Dynamic computed tomography in solitary pulmonary nodules

Objective: To evaluate the utility of dynamic computed tomography (CT) imaging in the management of solitary pulmonary nodules. Methods: We examined solitary pulmonary nodules in 45 patients. The nodules included in the study were solid, homogenous, and spherical or oval-shaped in precontrast images. Nodules that had calcification or fat density were excluded from the study. We were not able to obtain clinical or pathological diagnosis of the nodules in 23 patients, and we excluded these patients from statistical analysis. Patients were examined with 2-mm collimation and I-mm reconstruction interval. Computed tomography examinations were done before and after injection of contrast material. Computed tomography scans of the nodule were obtained in the first, second, third, fourth, and fifth minutes after contrast injection. Results: The malignancy prevalence was 40%. The mean enhancement of malignant nodules were significantly higher than the benign ones. Also, the peak attenuation value obtained after the administration of contrast material was 82.44 +/- 19.56 HU in malignant lesions and 54 +/- 23.10 HU in benign ones, with statistical significance (P = 0.006). Using enhancement values greater than 15 HU as a threshold for malignancy, the calculated sensitivity, specificity, positive and negative predictive values, and accuracy of the dynamic CT examination were 100%, 69.2%, 69.2%, 100%, and 81%, respectively. Conclusion: Dynamic CT imaging demonstrates significantly greater enhancement in malignant nodules than in benign ones. Lung nodule enhancement of 15 HU or less strongly indicates benignity.