Correlation between mean lung density and lung function test in patients with chronic obstructive pulmonary disease by dual phase CT / 西安交通大学学报(医学版)

ABSTRACT: Objective: To investigate the correlation between the biphasic mean lung density (MLD) measured by a computer-aided method and the pulmonary function test (PFT) in patients with chronic obstructive pulmonary disease (COPD). Methods: Sixty COPD patients diagnosed in The Affiliated Hospital of Yan'an University from June 2017 to June 2018 were retrospectively recruited. CT scans at the end of inspiratory phase and the end of expiratory phase were performed. MLD of the whole lung and individual lobes were measured by a three-dimensional method, and PFT was performed within one week. The correlation between MLD and PFT was analyzed. Results: We found a slight positive correlation between MLDin and PFT of the whole lung and each lung lobe (P<0.05). MLDex, MLDex-MLDin of the whole lung and each lung lobe showed moderate to high positive correlation with PFT (P<0.01), and MLDex/in of the whole lung and each lung lobe showed moderate to high negtive correlation with PFT (P<0.01). Conclusion: Quantitative measurement of mean lung density in COPD patients is correlated with lung function and MLDex/in of the whole lung shows the highest correlation.

Changing curve of mean lung density of normal preschool children based on computer assisted measurement / 实用放射学杂志

Objective To investigate the changing curve of mean lung density (MLD)in normal preschool children based on CT quantitative measurement.Methods Chest CT data of 409 preschool children were reviewed retrospectively from the "digital lung"database.A computerized algorithm based on the "digital lung"was applied to all examinations in a batch manner.The MLD values of total lung,right lung,left lung and each lobe were obtained automatically.Results There was no correlation between the gender and MLD,however a moderately negative correlation was found between the age of month and MLD (P＜0.05).No significant difference of MLD was found between genders of the same age of month group,except in left lower lobe of 49-60 months of age (P=0.043). The MLD was decreased gradually with age (P＜0.05).Conclusion There is not a statistical difference in MLD between the preschool boys and preschool girls of the same age of month.With the growth of preschool children,the MLD is gradually decreased.

Measurement of inspiratory and expiratory lung density: a quantitative CT study in children under 5 years old / 中华放射学杂志

Objective To measure the average value of CT lung density at the phase of end inspiration and end expiration in children under 5 years.Methods Sixty patients with normal lungs who underwent chest CT for reasons caused by trauma etc.in our institute from January 2010 to March 2012 were enrolled to the study.All of the patients were divided into end inspiration group and end expiration group through random number table.CT images of the phase of end inspiration and end expiration were taken.Three levels of CT images were chosen to measure the lung density,which were 2 cm above the arch,1 cm below the carina and 2 cm above diaphragm.Lung density was measured at anterior,posterior,lateral,medial and central of the images at each level in each lung.The average lung density of each and entire lung were respectively calculated.The influence of phase,level,location was quantified using analysis of variance methods and LSD method.Results The average lung density at end inspiration was (-766 ±56)HU for the left,right and both lung.At end expiration,the average lung density of the left,right and both lungs was (-625 ± 86),(-647 ± 85) and (-636 ± 86) HU respectively.The average densities at anterior,posterior,lateral,medial and central of the left lung at end inspiration were (-798±63),(-733±68),(-767±64),(-754 ±65),(-775 ±63)HU respectively.The average densities at anterior,posterior,lateral,medial and central of the right lung were (-796 ± 70),(-736 ± 65),(-769 ± 64),(-754 ± 62),(-776-± 59) HU respectively.At end expiration phase,the average densities at anterior,posterior,lateral,medial and central of the left lung were (-692±91),(-555±116),(-639±91),(-598±103),(-640±98) HU respectively.The average densities at anterior,posterior,lateral,medial and central of the right lung were (-712 ± 90),(-575±121),(-657±90),(-619±95),(-670±87) HU respectively.The statistical differences of these five measurement areas were significant at both inspiration and expiration phase (F=12.55,11.29,23.31,25.47,P＜0.01).The posterior lung density was the highest and the anterior was the lowest.As for the other measurement areas,in descending order were medial,lateral,and central.Conclusion The lung density at end inspiration and end expiration in children under 5 years old is described to provide reference for the clinical work.

Correlation of physiological and radiological characteristics in chronic obstructive pulmonary disease.

Background. Diagnosis of chronic obstructive pulmonary disease (COPD) is confirmed on spirometry but the diagnosis of emphysema remains problematic. The objective of this study was to evaluate the utility of chest radiograph (CXR) and computed tomography (CT) for the diagnosis of emphysema and to correlate these findings with pulmonary function tests (PFTs). Methods. Thirty-five patients with COPD were studied. In all of them, CXR, CT and PFTs were done; three patients had bronchiectasis on CT and were excluded from the study. Chest radiographs (CXRs) were scored for signs of hyperinflation. Lung densities were measured on CT. Results. Functional indices of hyperinflation, i.e. functional residual capacity (FRC), residual volume (RV) and RV/total lung capacity (TLC) had significant correlation with CXR scores. The mean retrosternal space (RSP) measurement was 2.63±0.6 cm (range 1.2 to 3.6cm). Mean lung density (MLD) was -867.91 Hounsfield units (HU) which significantly correlated with functional indices of hyperinflation (FRC, RV, TLC, RV/TLC). Conclusions. In Indian population hyperinflation was found to occur even with lesser values of RSP than the western criteria. CT lung density gives good radiological evidence of emphysema and correlates with lung function abnormalities.

Unilateral Hyperlucency of the Lung: A Systematic Approach to Accurate Radiographic Interpretation

The radiographic appearance of a unilateral hyperlucent lung is related to various conditions, the accurate radiographic interpretation of which requires a structured approach as well as an awareness of the spectrum of these entities. Firstly, it is important to determine whether a hyperlucent hemithorax is associated with artifacts resulting from rotation of the patient, grid cutoff, or the heel effect. The second step is to determine whether or not a hyperlucent lung is abnormal. Lung that is in fact normal may appear hyperlucent because of diffusely increased opacity of the opposite hemithorax. Thirdly, thoracic wall and soft tissue abnormalities such as mastectomy or Poland syndrome may cause hyperlucency. Lastly, abnormalities of lung parenchyma may result in hyperlucency. Lung abnormalities can be divided into two groups: a) obstructive or compensatory hyperinflation; and b) reduced vascular perfusion of the lung due to congenital or acquired vascular abnormalities. In this article, we describe and illustrate the imaging spectrum of these causes and outline a structured approach to accurate radiographic interpretation.

Dependent Lung Opacity at Thin-Section CT: Evaluation by Spirometrically-Gated CT of the Influence of Lung Volume

OBJECTIVE: To evaluate the influence of lung volume on dependent lung opacity seen at thin-section CT. MATERIALS AND METHODS: In thirteen healthy volunteers, thin-section CT scans were performed at three levels (upper, mid, and lower portion of the lung) and at different lung volumes (10, 30, 50, and 100% vital capacity), using spirometric gated CT. Using a three-point scale, two radiologists determined whether dependent opacity was present, and estimated its degree. Regional lung attenuation at a level 2 cm above the diaphragm was determined using semiautomatic segmentation, and the diameter of a branch of the right lower posterior basal segmental artery was measured at each different vital capacity. RESULTS: At all three anatomic levels, dependent opacity occurred significantly more often at lower vital capacities (10, 30%) than at 100% vital capacity (p = 0.001). Visually estimated dependent opacity was significantly related to regional lung attenuation (p < 0.0001), which in dependent areas progressively increased as vital capacity decreased (p < 0.0001). The presence of dependent opacity and regional lung attenuation of a dependent area correlated significantly with increased diameter of a segmental arterial branch (r = 0.493 and p = 0.0002; r = 0.486 and p = 0.0003, respectively). CONCLUSION: Visual estimation and CT measurements of dependent opacity obtained by semiautomatic segmentation are significantly influenced by lung volume and are related to vascular diameter.

Quantitative Analysis of Lung HRCT in Asymptomatic Nonsmokers and the Relationship with Pulmonary Function Test Results / 实用放射学杂志

Objective To study the changes with aging of lung density parameters on inspiratory and expiratory HRCT in asymptomatic nonsmokers,and the correlation with pulmonary function test(PFT).Methods Lung HRCT scans were performed at end inspiratory and end expiratory in 63 subjects,and PFT were performed in 32 of them.All the subjects were divided into 5 groups according to the ages.Lung HRCT quantitative parameters of each groups were measured,and the correlation with PFT results was assessed.Results In each age group,the mean lung density of expiratory lung HRCT and the overall lung density difference between inspiratory and expiratory HRCT was significant decrease(P

Volume-Controlled Histographic Analysis of Pulmonary Parenchyma in Normal and Diffuse Parenchymal Lung Disease: A Pilot Study

PURPOSE: To evaluate the clinical usefulness of a home-made histographic analysis system using a lung volume controller. MATERIALS AND METHODS:Our study involved ten healthy volunteers, ten emphysema patients, and two idio-pathic pulmonary fibrosis (IPF) patients. Using a home-made lung volume controller, images were obtained in the upper, middle, and lower lung zones at 70%, 50%, and 20% of vital capacity. Electron beam tomography was used and scanning parameters were single slice mode, 10-mm slice thickness, 0.4-second scan time, and 35 -cm field of view. Using a home-made semi-automated program, pulmonary parenchyma was isolated and a histogram then obtained. Seven histographic parameters, namely mean density (MD), density at maximal frequency (DMF), maximal ascending gradient (MAG), maximal ascending gradient density (MAGD), maxi-mal descending gradient (MDG), maximal descending gradient density (MDGD), and full width at half maxi-mum (FWHM) were derived from the histogram. We compared normal controls with abnormal groups includ-ing emphysema and IPF patients at the same respiration levels. RESULTS: A normal histographic zone with +/-1 standard deviation was obtained. Histographic curves of normal controls shifted toward the high density level, and the width of the normal zone increased as the level of inspi-ration decreased. In ten normal controls, MD, DMF, MAG, MAGD, MDG, MDGD, and FWHM readings at a 70% inspiration level were lower than those at 20% (p<0.05). At the same level of inspiration, histograms of emphysema patients were located at a lower density area than those of normal controls. As inspiration status decreased, histograms of emphysema patients showed diminished shift compared with those of normal con-trols. At 50% and 20% inspiration levels, the MD, DMF, and MAGD readings of emphysema patients were significantly lower than those of normal controls (p<0.05). Compared with those of normal controls, his-tograms of the two IPF patients obtained at three inspiration levels were located in an area of higher density. CONCLUSION: Using a home-made histographic analysis system which included a lung volume controller, pa-tients with diffuse parenchymal lung disease could be distinguished from normal controls. The method may be useful for the diagnosis and follow up of diffuse parenchymal lung diseases.

CT Densitometry of Lung Mass: The Effect of Reconstruction Algorithm

PURPOSE: To evaluate the effect of reconstruction algorithms on the CT measurement of mean lung mass density and normal thoracic structures. MATERIALS AND METHODS: Forty-six patients with a 2-9cm-sized lung mass underwent thoracic CT examinations with intravenous contrast enhancement and using a CT HiSpeed Advantage scanner (GE Medical Systems). In each examination, the axial image of the lung mass was reconstructed using soft, standard, detail, and bone algorithms. The mean value and standard deviation of mass density in Hounsfield Units (HU) were measured using ROIs of three different sizes (50 mm2, 200 mm2, and 350 mm2 or more), and the same method was used to measure the density of normal lung, muscle, bone, and vessels. In 21 patients, mass density was also measured on unenhanced and delayed enhanced images and the degree of enhancement was calculated. RESULTS: The average maximum difference in mean mass density in the images of the four different algorithms was less than 1 (range, 0.1 -1.9) HU (ROI size, 350 mm2 or more), 0 -4.2 HU (200 mm 2), and 0.1 -3.6 HU (50mm2). The average maximum difference in the degree of lung mass enhancement was 0.5 -1.2 (range, 0 -1.6 )HU (ROI size, 350 mm2 or more). The mean density of the four normal thoracic structures was highest in images reconstructed with the bone algorithm, though there was no significant difference between the four different algorithms (p = 1.000). CONCLUSION: The measured mean CT density of a lung mass larger than 2 cm does not significantly change according to the reconstruction algorithm used. When using a small ROI, however, the density difference may increase.

Quantitative CT of Lung in Healthy Koreans :Evaluation with PULMO-CT

PURPOSE: Spirometric gating quantitative CT, PULMO-CT, is an objective method for the measurement of pulmonary parenchymal attenuation at a constant level of inspiration. In order to obtain a normal value for quantitative CT of the lung, the authors therefore used PULMO-CT to evalvate the lung density of healthy koreans with different respiratiory status. MATERIALS AND METHODS: Twenty healthy Korean volunteers, 18 men and 2 women, ranging in age from 24 to 27 years and with normal chest radiography, were evaluated using the PULMO-CT option of Somatom Plus(Siemens, Erlangen, Germany). Spirometric gating HRCT images, at levels of 50% and 20% of vital capacity, were obtained at the level of the tracheal carina and at 5cm above and below this point. The images were analyzed by semiautomatic programs and the results were evaluated using the Student t-test. RESULTS: The mean attenuation value of lung parenchyma at 50% of vital capacity was -791HU27.1 and at 20% was -700HU+/-42.9. The difference in lung attenuation was 91HU and was statistically significant(p<0.001). The for 58% of participants, the highest reading for of lung attenuation at 50% of vital capacity was between -899HU and -800HU, and for 20.3% of participants, this reading was between -799HU and -700HU. At 20% of vital capacity, the largest proportion of participants(43.8%) had a reading of between -799HU and -700HU; the reading of 35.2% was higher than -699HU. CONCLUSION: Respiratory status significantly affects the quantitative accessment of pulmonary parenchyma; in order to determine, during quantitative HRCT, the parameters of a pathologic condition, lung parenchyma of differing respiratory status must be evaluated.