Primarily, VRI will be compared to perfusion (Q) scan by predicted post-operative (ppo) FEV1 and DLCO as predicted by VRI versus as predicted by Q scan. Secondary, the ppo as predicted by each test will be compared with the actual FEV1 and DLCO at 3 months post-operative; If these two methods provide similar results, VRI will be deemed an acceptable alternative to Q scan for determining patient selection for lung resection. Finally, the patient outcomes (30 day mortality and pulmonary complications) for those patients falling within guideline parameters using the VRI measurement will be analyzed to see if using VRI in clinical practice would indeed allow prediction of satisfactory results (similar to literature benchmarks).