MR of recurrent high-grade astrocytomas after intralesional immunotherapy.

PURPOSE: To describe the MR findings in six patients with recurrent cerebral astrocytomas before, immediately after, and 3 months after local immunotherapy with tumor-infiltrating lymphocytes and interleukin-2.
METHODS: Contrast-enhanced MR studies were obtained in six patients (three with anaplastic astrocytoma and three with glioblastoma multiforme) at the time of tumor recurrence, after a second resection and placement of an Ommaya catheter, at the end of immunotherapy, and thereafter at 3-month intervals. These MR studies were reviewed with special attention to pattern and degree of enhancement, edema, and mass effect.
RESULTS: In three patients, gross total removal of recurrent tumor was achieved and postimmunotherapy MR studies showed a flare phenomenon characterized by increased nodular enhancement, increased edema, and mass effect. On the 3-month follow-up examination, these findings had resolved, and no further tumor recurrence was seen during the following 12-month period. Neither of the two patients who had subtotal resection had a flare phenomenon. In one of these patients, the tumor was stable at the 12-month follow-up; the other patient had recurrent tumor at the 6-month follow-up. In the last patient, who also had subtotal tumor resection and progressive enhancement after immunotherapy, tumor progression was rapid.
CONCLUSION: After local immunotherapy, increased enhancement, edema, and mass effect are most likely the result of a flare phenomenon, but because rapid tumor progression may produce similar features, follow-up MR studies are indispensable. The flare phenomenon resolved by 3 months in all patients.