B is € '910bђ .

In order to objectively quantify emphysema, multiple light attenuation parameters based on histogram analysis

frequency distribution of attenuation values ​​of light were developed. The most commonly used methods are based on: measurement of average lung attenuation (MLA); area light is on

attenuation values ​​lower than the defined thresholds

BЂ "and led to a slight weakening percentile curve distribution. The first pathological-CT comparative study using a number of attenuation, Hayhurst

al. showed that the distribution curve of these densities was significantly shifted towards lower values ​​of attenuation in patients with emphysema

compared with normal people. In pathological, CT comparative study based on microscopic measurements

Gould and others. showed that the low attenuation values ​​Pyatiprotsentilnyy histograms were significantly associated with AWUV.

, Low Pyatiprotsentilnyy depends on the degree of emphysema, but also depends on the relative number of higher attenuation values ​​

appropriate airway walls, blood vessels, and any who wants to get right to shift the histogram. So, if emphysema is associated with other pulmonary diseases, the lowest Pyatiprotsentilnyy be underestimated

degree of emphysema. To overcome this limitation, the absolute threshold should be used and the relative area of ​​lung is

to reduce the value below this threshold measure. In 1988 Mtsјller

al. CT use commercially available program called density Maskb ® (General Electric Medical Systems, Milwaukee, Wisconsin, USA) that

Key points in this range reduced and automatically calculates the area of ​​selected pixels. In this study

Mtsјller al. comparison of the relative area of ​​color on a 1 -, see CT, after administration of contrast medium with the corresponding

macroscopic part of the fixed lung cut in the same plane, CT and evaluated using a modified method of picture-grading system of Thurlbeck

etc. .. The highest correlation observed attenuation values ​​of B € '910 HU, and, consequently, the threshold recommended by the

to identify emphysema. However, a significant correlation shows that only CT and pathologic assessment

statistically related, but does not mean that the share of the region received quantitative CT level >> << percentage area occupied by emphysema on pathologic specimen. In addition, the proposed threshold may be influenced by >> << administration of contrast lasix drug side effects material. In addition, panel classification does not reflect the extent participate in the lungs and emphysema underestimates

panlobular emphysema, especially in the initial stage. In an attempt to determine the best attenuation threshold for recognition of emphysema, a program that automatically recognizes

light traces light paths, attenuation value histogram defines and measures the light area occupied by pixels

included in a given range of values ​​of the damping was applied at 1 - mm CT sections. In thin sections obtained from CT lung top to the base of 1 -, cm intervals, the relative area of ​​the lung, expressed as a percentage

occupied by attenuation values ​​lower than various thresholds of B € '900BЂ "B € '970 HU was calculated. In >> << first study based on 63 patients resection of lung CT data compared to the macroscopic degree of emphysema measured on the horizontal

Paper set targets sections of the lungs, the authors previously validated computer method. It was shown that only the threshold for which there was no significant difference between the distribution >> << CT measurement and distribution of macroscopic measurements would be € '950BЂ ... HU. Thresholds B € '950BЂ ... HU underestimate emphysema, and thresholds

B € '950BЂ ... HU overestimate emphysema. Case by case comparison of the relative area occupied by attenuation values ​​of B € '950

HU (RA

and the relative area of ​​lung macroscopically occupied by emphysema was 4. 9% and the range of 0. 1BЂ. "19 9% . These data indicate that the relative area

light is weakening value B € '950 HU calculated on thin section CT obtained at full inspiration >> << was a method that allows objective quantification of macroscopic emphysema

in vivo and with an acceptable error. from McLean et al. recommended emphysema should be measured microscopically and macroscopically not, comparison

CT and morphometry should include microscopic measurements. AWUV Using a microscopic measurement of alveolar> ;> << a wall surface of 28 items mentioned in the surgical resection of tumors of the lung, Gould

al. reported significant correlations between AWUV and Pyatiprotsentilnyy low frequencies the attenuation curve

values ​​(r = '0 B € 77, P0 001.). designed for 13 - mm CT sections in a later study based on 38 patients also referred to as

to lung resection, the average distance between the layers. (MIWD) and mean perimeter (MP) was measured and the percentage surface area occupied by lung

attenuation value below the threshold of B € '900BЂ "B € '970BЂ ... HU was compared with the microscopic parameters. It was shown that a high correlation was obtained with B € '950 HU (g = 0. 70). Thus, both macro-and microscopic studies >> << conducted by a group of authors have suggested that RA is

Most Valuable measure the degree of emphysema. To predict lung surface to volume ratio of CT attenuation values ​​Coxson

al. B is € '910BЂ ... HU, as threshold and compared with CT measurement of histological evaluation of surface area.

lung capacity was calculated by summing the sizes vokseliv in each piece and light weight is determined by multiplying the average light

reduce the cost of the lungs. From these measurements, Coxson

etc. .. comparison of emphysema found in the same proportion of CT and point counting of samples withdrawn

showed that the volume fraction of damage 5BЂ ... mm in diameter measured by morphometry similar to the fraction of light

inflated above 10. 2BЂ mLb · ... he also showed that defeat 5BЂ ... mm in line lung inflated between 6. 0BЂ "10. 2BЂ ... mLb · g

and that regions inflated below 6. 0BЂ ... mLb · g

morphologically normal. This method was more accurate than the surface area occupied by emphysema, as these authors

decrease the ratio of surface to volume in mild emphysema, and surface area and tissue weight were reduced only in severe

the disease. << >>