Pulmonary nodules: CT evaluation of enhancement with iodinated contrast material

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.

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.

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).

Enhancement is an indicator of malignancy and vascularity.