Dynamic contrast-enhanced CT in advanced lung cancer after chemotherapy with/without radiation therapy : can it predict treatment responsiveness of the tumor?

Abstract

Purpose: To assess whether the enhancement pattern of tumors at early stages of treatment of advanced lung cancer using dynamic contrast-enhanced (DCE) CT is an useful tool to predict treatment response during follow-up.Methods: We evaluated two study groups in advanced lung cancer patients who underwent DCE-CT after chemotherapy or chemoradiotherapy. In group A, 65 patients with advanced lung cancer underwent both DCE-CT and PET-CT after the therapy, and the lesions were divided into two groups (noncomplete response and complete response groups) by the maximum standardized uptake value (SUVmax) as 2.5 on the PET-CT images. In group B, 42 patients underwent both DCE-CT and follow-up conventional CT and the lesions were divided into three groups (partial response, stable disease and progressive disease) according to the treatment response evaluated under RECIST 1.1 criteria on follow up conventional CT.The DCE-CT images were acquired before contrast media injection and 30, 60, 90, 120 seconds, and 5 minute after injection of contrast material. We measured the peak and net enhancement (PE and NE, respectively), relative enhancement ratio (RERs) at each time point, washout (WO) and time-density curves (TDCs) (type A, B, C, and D) on DCE-CT images.Results: The mean PE and NE attenuation values were significantly higher in the noncomplete response (NR) group than in the complete response (CR) group (p < 0.05). The DCE-CT images of tumors in the NR group showed rapid enhancement with a sharp acceleration slope, while in the CR group, a slow enhancement pattern was observed until the PE was reached. The RERs till 120 seconds on the DCE-CT images showed moderate correlations with SUVmax on the PET-CT images (r = 0.373 to 0.603, p < 0.05).NE and PE values were significantly higher in the progressive disease (PD) group than in the stable disease (SD) or partial response (PR) groups (p < 0.05). Types B, C, and D on TDCs were observed mostly in the PR and SD groups (96.0%), whereas type A was most frequent in the SD and PD groups (97.2%), which were significantly different in terms of PE and NE.Conclusions: Contrast enhancement patterns on DCE-CT images differed according to treatment results. Therefore, DCE-CT scans can be helpful in predicting treatment response of advanced lung cancer after treatment.