Biomedical Profiling of Lung Tumor via Ventilation-Induced Tumor Deformation: Implications on the Prognosis of Lung Cancer.

To quantitatively characterize tumor biomechanical rigidity via ventilation-induced tumor deformation (VITD) and assess its prognostic values. This study utilized 10-bin 4D-CT and PET scans for 16 lung cancer patients (7 squamous cell carcinoma (SCC) and 9 adenocarcinoma (AC)). First, tumor surface models were generated based on binary segmentation for 10 respiratory phases and regionally aligned using surface-based registration. The resultant shape descriptors () across respiration phases were assembled as an intra-subject VITD. Subsequently, tumor strain was approximate as the magnitude of the averaged shape changes (VITD mag) between end-of-exhale (EOE) and end-of-inhale (EOI) phases in the relevant regions - areas showing significant morphological correlations with the respective lung volume trajectory. Afterward, para-tumor stress (PTS) was approximated as the averaged displacements in the dilated para-tumor region, by deforming EOE to EOI 4D-CTs. Finally, VITD rigi was calculated as PTS over VITD mag. To assess the prognostic value of the VITD model, VITD mag and VITD rigi were correlated with PET-derived SUV max for AC and SCC tumors, respectively. On lung SCC tumors, VITD mag , the extent of maximal shape changes in respiration, was negatively associated with SUV max, indictive of elevated tumor metabolism (r= -0.88, p= 0.01). After controlling for PTS, an increase in the derived tumor rigidity (VITD rigi) was found to be significantly associated with increased SUV max , with r= 0.76 and p= 0.04. In contrast, on AC tumors, featuring surfactant overproduction and thus complex tissue composition, neither VITD mag nor VITD rigi presented a significant association with SUV max (p = 0.98 and 0.88). We introduced a novel noninvasive pipeline to characterize lung tumor rigidity based on VITD in 4D-CT. The derived VITD rigi in lung SCC significantly correlated with tumor metabolism, indicating tumor aggressiveness. The proposed VITD model provides new biomechanical evidence in lung SCC prognosis. For AC tumors with complex tissue composition, deeper radiographic profiling besides tumor deformation is needed to effectively characterize its biomechanical properties. [ABSTRACT FROM AUTHOR]