Analysis of the Internal Structure of Peripheral Pulmonary Lesions Using Endobronchial Ultrasonography: Discussion
Type IIIb, Heterogeneous Pattern Without Hyperechoic Dots and Short Lines: Twenty-two lesions (17.7%) were classified as type IIIb (Fig 11). The majority of lesions (18) were poorly differentiated adenocarcinoma, which had a high cell density and had formed a mass. The lesions were avascular and showed scant mottled or linear hyperechoic areas. The internal echoes were heterogeneous. Since the lesions extend outward, their margins tend to be roundish. This group included one case of moderately differentiated adenocarcinoma and three cases of poorly differentiated squamous cell carcinoma, in addition to the 18 cases of poorly differentiated adenocarcinoma.
Thus, of the 17 type Ia lesions, 15 were pneumonia and 1 was organizing pneumonia. Of the eight type Ib lesions, four were organizing pneumonia and three were tuberculomas. So, 23 of 25 type I lesions (92.0%) were benign disease, while 98 of 99 type II and III lesions (99.0%) were malignant (Table 2).
Twenty-one of 24 type II lesions (87.5%) were well-differentiated adenocarcinomas review asthma inhaler. All 22 type IIIb lesions were malignant, including 18 cases (81.8%) of poorly differentiated adenocarcinoma.
EBUS uses high-frequency ultrasound (20 MHz) to create detailed images of the internal structures of lesions, although it cannot image tissue that is external to the lesion. Endoscopic ultrasonography has been used to examine the internal structure of pancreatic lesions, and the results have been correlated with histopathology in cases of cystic tumors, calcifications, and pancreatic stones. Some investigators have reported that dynamic MRI provides information on enhanced patterns of peripheral pulmonary lesions.’ Awaya et al has reported that the bronchi and vessels can be seen as they cross peripheral lesions. The advantage of MRI is that it is less invasive than EBUS, but the images are of poorer quality because the beating heart and breathing introduce motion artifacts.
Figure 11. EBUS images of a type IIIb lesion. The lesions were avascular, and mottled or linear hyperechoic areas could scarcely be seen. The internal echoes were heterogeneous.