Use of magnetic resonance imaging in central nervous system tumors.

MRI provides additional information about tumor location, extent, and margins. MRI was used in 158 patients with CNS tumors for treatment planning from 1985-89 and they were studied in a prospective manner. The most common site was cerebrum (73 pts), then extradural spinal axis (21 pts) posterior fossa (17 pts), brain stem (14 pts) and pituitary (13 pts), etc. The most common histological primary tumor was glioblastoma multiform (25 pts), then low grade astrocytoma (22 pts), anaplastic astrocytoma (14 pts), pituitary tumor (13 pts), medulloblastoma (9 pts), ependymoma (7 pts), and germ cell tumors (6 pts). Twenty-nine patients had metastasis to the brain. A majority of the patients with CNS tumors had the studies using Gadolinium-DTPA. Of the patients with CNS tumors, 120 (76%) had better information based on the MRI, which improved the treatment planning (using the three dimensional images) and field arrangement. In 89 patients (56%) the MRI was very decisive in the treatment volume and field arrangement. In 31 patients (20%) the MRI was beneficial and confirmed the treatment plan. MRI provides important additional information for radiation therapy planning.