Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera.

In SPECT/CT systems x-ray and γ-ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high x-ray doses and deteriorate its functioning. We studied the NaI(Tl) response to x-ray pulses with a photodiode, PMT and gamma camera, respectively. First, we exposed a NaI(Tl)-photodiode assembly to x-ray pulses to investigate potential crystal afterglow. Next, we exposed a NaI(Tl)-PMT assembly to 10 ms LED pulses (mimicking x-ray pulses) and measured the response to flashing LED probe-pulses (mimicking γ-pulses). We then exposed the assembly to x-ray pulses, with detector entrance doses of up to 9 nGy/pulse, and analysed the response for γ-pulse variations. Finally, we studied the response of a Siemens Diacam gamma camera to γ-rays while exposed to x-ray pulses. X-ray exposure of the crystal, read out with a photodiode, revealed 15% afterglow fraction after 3 ms. The NaI(Tl)-PMT assembly showed disturbances up to 10 ms after 10 ms LED exposure. After x-ray exposure however, responses showed elevated baselines, with 60 ms decay-time. Both for x-ray and LED exposure and after baseline subtraction, probe-pulse analysis revealed disturbed pulse height measurements shortly after exposure. X-ray exposure of the Diacam corroborated the elementary experiments. Up to 50 ms after an x-ray pulse, no events are registered, followed by apparent energy elevations up to 100 ms after exposure. Limiting the dose to 0.02 nGy/pulse prevents detrimental effects. Conventional gamma cameras exhibit substantial dead-time and mis-registration of photon energies up to 100 ms after intense x-ray pulses. This is due PMT limitations and due to afterglow in the crystal. Using PMTs with modified circuitry, we show that deteriorative afterglow effects can be reduced without noticeable effects on the PMT performance, up to x-ray pulse doses of 1 nGy.

Towards an individualized management strategy for patients with chronic venous disease: Results of a Delphi consensus.

Objective To obtain consensus on management criteria for symptomatic patients with chronic venous disease (CVD; C2-C6) and superficial venous reflux. Method We used a Delphi method by means of 36 statements sent by email to experts in the field of phlebology across the world over the course of three rounds. The statements addressed criteria for different venous treatments in patients with different characteristics (e.g. extensive comorbidities, morbid obesity and peripheral arterial disease). If at least 70% of the ratings for a specific statement were between 6 and 9 (agreement) or between 1 and 3 (disagreement), experts' consensus was reached. Results Twenty-five experts were invited to participate, of whom 24 accepted and completed all three rounds. Consensus was reached in 25/32 statements (78%). However, several statements addressing UGFS, single phlebectomies, patients with extensive comorbidities and morbid obesity remained equivocal. Conclusion Considerable consensus was reached within a group of experts but also some gaps in available research were highlighted.

Postural Diameter Change of the Saphenous Trunk in Chronic Venous Disease.

OBJECTIVE: The aim of this study was to analyze the correlation between the extent of diameter change from standing to supine position ("postural diameter change," PDC), and patient or duplex ultrasound (DUS) characteristics in lower limbs with and without saphenous trunk (ST) reflux. METHODS: Measurements were carried out in 193 limbs with primary great saphenous vein, anterior accessory saphenous vein, or small saphenous vein reflux, and 48 control limbs without ST reflux. The inner diameter of the ST was measured with DUS in the standing and lying positions. The PDC, calculated as a percentage, followed the formula: (standing diameter - lying diameter)/standing diameter × 100. Clinical findings (according to the highest "C" - of the CEAP classification), venous clinical severity score, body mass index (BMI), time of visit, and inside and outside temperature were documented. Limbs were divided into two groups using the median value of PDC as a cut off to increase interpretability of the analysis. RESULTS: The median PDC of the ST was 19% in limbs with ST reflux compared with 24% in control limbs (p = .16). In limbs with and without ST reflux, only older age and increased BMI were independently associated with a low PDC of the ST (R(2) 0.13). In limbs with ST reflux, median PDC was significantly lower in C4-C6 (16%, interquartile [IQR] 8-21) than in C0-C1 (23%, IQR 12-35) or C2-C3 limbs (21%, IQR 11-33; p = .016). In addition, PDC was significantly lower in veins with a large diameter (>7 mm) than in those with a small diameter (p = .003). CONCLUSION: Low PDC of the ST correlates with older age and increased BMI. Whether PDC might become a useful additional DUS tool to classify the severity of chronic venous disease and thereby influence the management strategy should be further investigated.

Predictors of Recanalization of the Great Saphenous Vein in Randomized Controlled Trials 1 Year After Endovenous Thermal Ablation.

OBJECTIVE/BACKGROUND: The objective was to identify predictors to develop and validate a prognostic model of recanalization of the great saphenous vein (GSV) in patients treated with endovenous thermal ablation (EVTA). METHODS: The search strategy of Siribumrungwong was updated between August 2011 and August 2014 using MEDLINE, Embase, and the Cochrane register to identify randomized controlled trials (RCTs), in which patients presenting with GSV reflux were treated with radiofrequency or endovenous laser ablation. Leg level data (n = 1226) of 15/23 selected RCTs were pooled. The primary outcome was recanalization of the GSV; the secondary outcome was change in health related quality of life (HRQoL) measured by the Chronic Venous Insufficiency quality of life Questionnaire or Aberdeen Varicose Vein Questionnaire 1 year post-procedure. Candidate predictors were age, sex, body mass index, clinical class, GSV diameter, saphenofemoral junction reflux, type of device, energy, and length of treated vein. RESULTS: At 1 year, 130 GSVs were recanalized (11%). Clinical class (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.4-3.3) and diameter (OR 1.8, 95% CI 1.2-2.7) of the GSV were the strongest predictors of recanalization. Other predictors included in the final model were sex, type of device, and length of treated vein. The performance of the recanalization model was moderate, with an area under the curve above 0.717. GSV diameter, type of device, and amount of energy delivered were the only predictors of the change of HRQoL. None of the candidate predictors were included in the final HRQoL model (R(2) = .027). CONCLUSION: There are several important prognostic factors for GSV recanalization and change of HRQoL after EVTA. However, the performance of each model was unsatisfactory to allow use in clinical practice yet.

Five-year results of a randomized clinical trial of conventional surgery, endovenous laser ablation and ultrasound-guided foam sclerotherapy in patients with great saphenous varicose veins.

BACKGROUND: A variety of techniques exist for the treatment of patients with great saphenous vein (GSV) varicosities. Few data exist on the long-term outcomes of these interventions. METHODS: Patients undergoing conventional surgery, endovenous laser ablation (EVLA) and ultrasound-guided foam sclerotherapy (UGFS) for GSV varicose veins were followed up for 5 years. Primary outcome was obliteration or absence of the treated GSV segment; secondary outcomes were absence of GSV reflux, and change in Chronic Venous Insufficiency quality-of-life Questionnaire (CIVIQ) and EuroQol - 5D (EQ-5D™) scores. RESULTS: A total of 224 legs were included (69 conventional surgery, 78 EVLA, 77 UGFS), 193 (86.2 per cent) of which were evaluated at final follow-up. At 5 years, Kaplan-Meier estimates of obliteration or absence of the GSV were 85 (95 per cent c.i. 75 to 92), 77 (66 to 86) and 23 (14 to 33) per cent in the conventional surgery, EVLA and UGFS groups respectively. Absence of above-knee GSV reflux was found in 85 (73 to 92), 82 (72 to 90) and 41 (30 to 53) per cent respectively. CIVIQ scores deteriorated over time in patients in the UGFS group (0.98 increase per year, 95 per cent c.i. 0.16 to 1.79), and were significantly worse than those in the EVLA group (-0.44 decrease per year, 95 per cent c.i. -1.22 to 0.35) (P = 0.013). CIVIQ scores for the conventional surgery group did not differ from those in the EVLA and UGFS groups (0.44 increase per year, 95 per cent c.i. -0.41 to 1.29). EQ-5D™ scores improved equally in all groups. CONCLUSION: EVLA and conventional surgery were more effective than UGFS in obliterating the GSV 5 years after intervention. UGFS was associated with substantial rates of GSV reflux and inferior CIVIQ scores compared with EVLA and conventional surgery. REGISTRATION NUMBER: NCT00529672 (http://www.clinicaltrials.gov).

Management strategies for patients with varicose veins (C2-C6): results of a worldwide survey.

OBJECTIVES: This study evaluated how patient characteristics and duplex ultrasound findings influence management decisions of physicians with specific expertise in the field of chronic venous disease. METHODS: Worldwide, 346 physicians with a known interest and experience in phlebology were invited to participate in an online survey about management strategies in patients with great saphenous vein (GSV) reflux and refluxing tributaries. The survey included two basic vignettes representing a 47 year old healthy male with GSV reflux above the knee and a 27 year old healthy female with a short segment refluxing GSV (CEAP classification C2sEpAs2,5Pr in both cases). Participants could choose one or more treatment options. Subsequently, the basic vignettes were modified according to different patient characteristics (e.g. older age, morbid obesity, anticoagulant treatment, peripheral arterial disease), clinical class (C4, C6), and duplex ultrasound findings (e.g. competent terminal valve, larger or smaller GSV diameter, presence of focal dilatation). The authors recorded the distribution of chosen management strategies; adjustment of strategies according to characteristics; and follow up strategies. RESULTS: A total of 211 physicians (68% surgeons, 12% dermatologists, 12% angiologists, and 8% phlebologists) from 36 different countries completed the survey. In the basic case vignettes 1 and 2, respectively, 55% and 40% of participants proposed to perform endovenous thermal ablation, either with or without concomitant phlebectomies (p < .001). Looking at the modified case vignettes, between 20% and 64% of participants proposed to adapt their management strategy, opting for either a more or a less invasive treatment, depending on the modification introduced. The distribution of chosen management strategies changed significantly for all modified vignettes (p < .05). CONCLUSIONS: This study illustrates the worldwide variety in management preferences for treating patients with varicose veins (C2-C6). In clinical practice, patient related and duplex ultrasound related factors clearly influence therapeutic options.

Comparing mercury concentrations across a thirty year time span in anadromous and non-anadromous Arctic charr from Labrador, Canada.

Anadromous and non-anadromous Arctic charr (Salvelinus alpinus) from multiple sample sites in Labrador, Canada were used to investigate possible differences in total mercury concentration ([THg]) between 1977-78 and 2007-09. The mean [THg] of anadromous Arctic charr was 0.03 µg/g wet weight (ww) in 1977-78 and 0.04 µg/g ww in 2007-09, while mean concentrations in non-anadromous conspecifics were 0.18 µg/g ww in 1977-78 and 0.14 µg/g ww in 2007-09. After correcting for the effects of fish age and fork-length, there was no widespread difference in the mean [THg] of anadromous or non-anadromous fish between the two time periods. However, at individual sites sampled during both time periods, [THg] increased, decreased, or did not change. The mean age of sampled fish declined from 9.0 years in 1977-78 to 8.2 years in 2007-09 for anadromous fish, and from 11.7 years to 10.5 years in non-anadromous Arctic charr. Similarly, mean fork-lengths decreased from 450 mm to 417 mm in anadromous and from 402 mm to 335 mm in non-anadromous fish between 1977-78 and 2007-09. The mean annual temperature at four Labrador weather stations increased by 1.6°C to 2.9°C between the two sampling periods. The lack of an overall trend in anadromous or non-anadromous Arctic charr [THg] despite warming temperatures that favour increased mercury methylation suggests that regional changes in climate-driven factors have had limited impacts on mercury exposure in Labrador freshwater or marine fish.

How specific are venous symptoms for diagnosis of chronic venous disease?

OBJECTIVE: The objective of this study is to evaluate whether and which 'venous' symptoms are characteristic for patients affected with chronic venous disease compared to patients with other diseases of the lower limbs (e.g. arthrosis, peripheral arterial disease, spinal disc herniation). METHODS: A cross-sectional study was performed to compare the frequency of venous symptoms among 76 patients with chronic venous disease and reflux and 74 patients with other diseases of the legs without reflux. The VEINES-Sym of the VEINES-QOL/Sym questionnaire was used to evaluate the frequency of symptoms. Demographic, clinical classification and ultrasound findings were also noted. RESULTS: A total of 122 patients were included for analysis (response rate of 87%). Presence of venous symptoms was slightly more often reported in the chronic venous disease group than in the non-chronic venous disease group, but differences were small and statistically non-significant. Severity of chronic venous disease as classified by the CEAP classification was not associated with higher proportions of patients reporting symptoms than in non-chronic venous disease patients, except for swelling (p = .016) and itching (p = .007) in C3-C6 patients. The largest difference between the chronic venous disease and non-chronic venous disease group was observed for the time of the day at which symptoms were most intense; patients with chronic venous disease were more likely to experience symptoms at the end of the day (p < .001). CONCLUSIONS: The small differences in prevalence of reported 'venous' symptoms between chronic venous disease patients and patients with other diseases of the legs suggest that these symptoms may be less specific for patients with chronic venous disease and refluxing veins than is usually assumed.

In vivo effects of foam sclerotherapy on coagulation.

OBJECTIVE: The aim of this study was to evaluate whether foam sclerotherapy (FS) induces changes in CAT (calibrated automated thrombinography) and other coagulation parameters which could indicate an increased risk of thrombotic events. METHODS: Blood samples from eight patients treated with FS were taken before treatment and 30 minutes, one and four hours and one week after treatment. CAT parameters (ETP1n, Peak1n, Lag time 1), thrombin antithrombin complexes (TAT), d-dimers, fibrinogen, Von Willebrand (vWf Ag) factor and platelet-derived microparticles (MIPAs) were measured. RESULTS: Significant changes over time for Peak1n, fibrinogen, d-dimers, vWfAg and TAT complexes were observed. CAT parameters decreased over time, except for Lag time 1. D-dimers and TAT complexes increased and fibrinogen, vWf Ag, MIPA's decreased during the first hours. CONCLUSION: The findings in this study support the hypothesis that FS initiate coagulation pathways, but there is no evidence that this activation results in an increased thrombosis risk.

Translation and validation of the Dutch VEINES-QOL/Sym in varicose vein patients.

OBJECTIVES: To translate from English to Dutch and evaluate the psychometric properties of the VEnous INsufficiency Epidemiological and Economic Studies (VEINES) questionnaire, divided in symptom (VEINES-Sym) and quality of life (VEINES-QOL) subscales. METHODS: Standard forward-backward translation method was used to translate the 26 items of the VEINES-QOL/Sym. Eligible patients had to complete a standardized questionnaire. Demographic, venous disease characteristics, clinical venous signs, CEAP (clinical, aetiological, anatomical and pathological elements) classification and ultrasound findings were also noted. If item's scores were in an extreme category in more than 70% of patients a floor or ceiling effect was present. Feasibility of the individual items was considered poor if 5% or more of the responses were missing. The validity was tested by comparing the VEINES-QOL/Sym scores to the Short Form 36 (SF-36) scores and across the different 'CEAP' categories. Confirmatory factor analysis was used to assess the underlying structure of the VEINES-QOL/Sym. RESULTS: Sixty-six patients were included (response rate of 72%). None of the 26 items missed <10% of responses, but two showed ceiling effect. Both the VEINES-QOL and VEINES-Sym showed an excellent internal consistency (Cronbach's alpha of 0.88 and 0.81, respectively). The VEINES-QOL demonstrated a good construct validity for the physical component of the SF-36, but not for the mental component (rho = 0.62 and 0.22, respectively), as expected. The VEINES-Sym correlated poorly to both SF-36's components. According to the confirmatory principle axis factoring, only three out of 25 items did not load sufficiently on the factor. CONCLUSIONS: The Dutch VEINES-QOL/Sym can be used for health-related quality of life research in varicose veins patients and the evaluation of therapies.

Comparative analysis of total mercury concentrations in anadromous and non-anadromous Arctic charr (Salvelinus alpinus) from eastern Canada.

Previous research has documented that total mercury concentrations ([THg]) are lower in anadromous Arctic charr than in non-anadromous conspecifics, but the two life-history forms have rarely been studied together. Here, data from nine pairs of closely-located anadromous and non-anadromous Arctic charr populations were used to explore the impact of biological and life-history factors on individual [THg] across a range of latitudes (49-81° N) in eastern Canada. Unadjusted mean [THg] ranged from 20 to 114 ng/g wet weight (ww) in anadromous populations, and was significantly higher in non-anadromous populations, ranging from 111 to 227 ng/g ww. Within-population variations in [THg] were best explained by fish age, and were often positively related to fork-length and δN-inferred trophic level. Differences in [THg] were not related to differences in length-at-age (i.e., average somatic growth rate) among populations of either life-history type. Mercury concentrations were not related to site latitude in either the anadromous or non-anadromous fish. We conclude that the difference in Arctic charr [THg] with life-history type could not be explained by differences in fish age, fork-length, trophic position, or length-at-age, and discuss possible factors contributing to low mercury concentrations in anadromous, relative to freshwater, fish.

Basal mercury concentrations and biomagnification rates in freshwater and marine food webs: effects on Arctic charr (Salvelinus alpinus) from eastern Canada.

Patterns of total Hg (THg) and methyl Hg (MeHg) biomagnification were investigated in six pairs of co-located lacustrine and marine food webs supporting a common predator, Arctic charr. Mercury biomagnification rates (the slope of log Hg concentration versus δ(15)N-inferred trophic level) did not differ significantly between the two feeding habitats for either THg or MeHg, but THg and MeHg concentrations at the base of the food web were higher in the lacustrine environment than in the marine environment. The proportion of THg as MeHg was related to trophic level, and the relationship was statistically similar in the lacustrine and marine habitats. The biomagnification rate of MeHg exceeded that of THg in both habitats. We conclude that the known difference in Hg concentration between anadromous and non-anadromous Arctic charr is driven by differential Hg concentrations at the base of the lacustrine and marine foodwebs, and not by differential biomagnification rates.

Validation of the chronic venous insufficiency quality of life questionnaire in Dutch patients treated for varicose veins.

BACKGROUND: The Chronic Venous Insufficiency Quality of Life Questionnaire (CIVIQ) is a disease-specific instrument to measure the impact of chronic venous insufficiency (CVI) on patients' lives. The objective of this study is to test the psychometric properties of the CIVIQ, and to validate the use of the questionnaire translated into the Dutch language. METHODS: A standardised questionnaire, including CIVIQ and Short Form (36) Health Survey (SF-36), was obtained before and 1 month after treatment to all new patients with varicose veins. The feasibility was tested by missing responses and response distribution. CIVIQ scores were compared to the SF-36 scores and between different levels of severity of varicose veins. The CIVIQ's reliability was assessed using Cronbach's alpha and test-retest reliability. The structure was studied using factor analysis. The scores before and after therapy were compared to assess responsiveness. RESULTS: There was a response rate of 93.5%. None of 20 items missed < 10% of responses, but three showed ceiling effect. The CIVIQ correlated well with the physical and moderately with the mental MCS of the SF-36, suggesting a good construct validity of the CIVIQ. The median CIVIQ scores increased significantly with the severity of varicose veins. The CIVIQ showed an excellent internal consistency and an excellent test-retest reliability. The CIVIQ score decreased in 76% of patients after treatment. The results were in accordance with the Norman's rule and showed a median effect size. CONCLUSION: This study confirms the feasibility, validity, reliability and responsiveness of the CIVIQ in patients with varicose veins. The psychometric properties of the Dutch CIVIQ were comparable to the original French version.