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Introduction COPD affects the small airways and is associated with ventilation heterogeneity. There are little data on the multiple-breath washout (MBW) in patients with COPD, particularly the variability over 8 weeks, using a shortened sulfur hexafluoride (SF6) washout. This work evaluated the repeatability of the lung clearance index (LCI)1/40 and LCI1/20 among subjects with COPD and compared to spirometry and clinical markers. Methods The MBW was performed on patients with COPD to determine ventilation heterogeneity globally (LCI), at conductive (Scond) and acinar (Sacin) levels. The LCI was repeated in triplicate and measured at a traditional 1/40th washout and retrofitted to a shortened 1/20th end tidal SF6 concentration washout. Tests were repeated after 20 min and 8 weeks to determine within and between visit repeatability and compared with spirometry. Results Eighty-four subjects were recruited to perform LCI and spirometry with 20 subjects performing the repeatability protocol. There were weak correlations between forced expiratory volume in 1 s ( FEV1) per cent predicted and LCI1/40th r=−0.311 (p=0.02), and LCI1/20th r=−0.40 (p, It is feasible to shorten the LCI to a 1/20th washout in patients with COPD, and this leads to a time saving of 32% and therefore may allow for easier use in clinical settings https://bit.ly/3v9UsXd

Background Focal hepatic lesions incidentally detected during ultrasound usually need further step for proper characterization. The aim of this study was to highlight the efficacy of microbubble contrast-enhanced ultrasonography (CEUS) in characterization of focal liver lesions. This prospective study was conducted on 60 patients presented with hepatic focal lesions in the period from January 2019 to June 2020. CEUS studies were performed after a baseline conventional ultrasound with the same machine by the same operator. The ultrasound contrast agent used is second-generation US contrast agent. The enhancement patterns of the hepatic lesions were studied during the vascular phases up to 5 min and the data were correlated with histopathology, triphasic contrast-enhanced CT, and clinical follow-up. Results CEUS demonstrated a sensitivity of 94.2%, specificity of 88.9%, positive predictive value of 91%, negative predictive value of 94.1%, and accuracy of 92.3% for characterization of hepatic focal lesions, compared to a sensitivity of 100%, specificity of 81.8%, positive predictive value of 84%, negative predictive value of 100%, and accuracy of 90.7% for triphasic CT. Conclusion CEUS is an effective tool in characterization of HFLs and recommended as a second diagnostic step after conventional ultrasound to immediately establish the diagnosis especially in patients with contraindications to CECT.

Sulphur hexafluoride (SF6) gas insulated switchgear (GIS) is widely used in electrical power supply system and therefore needs regular preventive maintenance. Prediction and diagnosis analysis of faults in GIS using SF6 gas by-products was introduced previously by using 4 to 8 types of by product gases. As latest development on gas analyser, more by-product gases can be detected and used for condition monitoring of the GIS. The type, number, concentration and chemical stability of by-product gases of SF6 GIS are found to be closely correlated to the type of defect. However, the number of by-product gases used increases, the pattern for faults classification become more complex. Thus, further analysis on increasing number of by product gases using intelligent techniques such as pattern recognition is required. In this article, 12 significant by-products captured due to various sources of partial discharge fault in GIS were used. Random Forest (RF) was selected in this work as a multi-class classification technique. The analyses using RF pattern recognition with eight algorithms based on the presence and concentration of the gas by-products were carried out. The RF algorithm successfully recognises a given defect with an accuracy of 87.5% for all defects fault classification. The performance of the RF algorithm is 1.5 times better than the decision table algorithm which is the next best algorithm. This research illustrates the feasibility and applicability of an effective GIS diagnostic using gas by-products analyses, and in particular, using the RF pattern recognition.

To evaluate the dispersion of a heavy gas, such as sulphur hexafluoride, with a low Froude number in a built environment, an experimental and numerical simulation study was conducted. The experiment was carried out using seven different injection inlet configurations in an experimental chamber. The release rate was found to have a great effect on the concentration in the lower part of the chamber. The obstacle in the middle of the chamber could cause a non-uniform distribution of concentration, particularly due to variations in locations and angles of the release outlets. Additionally, numerical simulations were carried out to evaluate four turbulence models: the standard k- ε model, the realizable k- ε model, the re-normalization group (RNG) k- ε model and the shear stress transport (SST) k-ω model. Four indicators were used to evaluate the turbulent model performance. In general, the SST k-ω model performed the best, with geometric mean bias ( MG) = 0.968 and geometric variance ( VG) = 1.09 at 0.055 m height, and with MG = 0.384 and VG = 2.80 at 0.6 m height. The standard k- ε model was the next best in performance, followed by the realizable k- ε and the RNG k- ε model.

C4F7N (fluorinated nitrile) gas mixture has been utilized as the gas insulating medium to replace the most greenhouse gas SF6 (sulphur hexafluoride). Nowadays, there are few reports on the toxicity mechanism of C4F7N and studies on the application risk of C4F7N is insufficient. In this paper, we carried out acute toxicity tests for C4F7N gas systematically. The changes of vital signs of rats after exposure to C4F7N were analyzed and the influence of C4F7N on the main organs of rats was revealed for the first time. It was found that rats developed symptoms of respiratory rate decrease, respiratory mucosa damage, movement systems impairment and abnormal blood cell count after exposure to C4F7N. Pathological section results showed that 1.5% C4F7N could damage the lung, kidney, intestine and brain tissues of rats to a certain extent, but has little influence to the eye, skin, heart and liver. The LC50 (rat, 4 h) of C4F7N gas is in the range of 15,000 ppm (1.5%) and 20,000 ppm (2%). Relevant research results not only reveal the acute toxicity mechanism of C4F7N, but also provide important reference for the safety protection of scientific researcher, equipment production, engineering operation and maintenance personnel.

Background Stress echocardiography has become established as the most widely applied non-invasive imaging test for diagnosis of coronary artery disease within the UK. However, stress echocardiography has been substantially qualitative, rather than quantitative, based on visual wall motion assessment. For the first time, we have identified and validated quantitative descriptors of cardiac geometry and motion, extracted from ultrasound images acquired using contrast agents in an automated way. Purpose To establish whether these novel imaging features can be generated in an automated, quantifiable and reproducible way from images acquired with perfluoropropane contrast, as well as investigating how these extracted measures compare to those extracted from sulphur hexafluoride contrast and non-contrast studies. Methods 100 patients who received perfluoropropane contrast during their stress echocardiogram were recruited. Their stress echocardiography images were processed through a deep learning algorithm. Novel feature values were recorded and a subset of 10 studies were repeated. The automated measures of global longitudinal strain (GLS) and ejection fraction (EF) extracted from these images were compared to values previously extracted from sulphur hexafluoride contrast and non-contrast images using the same software. Results A full set of 31 novel imaging features were successfully extracted from 79 studies acquired using the perfluoropropane contrast agent with a dropout rate of 14% (n=92, 8 incomplete image sets). Repeated analysis in a subset of 10 perfluoropropane cases demonstrated excellent reproducibility of the extracted feature values (R2=1). Automated values of GLS and EF, at both rest (GLS = −16.4±4.8%, EF = 63±13%) and stress stages (GLS = −17.7±5.8%, EF = 68±11%), were extracted from 83 perfluoropropane studies, with a dropout rate of 16% (n=99, fewer incomplete sets as short axis view not required). The ranges of GLS and EF measures extracted from the perfluoropropane images were comparable to the other contrast studies (n=222) (Rest GLS = −16.8±5.8%, Rest EF = 63±10%; Stress GLS = −19.1±6.7%, Stress EF = 71±9%) and non-contrast studies (n=86) (Rest GLS = −15.7±5.3%, Rest EF = 57±10%; Stress GLS = −17.3±6.4%, Stress EF = 61±14%). Conclusions Novel features and clinically relevant measures were extracted from images acquired using perfluoropropane contrast for the first time in a fully automated and reproducible way using a deep learning algorithm. The analysis failure rate and generated measures are comparable to those extracted from images using other commonly used sulphur hexafluoride contrast agents and non-contrast stress echocardiography studies. These findings demonstrate that deep learning algorithms can be used for automated quantitative analysis of stress echocardiograms acquired using various contrast agents and in non-contrast studies to improve stress echocardiography practice. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Lantheus Medical Imaging, Inc.

This study aimed to identify the risk factors for endothelial cell density (ECD) loss after Descemet membrane endothelial keratoplasty (DMEK) and analyse whether donor tissues from cold versus organ culture differ in terms of ECD loss after DMEK. Consecutive DMEK cases from a prospective database for Fuchs’ endothelial corneal dystrophy were retrospectively analysed between 2011 and 2016 at the University of Cologne, and the possible risk factors for ECD loss, including patient-related factors, type of tamponade (air or 20% sulphur hexafluoride gas), type of surgery (triple DMEK or DMEK alone), re-bubbling, immune rejection, and donor-related factors were determined. Eight hundred and forty-one eyes were selected. There was no significant difference in the best-corrected visual acuity (logarithm of the minimal angle of resolution) and corneal thickness (P = 0.540 and P = 0.667) between groups. Immune reactions were more common in cold cultures (P = 0.019), but ECD loss (1 year after DMEK) was greater in organ cultures (38.3 ± 0.8%) than in cold cultures (34.7 ± 1.4%) (P = 0.022). Only re-bubbling was significantly associated with ECD loss (P

Simple Summary Enteric methane emissions from ruminants are a major contributor to atmospheric greenhouse gas accumulation in agricultural production systems, which may consequently contribute to climate change. Accurate measurement of methane production in ruminants is vital to develop robust national greenhouse gas emission inventories and to evaluate mitigation strategies of methane emissions. This review summarizes several common methane measurement techniques suitable for ruminant production and discusses the advantages and disadvantages of each method. There is not a perfect technique for all situations. The appropriate technique depends on the objectives and resources available. Sophisticated techniques such as respiration chambers, sulphur hexafluoride tracer and ventilated hood are usually highly accurate but labor and time intensive. Simplified techniques such as GreenFeed, sniffer method, facemask, laser methane detector and portable accumulation chamber may be less accurate but are rapid with a high throughput. In general, an understanding of measurement mechanisms and the advantages and disadvantages with an appreciation of animal behavior and welfare is necessary for all techniques. Abstract To identify relationships between animal, dietary and management factors and the resulting methane (CH4) emissions, and to identify potential mitigation strategies for CH4 production, it is vital to develop reliable and accurate CH4 measurement techniques. This review outlines various methods for measuring enteric CH4 emissions from ruminants such as respiration chambers (RC), sulphur hexafluoride (SF6) tracer, GreenFeed, sniffer method, ventilated hood, facemask, laser CH4 detector and portable accumulation chamber. The advantages and disadvantages of these techniques are discussed. In general, RC, SF6 and ventilated hood are capable of 24 h continuous measurements for each individual animal, providing accurate reference methods used for research and inventory purposes. However, they require high labor input, animal training and are time consuming. In contrast, short-term measurement techniques (i.e., GreenFeed, sniffer method, facemask, laser CH4 detector and portable accumulation chamber) contain additional variations in timing and frequency of measurements obtained relative to the 24 h feeding cycle. However, they are suitable for large-scale measurements under commercial conditions due to their simplicity and high throughput. Successful use of these techniques relies on optimal matching between the objectives of the studies and the mechanism of each method with consideration of animal behavior and welfare. This review can provide useful information in selecting suitable techniques for CH4 emission measurement in ruminants.

Purpose This study explores autologous neurosensory autograph for a patient with a chronic full-thickness macular hole (FTMH) and idiopathic macular telangiectasia type 2 (IMT2). Observations The patient had a chronic 1355 μm FTMH and best corrected visual acuity (BCVA) of 2 logMAR units after two unsuccessful attempts to close the macular hole. Following a 25-gauge vitrectomy, a 2-disc diameter neurosensory autograft from the supertemporal retina was mobilized and secured with perfluoro-N-octane (PFO) tamponade. After being postured supine for one week, the PFO was exchanged for silicone oil. Two months later, silicone oil was exchanged for 20% sulphur hexafluoride (SF6). Conclusions and importance The graft achieved anatomical and functional success with BCVA of 0.6 logMAR units. This case supports autologous neurosensory autograph as a technique for achieving closure of chronic macular holes refractory to conventional treatment.

Echo contrast agents, such as SonoVue®, (Bracco, Milan, Italy) are often used to enhance diagnosis. Although their use is safe, some rare side effects could be severe or even fatal. We are reporting a case of severe systemic allergic reaction after infusion of SonoVue®. After a brief review of the literature, the aim of this paper is to draw attention to this risk and recall the safety instructions coming with the use of ultrasound contrast agents.

Ventilation heterogeneity is frequent in bronchial asthma and can be assessed using multiple breath wash-out testing (MBW). Most data is available in paediatric patients and using nitrogen as a tracer gas. We aimed to evaluate sulphur hexafluoride (SF6) MBW in adult asthmatics. Spirometry, whole-body plethysmography, impulse oscillometry and SF6-MBW were prospectively performed. MBW parameters reflecting global (lung clearance index, LCI), acinar (Sacin) and conductive (Scond) ventilation heterogeneity were derived from three consecutive wash-outs. LCI was calculated for the traditional 2.5% and an earlier 5% stopping point that has the potential to reduce wash-out times. 91 asthmatics (66%) and 47 non-asthmatic controls (34%) were included in final analysis. LCI2.5 and LCI5 were higher in asthmatics (p acin and Scond were elevated (p 2.5 and 3.5% for LCI5 in asthmatics. Forty-one asthmatic patients had normal spirometry. ROC analysis revealed an AUC of 0.906 for the differentiation from non-asthmatic controls exceeding diagnostic performance of individual and conventional parameters (AUC = 0.819, p 6-MBW is feasible and reproducible in adult asthmatics. Ventilation heterogeneity is increased as compared to non-asthmatic controls persisting in asthmatic patients with normal spirometry. Diagnostic performance is not affected using an earlier LCI stopping point while reducing wash-out duration considerably.

Submacular haemorrhages, which are mostly caused by exudative age-related macular degeneration, lead to a significant deterioration of visual acuity and have a poor prognosis. Therefore, quick implementation of treatment is essential. The aim was to report a case of 68-year-old patient suffering from extensive haemorrhage covering the macula treated with pure sulphur hexafluoride (SF6) gas infusion and two anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections. A patient was referred to the clinic due to a sudden deterioration of vision and the appearance of a black spot in central vision in the right eye. The patient underwent the infusion of 0.5 ml of pure SF6 followed by maintenance of face-down position postoperatively resulting in partial displacement of submacular haemorrhage. One month after the surgery the patient was referred to two intravitreal injections of anti-VEGF in monthly intervals. The effectiveness of the treatment is confirmed by OCT examination and visual acuity results (from CF 1’ before treatment to 5/12 after the treatment). A combination of SF6 gas infusion and anti-VEGF intravitreal injections turned out to be an effective and safe method of submacular haemorrhage treatment. Early diagnosis and treatment implementation resulted in significant improvement of visual acuity.

Intraocular gas tamponades are an important tool in modern vitreoretinal surgery. However, there is considerable variation in their use and perceptions amongst clinicians regarding these agents.An electronic survey of vitreoretinal surgeons in the UK was undertaken to establish the patterns of use and surgeons' estimates of the longevity and expansion timing of gas tamponades. In addition, data were prospectively collected on the longevity of gas tamponades in 114 patients from our unit. An analysis was performed to identify patient or surgery factors affecting gas longevity RESULTS: A wide variation in the patterns of use and estimates of longevity and expansion timing of intraocular tamponades was found in the survey of vitreoretinal surgeons. Data from our unit give informed estimates on the longevity of three commonly used tamponades. For 30 % sulphur hexafluoride (SF6), mean 18.0 days, standard deviation (SD) 2.6 days. For 20 % hexafluoroethane (C2F6), mean 34.5 days, SD 3.3 days. For 15 % perfluoropropane (C3F8), mean 67.7 days SD 5.5 days. In the C2F6 group there was correlation between longer duration of the gas bubble and longer axial length (r = 0.438, p = 0.02) and longer gas duration with male sex (p = 0.002).We present informed gas tamponade longevity figures in clinical practice and report statistically significant associations between longer gas longevity and increasing axial length and male sex.

Continuous intraoperative optical coherence tomography (iOCT) integrated into the operating microscope is a new modification in the current operating microscope to aid in the surgical procedures involving both the anterior and the posterior segment. This helps in intraoperative planning, modification of the surgical steps if required and confirmation of the surgical endpoint in the operating room itself. iOCT was used for the successful management of descemet’s membrane detachment (DMD) following deep anterior lamellar keratoplasty (DALK) with intracameral injection of 20% Sulphur hexafluoride. The gas was injected under direct visualization through the microscope with continuous real time monitoring of the change in height of the detached Descemet’s membrane (DM). Additionally stab incisions were given through the anterior cornea due to the presence of residual fluid above the DM which was visible on continuous iOCT images. This led to the successful apposition of the DM which otherwise would have remained detached due to the residual fluid. This highlights the importance of continuous iOCT monitoring of the ophthalmic surgical procedures in order to produce a successful anatomical outcome of the surgery without disruption of the surgical procedure.

Background: The multiple-breath washout (MBW) with 4% sulphur hexafluoride (SF6) is a sensitive method to detect and monitor ventilation inhomogeneity (VI) in infancy. A new infant SF6 MBW methodology using currently available equipment was recently proposed. Aims: We compared lung clearance index (LCI) and functional residual capacity (FRC) outcomes in healthy infants from the new SF6 MBW technique with published normative data. Methods: Unselected healthy infants from the prospective Bern-Basel Infant Lung Development (BILD) birth cohort underwent MBW measurements using the new SF6 MBW technique (Spiroware 3.2; Ecomedics, Duernten, Switzerland). Measurements were performed in unsedated infants during quiet natural sleep according to the ATS/ERS standards. We report the mean (standard deviation (SD)), within-test coefficient of variation (CV), and upper limit of normal (mean + 1.64*SD). Results: We performed MBW measurements using the new method in 28 healthy infants. Two technically acceptable measurements were available in 23 healthy infants (82%) at ~5 weeks post-natal age (51% male, age: 5.5 weeks (0.9), weight: 4.5kg (0.6)). Mean FRC adjusted for weight was 17.2 (3.5) ml/kg (CV: 6.8%) and mean LCI was 7.2 (0.7) (CV: 9.7%, ULN: 8.3). These values differ considerably from published normative data using Wbreath software (FRC: 23.9 (4.0) ml/kg; LCI: 6.8 (0.6); Fuchs et al. 2011). Conclusions: Measurements from the new SF6 MBW setup generate FRC values approximately 30% higher and LCI 6% lower than for the former setup. These preliminary data highlight the need for new equipment specific reference values.

422 Background: In the era of parenchymal sparing surgery, detecting more colorectal liver metastases (CRLM) is essential to optimize the treatment. We evaluated the added-value of contrast enhanced intraoperative ultrasound (CE-IOUS) with a prospective design. Methods: We used an optimal 2-stage Simon’s design for this two-center study open for patients with operable CRLMs. Primary objective was the justified clinical utility of contrast-enhanced IOUS. Secondary objectives included detection rate of CRLMs, characterization rate of focal liver lesions, specific toxicity and detection of missing CRLMs. Results: Among the 58 eligible patients, 54 were eligible and assessable. Of these 54 patients, 36 were men (66.7%), median age was 63.6 years (range, 37-81), and 43 patients underwent pre-operative chemotherapy. The median number of CRLMs was 2 (range, 1-11). Pre-operative staging was performed using MRI in all 58 eligible patients, CT scan in 41 (70%) and PET-scan in 21 (36%). Compared to pre-operative staging, IOUS allowed identification of 40 new CRLMs in 11 (20.4%) patients. Furthermore, compared to IOUS, CE-IOUS allowed identification of 9 additional CRLMs in 8 (14.8%) patients. The correct detection rate based on pathological exams was 0.94. No additional missing CRLM was diagnosed. The surgical procedure was altered in 5 (9.26%) patients but was justified only in 4 patients (one lesion was ablated without previous biopsy), leading to a clinical utility rate of 7.70% (95 CI, [3.2, 18.6]). There was no specific toxicity reported. Conclusions: Despite the primary endpoint not met for one protocol violation,the Uliis study demonstrates an added-value for CE-IOUS for surgeons treating CRLMs, especially for advanced cases pre-treated by chemotherapy. Clinical trial information: NCT01880554.

Under the Greenhouse Gas Reporting Program (GHGRP), the US Environmental Protection Agency (EPA) receives reports of production, imports and exports of SF6 in bulk and inside of electrical equipment. EPA also receives reports of SF6 emissions, consumption and/or related parameters from users of SF6, including manufacturers and users of electrical transmission and distribution equipment, semiconductor manufacturers, and magnesium producers and processers. Based on these reports, EPA estimates the consumption of SF6 by each industry, including facilities that do not report to the GHGRP. In this paper, we compare the consumption estimated based on reports from SF6 suppliers (producers, importers and exporters) to the consumption estimated based on reports from SF6 users, discussing differences and possible reasons for them. We find that in the one year studied, 2012, consumption based on reports from users accounted for 59% of the consumption based on reports from suppliers. We conclude that the unce...

Objective Comparison of the diagnostic findings of MRI, CT and CEUS in children with benign and malignant and portal venous anomalies of the liver. Materials/methods Retrospective analysis of the diagnostic findings of CEUS, MRI and CT scans in 56 children (age 0-17 years) with a total of 60 benign and malignant liver lesions and anomalies of the portal vein/perfusion. All patients underwent CEUS using sulphur hexafluoride microbubbles and a multi-frequency probe (1-5 MHz, 6-9 MHz). Cine-loops were stored up to 3 minutes. MRI was performed in 38 lesions. CT was performed in 8 lesions. Results Out of the 56 patients 49 liver lesions (48 benign, 1 malignant), 9 anomalies of the portal vein/perfusion and 2 of the biliary system were detected. 16/49 lesions were analyzed histopathologically. Using CEUS, the characterization of the lesions was possible in 45 out of 49 cases. In 32 cases, CEUS provided the exact diagnosis. Only two benign lesions were falsely categorized as malignant.Findings of MRI and CEUS were concordant in 84% of cases (n = 32/38). CEUS considered 1 benign lesion to be malignant. 2 lesions were not detectable and in 3 lesions no definite diagnosis was established using MRI.Findings of CT and CEUS were concordant in 5 of 8 cases. In 21 lesions CEUS as the only imaging modality was found to be sufficient for diagnostics. Conclusion Despite the restricted indications for using CEUS in children, it offers a high diagnostic detection rate (93%) for characterization of liver lesions and portal vein anomalies.

A capnodynamic calculation of effective pulmonary blood flow includes a lung volume factor (ELV) that has to be estimated to solve the mathematical equation. In previous studies ELV correlated to reference methods for functional residual capacity (FRC). The aim was to evaluate the stability of ELV during significant manipulations of cardiac output (CO) and assess the agreement for absolute values and trending capacity during PEEP changes at different lung conditions. Ten pigs were included. Alterations of alveolar carbon dioxide were induced by cyclic reoccurring inspiratory holds. The Sulphur hexafluoride technique for FRC measurements was used as reference. Cardiac output was altered by preload reduction and inotropic stimulation at PEEP 5 and 12 cmH2O both in normal lung conditions and after repeated lung lavages. ELV at baseline PEEP 5 was [mean (SD)], 810 (163) mL and decreased to 400 (42) mL after lavage. ELV was not significantly affected by CO alterations within the same PEEP level. In relation to FRC the overall bias (limits of agreement) was −35 (−271 to 201) mL, and percentage error 36 %. A small difference between ELV and FRC was seen at PEEP 5 cmH2O before lavage and at PEEP 12 cmH2O after lavage. ELV trending capability between PEEP steps, showed a concordance rate of 100 %. ELV was closely related to FRC and remained stable during significant changes in CO. The trending capability was excellent both before and after surfactant depletion.

We quantified the degree and dynamics of metamorphopsia changes in patients subjected to full-thickness macular hole surgery.This prospective interventional case series included 10 eyes of 10 patients with full-thickness macular hole (mean age 66.2±6.0 years). The patients underwent a complete ophthalmological examination including SD-OCT. The severity of metamorphopsia (expressed as M-score) was evaluated with M-CHARTS. 20-gauge pars plana vitrectomy with trypan blue staining, internal limiting membrane peeling and 20% sulphur hexafluoride tamponade was performed. Time course of metamorphopsia changes and their relation to best corrected visual acuity (BCVA) and OCT parameters were assessed.Significant but not total M-score decrease was observed one month postoperatively (0.72±0.44 vs. 0.50±0.36, z=-2.207, p=0.0353, power=0.26, pre- vs. post-op), with subsequent stabilization (0.41±0.41 three months and 0.37±0.44 six months post-op). The differences between M-score one month, three months and six months postoperatively were not significant. Baseline M-score correlated significantly with postoperative values at three follow-ups (rho=0.853, 0.715, 0.847; p0.05 for all; power=0.94, 0.58, 0.79). Baseline M-score did not correlate with macular hole dimensions (including basis p=0.154, minimal diameter p=0.051 or height of the border p=0.700). No correlation between M-score and the following parameters was found either pre- or postoperatively: BCVA, central foveal thickness, central subfield macular thickness and central subfield macular volume.In patients with successfully operated full-thickness macular hole, M-score decreased as early as one month postoperatively and was stable afterwards. The baseline M-score was a prognostic factor for the postoperative M-score. M-score turned out to be independent from BCVA and macular hole dimensions.

Nitrogen multiple breath washout test is a safe, feasible and repeatable method for infants with cystic fibrosis. It may outperform sulphur hexafluoride variant with respect to its better suitability for long time follow up and lower technical demands

Existing surgical modes for retinal detachment are elaborate and extremely complex. We have treated 20 cases of rhegmatogenous retinal detachment with pneumatic retinopexy which is Iess time consuming and does not require hospitalization. After pneumatic retinopexy reattachment of retina was achieved in 15 (75%) eyes. In 2 eyes retinal reattachment was achieved after repeating intravitreal injection of sulphur hexafluoride gas. Remaining 3 eyes were secondarily treated with scleral buckle surgery. One case needed vitreoretinal surgery. In pneumatic retinopexy there is minimum tissue handling and functional results are good.

We report two cases of opacified explanted intraocular lenses (IOL).The first lens was explanted from a cataract patient, then treated in vitro with trypsin/ethylene-diamine-tetra-acetic acid. The second hydrophilic acrylic IOL was explanted from a patient who had undergone sulphur hexafluoride (SF6) gas endotamponade surgery to repair a retinal detachment.

Introduction: Commercial N 2 -WO systems need modifications for use in young children and must be validated before widespread use. Aim: To compare LCI and FRC from Eco Medics Exhalyzer-D N 2 -WO to a custom-built AMIS 2000 Mass Spectrometer sulphur hexafluoride washout (SF 6 -WO) in preschool (3-6y)controls and patients with cystic fibrosis(CF) Methods: Washouts were performed on the same day. SF 6 -WO to standard lab protocol, N 2 -WO with a low deadspace filter and modified capnostat. A face mask with putty was used for all tests Results: 42 children were tested (25 CF). Mean age 5.1y CF, 4.8y, mean height and weight no difference CF vs. control . SF 6 -WO was not possible in 2 children, N 2 -WO was not possible in 6 Figure: Bland Altman (BA) plots for CF (black), Control (red), FRC (top) and LCI (bottom) FRC N2 was significantly higher than FRC SF6 in both groups. LCI N2 -LCI SF6 in controls showed good agreement. LoA were wider for children with CF, but there was no significant group difference (table 1). In children with CF only the BA plots suggest increased FRC N2 -FRC SF6 with increasing FRC, and decreased LCI N2 -LCI SF6 with increasing LCI (figure) Conclusion: Device specific reference values are needed for FRC and LCI in preschool children with CF.

A key challenge for future switching technologies, especially in the context of the substitution of the strong greenhouse gas sulphur hexafluoride and the ongoing development of DC grids, is the increase of the contact opening velocity within switching devices. Thus, in this contribution a compact helical coil operating mechanism is developed and first experimental investigations are performed to characterize the accelerating and breaking performance of the mechanism. The helical coil arrangement is supplied by currents up to values of several kilo-amperes and the movement of the mechanism is analyzed.

A desktop fume hood installed with an innovative design of flow boundary-layer separation controllers on the leading edges of the side plates, work surface, and corners was developed and characterized for its flow and containment leakage characteristics. The geometric features of the developed desktop fume hood included a rearward offset suction slot, two side plates, two side-plate boundary-layer separation controllers on the leading edges of the side plates, a slanted surface on the leading edge of the work surface, and two small triangular plates on the upper left and right corners of the hood face. The flow characteristics were examined using the laser-assisted smoke flow visualization technique. The containment leakages were measured by the tracer gas (sulphur hexafluoride) detection method on the hood face plane with a mannequin installed in front of the hood. The results of flow visualization showed that the smoke dispersions induced by the boundary-layer separations on the leading edges of the side plates and work surface, as well as the three-dimensional complex flows on the upper-left and -right corners of the hood face, were effectively alleviated by the boundary-layer separation controllers. The results of the tracer gas detection method with a mannequin standing in front of the hood showed that the leakage levels were negligibly small (≤0.003 ppm) at low face velocities (≥0.19 m/s).

Purpose: To compare the anatomic success between repair of rhegmatogenous retinal detachment (RRD) with superior breaks and repair of RRD with inferior breaks, by performing primary vitrectomy and using similar techniques and the same gas. Methods: Eighty-two consecutive eyes of 80 patients with RRD were included in this retrospective comparative study. The eyes were divided into two groups according to the location of the breaks: superior (n = 62) and inferior (n = 20). All the patients underwent a standard, 3-port, 20-gauge pars plana vitrectomy with 20% sulphur hexafluoride gas tamponade performed by the same surgeon. The main outcome measured was the primary anatomic reattachment at 3 months after surgery. Results: The primary anatomic success rate in the inferior group was significantly lower than that in the superior group (80% versus 98%, p = 0.012). In the inferior group, the primary anatomic success rate in patients whose symptoms lasted for more than 2 weeks was significantly lower than that in others (5/9 versus 11/11, p = 0.026). Multivariate logistic regression analysis identified inferior break as the only independent risk factor for redetachment (odds ratio, 11.88; p = 0.034). Conclusion: The anatomic success of primary vitrectomy for RRD with inferior breaks is lower than that for RRD with superior breaks. In particular, the duration of symptoms longer than 2 weeks is associated with a worse outcome in patients who had RRD with inferior breaks.

SF6(sulphur hexafluoride) is the gas most commonly used in high voltage power equipments. Due to the fact that SF6 is a greenhouse gas with a very high global warming potential, alternatives have b...

With the increase of the operating time of sulphur hexafluoride (SF6) electrical equipment, the different degrees of discharge may occur inside the equipment. It makes the insulation performance of the equipment decline and will cause serious damage to the equipment. Therefore, it is of practical significance to diagnose fault and assess state for SF6 electrical equipment. In recent years, the frequency of monitoring data acquisition for SF6 electrical equipment has been continuously improved and the scope of collection has been continuously expanded, which makes massive data accumulated in the substation database. In order to quickly process massive SF6 electrical equipment condition monitoring data, we built a two-level fault diagnosis model for SF6 electrical equipment on the Hadoop platform. And we use the MapReduce framework to achieve the parallelization of the fault diagnosis algorithm, which further improves the speed of fault diagnosis for SF6 electrical equipment.

Purpose To determine the value of contrast-enhanced ultrasound (CEUS) for fusion–guided, percutaneous biopsies of focal liver lesions. Materials and Methods Eighty patients with focal liver lesions identified on CT/MRI were enrolled. For percutaneous US guided biopsy planning, real-time fusion of CT/MRI with USG was performed, and subsequently CEUS was performed using sulphur hexafluoride microbubble (SonoVue, n = 40) and perfluorobutane-containing microbubble (Sonazoid, n = 40). We evaluated visibility and technical feasibility confidence level. Technical failure and occurrence of change of the target were also assessed. Results Among the 80 patients, four were technical failure for image fusion and one were technical failure for CEUS. Confirmative histologic diagnostic results were reported in 72 patients (90%) and the remaining patients were also helpful for making the final diagnosis using pathology results. Targeted lesion was changed in 22 patients (27.5%) on CEUS. As the lesion is necrotic, presumed target was more frequently changed after CEUS. Confidence level of technical success of procedure was significantly increased on CEUS comparison with B-US (p Conclusion CEUS would be helpful for planning of hepatic biopsy in terms of tumor visibility and viable portion assessment, and consequently higher operator confidence, compared with B-US.

Giriş: Sülfür hekzaflorid (SF-6 ) biyolojik açıdan etkisiz kabul edilmesine rağmen, akut maruziyetlerde oksijen ile yer değiştirerek asfiksi ve ölüme neden olabilir. SF-6 tıbbi cihazlardan uzay sanayisine kadar pek çok alanda kullanılmaktadır. Olgu Sunumu: On dokuz ve otuz iki yaşlarında iki elektrik işçisi, yüksek gerilimli elektriği kesmek için kullandıkları cihazın arıza yapması sonucu ortaya çıkan SF-6 adlı gaza yaklaşık 5-10 dakika maruz kalma ve takiben bulantı, kusma, baş dönmesi şikayetleri ile acil servisimize getirildi. Başvuru anında her iki hastanın da genel durumu iyi, bilinci açık ve vital bulguları stabil idi. Fizik muayene bulguları normal sınırlarda olan hastalar takip ve tedavi amaçlı acil gözlem ünitesine yatırıldı. Hastalar gözlem sürecinin ardından şifa ile taburcu edildi. Sonuç: Her ne kadar kimyasal ve biyolojik olarak zararsız olsa da SF-6 acil servislerde nadir görülen bir toksik ajan olup akut maruziyetlerde ölüm riski taşımaktadır. Bu nedenle hastaların ölümcül komplikasyonlar açısından gözlem altına alınması ve izlenmesi faydalı olacaktır., Introduction: Although sulfur hexafluoride (SF-6) is considered biologically inert, it may cause asphyxia and death, replacing oxygen. SF-6 is used in many areas, varying from medical devices to the aerospace industry. Case Report: Two electricity workers, who were 19 and 32 years old, were admitted to our emergency deperatment with complaints of nausea, vomiting, and dizziness after SF-6 exposure of about 5-10 minutes because of malfunction of their high-voltage circuit breaker. At admission, the general condition and mental status of both patients were good. Their vital signs were stable. The patients, with normal physical examination findings, were hospitalized to the emergency observation unit for follow-up and treatment. Both patients were discharged after follow-up. Conclusion: Although it is considered chemically and biologically inert, a rare toxic agent in the emergency department, SF-6, has a risk of death in acute exposure. Monitoring and follow-up of these patients are necessary for reducing fatal complications

Sulphur hexafluoride (SF 6 ) is one of the most widely used gaseous dielectrics for electric power systems and a number of high-voltage applications. There are many industrial applications where the electric corona discharge is used. In most cases the corona discharge is an inherently dynamic process; all parameters vary in time. Monte Carlo simulation of corona discharges in gas offers several advantages to study fundamental processes. Furthermore, it gives a fair qualitative description of the corona discharge itself as a function of space and time. This paper describes the development of negative coronas in SF 6 in a point–plane gap. Detailed structure of avalanches is presented, the total field distribution, propagation of successive avalanches and ion distribution are studied.

Background Computed tomography (CT) is the most common staging investigation in colorectal cancer (CRC). Up to 25% of patients are found to have previously undetected hepatic lesions when intraoperative ultrasound (IOUS) of the liver is used during CRC resection. We aimed to assess the ability of IOUS to detect additional liver lesions/metastases at primary colorectal resection, and to evaluate whether contrast-enhanced IOUS (CE-IOUS) improves the detection and characterization of hepatic lesions. Methods We performed a single-centre, prospective pilot study. At CRC resection, patients underwent IOUS of the liver. Contrast-enhanced IOUS of the liver was undertaken using i.v. sulphur hexafluoride micro-bubbles (SonoVue®, 4.8 ml). Findings of CT, non-enhanced IOUS and CE-IOUS were compared. Changes in staging or management were noted. Additional lesions were corroborated with iron oxide magnetic resonance imaging (MRI). Results Among 21 patients, IOUS demonstrated additional lesions in seven (33%). Contrast altered the diagnosis of non-enhanced IOUS in four (20%) and changed the management strategy in three (14%) patients. Thus, IOUS in combination with the contrast agent altered the intraoperative or postoperative management plan in four patients. Conclusions In the first study of its kind, early results suggest that the ability of IOUS to detect additional metastases is improved by CE-IOUS, and that this may impact on surgical staging and management.

Background Vitreous substitutes presently in use for intraoperative tamponade are perfluorocarbon liquids (PFCL) and for post operative tamponade are silicon oil (SO), sulphur hexafluoride (SF6) and perfluorocarbon gas (PFC). Several factors are important for a thorough understanding of each of these vitreous substitutes. The absorption or necessity for removal, indications for use (including clinical studies and special surgical methods), additives and complications of use have to be considered. Methods Three port standard pars plana vitrectomy was performed in 60 consecutive cases requiring intra-vitreal intervention. PFCL was used intra-operatively in 30 cases (PFCL group and X group). The eyes were implanted with SO (silicon oil subgroup), PFC (C3F8 sub-group) and SF6 (SF6 sub-group) in twenty cases each. Apart from best corrected visual acuity (BCVA), the retinal status and the longevity of gas when used, changes and reaction in both the anterior and posterior segments were noted. Result The difference of postoperative BCVA in the PFCL and non-PFCL groups was statistically significant with p < 0.001. In both the PFCL and non-PFCL groups the difference between preoperative and postoperative BCVA was statistically significant with p < 0.0001. All three vitreous substitutes studied are effective given the case where they had been utilised. Conclusion PFCL is invaluable in the management of complicated retinal detachment (RD). Where a vitreous microsurgery is indicated, the visual outcome is good. SF6 is useful for short-term tamponade. Silicon oil and C3F8 are useful for longer tamponade.

Luis Arias1,2, Jordi Monés11Institut de la Màcula i de la Retina, Centro Médico Teknon, Barcelona; 2Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, BarcelonaPurpose: To determine the efficacy and safety of treating predominantly hemorrhagic age-related macular degeneration (AMD) with transconjunctival sutureless vitrectomy (TSV), tissue plasminogen activator (tPA), sulphur hexafluoride (SF6), and intravitreal bevacizumab.Methods: Retrospective study, consecutive case series. Patients with acute hemorrhagic AMD treated with 25- or 23-gauge TSV, subretinal or intravitreal tPA, fluid-air-SF6 exchange and intravitreal injection of bevacizumab. All operations were performed within the first 5 days after the start of symptoms, which consisted of visual acuity (VA) loss and central scotoma.Results: Fifteen eyes from 15 patients were included. The patients’ mean age was 79.6 years, and the mean follow-up was 11.8 months. Five patients (33%) were receiving oral anticoagulant treatment. At baseline, the mean VA (logMAR values) was 1.5 (20/640 Snellen equivalent). At the last follow-up visit, the mean VA was 1.1 (20/250) (P < 0.0001; paired t-test). The submacular hemorrhage was successfully displaced in all the cases. Complications consisted of three cases of vitreous hemorrhage and a tear or the retinal pigment epithelium. Twelve cases (80%) did not require further treatment during the follow-up period.Conclusion: A surgical approach with 25- or 23-gauge TSV, tPA, SF6 and intravitreal bevacizumab is an efficacious and safe procedure in patients with hemorrhagic AMD. Early treatment is advisable for obtaining the optimal outcome.Keywords: Hemorrhagic age-related macular degeneration, tissue plasminogen activator, intravitreal bevacizumab; transconjunctival sutureless vitrectomy

Study Objective To determine whether transvaginal hysterosalpingo-contrast sonography (HyCoSy) with a new dedicated contrast-enhanced ultrasound technique, can contribute to accurate diagnosis of tubal occlusion. Design Prospective observational study (Canadian Task Force classification II-2). Setting University hospital. Patients Two-hundred twelve patients with primary or secondary infertility. Interventions All patients underwent transvaginal HyCoSy. If the tubes showed no evidence of patency after injection of air-saline solution, a solution with sulphur hexafluoride bubbles (SonoVue) was injected into the uterine cavity and tubes while contrast-tuned imaging (CnTI) was applied. Patients with tubal occlusion underwent laparoscopic chromoperturbation. Measurements and Main Results Of the 212 patients who underwent tubal insufflation with air-saline solution, 52 demonstrated tubal occlusion, bilateral in 21 patients and unilateral in 31 patients, for a total of 73 suspected occluded tubes. At the HyCoSy test with SonoVue and CnTI, only 47 tubes seemed to be occluded, and in the other 26 tubes, passage of SonoVue was observed. HyCoSy with Sono Vue demonstrated high concordance for tubal obstruction with the laparoscopic dye test (94%). Conclusions HyCoSy with SonoVue and CnTi is a low acoustic pressure technique in which bubbles are not immediately destroyed and can be detected for several minutes. This enables the signal sent to the equipment to be filtered from the echoes emanating from other tissues. Therefore, excluding the fundamental image, the bubbles are clearly observed, with no visualization of pelvic tissues and organs. This allows easier evaluation of tubal patency, provides a more accurate assessment of tubal occlusion, and enables better visualization of the tubal course.

In order to better evaluate the consequences of an accidental release of heavy gas, such as uranium hexafluoride (UF6), in some installations in the nuclear fuel cycle, an experimental and numerical study was conducted by IRSN on heavy gas dispersion in a ventilated room. This study was based on about 20 injection configurations of a large quantity of a heavy tracer gas, sulphur hexafluoride (SF6), inside two ventilated rooms of different sizes. Stratification of the tracer gas was detected in all the configurations studied, even at low concentrations. Numerical simulations performed with the multidimensional CFX code enabled the stratification and the concentration levels reached in the rooms to be predicted overall, and the higher the air flow rate, the more satisfactory the comparison between simulation and experiment. © 2007 Elsevier B.V. All rights reserved.

Electrical equipment using SF6 forms an integral part of the electricity networks, providing a safe and reliable power supply throughout the world including most European countries. SF6-emissions potentially occur in all lifecycle-phases of electrical equipment—manufacture, use and decommissioning. A study summarized in this paper finds that SF6 emissions throughout the life-cycle have substantially been reduced since the mid-nineties. Almost all available and economically feasible reduction options have been accessed at least partly. The study demonstrates that, until 2020, further reductions can be achieved if these reduction options are fully implemented throughout Europe. This paper gives an overview of reduction potentials and costs, as well as the real and projected emission development between 1995–2020.

Bulk age determinations, based upon chlorofluorocarbons and sulphur hexafluoride measurements of samples from twenty-one chalk groundwater supplies in southern England, Indicate that waters of relatively recent age predominate In both unconfined and partially confined situations. Water from pumping stations located on chalk below Palaeogene cover can be distinguished hydrochemically, and a likely interpretation is that these supplies are receiving a small proportion of recharge via induced via induced leakage. Whilst water which is abstracted from the chalk always involves mixing processes, for a sub-set of confined supplies, ‘piston’ flow could be inferred as a dominant mechanism - resulting in bulk groundwater ages of a few decades. Other supplies are the product of complex mixing. Although low-level chlorofluorocarbon enrichment was encountered for half the catchments sampled, they and sulphur hexafluoride appear to provide independent corroboration to microbiological indicators of the presence of rapid recharge.

The aim of the study was to assess how deep into the acinar region the airway response to cold dry-air hyperventilation challenge (CACh) reaches in subjects with asthma of different severity. Peripheral airway function was measured using a single-breath sulphur hexafluoride (SF 6 ) and helium (He) washout test and overall airway function by forced expiratory volume in one second (FEV 1 ) at rest, after CACh and β 2 -therapy in 55 adults with a history of asthma. The normalised phase-III slopes (Sn III ) for SF 6 and He were used to assess peripheral airway obstruction and the (SF 6 -He) Sn III difference to indicate where obstruction occurred. While a greater He versus SF 6 slope increase indicates a response close to the acinar entrance, the reverse indicates a response deeper into the acinar airspaces. Twelve subjects had a major fall in FEV 1 (≥20%) after CACh, 16 a minor fall (10–19%), and 27 did not react. Resting He and SF 6 Sn III were significantly greater in major responders with respect to minor and nonresponders, while resting FEV 1 did not differ between the three groups. The major responders showed marked increases of He and SF 6 Sn III after CACh, with greater increase for He resulting in a negative (SF 6 -He) Sn III difference. To conclude, airways close to the acinar entrance participate in the overall airway response to cold-air challenge in asthmatic adults with marked airway hyperresponsiveness to cold, dry air.

The requirement to tackle anthropogenic greenhouse gas (GHG) emissions has become increasingly urgent as understanding of the risks of climate change has advanced. The scientific community has been developing mechanisms to bring about a reduction in the quantities of anthropogenic GHG emissions in order that responsibility for anthropogenic climate forcing may be equitably assigned and specific, pragmatic emissions reduction targets can be set and progress measured. The ‘carbon footprint’ is increasingly being recognised as a valuable indicator in the field of GHG emissions management. For ease of application the definition the “carbon footprint” has been limited to the inclusion of emissions of carbon dioxide (CO2) and methane (CH4) by Wright et al. (2011). However, in some cases a more complete measure is needed that includes the full array of Kyoto “basket” GHGs – CO2, CH4, nitrous oxide (N2O), sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). Outside of the academic literature the conventional approach is to term this metric a “GHG inventory” (UN, 1998; Ranganathan et al., 2004). However, in the academic literature the term “GHG inventory” has been used to account for various different collections of GHGs and other climate-influencing gases, leading to confusion over the definition of the “GHG inventory”. Consequently, an alternative term, the “climate footprint”, has been proposed (Wiedmann and Minx, 2008; Wright et al., 2011) which aims to eliminate this confusion. The question is: should we continue using the commonly-used term, “GHG inventory”, and endeavour to impose and promote a strict definition or should we introduce a new, rigorously defined term, the “climate footprint”

Gas insulated switchgear (GIS) plays a vital role in high voltage transmission of electrical energy due to its advantages of high reliability and performance, compact in dimensions and outstanding compatibility with the environment. It uses sulphur hexafluoride gas as its insulant and coolant because of its high dielectric strength and excellent arc quenching ability. Gas insulated switchgear in operation suffers the challenge of its insulation decomposition and eventually failure due to the activities of partial discharge that arouses from defects. This failure is catastrophic and it will lead to entire power out stage that will affect all categories of human activities, so there is a need for Gas insulated switchgear condition monitoring and diagnoses in order to carry out preventive maintenance. This paper reviews diagnostic techniques and methods for Gas insulated switchgear insulation degradation caused by partial discharge for the purpose of carrying out preventive maintenance to avert its failure.

The need for compact substations in the densely populated areas has led to the development of gas insulated substations (GIS) which offer a best alternative to conventional air insulated substation in technical, environmental and operational features. The entire parts of these substations are housed in earthed metallic enclosures filled with sulphur hexafluoride gas (SF 6 ). Further research in the field of GIS helps in developing HVDC transmission of power through Gas insulated transmission. The major problem associated with the Gas insulated substations is the particle contamination which generally arises due to manufacturing or operational cycles. The understanding of the particle movement is of vital importance as these tend to increase the breakdown chances of gas insulation. The present work focuses on the determination of lift off fields on commonly encountered metallic particle contaminants in gas insulated busducts working on DC voltages. New dimensions of the busduct are proposed in order to reduce the electrostatic fields on the particles thereby reducing the chances of the breakdown.

With special respect to HVDC transmission, an artificial protrusion is investigated experimentally in compressed sulphur hexafluoride (SF 6 ) gas. Varied test parameters are voltage waveform and gas pressure. Corona inception and breakdown voltages are measured at DC and AC. Lightning and switching impulse breakdown voltages are evaluated at repeated constant amplitude stress. Composite voltage stress consisting of lightning impulse superimposed to DC bias is further examined. In this case, no significant reduction of lightning impulse breakdown voltage was observed at high gas pressure.

Choroidal neovascular membrane (CNVM) is one of the most common causes of submacular hemorrhage (SMH). Conventional treatment involves management of the SMH with pneumatic displacement with or without tissue plasminogen activator (TPA) followed by intravitreal injection of bevacizumab in a second sitting. We decided to assess the efficacy of treating SMH secondary to CNVM with pneumatic displacement using sulphur hexafluoride (SF6) gas and intravitreal bevacizumab. Four patients with SMH secondary to CNVM were included in this study. Intravitreal bevacizumab, 0.05 ml, along with 0.5 ml of SF6 was injected through the pars plana into the vitreous cavity. Postoperative best corrected visual acuity improved in all eyes with complete or partial displacement of SMH out of the foveal area.

The aim of this study was to compare the diagnostic accuracy of the late phase of CEUS and the hepatobiliary phase of CE-MR with Gd-BOPTA in the characterization of focal liver lesions in terms of benignity and malignancy. A total of 147 solid focal liver lesions (38 focal nodular hyperplasias, 1 area of focal steatosis, 3 regenerative nodules, 8 adenomas, 11 cholangiocarcinomas, 36 hepatocellular carcinomas and 49 metastases) were retrospectively evaluated in a multicentre study, both with CEUS, using sulphur hexafluoride microbubbles (SonoVue, Bracco, Milan, Italy) and CE-MR, performed with Gd-BOPTA (Multihance, Bracco, Milan, Italy). All lesions thought to be malignant were cytohistologically proven, while all lesions thought to be benign were followed up. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and accuracy were calculated for the late phase of CEUS and the hepatobiliary phase of CE-MRI, respectively, and in combination. Analysis of data revealed 42 benign and 105 malignant focal liver lesions. We postulated that all hypoechoic/hypointense lesions on the two phases were malignant. The diagnostic errors were 13/147 (8.8%) by CEUS and 12/147 (8.2%) by CE-MR. Sensitivity, specificity, PPV, NPV and accuracy of the late phase of CEUS were 90%, 93%, 97%, 80% and 91%, 93%, 97%, 81% and 92% for the hepatobiliary phase of CE-MRI, respectively. If we considered both techniques, the misdiagnosis diminished to 3/147 (2%) and sensitivity, specificity, PPV, NPV and accuracy were 98%, 98%, 99%, 95% and 98%. The combination of the late phase of CEUS and the hepatobiliary phase of CE-MR in the characterization of solid focal liver lesions in terms of benignity and malignancy is more accurate than the two techniques used separately.

In a bulk-glass triangular Faraday current sensor, the stringent conditions required to provide critical-angle reflection at each reflecting surface are difficult to achieve. High tolerances for both the optical geometry of the sensor and the wavelength of the laser source are required. Here we present a method of essentially tuning the sensor for optimum operation by matching the angle of reflection at each surface to the wavelength of the laser source. This is done by controlling the gaseous environment external to each of the reflecting surfaces. The technique is demonstrated using sulphur hexafluoride (SF6), which has the advantage of a relatively large refractive index.

SUMMARY The efficacy and side effects of sulphur hexafluoride (SF6) in the reformation of the flat anterior chamber (AC) after standard trabeculectomies were studied. Ten patients with lenticulocorneal touch following trabeculectomy were enrolled. All had water-tight conjunctival wounds with overflowing fistulas. In 5, one to four surgical attempts to reform the AC were unsuccessful. Two to seven days after trabeculectomy, the AC was reformed by a single injection of SFt/air mixture (20-40%). Gas was injected through the limbus at 3 or 9 o'clock. The AC remained deep after absorption of the gas in 2-7 days. All patients had stromal oedema in the first 4 days. This resolved and specular microscopy did not show any abnormality. After a mean follow-up of 2.5 years, all had normal intraocular pressure, 3 with one topical antiglaucoma treatment. Three patients developed cataracts before and 3 after reformation of the AC. The latter 3 were not anterior capsular cataracts as induced by gases. SFt/air mixture (20-40%) is inert and kind to the cornea and, as it is absorbed in less than 7 days, it exerts minimal damage to the crystalline lens. It is effective in the reformation of flat A Cs.

Sulphur hexafluoride (SF6) gas-insulated substations (GIS) are exposed to the same types of overvoltages as conventional substations, such as lightning overvoltages, switching overvoltages and temporary overvoltages. Possible means to limit overvoltages in a GIS are active gap (SiC) surge arresters and metal oxide (ZnO) surge arresters. The objective of this work is to study the effects of the system configuration on the performance of these two types of overvoltage limiting devices. The results obtained from the study are presented and discussed, and some general conclusions are suggested.