Abstract
Objective The objective is to assess the value of spatial distribution difference in iodine concentration between malignant and benign solitary pulmonary nodules (SPNs) by analyzing multiple parameters of spectral CT. Methods Sixty patients with 39 malignant nodules and 21 benign nodules underwent chest contrast CT scans using spectral imaging mode during pulmonary arterial phase (PP), arterial phase (AP), and venous phase (VP). Iodine concentrations of proximal and distal regions in pulmonary nodules on iodine-based material decomposition images were recorded. Normalized iodine concentration (NIC) and the differences in NIC between the proximal and the distal regions (dNIC) were calculated. The two-sample t-test and Mann–Whitney U-test were performed to compare the multiple parameters generated from spectral CT between malignant and benign nodules. Receiver operating characteristic (ROC) curves were generated to calculate sensitivity and specificity. Results NIC in the proximal region (NICpro) and NIC in the distal region (NICdis) between malignant and benign nodules at AP (NICpro, P=0.012; NICdis, P=0.024), and VP (NICpro, P=0.005; NICdis, P =0.004) were significantly different. NICpro at PP (P = 0.037) was also found significantly different between malignant and benign nodules; however, no significant differences were found in NICdis at PP (P = 0.093). In addition, the dNIC of malignant nodules was significantly higher than that of benign ones at PP (median and interquartiles (0.31, 0.11, 0.57 versus -0.26, -0.5, -0.1); p≤0.001), AP (mean dNIC, 0.093 ±0.094 versus -0.075±0.060; p≤0.001), and VP (mean dNIC, 0.171±0.137 versus -0.183±0.127; p≤0.001). The sensitivity and specificity (93%, 95%, respectively) of dNIC during VP were higher than other parameters, with a threshold value of -0.07. Conclusions Spectral CT imaging with multiple parameters such as NICpro, NICdis, and dNIC may be a new method for differentiating malignant SPNs from benign ones.
Highlights
Solitary pulmonary nodules (SPNs) which are defined as the isolated, round, or oval areas of increased opacity less than or equal to 3cm in diameter, surrounded by lung parenchyma, should not be associated with atelectasis, pulmonary hilar enlargement, or pleural effusion [1,2,3]
Gemstone spectral imaging (GSI) is a novel introduced technique based on the rapid switching between high- and low-energy data sets from view to view during a single rotation on the high-definition GE Discovery CT750 HD scanner, which provides more analyzing tools and quantitative parameters to help distinguish the malignant SPNs from the benign ones [8, 10]
Significant differences were found in NICpro at PP (median and interquartiles (0.67, 0.41, 1.19 versus 0.38, 0.19, 0.82); P = 0.037)
Summary
Solitary pulmonary nodules (SPNs) which are defined as the isolated, round, or oval areas of increased opacity less than or equal to 3cm in diameter, surrounded by lung parenchyma, should not be associated with atelectasis, pulmonary hilar enlargement, or pleural effusion [1,2,3]. Gemstone spectral imaging (GSI) is a novel introduced technique based on the rapid switching between high- and low-energy data sets from view to view during a single rotation on the high-definition GE Discovery CT750 HD scanner, which provides more analyzing tools and quantitative parameters to help distinguish the malignant SPNs from the benign ones [8, 10]. It could enable the generation of material decomposition images that allows one to measure iodine component on iodine-enhanced images, and this is considered to be comparable to the real value of enhancement. Iodine concentration on iodine-enhanced images generated from spectral CT reflects the blood supply
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