Separation between the chest wall and subpleural lung lesions: A two-step method to preoperatively exclude invasion or focal pleural adhesion by multidetector computed tomography

Correlation between pleural tags on CT and visceral pleural invasion of peripheral lung cancer that does not appear touching the pleural surface

OBJECTIVES

To evaluate the association between a sign and visceral pleural invasion (VPI) of peripheral non-small-cell lung cancer (NSCLC) that does not appear touching the pleural surface.

METHODS

A total of 221 consecutive patients with NSCLC that did not appear touching the pleural surface, ≤ 3 cm in solid tumor diameter, and was surgically resected between January 2009 and December 2015 were included. We focused on the flat distortion of the tumor caused by an arch-shaped linear tag between the tumor and the pleura on CT and named it a bridge tag sign. We evaluated the associations between the clinicopathological features of the tumor, including the bridge tag sign, and VPI. We also evaluated the associations between histopathological findings and the bridge tag sign. The utility of the bridge tag sign in the diagnosis of VPI was statistically assessed.

RESULTS

The bridge tag sign was observed in 48 (20.8%) patients. VPI was positive in 9 (4.1%) patients; among these, the bridge tag sign was positive in 8 patients. In multivariate analysis, a bridge tag sign was significantly associated with VPI. The bridge tag sign was associated with longer contact length of the pleura with the tumor and trapezoid type pleural retraction. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the bridge tag sign in the diagnosis of VPI were 88.9%, 83.5%, 83.7%, 18.6%, and 99.4%, respectively.

CONCLUSIONS

A bridge tag sign on CT might improve the accuracy of the prediction of VPI.

KEY POINTS

• We present the bridge tag sign which is defined as a flat distortion of an NSCLC tumor by an arch-shaped linear tag between the tumor and chest wall or interlobar fissure. • The bridge tag sign was an independent predictive factor for visceral pleural invasion. • The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the bridge tag sign in the diagnosis of visceral pleural invasion were 88.9%, 83.5%, 83.7%, 18.6%, and 99.4%, respectively.

Usability of the lateral decubitus position on four-dimensional ultra-low-dose computed tomography for the detection of localized pleural adhesion in the pulmonary apical region

BACKGROUND

Localized pleural adhesion (LPA) evaluation in the apical region is difficult even with four-dimensional ultra-low-dose computed tomography (4D-ULDCT) in the supine position due to smaller pleural movements.

PURPOSE

To assess usability of 4D-ULDCT in the lateral decubitus (LD) position for LPA detection in the apical region.

MATERIAL AND METHODS

Forty-seven patients underwent 4D-ULDCT of a single respiration cycle with 16-cm coverage of body axis in supine and LD positions with the affected lung uppermost. Intraoperative thoracoscopic findings confirmed LPA presence. A pleural point and a corresponding point on costal outer edge were placed in identical axial planes at end-inspiration. Pleuro-chest wall distance between two points (PCD) was calculated at each respiratory phase. In the affected lung, average change in amount of PCD (PCD_ACA) was compared between patients with and without LPA in total and two sub-groups (non-COPD and COPD, non-emphysematous and emphysematous patients) in supine and non-dependent (ND) LD positions. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal thresholds in PCD_ACA for differentiating patients with LPA from those without.

RESULTS

In COPD/emphysematous patients and total population, PCD_ACA with LPA was smaller than in those without in the supine and NDLD positions for overall, lateral, and dorsal regions. For the lateral region in COPD patients, area under ROC curve (AUC) increased from supine (0.64) to NDLD position (0.81). For the dorsal region in emphysematous patients, AUC increased from supine (0.76) to NDLD position (0.96).

CONCLUSION

4D-ULDCT in LD position may be useful for LPA detection in apical regions for COPD and/or emphysematous patients.