Densitometry for assessment of effect of lung volume reduction surgery for emphysema

Abstract

To explore if change in the extent of emphysema correlated with change in lung function, the effect of resection of emphysematous tissue was studied by computed tomography (CT) densitometry. In addition, the current authors studied how surgery-induced change in emphysema related to lung density in control subjects.In total, 30 patients (14 females; mean¡SD age 59¡10 yrs) with severe emphysema before and 3 months after lung volume reduction surgery (LVRS), 48 patients with moderate emphysema and 76 control subjects were investigated. Lung density (15th percentile point) of both lungs and heterogeneity of lung density between 12 isovolumetric partitions in each lung were calculated from chest CT images.The 15th percentile point and its heterogeneity could distinguish controls from subjects with moderate emphysema with a sensitivity and specificity of .95%. LVRS significantly increased lung density by 5.0¡10.9 g?L -1 (n530). Improvement in the diffusing capacity of the lung for carbon monoxide and in residual volume significantly correlated with an increase in lung density (n520 and 28, respectively). Change in forced expiratory volume in one second did not correlate with change in lung density.In conclusion, lung density 15th percentile point is a valuable surrogate marker for detection of both the extent of and reduction in emphysema.

Assessing the Relationship Between Lung Cancer Risk and Emphysema Detected on Low-Dose CT of the Chest

“…6 Moreover, quantification of emphysema using CT has been used to follow the effects of replacement therapy in patients with ␣ 1 -antitrypsin deficiency. 19,20 However, the clinical significance of emphysema on CT among individuals without symptoms or with normal pulmonary function tests remains unclear. A novelty of this study is the use of LDCT instead of high-resolution CT, as has been used in the aforementioned studies.…”

Lung densitometry: why, how and when

“…Fifth, as shown in Table 1, lung density measurements generally correlate with results of pulmonary function tests (PFT) (including spirometry, determination of static lung volumes and lung diffusing capacity for carbon monoxide), dyspnea and quality of life measurements and the multiparametric BODE index in patients with chronic obstructive pulmonary disease (COPD) (7,20,(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)47), with results of PFT in smokers and smokers at risk of emphysema (34)(35)(36)(37), with results of PFT in patients with LAM (3,38) and with results of PFT, exercise testing, and quality of life measurements in patients with lung fibrosis due to systemic sclerosis (21,39,40). Not surprisingly, because of the intrinsically continuous nature of the densitometry indexes shared with PFT, as opposed to the categorical nature of visual scores, in some studies of the above conditions the degree of correlation of densitometric parameters exceeded that of visual semi-quantitative rating (20,21).…”

“…For pulmonary emphysema, Perc1 and Perc at 15% (Perc15) are commonly used indexes (14). In particular, Perc15 is less affected by image noise and truncation effect as compared to Perc1, can be volume-corrected using a physiological sponge model (59) and has been utilized in longitudinal studies of emphysema (25,55,(60)(61)(62).…”

Three-dimensional computed tomography imaging in an animal model of emphysema

“…CT imaging can give useful information for the diagnosis of emphysema in humans today, which may even be superior to functional assessment [12]. The value of quantitative CT seems to be even stronger in assessing small changes in the lung parenchyma of human patients and may allow the visualisation of the progression of disease or quantification of changes due to interventions [15,16]. Micro-CT may have similar potential in assessing emphysematous changes in animal models of disease.…”