Background:Chronic rhinosinusitis is a common disease with a significant impact on the quality of life. Topical drug delivery to the paranasal sinuses is not efficient to prevent sinus surgery or expensive biologic treatment in a lot of cases as the affected mucosa is not reached. More efficient approaches for topical drug delivery are, therefore, necessary. In the current study, dual-energy CT (DECT) imaging was used to examine sinus ventilation before and after sinus surgery using a pulsating xenon gas ventilator in a cadaver head.Methods:Xenon gas was administered to the nasal cavity of a cadaver head with a laminar flow of 7 L/min and with pulsating xenon-flow (45 Hz frequency, 25 mbar amplitude). Nasal cavity and paranasal sinuses were imaged by DECT. This procedure was repeated after functional endoscopic sinus surgery (FESS). Based on the enhancement levels in the different sinuses, regional xenon concentrations were calculated.Results:Xenon-related enhancement could not be detected in most of the sinuses during laminar gas flow. By superimposing laminar flow with pulsation, DECT imaging revealed a xenon wash-in and wash-out in the sinuses. After FESS, xenon enhancement was immediately seen in all sinuses and reached higher concentrations than before surgery.Conclusion:Xenon-enhanced DECT can be used to visualize and quantify sinus ventilation. Pulsating air-/gas flow was superior to laminar flow for the administration of xenon to the paranasal sinuses. FESS leads to successful ventilation of all paranasal sinuses.

The original version of this article, published on 19 March 2018, unfortunately contained a mistake. The following correction has therefore been made in the original: The names of the authors Philipp A. Kaufmann, Ronny Ralf Buechel and Bernhard A. Herzog were presented incorrectly.

Knowledge of the lung vessel morphology in healthy subjects is necessary to improve our understanding about the functional network of the lung and to recognize pathologic deviations beyond the normal inter-subject variation. Established values of normal lung morphology have been derived from necropsy material of only very few subjects. In order to determine morphologic readouts from a large number of healthy subjects, computed tomography pulmonary angiography (CTPA) datasets, negative for pulmonary embolism, and other thoracic pathologies, were analyzed using a fully-automatic, in-house developed artery/vein separation algorithm. The number, volume, and tortuosity of the vessels in a diameter range between 2 and 10 mm were determined. Visual inspection of all datasets was used to exclude subjects with poor image quality or inadequate artery/vein separation from the analysis. Validation of the algorithm was performed manually by a radiologist on randomly selected subjects. In 123 subjects (men/women: 55/68), aged 59 ± 17 years, the median overlap between visual inspection and fully-automatic segmentation was 94.6% (69.2–99.9%). The median number of vessel segments in the ranges of 8–10, 6–8, 4–6, and 2–4 mm diameter was 9, 34, 134, and 797, respectively. Number of vessel segments divided by the subject's lung volume was 206 vessels/L with arteries and veins contributing almost equally. In women this vessel density was about 15% higher than in men. Median arterial and venous volumes were 1.52 and 1.54% of the lung volume, respectively. Tortuosity was best described with the sum-of-angles metric and was 142.1 rad/m (138.3–144.5 rad/m). In conclusion, our fully-automatic artery/vein separation algorithm provided reliable measures of pulmonary arteries and veins with respect to age and gender. There was a large variation between subjects in all readouts. No relevant dependence on age, gender, or vessel type was observed. These data may provide reference values for morphometric analysis of lung vessels.

Background: Nasal and paranasal cavities are supposed to contribute substantially to the vocal tract resonator properties.However, their acoustical effects as well as the effects of sinus surgery on the voice remain unclear.In this work we investigate resonance phenomena of paranasal sinuses prior to and after various rhinosurgical procedures in cadaveric human sinonasal tracts and corresponding 3D casts.Methodology: Nasal and paranasal cavities of formalin-preserved cadavers and corresponding 3D replicas were excited by sinetone sweeps from an earphone placed in the epipharynx.The response was picked up by a microphone at the nostrils.Different FESS procedures were performed and the acoustical responses following excitation were recorded.The measured acoustical changes in the obtained transfer functions were then evaluated.Results: Marked low frequency dips were detected in the transfer functions when sinus cavities were included in the nasal resonator system.These dips showed a significant correlation with sinus volumes.Following FESS procedures they moved upwards in frequency depending on the extent of the surgical intervention. Conclusions:The transfer functions obtained in cadaveric situs and 3D replicas showed dips at the resonance frequencies of the paranasal cavities.Marked acoustic effects in terms of increase in dip frequency following FESS procedures were reproducibly documented.

PURPOSE Dual energy CT (DECT) has recently been proposed as an improvement over single energy CT (SECT) for stopping power ratio (SPR) estimation for proton therapy treatment planning (TP), thereby potentially reducing range uncertainties. Published literature investigated phantoms. This study aims at performing proton therapy TP on SECT and DECT head images of the same patients and at evaluating whether the reported improved DECT SPR accuracy translates into clinically relevant range shifts in clinical head treatment scenarios. METHODS Two phantoms were scanned at a last generation dual source DECT scanner at 90 and 150 kVp with Sn filtration. The first phantom (Gammex phantom) was used to calibrate the scanner in terms of SPR while the second served as evaluation (CIRS phantom). DECT images of five head trauma patients were used as surrogate cancer patient images for TP of proton therapy. Pencil beam algorithm based TP was performed on SECT and DECT images and the dose distributions corresponding to the optimized proton plans were calculated using a Monte Carlo (MC) simulation platform using the same patient geometry for both plans obtained from conversion of the 150 kVp images. Range shifts between the MC dose distributions from SECT and DECT plans were assessed using 2D range maps. RESULTS SPR root mean square errors (RMSEs) for the inserts of the Gammex phantom were 1.9%, 1.8%, and 1.2% for SECT phantom calibration (SECTphantom), SECT stoichiometric calibration (SECTstoichiometric), and DECT calibration, respectively. For the CIRS phantom, these were 3.6%, 1.6%, and 1.0%. When investigating patient anatomy, group median range differences of up to -1.4% were observed for head cases when comparing SECTstoichiometric with DECT. For this calibration the 25th and 75th percentiles varied from -2% to 0% across the five patients. The group median was found to be limited to 0.5% when using SECTphantom and the 25th and 75th percentiles varied from -1% to 2%. CONCLUSIONS Proton therapy TP using a pencil beam algorithm and DECT images was performed for the first time. Given that the DECT accuracy as evaluated by two phantoms was 1.2% and 1.0% RMSE, it is questionable whether the range differences reported here are significant.

Purpose: Range uncertainty from X-ray CT number conversion to stopping power ratio (SPR) is one of the key factors limiting the potential of proton therapy. The large margins required for deep seated tumors degrade the organ sparing achievable with the technology. Of interest is the application of dual energy CT (DECT) to SPR estimation. In this planning study proton range differences between SECT and DECT have been quantified for brain cases. Methods: A last generation dual source DECT scanner was used to acquire SECT (150 kVp with Sn filtration) and DECT (additionally 90 kVp) scans of phantoms and 5 head trauma patients, acting as surrogate cancer patients. Phantom materials were characterized in terms of SPR in a particle beam to obtain reference values. IMPT treatment plans were generated on the basis of SECT and DECT SPR images for hypothetical brain tumors using a short and a long beam path. Range differences between SECT and DECT from plan recalculations were evaluated in beam-eye-view (BEV) by comparing the 80% isodose. Results: For the 18 phantom materials the SECT RMS SPR errors were 2.6% compared to 1.1% for DECT. Group median relative range differences between SECT and DECT plans were −1.0% for the short beam path over the 5 patients investigated in this study. For the long beam path the median difference was −1.4%. These relative range differences corresponded to −0.5 mm and −1.4 mm shifts respectively. Conclusion: This is the first study performing proton therapy treatment planning on DECT patient images. Important range differences of more than 1 mm were observed between SECT and DECT treatment plans, and DECT SPR accuracy was found superior on the basis of phantom measurements. While the patients investigated in this study did not have brain tumors, the findings we observed should apply to cancer patients. Deutsche Forschungsgemeinschaft (MAP); Bundesministerium fur Bildung und Forschung (01IB13001)

Background. Careful patient selection is the prerequisite to raise transplant benefit. In lung transplant (LT) candidates, the effect of body mass index (BMI) on postoperative outcome remains controversial, possibly due to the inaccuracy of BMI in discriminating between fat and muscle mass. We therefore hypothesized that assessment of body composition by muscle mass measures is more accurate than by BMI regarding postoperative outcome.Methods. All LT recipients from 2011 to 2014 were included and retrospectively analyzed. Lean psoas area (LPA) was assessed from pretransplant computed tomography scans, and associations with postoperative outcomes were investigated.Results. Included were 103 consecutive LT recipients with a mean pre-LT BMI of 22.0 +/- 4.0 kg/m(2) and a mean LPA of 22.3 +/- 8.3 cm(2). LPA was inversely associated with length of mechanical ventilation (p = 0.03), requirement of tracheostomy (p = 0.035), and length of stay in the intensive care unit (p = 0.02), while controlling for underlying disease, BMI, sex, age, and procedure; in contrast, BMI was not (p = 0.25, p = 0.54, and p = 0.42, respectively.). Multiple regression analysis revealed that the 6 minute walk distance at the end of pulmonary rehabilitation was significantly associated with LPA (p = 0.02).Conclusions. LPA can easily be assessed in LT candidates as part of pretransplant evaluation and was significantly associated with short-term outcome, whereas BMI was not. Assessment of LPA may provide additional information on body composition beyond BMI. However, the clinical utility has to be further evaluated. (C) 2016 by The Society of Thoracic Surgeons

Background and Objectives Sialolithiasis is a common disease of the major salivary glands. Owing to the variety of conservative and minimally invasive techniques, it is now possible to treat most cases of sialolithiasis without removal of the affected salivary gland. One treatment option is the endoscopic removal of the calculi. In cases of larger concretions, intraductal disintegration using laser‐induced shock waves can be appropriate to allow endoscopic removal. In the present study, we investigated whether physical and radiological parameters of salivary stones can effectively predict the applicability of laser lithotripsy. Furthermore, we determined to what extent the applied laser energy resulted in tissue damage. Study Design/Materials and Methods In addition to basic parameters like size and density, we analysed 47 salivary stones using fluorescence spectroscopy, infrared spectroscopy, Raman spectroscopy, and dual‐energy computed tomography. Subsequent fragmentation of all stones was performed with a Ho:YAG laser in a near‐contact manner. Fragmentation rates were calculated and correlated with the previously measured physical and radiological parameters. Finally, to test for tissue damage, we performed HE‐histology of salivary duct mucosa treated with the same laser energy used for stone fragmentation. Results Blue light excitation induced either green or red fluorescence emission. Dual‐energy CT resulted in evidence of calcium‐containing material. Infrared spectroscopy and Raman spectroscopy, both identified carbonate apatite as the main component of salivary stones. Disintegration into pieces smaller than 2 mm was possible in all cases. Fragmentation rates depended on the energy per pulse applied but not on any of the analysed physical and radiological parameters. In contrast to lithotripsy with 500 mJ per pulse, which was associated with no tissue damage, lithotripsy with 1,000 mJ per pulse resulted in damage of salivary duct mucosa. This suggests that the optimal laser energy for stone fragmentation is between 500 and 1,000 mJ per pulse. Conclusion Laser lithotripsy using Ho:YAG laser is a highly efficient treatment, at least in vitro . All salivary stones could be disintegrated irrespective of their physical and radiological composition. Lasers Surg. Med. 47:342–349, 2015. © 2015 Wiley Periodicals, Inc.

Abstract Objectives: The aim of the study was to determine whether automated quantification of pulmonary perfused blood volume (PBV) in dual-energy computed tomography pulmonary angiography (DE-CTPA) can be used to assess the severity of chronic thromboembolic pulmonary hypertension (CTEPH). Methods: Automated quantification of PBV was performed in 25 consecutive CTEPH patients undergoing DE-CTPA. PBV values were correlated with cardiac index and pulmonary vascular resistance quantified by right heart catheterization and walking distance in the 6-minute walk test using Pearson’s correlation coefficient and multivariate linear regression analysis to control for age and gender. Results: DE-CTPA derived PBV values inversely correlated with systolic (r = –0.64, p = 0.001) and mean (r = –0.57, p = 0.004) pulmonary arterial pressure. There was a trend for PBV values to inversely correlate with pulmonary vascular resistance (r = –0.20, p = 0.35). No significant correlation was found between PBV values and cardiac index or 6-minute walking distance. These correlations were confirmed to be independent of age and gender on multivariate linear regression analysis. Conclusion: DE-CTPA can be used for an automated quantification of pulmonary PBV in chronic thromboembolic pulmonary hypertension. PBV values correlate inversely with systolic and mean pulmonary arterial pressure and can thus be used to estimate the severity of pulmonary hypertension in these patients. Citation Format: • Meinel FG, Graef A, Thierfelder KM et al. Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension. Fortschr Röntgenstr 2014; 186: 151 – 156

The velocity of collateral filling can be assessed in dynamic time-resolved computed tomography (CT) angiographies and may predict initial CT perfusion (CTP) and follow-up lesion size. We included all patients with an M1± internal carotid artery (ICA) occlusion and follow-up imaging from an existing cohort of 1791 consecutive patients who underwent multimodal CT for suspected stroke. The velocity of collateral filling was quantified using the delay of time-to-peak (TTP) enhancement of the M2 segment distal to the occlusion. Cerebral blood volume (CBV) and mean transit time (MTT)-CBV mismatch were assessed in initial CTP. Follow-up lesion size was assessed by magnetic resonance imaging (MRI) or non-enhanced CT (NECT). Multivariate analyses were performed to adjust for extent of collateralization and type of treatment. Our study comprised 116 patients. Multivariate analysis showed a short collateral blood flow delay to be an independent predictor of a small CBV lesion (P<0.001) and a large relative mismatch (P<0.001) on initial CTP, of a small follow-up lesion (P<0.001), and of a small difference between initial CBV and follow-up lesion size (P=0.024). Other independent predictors of a small lesion on follow-up were a high morphologic collateral grade (P=0.001), lack of an additional ICA occlusion (P=0.009), and intravenous thrombolysis (P=0.022). Fast filling of collaterals predicts initial CTP and follow-up lesion size and is independent of extent of collateralization.

PurposeObesity is a worldwide pandemic, and obese patients face an increased risk of developing acute respiratory distress syndrome (ARDS). Prone positioning (PP) is a frequently used intervention in the treatment of ARDS. There are no data describing the impact of PP on morbidity and mortality in abdominally obese patients. We report our observations in abdominally obese ARDS patients treated with PP.Materials and methodsPatients with ARDS (n = 82) were retrospectively divided into 2 groups characterized by presence (n = 41) or absence (n = 41) of abdominal obesity as defined by a sagittal abdominal diameter of 26 cm or more.ResultsThere was no difference in cumulative time abdominally obese patients were placed in prone position from admission to day 7 (41.0 hours [interquartile range, 50.5 hours] vs 39.5 hours [interquartile range, 61.5 hours]; P = .65) or in overall intensive care unit mortality (34% vs 34%; P = 1). However, abdominally obese patients developed renal failure (83% vs 35%; P < .001) and hypoxic hepatitis (22% vs 2%; P = .015) more frequently. A significant interaction effect between abdominal obesity and prone position with respect to mortality risk (likelihood ratio, P = .0004) was seen if abdominally obese patients were treated with prolonged cumulative PP.ConclusionA cautious approach to PP should be considered in abdominally obese patients.

OBJECTIVETo evaluate if vascular and pulmonary parenchymal enhancement values in dual-energy (DE) CT pulmonary angiography (CTPA) can suggest the diagnosis of pulmonary congestion.METHODSDE-CTPA images of 90 out of 1321 patients negative for pulmonary embolism showed signs of congestive heart failure. We measured DE-derived pulmonary parenchymal [perfused blood volume (PBV)], pulmonary artery (PA) and left atrium (LA) enhancement values in these patients and in 142 control patients. Enhancement values were compared between the populations and correlated with serum values of B-type natriuretic peptide (BNP) and proBNP, where available.RESULTSNo significant difference of PBV but significant differences of mean PA and LA enhancement and individual enhancement differences (PA - LA) were found between the populations. PA - LA was higher in patients with elevated BNP and proBNP and was positively correlated with these values. Receiver operating characteristic analysis revealed a moderate discriminatory power of the PA - LA difference for the presence of cardiac biomarker elevations.CONCLUSIONPBV in DE-CTPA is not altered in patients with signs of congestive heart failure. However, differences in enhancement values in the pre- and post-pulmonary vessels were found in comparison with the control population.ADVANCES IN KNOWLEDGEAltered pulmonary vascular haemodynamics in pulmonary venous congestion are not reflected in dual-energy-derived PBV maps. In the diagnosis of left heart failure in patients with chest pain and dyspnoea, density measurements in the pulmonary artery and in the left atrium in CTPA images may be a helpful diagnostic tool.

In this pilot study we explored whether contrast-material bolus propagation time and speed in the pulmonary arteries (PAs) determined by dynamic contrast-enhanced computed tomography (DCE-CT) can distinguish between patients with and without pulmonary hypertension (PH).

OBJECTIVES:The aim of this study was to determine the feasibility of computed tomography (CT)-based dynamic myocardial perfusion imaging for the assessment of myocardial ischemia and infarction compared with cardiac magnetic resonance (CMR). BACKGROUND:Sequential myocardial CT perfusion imaging has emerged as a novel imaging technique for the assessment of myocardial hypoperfusion. METHODS:We prospectively enrolled subjects with known coronary artery disease who underwent adenosine-mediated stress dynamic dual-source CT (100 kV, 320 mAs/rot) and CMR (3-T). Estimated myocardial blood flow (eMBF) and estimated myocardial blood volume (eMBV) were derived from CT images, using a model-based parametric deconvolution technique. The values were independently related to perfusion defects (ischemic and/or infarcted myocardial segments) as visually assessed during rest/stress and late gadolinium enhancement CMR. Conventional measures of diagnostic accuracy and differences in eMBF/eMBV were determined. RESULTS:Of 38 enrolled subjects, 31 (mean age 70.4 ± 9.3 years; 77% men) completed both CT and CMR protocols. The prevalence of ischemic and infarcted myocardial segments detected by CMR was moderate (11.6%, n = 56 and 12.6%, n = 61, respectively, of 484 analyzed segments, with 8.4% being transmural). The diagnostic accuracy of CT for the detection of any perfusion defect was good (eMBF threshold, 88 ml/mg/min; sensitivity, 77.8% [95% confidence interval (CI): 69% to 85%]; negative predictive value, 91.3% [95% CI: 86% to 94%]) with moderate positive predictive value (50.6% [95% CI: 43% to 58%] and specificity (75.41% [95% CI: 70% to 79%]). Higher diagnostic accuracy was observed for transmural perfusion defects (sensitivity 87.8%; 95% CI: 74% to 96%) and infarcted segments (sensitivity 85.3%; 95% CI: 74% to 93%). Although eMBF in high-quality examinations was lower but not different between ischemic and infarcted segments (72.3 ± 18.7 ml/100 ml/min vs. 73.1 ± 31.9 ml/100 ml/min, respectively, p > 0.05), eMBV was significantly lower in infarcted segments compared with ischemic segments (11.3 ± 3.3 ml/100 ml vs. 18.4 ± 2.8 ml/100 ml, respectively; p < 0.01). CONCLUSIONS:Compared with CMR, dynamic stress CT provides good diagnostic accuracy for the detection of myocardial perfusion defects and may differentiate ischemic and infarcted myocardium.

Objective: It was the objective of this in-vitro study to investigate photon-based techniques for identifying the composition and fragmentation of salivary stones using a Ho:YAG laser. Materials and Method: Salivary stones (n=47) extracted from patients with clinical symptoms of sialolithiasis were examined in-vitro. After extraction, the stones were kept in Ringers solution until size and volume measurements could be performed. Thereafter, dual-energy CT scans (DECT) were performed to classify the composition of the stones. Subsequently, fluorescence measurements were performed by taking images under blue light excitation as well as by fluorescence spectroscopy, measuring excitation-emission-matrixes (EEM). Further investigation to identify the exact composition of the stone was performed by Raman spectroscopy and FTIR spectroscopy of stone fragments and debris. Fragmentation was performed in an aquarium set-up equipped with a mesh (hole: 1.5mm) using a Ho:YAG-laser to deliver laser pulses of 0.5, 1.0 and 1.5J/pulse at a frequency of 3Hz through a 200μm-fibre to the stone surface. The collected data were analyzed and fragmentation rates were calculated. Finally, correlation between stone composition and fragmentation was performed. Results: Blue light fluorescence excitation resulted in either fluorescence in the green spectral region or in a combination of green and red fluorescence emission. EEM-measurement showed the corresponding spectra. Raman spectroscopy showed a mixture of carbonate apatite and keratin. DECT results in evidence of calcium containing components. FTIR-spectroscopy results showed that carbonate apatite is the main component. Fragmentation experiment showed a dependency on the energy per pulse applied if the evaluation implies the ratio of fragmented weight to pulse, while the ratio fragmented weight to energy remains about constant for the three laser parameter used. Conclusion: The composition of salivary stones could be determined using different photonic techniques. Attempts to correlate salivary stone composition to fragmentation rates resulted in no correlation. Thus it could be concluded that each salivary stone could be easily destroyed using Ho:YAG-laser light by means of a 200μm bare fibre at lowest energy per pulse.

Patients with stone disease usually present to the urologist with acute colic pain. For the right choice of therapy the diagnosis needs to be confirmed using one of many imaging methods, including ultrasonography, abdominal radiography, intravenous urography, non-contrast-enhanced computed tomography (CT), CT and magnetic resonance imaging (MRI) urography and dual-energy CT. The techniques differ in the availability, diagnostic sensitivity and specificity and level of radiation exposure. Compared to the others dual-energy CT allows distinction between different stone compositions with high accuracy and can affect the choice of therapy. This article on imaging and diagnosis of urolithiasis discusses the different imaging methods and highlights dual-energy CT and its distinctive features.

Patienten mit einer Steinerkrankung stellen sich in der Regel mit kolikartigen Schmerzen vor. Vor Einleitung einer Therapie ist zur sicheren Diagnosestellung eine weiterführende Bildgebung erforderlich. Hierfür stehen die Sonographie, die konventionelle Röntgenabdomenaufnahme, das Ausscheidungsurogramm, die native Computertomographie (CT), die CT- und MR-Urographie und die Dual-Energy-CT zur Verfügung. Alle unterscheiden sich in der Verfügbarkeit, in der diagnostischen Sensitivität und Spezifität und in der Strahlenbelastung für den Patienten. Mit der Dual-Energy-CT wurde ein Verfahren entwickelt, das im Gegensatz zu den konventionellen die Steinzusammensetzung mit hoher Sicherheit unterscheiden und so die Therapie beeinflussen kann. In diesem Leitthemenbeitrag zur Bildgebung der Urolithiasis werden die einzelnen bildgebenden Verfahren vorgestellt und insbesondere das Dual-Energy-CT näher erläutert.

High-pitch dual spiral computed tomography (CT) acquisitions are a relatively novel technical development characterized by significantly reduced acquisition time and radiation exposure by avoiding data oversampling. This approach may therefore overcome major limitations of current cardiovascular CT imaging and be applicable to a variety of clinical settings. Given the great potential, we review technical principles, summarize available early scientific evidence and identify limitations of the technique.