Radial EBUS Findings for Ground Glass Opacity: Comparison of Radiologic and Pathologic Findings

Fig. 17.1

Basic configuration of the ultrasound image for GGO. Changes in configuration of signal images depend on changes in display ranges. (a) At a display range of 4 cm (red arrow), the scale on the right side corresponds to 5 mm (red arrow). (b) At a display range of 3 cm (red arrow), the scale on the right increases to 2 mm (red arrow) and enables visualization of subtle changes in echogenicity. GGO ground-glass opacity

17.3 R-EBUS Findings of GGO

1.

Blizzard sign

A blizzard sign seems to be similar to the snowstorm appearance of normal lung (Fig. 17.2a); however, on closer inspection, it is characterized by hyperechoic and coarse R-EBUS signals that clearly enhance in a wider area within a lesion. Specifically, a blizzard sign is defined as a hyperechoic and coarse R-EBUS signal that extends more than 1 cm away from the center of the ultrasound probe (Fig. 17.2b) [3–5].

Fig. 17.2

Comparison of different R-EBUS findings. (a) A normal lung shows the typical snowstorm appearance; (b) A GGO lesion shows blizzard sign; (c) A part-solid lesion shows mixed-blizzard sign. Adapted from Izumo et al. [5]. R-EBUS radial endobronchial ultrasound, GGO ground-glass opacity
2.

Mixed blizzard sign

A mixed-blizzard sign is defined as coarse R-EBUS signals that are scattered with hyperechoic dots and lines and mixed with hypoechoic areas [5] (Fig. 17.2c). The typical R-EBUS findings, HRCT findings, and pathologic findings of malignant GGO lesions are shown in Figs. 17.3 and 17.4.

Fig. 17.3

Imaging and histologic correlation of a pure GGO lesion. Axial slice HRCT shows a pure GGO in the right segment 3b (a). After confirming blizzard sign on R-EBUS (b), EBUS-GS transbronchial biopsy is performed under simultaneous fluoroscopy guidance (c) and histopathologic examination (hematoxylin and eosin) reveals adenocarcinoma (d). Histopathologic examination of the surgically resected GGO lesion confirms well-differentiated minimally invasive adenocarcinoma (hematoxylin and eosin) (e). Adapted from Izumo et al. [5]. GGO ground-glass opacity, HRCT high-resolution computed tomography, R-EBUS radial endobronchial ultrasound, EBUS-GS endobronchial ultrasound with a guide sheath

Fig. 17.4

Imaging and histologic correlation of a part-solid GGO lesion. Axial slice HRCT shows a part-solid GGO in the left segment 10a (a). After confirming mixed-blizzard sign on R-EBUS (b), EBUS-GS transbronchial biopsy is performed under simultaneous fluoroscopy guidance (c) and histopathologic examination (hematoxylin and eosin) reveals adenocarcinoma (d). Histopathologic examination of the surgically resected GGO lesion confirms well-differentiated invasive lepidic-predominant adenocarcinoma (hematoxylin and eosin) (e). Adapted from Izumo et al. [5]. GGO ground-glass opacity, HRCT high-resolution computed tomography, R-EBUS radial endobronchial ultrasound, EBUS-GS endobronchial ultrasound with a guide sheath

17.4 Targets

From June 2012 to June 2014, 1,134 patients underwent EBUS-GS for peripheral lung lesions. Of them, 187 were found to have GGOs, 116 of which were diagnosed as lung adenocarcinoma by EBUS-GS (Table 17.1); 103 of 116 patients subsequently underwent surgical resection.

Table 17.1

Baseline characteristics of patients with GGO lung adenocarcinoma (n = 116)^a

Variable

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