Does Combining Lung Ventilation Information to Perfusion Provide Any Additional Value for Treatment Planning?
X Shi*, T Diwanji, S Chen, W D'Souza, N Mistry, University of Maryland School of Medicine, Baltimore, MDSU-E-J-96 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: Recently, there have been efforts to incorporate regional lung function during treatment planning to limit radiation toxicity in the lungs. However, most efforts have focused on using either perfusion or ventilation alone in designing a function based treatment plan. There have been no reports whether combining the two metrics of lung function will add value. In this study, we test whether the two modalities provide redundant information by analyzing the distribution of perfusion in areas of low and high ventilation.
Methods: Five patients with non-small cell lung cancer (NSCLC) were recruited in a prospective study. Perfusion imaging was carried out using dynamic contrast enhanced MRI, and ventilation imaging was carried out using 4DCT. Anatomical and functional images were matched using an affine transform. The lung was segmented into regions of high and low ventilation using the threshold as the mean of lung ventilation. For both regions, the average pulmonary blood flow (PBF) value and the histogram of the PBF distribution were obtained and compared.
Results: Visual spatial assessment of lung ventilation/perfusion images show areas of general agreement as expected (V/Q match). However, this is not true on a voxel-by-voxel assessment. For 4 out of 5 patients, the average PBF value is similar (0.123 vs 0.127; 0.049 vs 0.045; 0.062 vs 0.063; 0.091 vs 0.080) between areas of low and high ventilation. The remaining patient had only one functioning lung showing high correspondence between ventilation and perfusion.
Conclusion: The necessity of including the ventilation information into functional treatment planning for patients with thoracic tumors was investigated. Early results suggest that for most cases combining ventilation and perfusion can provide additional insight for function based treatment planning. Further studies are needed to validate the findings from this preliminary study.
Funding Support, Disclosures, and Conflict of Interest: Supported by Varian Medical Systems