Early Effects of Gamma Knife Surgery on Malignant and Benign Intracranial Tumors

Abstract

To assess the early response of intracranial tumors to Gamma Knife surgery, we performed a prospective investigation of 42 patients treated by Gamma Knife surgery for different types of intracranial tumors. The clinical condition, tumor volume, treatment results and their temporal correlation with the irradiation were analyzed, based on MRI performed on the same MR scanner. Volume reduction in the tumors measured at the latest follow-up ranged from 0.2 to 100%. All except 1 malignant tumor showed decreasing size and improving peritumoral edema 1–7 months after radiosurgery. In 30 benign tumors, 13 showed either a decrease or no change in volume. However, an initial volume increase was observed in 17 tumors, with a maximum at 3–9 months, which subsequently regressed. In 2 meningioma patients, peritumoral edema increased and needed steroid treatment. Sequential PET-FDG imaging of the patients showed decreasing FDG uptake, indicating a decrease tumor in metabolism. The PET findings correlated well with the loss of contrast enhancement on MR images. In conclusion, intracranial tumors respond to Gamma Knife surgery from an early stage. Different tumors have different responses to radiosurgery. It is too early to offer a prognosis of long-term effects based on the limited material. However, sequential clinical, MR and PET follow-ups provide an excellent opportunity to investigate the evolving irradiation effects in vivo.

The Effectiveness and Factors Related to Treatment Results of Gamma Knife Radiosurgery for Meningiomas

“…Our method is to measure the tumor's area on every slice. The sum of the areas was multiplied by thickness of MR image (0.3 cm) thus giving the total tumor volume [3]. In 80 meningiomas, the baseline tumor volumes (BTVs) were stratified into 4 groups: BTV 1 (=5 ml, n>38), BTV 2 (5-10 ml, n>21), BTV 3 (10-15 ml, n>14), and BTV 4 (15-20 ml, n>7).…”

1-11C-Acetate Versus 18F-FDG PET in Detection of Meningioma and Monitoring the Effect of γ-Knife Radiosurgery

“…The increased application of radiosurgery in the treatment of meningiomas has created a demand for higher precision in diagnostic imaging in pretreatment planning for postoperative tumor remnants or recurrences (14,43,44). The traditional criteria for the assessment of surgical results-eradication of the tumor-cannot be applied in radiosurgery, and arrest of tumor growth is considered a success (43).…”

A clinical study for evaluating early radiotherapy effect in patients with brain tumor using 99Tcm-HL91 spect

“…The past study showed that MRI or CT could show the tumor diminution 1-2 months later radiotherapy and about 4%-40% of brain tumors were seen to enlarge on MRI during radiotherapy, which is suggestive of breakdown of the blood-brain barrier (BBB) [7][8][9] . So conventional CT and MRI have disadvantage evaluation in curative effect, especially early curative effect of radiotherapy in patients with brain tumors.…”