Program Information
Ventilation and Strain for Lung Functional Mapping: Which One Is More Sensitive Biomarker to Deformation Changes?
I Duarte1*, T Cui2 , F Yin3 , J Cai4 , (1) ,,,(2) Cleveland Clinic, Cleveland, OH, (3) Duke University Medical Center, Durham, NC, (4) Duke University Medical Center, Durham, NC
Presentations
TU-C2-GePD-JT-1 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Joint Imaging-Therapy ePoster Theater
Purpose: Purpose: Lung strain and lung ventilation are promising biomarkers to assess lung function in radiotherapy response assessment. This study aims to determine which functional metric is more sensitive and can potentially reveal more information about lung deformation changes.
Methods: The end-of-exhalation (EOE) and the end-of-inhalation (EOI) phases from 4DCT scans of 10 patients were registered via deformable image registration (VelocityAI) to calculate the displacement vector fields (DVFs). 3D lung ventilation maps and strain maps were generated based on the DVFs from each image registration. The voxel-by-voxel algorithm used to calculate the ventilation maps was based on computing the Jacobian Determinant of the DVF which provides information about the local behavior of a vector-valued function. The lung strain, defined as a change in displacement, was computed voxel-wise through an algorithm which calculates a 3x3 tensor that directly measures both the magnitude and direction of the long deformation and determines the three principal strains at each voxel. The DVFs were modified in magnitude and direction, the mean of the absolute percentage differences between the maps generated from the original DVFs versus the altered DVFs were calculated.
Results: For a uniform 15% and 50% change in DVF magnitude, the mean percent differences for strain were 0.62% and 2.14% respectively, while 0.94% and 3.63% for ventilation. For a change in DVF direction (an angle change), the differences were 2.59% for strain and 4.90% for ventilation.
Conclusion: Preliminary results suggest that lung ventilation might be a more sensitive metric to deformation changes, compared to strain, showing larger percent differences when DVFs are altered and new maps are generated. This will be further tested with different DVF modifications and with a larger data set.
Funding Support, Disclosures, and Conflict of Interest: NIH R21CA195317
Contact Email: