Quantification of Pulmonary Inflammatory Processes Using Chest Radiography: Tuberculosis as the Motivating Application.

The purpose of this work was to develop a quantitative method for evaluating the pulmonary inflammatory process (PIP) through the computational analysis of chest radiography exams in posteroanterior (PA) and lateral views. The quantification procedure was applied to patients with tuberculosis (TB) as the motivating application.A study of high-resolution computed tomography (HRCT) examinations of patients with TB was developed to establish a relation between the inflammatory process and the signal difference-to-noise ratio (SDNR) measured in the PA projection. A phantom essay was used to validate this relation, which was implemented using an algorithm that is able to estimate the volume of the inflammatory region based solely on SDNR values in the chest radiographs of patients.The PIP volumes that were quantified for 30 patients with TB were used for comparisons with direct HRCT analysis for the same patient. The Bland-Altman statistical analyses showed no significant differences between the 2 quantification methods. The linear regression line had a correlation coefficient of R = 0.97 and P < 0.001, showing a strong association between the volume that was determined by our evaluation method and the results obtained by direct HRCT scan analysis.Since the diagnosis and follow-up of patients with TB is commonly performed using X-rays exams, the method developed herein can be considered an adequate tool for quantifying the PIP with a lower patient radiation dose and lower institutional cost. Although we used patients with TB for the application of the method, this method may be used for other pulmonary diseases characterized by a PIP.

Objective CT-based quantification of lung sequelae in treated patients with paracoccidioidomycosis.

This study presents methodology for objectively quantifying the pulmonary region affected by emphysemic and fibrotic sequelae in treated patients with paracoccidioidomycosis. This methodology may also be applied to any other disease that results in these sequelae in the lungs.Pulmonary high-resolution computed tomography examinations of 30 treated paracoccidioidomycosis patients were used in the study. The distribution of voxel attenuation coefficients was analyzed to determine the percentage of lung volume that consisted of emphysemic, fibrotic, and normal tissue. Algorithm outputs were compared with subjective evaluations by radiologists using a scale that is currently used for clinical diagnosis.Affected regions in the patient images were determined by computational analysis and compared with estimates by radiologists, revealing mean (± standard deviation) differences in the scores for fibrotic and emphysemic regions of 0.1% ±â€Š1.2% and -0.2% ±â€Š1.0%, respectively.The computational results showed a strong correlation with the radiologist estimates, but the computation results were more reproducible, objective, and reliable.

Analysis of biological tissues in infant chest for the development of an equivalent radiographic phantom.

PURPOSE: The main purpose of the present study was to determine the amounts of different tissues in the chest of the newborn patient (age ≤1 year), with the aim of developing a homogeneous phantom chest equivalent. This type of phantom is indispensable in the development of optimization procedures for radiographic techniques, including dosimetric control, which is a crucial aspect of pediatric radiology. The authors present a systematic set of procedures, including a computational algorithm, to estimate the amounts of tissues and thicknesses of the corresponding simulator material plates used to construct the phantom. METHODS: The Gaussian fit of computed tomographic (CT) analysis was applied to classify and quantify different biological tissues. The methodology is summarized with a computational algorithm, which was used to quantify tissues through automated CT analysis. The thicknesses of the equivalent homogeneous simulator material plates were determined to construct the phantom. RESULTS: A total of 180 retrospective CT examinations with anterior-posterior diameter values ranging 8.5-13.0 cm were examined. The amounts of different tissues were evaluated. The results provided elements to construct a phantom to simulate the infant chest in the posterior-anterior or anterior-posterior (PA/AP) view. CONCLUSIONS: To our knowledge, this report represents the first demonstration of an infant chest phantom dedicated to the radiology of children younger than one year. This phantom is a key element in the development of clinical charts for optimizing radiographic technique in pediatric patients. Optimization procedures for nonstandard patients were reported previously [Pina et al., Phys. Med. Biol. 49, N215-N226 (2004) and Pina et al., Appl. Radiat. Isot. 67, 61-69 (2009)]. The constructed phantom represents a starting point to obtain radiologic protocols for the infant patient.