Ground-glass opacity on thin-section CT: Value in differentiating subtypesof adenocarcinoma of the lung

OBJECTIVE. The purpose of this study was to determine whether thin-section CT could be used to differentiate small localized bronchioloalveolar carcin oma from peripheral adenocarcinoma having a bronchioloalveolar (replacement ) growth pattern of alveolar lining cells and from adenocarcinoma not havin g a replacement growth pattern on the basis of the extent of ground-glass o pacity revealed by thin-section CT. MATERIALS AND METHODS. One hundred twenty-four small, surgically resected, peripheral adenocarcinomas from 119 patients (67 men and 52 women; mean age , 60 years) were studied. Lesion diameters were 0.4-2.0 cm (median, 1.5 cm) . The extent of ground-glass opacity within lesions on preoperative thin-se ction CT was reviewed retrospectively by three thoracic radiologists. On th e basis of replacement growth of alveolar lining cells, small ade nocarcino mas were classified histologically as localized bronchioloalveolar carcinom as (n = 32) or as adenocarcinomas with (n = 53) or without (n = 29) a repla cement growth pattern of alveolar lining cells. RESULTS. The percentage of lesions that had ground-glass opacity was signif icantly greater in localized bronchioloalveolar carcinomas (mean, 56.7% +/- 33.04%) than in adenocarcinomas with a replacement growth pattern (mean, 2 6.3% +/- 25.3%, p < .001) or in adenocarcinomas without a replacement growt h pattern (mean, 8.3% +/- 4.7%, p < .001). CONCLUSION. Determination of the ground-glass opacity area in each tumor as revealed on thin-section CT was useful for differentiating small localized bronchioloalveolar carcinomas from small adenocarcinomas not having a repl acement growth pattern.