PURPOSE: Visualization of a posterior junction line on chest x-ray is evidence for emphysema. The correlation between a CT posterior junction line and emphysema is less clear.
METHODS: 137 patients were identified with CT and PFT's performed within 3 months in a University hospital. The posterior junction line was measured at 2 levels by a blinded investigator. The width of the line was correlated to CT evidence of emphysema and with clinical and PFT data.
RESULTS: The posterior junction line was only weakly correlated to CT emphysema severity scoring (r2 = −0.25, p<0.01). Narrower junction line showed little correlation with PFT evidence of emphysema as assessed by FEV1/FVC ratio (r = 0.08) and DLCO percent predicted (r = 0.14). The ROC curve for posterior junction line width for the diagnosis of emphysema was only 0.73, with a maximum accuracy at 1.2 cm.
CONCLUSION: Our data suggests that there is only weak statistical correlation between the posterior junction line and emphysema and it should not be considered clinically useful.
CLINICAL IMPLICATIONS: Though a posterior junction line on CXR is stongly indicative of emphysema, visualization of a PJL on CT should not be taken as evidence of hyperinflation or airflow obstruction. Standard CT criteria for emphysema is more sensitive and specific.
DISCLOSURE: Gina Zarrilli, No Financial Disclosure Information; No Product/Research Disclosure Information