15O-Water Dynamic Positron Emission Tomography in Patients with Non-Small Cell Lung Cancer: Early Decrease in Blood Flow After Anti-Angiogenic Treatment is Correlated with a Shorter Time to Tumour Progression

Purpose: To evaluate tumour blood flow in patients with non-small cell lung cancer (NSCLC) who underwent chemotherapy with bevacizumab before and after administration of chemotherapy using 15O-water positron emission tomography (PET), and to investigate the effects of bevacizumab on tumour blood flow changes and progression-free survival (PFS).Methods: Twelve patients with NSCLC were enrolled. Six patients had chemotherapy with bevacizumab, and the other six had chemotherapy without bevacizumab. 15O-water dynamic PET scans were performed within 1week before the start of chemotherapy and within 1 week after the first day of chemotherapy. Tumour blood flow was analysed quantitatively using a single one‑tissue compartment model with the correction of pulmonary circulation blood volume and arterial blood volume via an image-derived input function. Results: In the bevacizumab group mean tumour blood flow had reduced statistically significantly post-chemotherapy (pre-chemotherapy 0.27 ± 0.14 mL/cm3/min, post‑chemotherapy 0.18 ± 0.12 mL/cm3/min). In the no bevacizumab group there was no significant difference between mean tumour perfusion pre-chemotherapy (0.42 ± 0.42 mL/cm3/min) and post-chemotherapy (0.40 ± 0.27 mL/cm3/min). In the bevacizumab group there was a positive correlation between the blood flow ratio (tumour blood flow post-chemotherapy/tumour blood flow pre-chemotherapy) and PFS (correlation coefficient 0.94).Conclusion: Mean tumour blood flow decreases within 1–2 days after bevacizumab administration. Greater reductions in blood flow were associated with shorter PFS.