to University of Wisconsin-treated and saline-treated animals, especially in skin and muscle when CI times did not exceed 10 hr. CONCLUSION Severe inflammation and tissue damage are observed after prolonged CI in muscle and nerve. Ischemia times in vascularized composite allotransplantation should be kept as short as possible and certainly below 10 hr.

Aims The Neo™ System (CVRx) is an implantable device, CE certified for the treatment of resistant hypertension and investigationally used to treat systolic heart failure by electrical stimulation of the carotid baroreceptors. It is unknown whether interaction might exist between the Neo System and implantable cardioverter-defibrillators (ICDs). Methods and results Compatibility of the Neo device was tested in seven consecutive patients with pre-existing ICDs. Intra- and post-operative testing was completed with ICD and Neo settings programmed to provoke interaction. Intracardiac electrograms were printed to determine interaction with the ICD. Interaction testing during implantation and follow-up showed that there was no device–device interaction. No interaction was observed at maximum atrial and ventricular sensitivity settings and maximum Neo output settings. Conclusion Combined therapy with the Neo device and at least in this study reported that transvenous ICD systems can be performed safely.

Objectives To investigate the impact of aortic valve calcification and brain morphology on acute peri-procedural cerebrovascular events (CVEs) in patients undergoing transcatheter aortic valve implantation (TAVI). Background Aortic valve calcification and stenosis can be assessed with echocardiography. Cerebral magnetic resonance imaging (MRI) depicts and quantifies morphological signs of hypoperfusion and vascular embolism, which is of special interest in patients with severe aortic stenosis. Furthermore, subjects who undergo TAVI are prone to suffer of clinically silent peri-procedural CVEs. Methods A total of 119 patients referred to TAVI were investigated for aortic valve calcification using trans-esophageal echocardiography. Cerebral MRI prior to and immediate after implantation was performed in all patients using a dedicated scan protocol. Prior to TAVI, brain morphology was characterized. Post TAVI, brains were investigated for the onset of acute peri-procedural CVEs using diffusion weighted imaging (DWI). Results Seventy-eight patients (65.5%) revealed acute peri-procedural CVEs on MRI after TAVI with a favor of the left hemisphere (57.5%). The degree of valve calcification was associated with peri-procedural CVEs. Patients with a high WML burden had an increased risk for CVEs ((OR) 2.36 (95% CI: 1.09–5.15; P = 0.037)), especially when distributed periventricular ((OR: 3.27; 95% CI: 1.47–7.26; P = 0.0038)). Conclusion In patients undergoing TAVI, the degree of aortic valve calcification and periventricular WML burden were correlated with acute peri-procedural CVEs. Future studies are needed to evaluate their independent value for the long-term clinical outcome.

Objective:The aim of this study was to determine optimal window settings for conventional polyenergetic and virtual monoenergetic images derived from computed tomography pulmonary angiogram (CTPA) examinations of a novel dual-layer spectral detector computed tomography system (DLCT).Methods

Background Accurate assessment of coronary stents after PCI using non-invasive imaging remains challenging despite technological improvements. New bioresorbable vascular scaffolds (BVS) have recently become available promising improved non-invasive imaging properties, which however have not be examined specifically yet. Therefore we investigated CT and MRI visualization properties of the only two CE-marked coronary BVSs. Methods The Abbott Absorb and the Elixir DESolve BVS were placed in plastic tubes filled with contrast agent and scanned with a latest generation CT respectively MR system. For CT image quality was assessed by two blinded, independent readers and in-scaffold diameter difference as well as in-scaffold attenuation difference were measured. For MRI in-scaffold signal intensity, in-scaffold lumen visibility and in-scaffold signal homogeneity were measured. Results In CTA both BVSs showed no significant difference to nominal tube diameter (DESolve 101%, Absorb 100%) and to nominal tube attenuation (DESolve 96%, Absorb 98%) and were both rated with the highest score for unrestricted lumen visualization. In MRA both BVSs showed unimpaired signal intensity (DESolve 103%, Absorb 100%), lumen visibility (DESolve 92%, Absorb 89%) and lumen homogeneity (DESolve SD 7.1%, Absorb SD 9.5%) when compared to the unstented tube. There was no significant difference between CTA and MRA results of both BVSs. Conclusions Coronary BVSs show no relevant impairment for subjective and objective measures of in-stent lumen visualization by CT and MRI and will therefore allow reliable non-invasive assessment of coronary artery patency after PCI with deployment of a BVS, which is an (additional) advantage when compared to conventional stents.

Background Baroreflex activation therapy (BAT) by electrical stimulation of baroreceptors at the carotid sinus is a promising therapeutic approach to reduce elevated blood pressure (BP). To assess the efficacy of long-term BAT, we investigated acute BP alterations after device deactivation and reactivation (on/off effects) in patients on chronic BAT, as well as chronic BP reductions. Method Resistant hypertension patients (n = 17) were enrolled in an open-label, single-arm evaluation of unilateral BAT after exclusion of secondary hypertension. Initial eligibility criteria were SBP≥ 140 mmHg, despite stable medical therapy with at least three antihypertensive drugs including at least one diuretic. For on/off testing, several office cuff BP measurements were performed: at rest with activated device, 4-6 min after deactivation, and 4-6 min after reactivation. Results Before BAT, mean office cuff BP was 179 ± 25 over 98 ± 18 mmHg. At the time of on/off testing (15.1 ± 8.7 months after initial activation and before deactivation), BP was reduced to 147 ± 29 over 84 ± 20 mmHg. On deactivation, SBP increased to 158 ± 38 mmHg (P = 0.004) and DBP to 89 ± 23 mmHg (P = 0.04). After reactivation, SBP decreased to 144 ± 34 mmHg (P = 0.002 vs. deactivation) and DBP to 83 ± 23 mmHg (P = 0.009). There was no correlation between duration of chronic BAT and systolic or diastolic acute on/off response. Conclusion Unilateral BAT reduces BP in patients with resistant hypertension in the long term. There is a significant on/off effect on BP, supporting the efficacy of BAT. The acute on/off response to BAT does not depend on treatment duration. Thus, no evidence of tolerance over time to chronic BAT was found.

Summary Kv1.3-channels are critically involved in activation and function of effector memory T cells. Blocking Kv1.3-channels was investigated for its effect on skin rejection in a rat limb-transplantation-model. Animals received the Kv1.3-blocker correolide C systemically or locally as intra-graft-treatment in combination with tacrolimus. Systemic (intraperitoneal) administration of correolide C resulted in slight, but significant prolongation of allograft survival compared with untreated and placebo treated controls. In 4/6 correolide C treated animals, histology showed an intact epidermis and a mild infiltrate by day 10. High correolide C plasma trough levels correlated with prolonged allograft survival. A decrease in CD4+ and CD8+ effector memory T cells was observed in allograft skin, peripheral blood and the spleen on day 5. When applied subcutaneously in combination with systemic tacrolimus (30 days+/−anti-lymphocyte serum) detectable, but insignificant prolongation of graft survival was achieved. 2/5 animals showed an intact epidermis and a mild infiltrate until day 45. Tapering systemic tacrolimus and weaning on day 50 resulted in rejection by day 55, regardless of local correolide C treatment. Subcutaneous injection did not lead to systemic plasma levels. The Kv1.3-channel is a potential drug target worth exploring in more detail for immunosuppression in vascularized composite allotransplantation.