The aim of this study was to determine whether solitary pulmonary
tuberculoma and malignant
tumor can be differentiated on the basis of magnetic resonance (MR) signal intensity. Twenty-eight patients with solitary pulmonary lesions were prospectively studied with MR imaging: T1-weighted, enhanced T1-weighted,
proton density-weighted, and T2-weighted spin echo images were obtained. The confirmation methods used were computed tomography (CT)-guided biopsy in seven patients with
lung cancer and four patients with
tuberculosis; surgery in ten patients with
lung cancer and five patients with
tuberculosis; and laboratory data in two patients with
tuberculosis. Morphologic features and MR signal intensity were examined in detail. As the test for detection of
tuberculoma, signal difference on T2-weighted images was carefully analyzed. The signal intensity ratio of the nodule to thoracic muscle signal intensity was measured. The signal intensities obtained from the
lung cancers and
tuberculomas were variable on pre-and post-enhanced T1-weighted images and
proton density-weighted images. Masses were hypointense in 2 of 17 patients with
lung cancer and in 9 of 11 patients with
tuberculoma on T2-weighted images (sensitivity 82%, specificity 89%, accuracy 87%). The mean signal intensity ratios of the
tuberculomas to muscle were significantly lower than those of malignant
tumors on T1-weighted, enhanced T1-weighted,
proton density-weighted, and T2-weighted images (P < 0.0001). After
gadolinium-DTPA enhancement, 2 malignant
tumors and 7
tuberculomas showed a marginal rim enhancement pattern, whereas 15 malignant
tumors and 2
tuberculomas revealed a diffuse enhancement. The results of MR imaging were consistent with those of CT in 84% of the patients. MR imaging is a helpful adjunctive method in terms of differentiating a
tuberculoma from a malignant
tumor.