Diagnosis of the invasiveness of lung adenocarcinoma manifesting as ground glass opacities on high-resolution computed tomography

Abstract

Background: To explore the diagnostic method in assessing the malignancy of pulmonary adenocarcinoma characterized by ground glass opacities (GGO) on computed tomography (CT).

Methods: Preoperative CT data for preinvasive and invasive lung adenocarcinomas were analyzed retrospectively. GGO lesions that were detected on lung windows but absent using the mediastinal window were subject to adjustment of the window width, which was reduced with the fixed interval of 100 HU until the lesions were no longer evident, with a fixed mediastinal window level of 40 HU. The shape, smoking habits, size of the lesion on the lung window, and window width at which lesions disappeared were compared and receiver operating characteristic curves were used to determine the optimal cut-off of the lesion size and window width to differentiate between these invasive and preinvasive lesions.

Results: Of the 209 lung adenocarcinomas, 102 were preinvasive (25 atypical adenomatous hyperplasia and 77 adenocarcinoma in situ), while 107 were invasive (78 minimally invasive adenocarcinoma and 29 invasive adenocarcinoma). The shape, lesion size, and window width at which lesions were no longer evident differed significantly between the two groups (P < 0.05). The size of 8.9 mm and a window width of 1250 HU were the optimal cut-off to differentiate between preinvasive and invasive lesions.

Conclusion: The shape, size of the lesion, and window width on high-resolution CT may be useful in assessing the invasiveness of lung adenocarcinoma that manifests as GGO. Irregular lesions that disappear at window width <1250 HU, with a diameter of > 8.9 mm are more likely to be invasive.

Keywords: Lung neoplasms; X‐ray computed; neoplasm invasion; tomography.

Figure 1

Receiver operating characteristic (ROC) curve analysis, size

Figure 2

Receiver operating characteristic (ROC) curve analysis, width.

Figure 3

A 63 year‐old male patient with a pathological diagnosis of atypical adenomatous hyperplasia (hematoxylin‐eosin stain, ×200). The computed tomography image shows a 4 mm ground glass opacity in the right lower lobe. From left to right, followed by lung window, mediastinal window width of 1800 HU, 1600 HU, and 1500 HU. The size of the lesion decreased gradually and was invisible at a mediastinal window width of 1500 HU.

Figure 4

A 39 year‐old female patient with a pathological diagnosis of adenocarcinoma in situ (hematoxylin‐eosin stain, ×100). The computed tomography image shows a 6 mm ground glass opacity in the right middle lobe. From left to right, followed by lung window, mediastinal window width of 1800 HU, 1600 HU, 1400 HU, and 1300 HU. The size of the lesion decreased gradually and was invisible on the mediastinal window with a window width of 1300 HU.

Figure 5

A 57 year‐old male patient with a pathological diagnosis of minimally invasive adenocarcinoma (hematoxylin‐eosin stain, ×100). In the right upper lobe there was a 6.5 mm ground glass opacity on computed tomography. From left to right, followed by lung window, mediastinal window width of 1800 HU, 1600 HU, 1400 HU, 1200 HU, and 1000 HU. The size of the lesion decreased gradually and was invisible with a mediastinal window width of 1000 HU.

Figure 6

A 55 year‐old male patient with a pathological diagnosis of invasive adenocarcinoma (hematoxylin‐eosin stain, ×100). The computed tomography image shows a 12‐mm ground glass opacity in the right upper lobe. From left to right, followed by lung window, mediastinal window width of 1800 HU, 1600 HU, 1400 HU, 1200 HU, 1000 HU, and 900 HU. The size of the lesion decreased gradually and was invisible at a mediastinal window width of 900 HU.