Pulmonary nodules: CT evaluation of enhancement with iodinated contrast material.

Abstract

PURPOSE: To determine if the degree of enhancement of pulmonary nodules is directly related to the likelihood of malignancy and to the vascularity of the nodule. MATERIALS AND METHODS: Uncalcified 6-40-mm-diameter pulmonary nodules were studied in 163 patients with malignant neoplasm (n = 111), granuloma (n = 43), and benign neoplasm (n = 9). Serial thin-section computed tomography (CT) was performed before and after injection of 100 mL of nonionic contrast material at 2 mL/sec. The maximum level of enhancement was recorded. Eighteen histologic specimens were graded after vascular staining. RESULTS: Malignant neoplasms enhanced (median, 40.0 HU; range, 20-108 HU) significantly more than granulomas and benign neoplasms (median, 12.0 HU; range, -4 to 58 HU) (P < .001). With 20 HU as the threshold for a positive test, sensitivity was 100%; specificity, 76.9%; positive predictive value, 90.2%; negative predictive value, 100%; and accuracy, 92.6% (prevalence of malignancy, 68.1%). Degree of enhancement was significantly related to amount of central vascular staining (P = .003). CONCLUSION: Enhancement is an indicator of malignancy and vascularity.