Dynamic contrast-enhanced CT to assess metabolic response in patients with advanced non-small cell lung cancer and stable disease after chemotherapy or chemoradiotherapy

Objectives To compare tumour enhancement patterns measured using dynamic contrast-enhanced (DCE)-CT with tumour metabolism measured using positron emission tomography (PET)-CT in patients with non-small cell lung cancer (NSCLC) and stable disease after chemotherapy or chemoradiotherapy. Methods After treatment, 75 NSCLC tumours in 65 patients who had stable disease on DCE-CT according to Response Evaluation Criteria in Solid Tumour (RECIST) were evaluated using PET-CT. On DCE-CT, relative enhancement ratios (RER) of tumour at 30, 60, 90, 120 s and 5 min after injection of contrast material were measured. Metabolic responses of tumours were classified into two groups according to the maximum standardized uptake value (SUVmax) by PET-CT: complete metabolic response (CR) with an SUVmax of less than 2.5, and noncomplete metabolic response (NR) with an SUVmax of at least 2.5. Results Using the optimal RER 60 cutoff value of 43.7 % to predict NR of tumour gave 95.7 % sensitivity, 64.2 % specificity, and 82.1 % positive and 95.0 % negative predictive values. After adjusting for tumour size, the odds ratio for NR in tumour with an RER 60 of at least 43.7 % was 70.85 (95 % CI = 7.95–630.91; P < 0.05). Conclusions Even when disease was stable according to RECIST, DCE-CT predicted hypermetabolic status of residual tumour in patients with NSCLC after treatment. Key Points • Dynamic contrast-enhanced CT (DCE-CT) can provide useful metabolic information about non-small cell lung cancer. • NSCLC lesions, even grossly stable after treatment, show various metabolic states. • DCE-CT enhancement patterns correlate with tumour metabolic status as shown by PET. • DCE-CT helps to assess hypermetabolic NSCLC as stable disease after treatment.