| Objective:To improve the diagnosis of pulmonary nodules in early time. Methods: 39 patients with solitary pulmonary nodules (SPNs, diameter≤4.0cm) underwent CT scan. Final diagnosis were confirmed histologically or cytologically by means of surgery. 39 patients(27 men,12 women; age range: 38~88, mean age: 59.77 years) with pulmonary nodules 0.9～4.0 cm(mean, 2.02cm) in diameter were studied. In 39 patients 29 were malignant (adenocarcinoma, n=10; bronchioloalveolar, n=2; squamous cell carcinoma, n=7; metastatic tumor, n=5; adenocarcinoma squamous carcinoma, n=1; small cell carcinoma, n=1; without pathologic specimen but confirmed by clinical survey, n=3), and 10 were benign (inflammatory nodules, n=4; hamartoma, n=1; tuberculosis, n=4; without pathologic specimen but confirmed by clinical survey, n=1). The diameter was defined as the average value of the anteroposterior and lateral diameter on CT scans obtained with a mediastinal window setting. Pulmonary nodules located in right upper lobe (n=14), middle lobe (n=5), lower lobe (n=3), left upper lobe (n=12), lower lobe (n=5); located in the inner field of lung (n=12), middle field(n=9), lateral field(n=18).Three slices CT scans through the center of the nodules were performed before and after the injection of 100ml iodinated contrast material (at the 15th, 35th, 75th, 135th, 195th second).Enhanced scanning including entire pulmonary nodules was done at the time of the 35th second. The scanning thickness was 3~5mm, pitch was 1.2~1.5. The speed of injection was 2ml/s by hyperbaric injector. The CT value of single-slice nodules was measured before and after enhancement. The largest number of the CT values in different time after enhancement was regarded as the the largest CT value after enhancement, which minus CT value before enhancement was regarded as the largest increased CT value. The time-attenuation curves were done and three-dimensional reconstruction of vessels was made.Results: No statistically significant differences were found between primary(n=24 ) and metastatic lung cancer(n=5). (P>0.05).Among the increased CT values of 29 malignant nodules, 23 were between 20~60Hu, 2 were less than 20Hu, 4 were more than 60Hu; Among the increased CT values of 10 benign nodules, 3 were between 20~60Hu, 3 were less than 20Hu, 4 were more than 60Hu. Statistically significant differences were found between malignant and benign SPNs when 20~60Hu of the increased CT value was considered as the diagnostic criteria of malignant nodules.Among 39 images of three-dimensional reconstruction of vessels, 29 had good quality. The imaging qualities of SPNs which located in the middle and lateral field(n=27) were better than that of those located in the inner field of lung(n=12)( p=0.0294, P<0.05).Among the vessels of 24 malignant SPNs, 2 were normal; 3 had thicker diameters; 17 had both thicker diameters and more quatities; 6 threaded through nodules of which 4 complicated with thicker diameters and more quatities); Among the vessels of 5 benign SPNs, 3 had more quatities and 2 were normal. The nodules which had thicker vessels with or without more quatities, or drilled through by vessels in the images of three-dimensional reconstruction implied malignant ones. The sensitivity was 75.9%, the specificity was 50% and the accuracy was 69.2% when these imaging manifestations were taken as the diagnostic criteria of malignant nodules.The sensitivity was 79.3%, the specificity was 60% and the accuracy was 74.4% when 20~60Hu of the largest increased CT value was as the criteria of malignant SPNs in the dynamic enhancement of pulmonary nodulesWhen dynamic CT enhancement and three-dimensional reconstruction of vessels were combined, the sensitivity was 96.6%, the specificity was 50% and the accuracy was 84.8%.Conclusion: 1. Dynamic enhanced CT scanning is of great value in differentiating malignant nodules from benign ones. 2. The images of pulmonary nodules which locate in the lateral and middle field of lung are more clear. 3. Three-dimensional rec...
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