[Differentiation of bronchogenic carcinoma from benign nodule by MR imaging: quantitative evaluation]

To distinguish benign from malignant nodules with MR imaging, 39 pulmonary nodules (23 bronchogenic carcinomas, nine tuberculomas and seven other benign lesions) were studied. MR equipment of 1.5 Tesla was used, and relative signal intensities of pulmonary nodules on T 2- and T 1-weighted images before and after administration of gadopentate dimeglumine were evaluated. On T 2-weighted images, the relative signal intensity of bronchogenic carcinomas to subcutaneous fat was 5.48 +/- 1.69, that of tuberculomas was -2.56 +/- 2.22 and that of other benign lesions was -0.88 +/- 3.37; the difference between tuberculomas and bronchogenic carcinomas was statistically significant (p < 0.05). On T 1-weighted images before and after administration of gadopentate dimeglumine, the relative signal enhancement of bronchogenic carcinomas was 17.6 +/- 2.0, that of other benign lesions was 20.0 +/- 5.2 and that of tuberculomas was -0.0074 +/- 0.763; the difference between tuberculomas and bronchogenic carcinomas as well as benign nodules was statistically significant (p < 0.001). The relative signal intensity on T 2-weighted images and the ratio of signal enhancement to noise could differentiate tuberculomas from bronchogenic carcinomas and other benign lesions. However, bronchogenic carcinomas and other benign lesions could not be differentiated by MR imaging.