Chest
Volume 97, Issue 2, February 1990, Pages 315-321
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Quantitation of Emphysema by Computed Tomography Using a “Density Mask” Program and Correlation with Pulmonary Function Tests

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We used a CT program “density mask” outlining areas with attenuation values less than —910 HU, to indicate areas of emphysema on a chest CT and to provide an overall percentage of lung involvement by emphysema. The “density mask” quantitation of emphysema was previously shown to correlate well with the pathologic assessment of emphysema in patients undergoing lung resection. We compared the CT quantitation of emphysema with mean lung density, overall lung volume on CT and pulmonary function tests in 85 patients. There was a significant correlation between the extent of emphysema on CT and FEV1/FVC percent of predicted, functional residual capacity percent predicted and Dsb percent predicted. Determination of the percentage of lung with areas of low attenuation by CT provides a useful method for quantitating emphysema in life and correlates significantly with pulmonary function tests.

(Cheat 1990; 97:315–321)

Section snippets

METHODS

We studied 85 patients, 52 males and 33 females, ranging in age from 40 to 78 years (mean age ± SD = 64 ± 8 yr). They were selected from patients tested in the Vancouver General Hospital Pulmonary Function Laboratory during investigation for suspected malignancy. Patients with tumors were included if the tumor was peripheral and less than 7 cm in diameter or central but obstructing one segment or less. The limit for a peripheral lesion of 7 cm in diameter was chosen since the volume of a

RESULTS

The CT “density mask” results for both lungs are summarized in Table 1, which shows mean lung density, total CT lung volume, total volume of emphysema, and percentage of lung with emphysema. There was good correlation between the mean lung density and each of the following: total CT lung volume, total CT volume of emphysema and percentage of lung with emphysema (all absolute r values = 0.66 to 0.67, p<0.001). The correlation between mean lung density and percentage lung involvement with

DISCUSSION

In this study we used the CT “density mask” program to quantitate areas with attenuation values less than —910 HU which were taken to represent areas of emphysema,10 and to provide an overall percentage of lung involvement by emphysema. The CT quantitation of emphysema was correlated with mean lung density, overall lung volume and with commonly performed pulmonary function tests that are affected in emphysema.

The mean lung density was found to correlate well both with the total CT lung volume

REFERENCES (25)

  • WL Foster et al.

    Centrilobular emphysema: CT-pathologic correlation

    Radiology

    (1986)
  • RS Jones et al.

    A theoretical and experimental analysis of anomalies in the estimation of pulmonary diffusing capacity by the single breath method

    Q J Exp Physiol

    (1961)
  • Cited by (0)

    Supported in part by grants from the Medical Research Council of Canada (MA-10042) and the B.C. Lung Association.

    Manuscript received April 24; revision accepted July 10.

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