The objective of this study was to investigate the correlation between dual-energy computed tomography (DECT)–based iodine quantitation and fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) imaging for response evaluation of lung cancers to treatment.Methods
In this prospective study, a total of 32 pairs of DECT and 18F-FDG PET/CT imaging acquired consecutively from 13 patients with primary or metastatic lung cancers receiving either radiotherapy alone or chemoradiotherapy were analyzed. Imaging examinations were performed before, immediately, and no later than 6 months after treatment for response evaluation. Iodine-related parameters including the total iodine uptake (TIU) and vital volume (VIV) from DECT and metabolic metrics such as the standardized uptake value normalized to lean body mass (SULpeak), metabolic tumor volume (MTV), and the total lesion glycolysis (TLG) from 18F-FDG-PET/CT were generated and measured by semiautomatic approaches. Dual-energy CT and PET/CT metrics were calculated and followed up with comparison with response evaluation criteria in solid tumors (RECIST).Results
Analysis of pretreatment imaging data revealed a strong correlation between DECT metrics (RECIST, TIU, and VIV) and 18F-FDG PET/CT metrics (MTV, TLG) with coefficients of R ranging from 0.86 to 0.90 (P < 0.01). With the delivery of treatment, all measured DECT and PET/CT metrics significantly decreased whereas the descending amplitude in RECIST was significantly smaller than that of the remaining parameters (P < 0.05). During follow-up examinations, both metrics followed a similar changing pattern. Overall, strong consistency was found between RECIST, TIU, VIV and SULpeak, MTV, TLG (R covers 0.78–0.96, P < 0.05).Conclusions
Semiautomatic iodine-related quantitation in DECT correlated well with metabolism-based measurements in 18F-FDG PET/CT, suggesting that DECT-based iodine quantitation might be a feasible substitute for assessment of lung cancer response to chemoradiotherapy/radiotherapy with comparison with 18F-FDG PET/CT.