Room: Karl Dean Ballroom C
Purpose: Esophageal cancer patients treated with chemo-radiation and surgery are at a risk of developing pulmonary complications. 4DCT-ventilation is an exciting imaging modality that uses 4DCT data to calculate lung ventilation. 4DCT-ventilation has been applied for functional avoidance and early toxicity assessment in the lung cancer population but has yet to be extended to esophageal cancer patients. The purpose of this study was to characterize 4DCT-ventilation-based spatial lung function for esophageal cancer patients.
Methods: Thirty-five esophageal cancer patients that underwent 4DCTs were used for the study. A 4DCT-ventilation map was calculated using the patientâ€™s 4DCT imaging and a density-change-based algorithm. To assess each patientâ€™s ventilation profile, radiologist interpretations and quantitative metrics were used. A radiologist interpreted the 4DCT-ventilation images for lobar-based defects and gravity-dependent atelectasis. The 4DCT-ventilation maps were reduced to single metrics intended to reflect the degree of ventilation heterogeneity. The quantitative metrics included the coefficient of variation (CoV) (standard-deviation/mean) and a metric based on superior-inferior ventilation third heterogeneity (Vent-SI). The functional profile of esophageal cancer patients was characterized, and for reference, compared to a cohort 35 lung cancer patients.
Results: Radiologist observation revealed that 29% of esophageal patients had lobar-based ventilation defects (74% for lung cancer patients) and 51% had gravity-dependent atelectasis. The CoV was larger and the Vent-SI metric was smaller for the lung cancer cohort (0.56 vs 0.53 for CoV and 69% vs 73% for Vent-SI) than the esophageal cohort (p<0.05), indicating that esophageal patients had a more homogenous lung function profiles than lung cancer patients.
Conclusion: The presented data demonstrated with both radiologist observations and quantitative metrics that about 30% of esophageal cancer patients have lung ventilation defects amenable to functional avoidance. Our study provides the first seminal data-set to advance 4DCT-ventilation applications in order to reduce thoracic toxicity for esophageal cancer patients.