Inflammatory pseudotumour of the lung presenting as multiple pulmonary nodules: case report.
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Biopsy, Needle↗
Biomedical subjects
W J Weiser
Publications and source records attributed to W J Weiser.
Evaluation of mammographic image quality: pilot study comparing five methods.
A radiograph is considered of high quality when it allows a radiologist to identify abnormalities with high sensitivity and specificity. Although many methods for assessing image quality have been devised, it is not clear which is most meaningful or how well these methods correlate with one another. A pilot study was undertaken to compare five methods of evaluating mammographic image quality. Each of the methods was used to form separate rankings of 11 mammographic system configurations. In two of the methods, observers (three radiologists and three physicists) subjectively ranked the "image quality" of radiographs of phantoms obtained with each configuration. The third method ranked the systems according to contrast as measured densitometrically with an aluminum step wedge, and the fourth, in terms of lowest to highest mean glandular radiation doses to the breast. In the final method, observers based their rankings on mammograms of patients. The intra- and interobserver variabilities of each ranking method were assessed, as well as the correlations between methods, by using standard nonparametric statistical tests. Intraobserver consistency was high with any of the image quality ranking methods; however, image quality rankings based on either of the two phantoms provided better agreement among observers than did rankings based on images of patients. Surprisingly, no significant degree of correlation was found between any two image quality evaluation methods. Our work may have two implications for the American College of Radiology Mammography Accreditation Program: (1) small variations in phantom scores do not necessarily correlate with subjective variation in image quality in radiographs of patients, and (2) when small numbers of radiographs are used, the assessment of the quality of mammograms of patients may vary considerably among radiologists.
Accreditation↗
Characterisation of mammographic parenchymal pattern by fractal dimension.
A consistent, quantitative, observer-independent method of characterising mammographic parenchymal pattern is described. The method is based on the calculation of the 'fractal dimension' of digitised mammograms. The degree of correlation between the parenchymal pattern classifications by a fractal-based system and those of radiologists is assessed. For a set of 70 mammograms, average weighted proportion agreement among three radiologists in calling Wolfe grades was 85%, while agreement between the radiologists and our fractal classifier was 84%. The method developed may prove to be useful in establishing an index of risk for breast cancer and, ultimately, in determining intervals between examinations for individuals in a mammographic screening programme.
Breast Neoplasms↗
Platelet phagocytosis and aggregation.
The addition of latex particles to native (no anticoagulant) or citrated human platelet-rich plasma (PRP), or to a once-washed platelet suspension causes platelet aggregation. This aggregation is associated with phagocytosis of the latex particles by the platelets and appears to be due to release of adenosine diphosphate (ADP) from the platelets. Adenosine and adenosine monophosphate, which are known to inhibit platelet aggregation induced by ADP, also block that induced by latex. These compounds do not prevent the phagocytosis of latex particles by the platelet. The addition of iodoacetate and 2,4-dinitrophenol in appropriate concentrations to the PRP, prior to the addition of the latex, blocks platelet aggregation and phagocytosis. This is also true for the chelating agent ethylenediaminetetraacetate (EDTA). Platelets left in contact with latex for a sufficient period of time show loss of their granules. Leucocytes phagocytose both latex and platelets that had themselves phagocytosed latex. It is concluded that phagocytosis of latex particles by platelets resembles that by white cells, and that in both processes metabolic changes appear to be involved.
Adenine Nucleotides↗