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Articles by J Hansson
Total Records ( 7 ) for J Hansson
  M. G Bouwhuis , S Suciu , S Collette , S Aamdal , W. H Kruit , L Bastholt , U Stierner , F Sales , P Patel , C. J. A Punt , M Hernberg , A Spatz , T. L. M ten Hagen , J Hansson , A. M. M Eggermont and for the EORTC Melanoma Group and the Nordic Melanoma Group
  Background

Appearance of autoantibodies and clinical manifestations of autoimmunity in melanoma patients treated with adjuvant interferon (IFN)-2b was reported to be associated with improved prognosis. We assessed the association of the appearance of autoantibodies after initiation of treatment with recurrence-free interval in two randomized trials that compared intermediate doses of IFN with observation for the treatment of melanoma patients.

Methods

Serum levels of anticardiolipin, antithyroglobulin, and antinuclear antibodies were determined using enzyme-linked immunosorbent assays in 187 and 356 patients in the European Organization for Research and Treatment of Cancer (EORTC) 18952 and Nordic IFN trials, respectively, immediately before and up to 3 years after random assignment. The association of the presence of at least one of the three autoantibodies with risk of recurrence was assessed by three Cox models in patients negative for all three autoantibodies at baseline (125 from the EORTC 18952 trial and 230 from the Nordic IFN trial): 1) a model that considered appearance of autoantibodies as a time-independent variable, 2) one that considered a patient autoantibody positive once a positive test for an autoantibody was obtained, and 3) a model in which the status of the patient was defined by the most recent autoantibody test. All statistical tests were two-sided.

Results

When treated as a time-independent variable (model 1), appearance of autoantibodies was associated with improved relapse-free interval in both trials (EORTC 18952, hazard ratio [HR] = 0.41, 95% confidence interval [CI] = 0.25 to 0.68, P < .001; and Nordic IFN, HR = 0.51, 95% CI = 0.34 to 0.76, P < .001). However, on correction for guarantee-time bias, the association was weaker and not statistically significant (model 2: EORTC 18952, HR = 0.81, 95% CI = 0.46 to 1.40, P = .44; and Nordic IFN, HR = 0.85, 95% CI = 0.55 to 1.30, P = .45; model 3: EORTC 18952, HR = 1.05, 95% CI = 0.59 to 1.87, P = .88; and Nordic IFN, HR = 0.78, 95% CI = 0.49 to 1.24, P = .30).

Conclusions

In two randomized trials of IFN for the treatment of melanoma patients, appearance of autoantibodies was not strongly associated with improved relapse-free interval when correction was made for guarantee-time bias.

  F Demenais , H Mohamdi , V Chaudru , A. M Goldstein , J. A Newton Bishop , D. T Bishop , P. A Kanetsky , N. K Hayward , E Gillanders , D. E Elder , M. F Avril , E Azizi , P van Belle , W Bergman , G Bianchi Scarra , B Bressac de Paillerets , D Calista , C Carrera , J Hansson , M Harland , D Hogg , V Hoiom , E. A Holland , C Ingvar , M. T Landi , J. M Lang , R. M Mackie , G. J Mann , M. E Ming , C. J Njauw , H Olsson , J Palmer , L Pastorino , S Puig , J Randerson Moor , M Stark , H Tsao , M. A Tucker , P van der Velden , X. R Yang , N Gruis and and the Melanoma Genetics Consortium
  Background

Carrying the cyclin-dependent kinase inhibitor 2A (CDKN2A) germline mutations is associated with a high risk for melanoma. Penetrance of CDKN2A mutations is modified by pigmentation characteristics, nevus phenotypes, and some variants of the melanocortin-1 receptor gene (MC1R), which is known to have a role in the pigmentation process. However, investigation of the associations of both MC1R variants and host phenotypes with melanoma risk has been limited.

Methods

We included 815 CDKN2A mutation carriers (473 affected, and 342 unaffected, with melanoma) from 186 families from 15 centers in Europe, North America, and Australia who participated in the Melanoma Genetics Consortium. In this family-based study, we assessed the associations of the four most frequent MC1R variants (V60L, V92M, R151C, and R160W) and the number of variants (1, ≥2 variants), alone or jointly with the host phenotypes (hair color, propensity to sunburn, and number of nevi), with melanoma risk in CDKN2A mutation carriers. These associations were estimated and tested using generalized estimating equations. All statistical tests were two-sided.

Results

Carrying any one of the four most frequent MC1R variants (V60L, V92M, R151C, R160W) in CDKN2A mutation carriers was associated with a statistically significantly increased risk for melanoma across all continents (1.24 x 10–6P ≤ .0007). A consistent pattern of increase in melanoma risk was also associated with increase in number of MC1R variants. The risk of melanoma associated with at least two MC1R variants was 2.6-fold higher than the risk associated with only one variant (odds ratio = 5.83 [95% confidence interval = 3.60 to 9.46] vs 2.25 [95% confidence interval = 1.44 to 3.52]; Ptrend = 1.86 x 10–8). The joint analysis of MC1R variants and host phenotypes showed statistically significant associations of melanoma risk, together with MC1R variants (.0001 ≤ P ≤ .04), hair color (.006 ≤ P ≤ .06), and number of nevi (6.9 x 10–6P ≤ .02).

Conclusion

Results show that MC1R variants, hair color, and number of nevi were jointly associated with melanoma risk in CDKN2A mutation carriers. This joint association may have important consequences for risk assessments in familial settings.

  S Zachrisson , J Hansson , A Cederblad , K Geterud and M. Bath
 

With the increasing use of computed tomography (CT) for urography examinations, the indications for ‘conventional’ projection urography have changed and are more focused on high-contrast details. The purpose of the present study was to optimise the beam quality for urography examinations performed with a Gd2O2S:Tb flat-panel detector for the new conditions. Images of an anthropomorphic phantom were collected at different tube voltages with a CXDI-40G detector (Canon Inc., Tokyo, Japan). The images were analysed by radiologists and residents in a visual grading characteristics (VGCs) study. The tube voltage resulting in the best image quality was 55 kV, which therefore was selected for a clinical study. Images from 62 patients exposed with either 55 or 73 kV (original tube voltage) at constant effective doses were included. The 55-kV images underwent simulated dose reduction to represent images collected at 80, 64, 50, 40 and 32 % of the original dose level. All images were included in a VGC study where the observers rated the visibility of important anatomical landmarks. For images collected at 55 kV, an effective dose of ~85 % resulted in the same image quality as for images collected at 73 kV at 100 % dose. In conclusion, a low tube voltage should be used for conventional urography focused on high-contrast details. The study indicates that using a tube voltage of 55 kV instead of 73 kV for a Gd2O2S:Tb flat-panel detector, the effective dose can be reduced by ~10–20 % for normal-sized patients while maintaining image quality.

  A Carlander , J Hansson , J Soderberg , K Steneryd and M. Bath
 

The purpose of the present study was to investigate if the exposure could be reduced from the clinical setting (resulting in an effective dose of 8 µSv for a neonate of weight 0.7 kg and height 25 cm at a tube voltage of 90 kV) without negatively influencing the image quality for a dual-side readout technique computed radiography (CR) system in chest radiography of premature neonates. Chest radiographs of premature neonates were acquired with the double-side readout technique CR system. The images underwent simulated dose reduction in steps of 20 % to represent five different radiation dose levels. Four image quality criteria, related to the visibility of important anatomical structures, were used in a visual grading study where five experienced radiologists rated how well the criteria were fulfilled for all images. When reducing the radiation dose, a decrease in image quality could be observed already at the 80 % dose level for all the structures. The results indicate that a decrease in exposure from the clinically used setting affects the image quality negatively for the CR system.

  J Hansson , P Sund , P Jonasson , L. G Mansson and M. Bath
 

According to European and national legislation, as well as international recommendations, X-ray examinations shall be optimised. However, with limited resources and hundreds of different types of X-ray examinations, it may be difficult to prioritise among the optimisation tasks at a radiology department. This work is focused on describing a method that can be used to determine the order of which the examinations should be optimised. In the Medical Exposure Directive from 1997, the European Commission prescribes the content of an optimisation process in relation to medical exposure. A reasonable interpretation of the directive is that the assurance of medical purpose for a justified examination is superior to the need of decreased radiation dose. This was used as a basis for developing a method for prioritisation among optimisation tasks. For each examination type, the following four yes/no questions are raised: (i) Is the present image quality unacceptable? (ii) Is the examination of particular importance? (iii) Is the radiation dose suspiciously high? (iv) Are there special dose level concerns, e.g. diagnostic reference levels? Arguing that a positive response to any of the four questions results in the examination being higher prioritised than otherwise and that the questions are labelled in order of decreasing relevance, it can be shown that the resulting flow chart, determining the order of which the examinations should be optimised, can be described by a 4-bit binary scale. In this way, each examination type is given a number from 0 to 15, a higher number corresponding to the examination being prioritised higher in the optimisation work. The method was applied to a general radiology department and resulted in a well-discriminated distribution of examinations prioritised for optimisation tasks. In conclusion, taking into account both medical outcome and potential risk, the proposed method can be used to determine the order in which examinations at a radiology department should be optimised.

  J Hansson , S Eriksson , A Thilander Klang and M. Bath
 

The purpose of the present work was to describe a method of using an imaging plate from a computed radiography system to determine the computed tomography (CT) dose profile (the tritium method) and to compare this method with point-dose measurements using a solid-state detector (CT Dose Profiler; RTI Electronics, Mölndal, Sweden) and the indirect method of comparing the air kerma-length product (PKL) at different beam collimations. The three methods were used to determine the full width at half maximum (FWHM) of the dose profile of a multi-slice CT at different nominal beam collimations. For all beam collimations, the obtained deviation between the tritium method and the CT Dose Profiler was smaller than 0.1 mm. The maximum relative error was 2 %. For the PKL method, the deviation from the CT Dose Profiler was between 0.2 and 0.4 mm, resulting in a relative error larger than 10 % for the smallest beam collimation even after normalisation to a known FWHM. In conclusion, the proposed method of using an imaging plate to determine the FWHM of the CT dose profile has a high accuracy and shows good agreement with the more advanced method of point-dose measurements using a solid-state detector.

  A Thilander Klang , K Ledenius , J Hansson , P Sund and M. Bath
 

The purpose of the present work was to investigate the reliability of subjective assessments of the low-contrast visibility in constancy control of computed tomography (CT). Axial CT images of a low-contrast phantom were acquired on an 8-slice multi-detector CT scanner at nine tube current settings ranging from 75 to 440 mA. Five medical physicists assessed the visibility of the low-contrast details in two sessions. In the first session, containing 54 images, the visibility was rated on an absolute scale by determining the number of visible details in each contrast group in each image. In the second session, 180 image pairs were presented to the observers with the task of determining if the two images had been acquired under identical conditions or not. In the absolute session, both the intra- and inter-observer variabilities were high. In the relative session, the variability was smaller, but an exposure difference of 50 % was needed for all observers to correctly identify a change in all cases. In conclusion, the present study indicates that subjective assessments of the low-contrast visibility in constancy control of CT are not reliable.

 
 
 
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