Use of CT Imaging to Quantify Progression and Response to Treatment in Lymphangioleiomyomatosis

Abstract

BACKGROUND:In lymphangioleiomyomatosis (LAM), infiltration of the lungs with smooth muscle-like LAM cells results in cystic destruction and decline in lung function, effects stabilized by sirolimus therapy. LAM lung disease is followed, in part, by high-resolution CT scans. To obtain further information from these scans, we quantified changes in lung parenchyma by analyzing image "texture."METHODS: Twenty-six texture properties were quantified by analyzing the distribution and intensity of pixels with a computer-aided system. Both cross-sectional and longitudinal studies were performed to examine the relationships between texture properties, cyst score (percentage of lung occupied by cysts), FEV 1 , and diffusion capacity for carbon monoxide (DLCO), and to determine the effect of sirolimus treatment. RESULTS:In the cross-sectional study, 18 texture properties showed significant positive correlations with cyst score. Cyst score and 13 of the 18 texture properties showed significant differences in rates of change after sirolimus treatment; 11 also significantly predicted FEV 1 and DLCO.CONCLUSIONS: Increased cyst score was associated with increased texture degradation near cysts. Sirolimus treatment improved lung texture surrounding cysts and stabilized cyst score. Eleven texture properties were associated with FEV 1 , DLCO, cyst score, and response to sirolimus. Texture analysis may be valuable in evaluating LAM severity and treatment response.

Quantitative analysis of airway obstruction in lymphangioleiomyomatosis

“…This association between severity of cystic deformation of the parenchyma and the number of small airways is in line with longitudinal patient data from the NHLBI LAM registry where, in a large cohort of LAM patients the forced expiratory volume in 1 s decline was more rapid in patients with a greater profusion of parenchyma cysts [ 18 ], while the diffusion capacity also correlates with the disease extent seen on CT scans [ 19 ]. Nowadays, the cyst CT score and image texture are even used to predict disease progression and response to sirolimus [ 20 ]. Moreover, similar results were obtained using histological scoring where an association was found with semi-quantitative estimation of the degree of cystic lesions and infiltration of LAM cells and patient survival [ 21 ].…”

Role of thoracic imaging in the management of lymphangioleiomyomatosis

“…Texture-based CT analysis can identify pulmonary segments and classify lung tissue into six categories (honeycombing, ground-glass, bronchovascular, nodular, emphysematous-like, normal) based on extrapolated texture features [65,66]. Only few studies investigated the diagnostic accuracy of these innovative post processing techniques in LAM, highlighting their ability to improve detection of cystic changes and evaluate lung parenchyma around the cysts [15,67]. Texture analysis could estimate grading and severity of LAM, as well as could correlate CT findings with lung function tests [14].…”

Clinical CT underestimation of the percentage volume occupied by cysts in patients with lymphangioleiomyomatosis

“…In a clinical protocol to monitor and treat patients with lymphangioleiomyomatosis (LAM), regular x-ray computed-tomography (CT) scans have been used to monitor the progress of the patients [1][2][3][4]. In particular, the cyst score, a Federal Food and Drug Administration (FDA)-approved CT-based imaging marker, serves as a quantitative measure of the extent of the lungs affected by the disease [1,2,5,6]. LAM is a rare disease that occurs primarily in women of child-bearing age.…”