The Study On Differential Diagnosis Of Solitary Pulmonary Nodule With Contrast-enhanced Inceremental Dynamic CT

ObjectiveTo evaluate the Differential diagnostic value of solitary pulmonary nodules (SPN) with incremental dynamic CT. Methods; Sixty - three cases with SPN were analyzed, including 39 priinary lung cancers, 11 tuberculomas, and 13 granuloms. Serial thin - section CT scans were performed before and 30 seconds, 1,2,3,4 minutes and 5 minutes after administration of iodinated contrast material at 3 ml/sec. The CT numbers of the inner area of the nodule before and after administration and the maximum level of enhancement were recorded. The time - attenuation curves of the nodule were obtained. The enhancement patterns of the nodules were analyzed. Results: CT value of lung cancer after enhancement significantil difered from that of plain scan (p < 0.01). CT value of tuberculomas after enhancement did not significantil-difer from that of plain scan ( pr'>0.05). All lung cancers were enhanced significantly greater than eleven tuberculomas (p <0. 01) , which did not show enhancement. The time - attenuation curve of lung cancers was significatly different from that of tuberculomas. With 20 HU as the threshold ,the sensitivity was87% ,the specificity was75% , and the accuracy was 82% , positive predictive value was 85% , negtive predictive value was 78%. The time - attenuation curve of lung cancers showed gradual enhancement and most of the lung cancers reached peak enhancement 1 minutes after administration of conerast material; Conclusion; ON conerast--en-hanoed scans, it indicates tuberculoma if the maxium attenuation of nodule is less than 20 HU. It appears to be a sign of malignancy when the CT attenuations are 20 to 60 HU.