Patrón de lectura radiológica digital para la clasificación de imágenes compatibles con silicosis / Digital reading radiation pattern for classification of image about silicosis (P0140-2013)

La silicosis es una enfermedad sin tratamiento. El programa de vigilancia de trabajadores expuestos a sílice está diseñado para detectarla lo más precozmente posible mediante una radiografía de tórax. A pesar de su rol fundamental, esta adolece de una gran variabilidad técnica y de interpretación. Para disminuir estos fenómenos, la OIT creó un sistema de clasificación ampliamente usado en Chile y el mundo. Este se basó en la radiografía análoga, la que ha sido reemplazada por el mismo set análogo, digitalizado. Si bien la OIT permite el uso de este nuevo tipo de imagen, indica que el patrón de comparación debe seguir siendo el análogo. Muchos estudios han demostrado que es mejor utilizar patrones de comparación digitales. El objetivo de este trabajo fue generar un set de radiografías digitales que representen las profusiones centrales de opacidades redondas del sistema de clasificación OIT. De un universo de 32.826 radiografías de pacientes expuestos a sílice, se obtuvo 252 radiografías, de las cuales 54 fueron informadas por 3 lectores acreditados, seleccionándose 8 casos que contaban con opacidades redondas puras de diferentes profusiones, las que se proponen como patrón digital para Chile.

Silicosis is a disease without treatment. The surveillance program for workers exposed to silica is designed to detect as early as possible by a chest radiograph. Despite its fundamental role, it suffers from a great technique and interpretation variability. To reduce these phenomena, the ILO created a classification system widely used in Chile and the world. This was based on analog radiography, which has been replaced by the same analog set, digitized. While the ILO permits the use of this new type of image it indicates that the pattern comparison must remain analog. Many studies have shown that it is best to use digital comparison patterns. The objective of this work was to generate a set of digital x-rays representing the central profusion of round opacities of ILO classification system. From a universe of 32,826 x-rays of patients exposed to silica, 252 films, of which 54 were reported for 3 accredited readers, selected 8 cases that had pure round opacities of different profusions was obtained, which are proposed as digital pattern for Chile.

From the definition of silicosis at the 1930 Johannesburg conference to the blurred boundaries between pneumoconioses, sarcoidosis, and pulmonary alveolar proteinosis (PAP).

The 1930 International Labour Office Conference on silicosis in Johannesburg identified silicosis by setting a medicolegal framework to its nosology: as with other occupational illnesses, its medical content was fixed under economic pressure. This article follows a reading of all the proceedings of this conference (debates and reports of experts) to examine their potential impact on the etiology and nosology of other diseases, specifically sarcoidosis and pulmonary alveolar proteinosis (PAP), "idiopathic" diseases in which inorganic particles may be involved. We propose renewed study of the role of inorganic particles in these diseases. To do this, we propose to mobilize detection means such as mineralogical analysis and electron microscopy and in depth interviewing that are currently seldom used in France, in order to establish diagnosis and the potential occupational and environmental origin of these diseases.

Silicosis: diferencias relevantes entre marmolistas y mineros / Silicosis: relevant differences between marble workers and miners

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Silica exposure and silicosis in Alberta, Canada.

OBJECTIVES: To study potential exposures to crystalline silica and the number of work-related cases of silicosis occurring in Alberta. METHODS: Exposure data comprising 343 occupational samples were collected at 40 worksites across 13 industries. To assess silicosis reporting, cases reported to the Alberta government, claims accepted by the Workers' Compensation Board for work-related silicosis, and billings to Alberta Health for medical services with a diagnostic code for silicosis during a similar time period were compared. RESULTS: Workers potentially over-exposed to airborne respirable crystalline silica were identified at most of the worksites evaluated. There were large discrepancies in the number of silicosis cases found. CONCLUSIONS: Many Alberta workers may be over-exposed to airborne respirable crystalline silica, and the incidence of work-related silicosis in Alberta may not be adequately represented by the official statistics.

[Diagnostic prediction of early silicosis patients using neural network and MALDI-TOF-MS in serum].

Serum of 79 workers exposed to silica and 25 healthy controls cases were determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). 7 protein peaks were selected and used by artificial neural network (ANN) to establish a diagnostic model. A blinded test showed that accuracy, sensitivity and specificity were 91.35%, 93.69%, and 84.52%, respectively. The diagnostic pattern was also established to distinguish each stage of silica-exposed population. The diagnostic pattern worked excellently with 89.23%, 94.20% and 92.37% of accurate rate for classifying phase 0, phase 0+, and phase I of silicosis, respectively.

High prevalence and advanced silicosis in active granite workers: a dose-response analysis including FEV1.

OBJECTIVE: To evaluate silica exposure and respiratory disease in granite workers. METHODS: A cross-sectional study of 440 active granite workers. RESULTS: Seventy-seven (17.5%) have silicosis, complicated in 15 of them; 18 have an obstructive ventilatory defect and 73 had exceeded 3.5 mg/m-year of cumulative silica exposure. Percent predicted FEV1 have a significant negative relation with mg/m(3)-year (P < 0.001) with a trend toward dose-response excluding silicotics and controlling for tobacco. The odds ratio (95% confidence interval) of having a percent predicted FEV1 below 50th percentile is 1.18 (0.66 to 2.11) for nonexposed smokers, 1.47 (0.76 to 2.84) for exposed nonsmokers, and 2.07 (1.12 to 3.85) for exposed smokers, in comparison with the control group. CONCLUSIONS: This study suggests that silica induces functional alteration regardless of silicosis and, in all likelihood, synergistically with tobacco. Exposure levels must be controlled better in these workers and those with silicosis must be relocated to risk-free jobs or retired.

Radiographic readings for asbestosis: misuse of science--validation of the ILO classification.

BACKGROUND: Radiographic readings for pneumoconiosis (both asbestosis and silicosis), even those using the International Labour Office (ILO) Classification, have received widespread negative coverage in the media and strong judicial rebuke. METHODS: The medical literature over the past 90 years was reviewed for the relationships between radiographic severity (standardized as the ILO profusion score) and indices of exposure to silica or asbestos, tissue burden of silica particles or asbestos fibers, histologic fibrosis, various measurements of pulmonary function and mortality. RESULTS: Evidence from many different disciplines has demonstrated that the ILO profusion score correlates with occupational exposure, dust burden in the lung, histologic fibrosis and, more recently, with physiologic impairment and mortality. CONCLUSIONS: The ILO Classification has therefore been validated as a scientific tool. Its fraudulent misuse by "hired-gun" physicians, attorneys and elements of the compensation system to falsify claims of asbestosis and/or silicosis (often in the same claimant) must be condemned.

Continued exposure to silica after diagnosis of silicosis in Brazilian gold miners.

BACKGROUND: There is a paucity of studies analyzing the effect of continued silica exposure after the onset of silicosis with regard to disease progression. The present study investigates differences in clinical and radiological presentation of silicosis among former workers with a diagnosis of silicosis, and compares workers who continued to be exposed to silica with those who stopped silica exposure after having received their diagnosis. METHODS: A sample of 83 former gold miners with a median of 21 years from the first diagnoses of silicosis, had their clinical and occupational histories taken and underwent both chest radiography (International Labor Organization standards) and spirometry. Their silica exposure was assessed and an exposure index was created. The main outcome was the radiological severity of silicosis and tuberculosis (TB). The statistical analysis was done by multiple logistic regression. RESULTS: Among the 83 miners, 44 had continued exposed to silica after being diagnosed with silicosis. Continuation of silica exposure was associated with advanced radiological images of silicosis (X-ray classification in category 3, OR = 6.42, 95% CI = 1.20-34.27), presence of coalescence and/or large opacities (OR = 3.85, CI = 1.07-13.93), and TB (OR = 4.61, 95% CI = 1.14-18.71). CONCLUSIONS: Differential survival is unlikely to explain observed differences in silicosis progression. Results reinforce the recommendation that silica exposure should be halted at an early stage whenever X-ray is suggestive of the disease.

A 40-year follow-up of whetstone cutters on silicosis.

The present study, consisted of two separate surveys, was initiated to clarify the development of clinical pictures of silicosis after termination of dust exposure. The first survey was a 40-year follow-up of radiographic pictures of the chest among 200 male whetstone cutters (Group I workers). The second survey was conducted in 75 male recipients (Group II workers) of disability compensation for silicosis due to whetstone dust exposure. The study on Group I workers made it clear that the proportion of those free of radiographic findings in the chest pictures decreased during a 40-year follow-up period from 84% in the 1st health examination in 1952-6 to 36% in the 3rd examination in 1995. The rate of progression of the disease from Category 1 to 3 (after ILO-guided classification) to higher categories in a 15-year period was as high as >50%. Longer service duration and higher category of chest radiography at the previous health examination were the influential factors in determining the rapid progression of silicosis. The latter observation was confirmed also through a similar analysis on Group II workers. Whetstone preparations contained SiO2 by about 50%. No industrial hygiene data were available for both groups of stone cutters, but the exposure of Group I workers was estimated to be about 1 mg/m3, or well in excess of the current occupational exposure limit.

Silicosis and tuberculosis: Part 2--a radiographic presentation of nodular tuberculosis and silicosis.

Indolent nodular pulmonary tuberculosis (TB) in workers exposed to silica dust may go undetected clinically and radiographically, especially in the absence of identification of tubercle bacilli in sputum. Illustrative cases demonstrating the radiographic manifestations of coexistent pulmonary silicosis and the indolent form of nodular TB are presented. Alterations in the usual chronologic progress, a rapid advance in nodular profusion or size outside the expected time frame, and distinct pattern alterations are features indicating the presence of TB associated with silicosis.

Silicosis and tuberculosis: a proposed radiographic classification of tuberculosis to accompany the ILO international classification of radiographs of pneumoconioses.

A significant proportion of workers exposed to silica dust are at risk of developing tuberculosis (TB). The higher the International Labor Organization (ILO) category of silicosis, the greater the TB risk. Subtle radiographic presentations of TB may be the initial manifestation of TB, particularly in the absence of sputum identification of TB bacilli. A proposed TB x-ray-reading form in addition to the ILO categorization of silicosis is offered. The implementation of a standardized TB x-ray-reading approach should alert the clinician to indolent TB lesions.

Pathology and pathophysiology of pneumoconiosis.

Cellular and molecular mechanisms, as well as associated gene expressions, in silicosis and asbestosis are widely investigated, and compound mechanisms involved in initiating inflammation and progression to fibrosis are comprehensively studied, though not yet totally understood. Recent advances in this field, especially concerning pathophysiology of these pneumoconioses, are reviewed in this article. Silicosis and asbestosis are two major types of pneumoconiosis. Although the clinico-pathologic features presented are apparently different, silicosis and asbestosis are both interstitial lung diseases caused by chronic exposure to airborne inorganic dusts, and the pathology of these two diseases is essentially a fibrosis.

The influence of silicosis on deteriorating lung function in gold miners.

STUDY OBJECTIVE: To reexamine the symptoms, lung function, and chest radiographs of older gold miners who continued to work in or around gold mines 5 years after their enrollment in the cohort. DESIGN: A follow-up study of a stratified sample of a cohort of gold miners. SETTING: A health-care center for 24 gold mines in Welkom, South Africa. POPULATION: A stratified, random sample of 242 miners who were part of a cohort of 1,197 gold miners who had been employed underground in gold mines for a mean period of 29 years. No silicosis was apparent on entry in 59 men, 78 had silicosis with category 1 nodule profusion, 73 had category 2, and 32 had category 3. MEASUREMENTS: The men were assessed with questionnaires, lung function tests, and chest radiographs approximately 4.5 years after their initial assessment. RESULTS: Radiologic features of silicosis had progressed an average of one subcategory (eg, 2/1 to 2/2) in the follow-up period. Lung function deteriorated more rapidly in the men with silicosis and the deterioration increased in proportion to the degree of silicosis at the start of the study. Thus, the annual loss of FEV1 was 37 mL in those without silicosis, 57 mL in those with category 1, 100 mL with category 2, and 128 mL in the men with category 3 nodule profusion (p=0.000001). A similar pattern of loss was noted for the FVC (p=0.00003) and the single-breath lung diffusion (p=0.004). These changes remained significant after controlling for age, original lung function, and for smoking. CONCLUSIONS: The men with silicosis suffered a substantial loss of lung function during the period of follow-up that was directly in proportion with the nodule profusion on their initial chest radiographs.

Value of the lymphoblastic transformation in patients with silicosis.

The authors verify whether in silicosis the accumulation of silicon dioxide (SiO2) particles in the lung can induce changes of the activated T lymphocytes in the peripheral blood. The lymphoblastic transformation of lymphocytes stimulated with phytohemagglutinin (PHA), concanavalin A (Con A), Mycobacterium tuberculosis (Mt) and purified protein derivative (PPD) was studied using the classical methods. It was observed that in patients exposed to SiO2 lymphocyte reactivity to the above stimulants decreases. Significant differences between patients and controls were observed only in the response to PHA (p < 0.001).