Energy spectrum computed tomography improves the differentiation between benign and malignant solitary pulmonary nodules

Purpose: To evaluate the diagnostic efficiency of computed tomography (CT) values at the 40~140 keV monochromatic level for the differential diagnosis of solitary pulmonary nodules (SPNs). Methods: Energy spectrum CT data of 44 patients with SPNs were analyzed retrospectively; 24 patients with malignant SPNs served as the malignant group and 20 patients with benign SPNs served as the benign group. The basic material concentration and the enhancement degree differences in double-phase enhanced scans were compared between the two groups. The sensitivity and specificity were calculated to determine diagnosis, and were compared with the pathology results. Results: The CT values at the 40~90 keV monochromatic level and the iodine concentrations of malignant group were higher than those of benign group in the arterial phase (all P < 0.05). The enhancement degree of the malignant group was higher than that for the benign group in the arterial phase (36.36 ± 33.18 HU vs 16.93 ± 24.17 HU t = 2.243, P = 0.030); however, the enhancement degrees of the two groups were similar in the venous phase (21.99 ± 15.87 HU vs 17.62 ± 24.15 HU t = 0.694, P = 0.493). The area under the curve of the enhancement degree in the arterial phase was 0.792. Conclusions: Monochromatic imaging and base material concentration of energy spectrum CT can help differentiate between benign and malignant SPNs.