TY - JOUR

T1 - Volume adjustment of lung density by computed tomography scans in patients with emphysema.

AU - Shaker, S B

AU - Dirksen, A

AU - Laursen, Lars Christian

AU - Skovgaard, L T

AU - Holstein-Rathlou, N H

N1 - Keywords: Absorptiometry, Photon; Aged; Airway Obstruction; Female; Follow-Up Studies; Forced Expiratory Volume; Humans; Image Processing, Computer-Assisted; Inhalation; Lung; Lung Volume Measurements; Male; Middle Aged; Pulmonary Diffusing Capacity; Pulmonary Emphysema; Smoking; Tomography, X-Ray Computed; Total Lung Capacity; Vital Capacity; alpha 1-Antitrypsin Deficiency

PY - 2004

Y1 - 2004

N2 - PURPOSE: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. MATERIAL AND METHODS: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. RESULTS: The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. CONCLUSION: Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema.

AB - PURPOSE: To determine how to adjust lung density measurements for the volume of the lung calculated from computed tomography (CT) scans in patients with emphysema. MATERIAL AND METHODS: Fifty patients with emphysema underwent 3 CT scans at 2-week intervals. The scans were analyzed with a software package that detected the lung in contiguous images and subsequently generated a histogram of the pixel attenuation values. The total lung volume (TLV), lung weight, percentile density (PD), and relative area of emphysema (RA) were calculated from this histogram. RA and PD are commonly applied measures of pulmonary emphysema derived from CT scans. These parameters are markedly influenced by changes in the level of inspiration. The variability of lung density due to within-subject variation in TLV was explored by plotting TLV against PD and RA. RESULTS: The coefficients for volume adjustment for PD were relatively stable over a wide range from the 10th to the 80th percentile, whereas for RA the coefficients showed large variability especially in the lower range, which is the most relevant for quantitation of pulmonary emphysema. CONCLUSION: Volume adjustment is mandatory in repeated CT densitometry and is more robust for PD than for RA. Therefore, PD seems more suitable for monitoring the progression of emphysema.

M3 - Journal article

C2 - 15323394

VL - 45

SP - 417

EP - 423

JO - Acta Radiologica - Series Diagnosis

JF - Acta Radiologica - Series Diagnosis

SN - 0365-5954

IS - 4

ER -