Omata S, et al. - Authors attempted to determine the useful computed tomography (CT) features for distinguishing between focal atelectasis (FA) and pleural dissemination (PD) with the intention of obtaining the optimal therapeutic strategy for thymic epithelial tumors (TET). It was observed that FA lesions tended to occur on the dorsal side; presented with shorter major and minor axes, a triangular shape, a spinous shadow and ground glass opacities (GGO) and be close to a peripheral pulmonary artery (PA). The location of 90% of PD lesions was in the left thorax, and all of them were ipsilateral to the tumor. Therefore, it was inferred that the site, size, and shape of a lesion; the presence of a spinous shadow/GGO; and the distance to the nearest PA were beneficial for distinguishing between PD and FA.

Methods

• The preoperative CT images of 27 TET, which included 40 PD and 40 FA lesions were retrospectively examined.
• For this study, 2 radiologists independently interpreted the pleural lesions without knowing the final diagnosis.
• The CT images were analyzed with the intention of determining the lesion location, size, and shape, presence of a spinous shadow and ground glass opacities (GGO) near to the lesion, and the shortest distance from the lesion to the nearest peripheral pulmonary artery (PA).

Results

• The occurrence of FA lesions tended to be on the dorsal side (90%, P=0.024).
• These lesions displayed shorter major and minor axes (P < 0.001), a triangular shape (43%, P=0.002), a spinous shadow (45%, P=0.001) and GGO (28%, P=0.006); and be close to a peripheral PA (P=0.007).
• Findings revealed the location of 90% PD lesions to be in the left thorax, and all of them were ipsilateral to the tumor (both P < 0.001).
• It was observed that the 9 examined factors demonstrated sensitivity, specificity, positive predictive, and negative predictive values of 85%, 95%, 94%, and 86%, respectively, for diagnosing FA (when ≥3 factors were present), and 90%, 48%, 63%, and 83%, respectively, for diagnosing PD (when ≥4 factors were present).