Photon-counting computed tomography in esophageal cancer: correlation of iodine concentration with histopathology and treatment response to neoadjuvant radiochemotherapy.

Abstract

Evaluating esophageal cancer (EC) response to neoadjuvant radiochemotherapy (NARC) has been challenging, but photon-counting CT (PCCT) provides multiparametric data, including iodine concentration (IC), which can be utilized for evaluation. This study explored the relationship between IC and histopathological features of EC, assessing its role in predicting NARC responses. Of 105 patients with EC, 85 (67 men; mean age 66.0 ± 11.0 years) met the inclusion criteria and underwent PCCT scans during the portal venous phase. Normalized iodine concentration (NIC) was calculated, and tumor characteristics, including stage, grade, and lymphovascular invasion, were analyzed. Statistical analyses included Mann-Whitney U tests, sensitivity, specificity, and area under the curve (AUC) calculations. Interobserver reliability of NIC measurements was assessed. Interobserver reliability for NIC was excellent (ICC = 0.99 for all tumors, p < 0.01). In adenocarcinoma, NIC was lower in good therapy responders (Becker 1a/1b: 0.40 ± 0.13) than poor responders (Becker 2/3: 0.51 ± 0.12, p = 0.01). An NIC cutoff ≤ 0.41 predicted good regression (OR = 4.77, p = 0.03; AUC = 0.704, sensitivity = 72.2%, specificity 64.7%). Poor response prediction showed moderate accuracy (AUC = 0.662). NIC values show excellent interobserver agreement and can predict treatment response to NARC in EC, particularly for adenocarcinomas, where lower NIC values are linked to better outcomes. While NIC provides good predictive value, further studies with larger sample sizes are needed to confirm these findings and explore additional factors influencing outcomes. Question Does photon-counting CT-derived iodine concentration correlate with key histopathological features in esophageal cancer and predict response to neoadjuvant radiochemotherapy? Findings Photon-counting CT-derived normalized iodine concentration in esophageal adenocarcinoma moderately predicted treatment response, despite no correlation with tumor grade or Ki-67. Clinical relevance Normalized iodine concentration values from photon-counting CT, obtained during routine staging exams, offer an objective method for predicting treatment response in esophageal adenocarcinoma, enabling more precise therapy planning and personalized patient management.