The effect of different statistical approaches on image quality data obtained from radiological examinations.

INTRODUCTION: Selection of optimal image acquisition protocols in medical imaging remains a grey area, the superimposed use of the Likert scale in radiological image quality evaluations creates an additional challenge for the statistical analysis of image quality data. Using a simulation study, we have trialled a novel approach to analysing radiological image quality Likert scale data. METHODS: A simulation study was undertaken where simulated datasets were generated based on the distribution of Likert scale values according to varying image acquisition protocols from a real dataset. Simulated Likert scale values were pooled in four different ways; the mean, median, mode and the summation of patient Likert scale values of which the total was assigned a categorical Likert scale value. Estimates of bias, MAPE and RMSPE were then calculated for all four pooling approaches to determine which method most accurately represented an expert's opinion. RESULTS: When compared to an expert's opinion, the method of summation and categorisation of Likert scale values was most accurate 49 times out of the 114 (43.0%) tests. The mean 28 times out of 114 (24.6%), the median 23 times out of 114 (20.2%) and the mode 17 times out of 114 (14.9%). CONCLUSION: We conclude that our method of summation and categorisation of Likert scale values is most often the best representation of the simulated data compared to the expert's opinion. IMPLICATIONS FOR PRACTICE: There is scope to reproduce this simulation study with multiple observers to reflect clinical reality more accurately with the dynamic nature of multiple observers. This also prompts future investigation into other anatomical areas, to see if the same methods produce similar results.

Trying to explain an effect of "per se" hydrostatic pressure on heart rate in fish.

Specific effects of "per se" hydrostatic pressure on mean heart rate have been studied on eels (Anguilla anguilla L.), both untreated and treated with atropine and propranolol, and on isolated eel's heart. Because temperature brings, by itself, heart rate modifications in fish, a quantitative study was performed in order to take away the increment of heart rate due to the water warming, which cannot entirely be suppressed during compression. The specific effects of "per se" pressure have been identified as a bradycardia above 24.5 degrees C and as a tachycardia below this temperature. The use of atropine and propranol, which abolish extrinsic heart control, shows that pressure acts both through extrinsic mechanisms of heart control and through a direct action on autonomic cardiac cells. This effect of "per se" pressure on cardiac cells is interpreted according to chemical kinetics laws. The hypothesis that pressure acts at the molecular level, possibly by the means of reversible structure modifications of some molecules, is suggested.

Adsorption mechanisms of carbofuran on silica: structure, kinetics, and solubility influence.

The adsorption processes of carbofuran from solutions in pure water onto silica (Aerosil 200) have been determined in order to bring greater coherence to previous results obtained directly on soils. Adsorption isotherms and their evolution with temperature reveal that adsorption is generally weak, increases with temperature, and does so significantly with concentration when the solubility limit is approached. Kinetics of dissolving, of adsorption on silica, and of desorption all obey an irreversible two-compartment model. Desorption rate is slower than adsorption rate. Consequences on the behavior of carbofuran in the environment are discussed.

[Arterial embolization in the treatment of neoplasic tumors].

Eight cancer patients treated at the centre François-Baclesse at Caen underwent arterial embolisation using Spongel. The technique was usually used in the presence of a contraindication to operation. In certain cases the problem was that of controlling haemorrhage following tumour invasion or secondary to complications of radiotherapy, under which circumstances was most successful. In addition, it was possible to reduce pain resistant to medical treatment. The method appeared to be a useful therapeutic complement post-radiotherapy for hypervascularised lesions.

[Results of intermittent catheterization in the management of neurogenic bladder]. / Resultado del cateterismo intermitente en el manejo de vejiga neurogénica.

The authors report the results obtained with the use of clean intermittent catheterization as and aid in the management of patients with neurogenic bladder of any etiology. The improvement obtained in 17 patients as to the attainment of urinary continence which was total in 11 and partial in 5 (94%), the absence of complications and the radiological improvement in these patients, justify the use of this procedure as an easy and safe method at a long term before considering surgical urinary derivation.

[Azygography in the study of malignant tumours of the oesophagus (author's transl)]. / L'azygographie dans l'étude radiologique des tumeurs malignes de l'oesophage

Up to the present time, no simple method has existed for gauging the true size of an oesophageal tumour. The intimate relations between the azygos vein and the oesophagus in the thorax between D3 and D8 justifies this new study: azygography. On the basis of 40 examinations, 13 of which were followed by surgery in patients suffering from carcinoma of the oesophagus, as was indicated by classical anatomical data, azygography made possible the evaluation of tumour extension in the mediastinum and the involvement of adjacent structures, such as the right pulmonary artery. Azygography thus aided in the precision of surgical indications and in the delineation of the volume to be irradiated. The examination is carried out by selective opacification after catheterisation via the femoral vein. Radiological findings distinguish involvement by deviation, compression, invasion, obstruction and collateral circulation. In certain cases a part of the tumour itself is opacifield by vessels with an anarchic pattern. Comparison of the results of radiological study with surgical findings shows that the examination makes it possible to predict, between the level of the third and eighth thoracic vertebrae, difficulties in or impossibility of dissection of the tumour as well as, in the case of involvement of the arch, the necessity for total oesophagectomy with additional cervical approach. The accuracy of the information obtained is certainly less valuable as far as the lower third is concerned. Non-traumatic, simple and rapid, azygography would appear to be the examination of choice in defining the exent of a tumour of the middle third of the oesophagus, as a complement to clinical findings and barium swallow, being particularly valuable in determining the volume to be irradiated or on a pre-operative assessment.