Pulmonary lymphangitic carcinomatosis: diagnostic performance of HRCT and ¹⁸F-FDG–PET/CT in correlation to clinical pathologic outcome.

Abstract

Rationale: To investigate the performance of high-resolution computed tomography (HRCT) versus ¹⁸F-FDG-PET/CT for the diagnosis of pulmonary lymphangitic carcinomatosis (PLC). Methods: In this retrospective institutional approved study, ninety-four patients addressed for initial staging of lung cancer with suspicion of PLC were included. Using double blind analysis, we assessed the presence of signs favoring PLC on HRCT (smooth or nodular septal lines, subpleural nodularity, peribronchovascular thickening, satellite nodules, lymph node enlargement and pleural effusion). ¹⁸F-FDG-PET/CT images were reviewed to qualitatively evaluate peritumoral uptake and to quantify tracer uptake in the tumoral and peritumoral areas. Histology performed on surgical specimens served as gold standard in all patients. Results: Among 94 included patients, 73% (69/94) had histologically confirmed PLC. Peribronchovascular thickening, lymph nodes involvement and increased peritumoral uptake were more often present in patients with PLC (p<0.009). Metabolic variables including tumor SUV_max, SUVmean, “metabolic tumor volume” (MTV) and total lesion glycolysis (TLG) as well as peritumoral SUV_max, SUVmean and their respective ratios to background were significantly higher in PLC group versus the non-PLC group (p≤0.0039). Sensitivity, specificity, and ROC area [95%CI] of peribronchovascular thickening (69%, 83% and 0.76 [0.67–0.85]) and increased peritumoral uptake (94%, 84% and 0.89 [0.81–0.97]) were similar (P = 0.054). Peritumoral SUV_max and SUVmean had a significantly higher sensitivity, specificity, and ROC area of 97%, 92% and 0.98 [0.96–1.00] and 94%, 88% and 0.96 [0.92–1.00] for detecting PLC (all p≤0.025). Conclusion: Qualitative evaluation of ¹⁸F-FDG-PET/CT and HRCT have similar performance for the diagnosis of PLC, both being outperformed by ¹⁸F-FDG-PET/CT quantitative parameters.