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 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).

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.