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

Abstract

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. 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. Using the optimal RER60 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 RER60 of at least 43.7 % was 70.85 (95 % CI = 7.95-630.91; P < 0.05). Even when disease was stable according to RECIST, DCE-CT predicted hypermetabolic status of residual tumour in patien