Dual-phase dual-energy CT in patients with lung cancer: assessment of the additional value of iodine quantification in lymph node therapy response

To investigate the potential contribution of iodine uptake calculation from dual-phase dual-energy CT (DE-CT) for lymph node staging and therapy response monitoring in lung cancer patients. Retrospective analysis of 27 patients with non-small cell lung carcinoma (NSCLC), who underwent dual-phase DE-CT before and after chemotherapy, was performed. Iodine uptake (mg/mL) and total iodine uptake (mg) were calculated using prototype software in the early (arterial) and late (venous) post-contrast circulatory phase in 110 mediastinal lymph nodes. The arterial enhancement fraction (AEF) was calculated and compared with lymph node size and response to chemotherapy. A significant difference of AEF was observed between enlarged (90.4 %; 32.3-238.5 %) and non-enlarged (72.7 %; -37.5-237.5 %) lymph nodes (p = 0.044) before treatment onset. A significantly different change of AEF in responding (decrease of 26.3 %; p = 0.022) and non-responding (increase of 43.0 %; p = 0.031) lymph nodes was demonstrated. A higher value of AEF before treatment was observed in lymph nodes with subsequent favourable response (88.6 % vs. 77.7 %; p = 0.122), but this difference did not reach statistical significance. The dual-phase DE-CT examination with quantification of ratio of early and late post-contrast iodine uptake is a feasible and promising method for the functional evaluation of mediastinal lymph nodes including therapy response assessment. aEuro cent Dual-phase DE-CT is beneficial for mediastinal lymph node assessment in NSCLC. aEuro cent Arterial to venous iodine uptake ratio was higher in enlarged lymph nodes. aEuro cent Change of arterial enhancement fraction correlated to therapy response.