Correlation between MR signal intensity and histologic findings in neurinomas and meningiomas of the brain

The signal intensity of magnetic resonance imaging (MRI) was compared with the histologic findings in 20 cases of neurinoma and 18 cases of meningioma. The apparatus was a Hitachi G-10 unit (0.15 T). The pulse sequences were SR (500/32), SE (1200/60), IR (1400/400). The intensity of tumor signal, as compared with that of normal white matter signal, was divided into 9 grades. In neurinomas, the signal intensity appeared markedly low with IR and markedly high with SE sequence in the Antoni B type, while it was slightly low with IR and minimally to markedly high with SE sequence in the Antoni A type, and intermediate between Antoni A type and B type in the mixed type. In meningiomas, it appeared moderately to slightly low with IR and slightly to moderately high with SE sequence in the meningotheliomatous type, minimally low with IR and minimally to slightly high with SE sequence in the fibrous type, and intermediate as compared with the above two in the transitional type. The angiomatous type was characterized by a low intensity on SR and IR images and an iso to high intensity on SE images, while the psammomatous type showed a low intensity with all of the sequences used. We clarified that the signal intensity on MRI varied among different histologic types of neurinoma or meningioma, and correlated differences in the intensity of signals on MRI to that of histologic characteristics, such as size and shape of cells, intercellular material, intracellular biologic polymers, area of membrane surface, blood flow and calcified matter.