RESUMO
Objective: To investigate the clinical value of gemstone energy spectral CT imaging for the quantitative analysis of early lung adenocarcinoma. Methods: 76 cases of pulmonary ground-glass nodules pathologically confirmed as precancerous lesion and early lung cancer (including pure ground-glass nodules in 46 cases and mixed ground-glass nodules in 30 cases) underwent chest CT scan first and then underwent contrast-enhanced gemstone energy spectral CT to get arterial phase images, venous phase images, and delayed phase images. All the lesions were set the region of interest (ROI). Cases of the pure ground-glass nodule (pGGN) were measured at the maximum level of lesions, cases of the mixed ground-glass nodule (mGGN) were measured in two areas of ground-glass and solid components, CT value and iodine concentrations of lesions in three-phase scanning were separately measured, and at the same time, iodine concentrations of the thoracic aorta were also measured. The normalized iodine concentrations (NICs) were calculated, that is, the ratio of iodine concentrations of lesions and the thoracic aorta. CT values of lesions were also measured at each stage of 70 keV. All the quantitative data were expressed by the mean ± standard deviation, and paired t-test was used for pairwise comparison. Results: In 76 cases, in the spectral CT imaging mode, the NIC value of solid components of the GGN was 0.33 ± 0.16 in the arterial phase (AP), 0.52 ± 0.25 in the venous phase (VP), and 0.58 ± 0.34 in the delayed phase (DP). There were significant differences of P values of NICs between each two phases in both solid component cases and the ground-glass component cases in AP/VP, VP/DP, and AP/DP (P < 0.05); there were no statistically significant P values of CT values between each two phases in three-period enhanced CT in both the solid component cases and the ground-glass component cases in AP/VP, VP/DP, and AP/DP (P > 0.05). Conclusion: Gemstone energy spectral CT with quantitative imaging can dynamically reflect the enhancement features of the pulmonary GGN.
RESUMO
PURPOSE: To quantitatively assess the value of dual-energy CT (DECT) in differentiating malignancy and benignity of solitary pulmonary nodules. MATERIALS AND METHODS: Sixty-three patients with solitary pulmonary nodules detected by CT plain scan underwent contrast enhanced CT scans in arterial phase (AP) and venous phase (VP) with spectral imaging mode for tumor type differentiation. The Gemstone Spectral Imaging (GSI) viewer was used for image display and data analysis. Region of interest was placed on the relatively homogeneous area of the nodule to measure iodine concentration (IC) on iodine-based material decomposition images and CT numbers on monochromatic image sets to generate spectral HU curve. Normalized IC (NIC), slope of the spectral HU curve (λHU) and net CT number enhancement on 70keV images were calculated. The two-sample t-test was used to compare quantitative parameters. Receiver operating characteristic curves were generated to calculate sensitivity and specificity. RESULTS: There were 63 nodules, with 37 malignant nodules (59%) and 26 benign nodules (41%). NIC, λHU and net CT number enhancement on 70keV images for malignant nodules were all greater than those of benign nodules. NIC and λHU had intermediate to high performances to differentiate malignant nodules from benign ones with the areas under curve of 0.89 and 0.86 respectively in AP, 0.96 and 0.89 respectively in VP. Using 0.30 as a threshold value for NIC in VP, one could obtain sensitivity of 93.8% and specificity of 85.7% for differentiating malignant from benign solitary pulmonary nodules. These values were statistically higher than the corresponding values of 74.2% and 53.8% obtained with the conventional CT number enhancement. CONCLUSIONS: DECT imaging with GSI mode provides more promising value in quantitative way for distinguishing malignant nodules from benign ones than CT enhancement numbers.