D. Eterovic et al., HIGH-RESOLUTION PULMONARY COMPUTED-TOMOGRAPHY SCANS QUANTIFIED BY ANALYSIS OF DENSITY DISTRIBUTION - APPLICATION TO ASBESTOSIS, British Journal of Industrial Medicine, 50(6), 1993, pp. 514-519
A new method for quantitative evaluation for high resolution computed
tomography (HRCT) of the lungs was developed by assessment of the dist
ribution of radiological densities within the lung slices. To enable e
ffective reduction of data and improve the sensitivity of detection of
abnormalities, the density distributions were analysed by curve fitti
ng through the gamma variate model. The output of two variables proved
most representative: the most frequent density (Hoansfield units; HU)
and width of distribution (HU). The method was applied to seven patie
nts with early asbestosis (positive histological finding and Internati
onal Labour Office (ILO) profusion score up to 0/1), 15 patients with
advanced stage of asbestosis (positive histological finding and ILO sc
ore above 1/2), and 13 normal controls. All patients with early asbest
osis had isolated reduction of diffusing lung capacity to carbon monox
ide (DLCO), whereas all patients with advanced asbestosis had reduced
DLCO and restrictive disease; two of them also had an obstruction patt
ern. The most frequent densities were significantly greater in the adv
anced asbestosis group (-567 HU) when compared with both the early asb
estosis group (-719 HU; p = 2 x 10(-6)), and controls (-799 HU; p = 0)
, and they also discriminated significantly between the early asbestos
is group and controls (p = 0.0002). Significantly stronger linear co''
elations were established between DLCO and the most frequent densities
(r = 0.86) than between DLCO and HRCT score (r = 0.57) or ILO score (
r = 0.34). It is concluded that fitting the curve of the density distr
ibution enables a more objective assessment of HRCT pulmonary scans, e
specially in the early stage of asbestosis.