[Dynamic enhanced CT evaluation of solitary pulmonary nodules].

Objective: To evaluate the value of dynamic enhanced-CT in differential diagnosis of solitary pulmonary nodules.

Methods: Sixty-three solitary pulmonary nodules were evaluated by dynamic enhanced multi-slice CT. Images were obtained before and at 20 s, 30 s, 45 s, 60 s, 75 s, 90 s, 120 s, 180 s, 300 s, 540 s, 720 s, 900 s and 1200 s after the injection of contrast media. All lesion enhanced parameters and morphological features were recorded. The differences between benign and malignant nodules were analyzed. The diagnostic sensitivity and specificity of solitary pulmonary nodules were evaluated by receiver operator characteristic analysis.

Results: CT enhancement value at 120 s [(29.5 ± 30.2) HU vs. (32.5 ± 14.7) HU, P = 0.023], washout at 20 min [(36.5 ± 24.6) HU vs. (15.6 ± 16.6) HU, P = 0.044], washout ratio at 20 min [(36.5 ± 24.6)% vs. (17.8 ± 14.5)%, P = 0.006], slope of washout at 20 min [(0.006 ± 0.005)%/s vs. (0.002 ± 0.0016)%/s, P = 0.001], type II (24/42 vs. 4/21, P = 0.004) and III (5/42 vs. 9/21, P = 0.005) curves were significantly different between benign and malignant nodules. Using the above mentioned parameters, the results of receiver operator characteristic analysis had a sensitivity of 64.3% and specificity of 84.2% for identification of malignant tumors. The morphological features including round-like, triangle-like, multi-angle, spiculation, light lobulation, the degree of edge (sharp, clear, blur), vessel convergence sign, vacuole sign, airing of bronchi, cut-off of the bronchi and depression of pleura were significantly different between benign and malignant nodules. The results of ROC analysis showed that the above mentioned morphological features had a sensitivity of 92.9% and specificity of 100% for differentiating malignant tumors from benign nodules. The results of ROC analysis showed that combination of morphological features and dynamic enhancement parameters had a sensitivity of 95.2% and specificity of 100% for identification of malignant tumors.

Conclusions: Dynamic enhanced CT images can evaluate morphological and enhancement features of solitary pulmonary nodules. Combination of morphological features and enhancement characteristics can improve the accuracy of diagnosis.