A preliminary study of discrimination among the components of small pulmonary nodules by MR imaging: correlation between MR images and histologic appearance.

Purpose: To investigate whether magnetic resonance (MR) imaging depicts the internal characteristics of small pulmonary nodules.

Methods: We reviewed MR images of 39 surgically resected pulmonary nodules 3 cm or less and compared the components within the nodules. In 22 malignant nodules, eight histologic components were characterized by signal and enhancement patterns on MR images.

Results: MR images obtained from any single sequence discriminated all components in 26 (67%) nodules, whereas the combination of images from various sequences allowed discrimination in 35 (90%). Fourteen of 16 components of aggregated tumor cells showed marked early enhancement. Although fibrotic and necrotic components showed no or slight early enhancement, nine of 10 fibrotic components showed hypointensity and six of seven necrotic components showed hyperintensity on T2-weighted images. Component characterization in eight histologies by MR imaging was possible in 71-100%.

Conclusion: Our study demonstrated that MR imaging offers the possibility of high tissue-contrast resolution in small pulmonary nodules.