Dual-energy dynamic CT of lung adenocarcinoma: correlation of iodine uptake with tumor gene expression

ObjectivesTo compare iodine content (IC) of solitary lung cancer using dynamic measurements of CT attenuation (Hounsfield Units, HU) and to correlate their quantitative CT data with expressions of vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) and hypoxia-inducible factor-1α (HIF-1α) using immunostaining methods.MethodsThis study included 18 patients with adenocarcinoma, who undergone dual energy dynamic multiphase CT to examine solitary lung nodules (6 part-solid and 12 solid nodules). Tumor size was 21.1 mm ± 8.1 (9-39 mm) [Mean ± SD (range)]. Contrast volume was determined by weight (2 ml/kg). Contrast volume and injection rate were 110.5 ml ± 17.2 (80-144 ml) and 1.84 ml/s ± 0.30 (1.3-2.4 ml/s), respectively. Enhancement values ([CT value at each delayed scan-CT value at unenhanced scan]) and net enhancement values ([peak CT value-CT value at unenhanced scan]) were calculated in HU from 65 keV monochromatic image. IC at each delayed scan was measured in mg/cm3 from the iodine-water material decomposition pair on the advantage workstation VolumeShare4. Immunostaining using VEGF, EGFR, and HIF-1α was performed by two pathologists, who evaluated the expression level of them subjectively. Statistical analyses were performed with rank correlation tests and regression analysis.ResultsIC at 2- and 3-minute delayed scan (x) and immunostaining score of HIF-1α (y) showed a significantly positive correlation (r = 0.64 and 0.52, p = 0.004 and 0.03): regression equation, y = 1.34 + 0.58 x and y = 1.51 + 0.55x, respectively.ConclusionsDual-energy dynamic multiphase CT can measure iodine content in lung adenocarcinoma. Iodine content at 2- and 3-minute delayed scan might correlate with the expression level of HIF-1α.