Magnetic resonance spectroscopy and perfusion weighted imaging as predictors for tumor response to gamma knife radiosurgery: A single center experience

Objective

To test the hypothesis that hemodynamic and metabolic characteristics of intracranial neoplasms detected with magnetic resonance spectroscopy and perfusion weighted imaging are efficient predictors of tumor response to radiosurgery.

Methods

Fifty-four patients with 59 intracranial neoplasms, who underwent evaluation with echoplanar PW and MRS imaging prior to gamma knife radiosurgery were selected for this retrospective analysis. The mean irradiation dose was 13.76 Gy. The mean follow up after GNR constituted 24 months. Predictive diagnostic accuracy was calculated with standard formulas. The association of tumor response to radiosurgery with pretherapeutic MRI parameters was estimated using the Mann–Whitney U test.

Results

Significant association was found between the perfusion and hemodynamic parameters of intracranial neoplasms and the outcome of GKR. Diagnostic accuracy of multimodel MRI was 89% among low grade and 65% among high grade neoplasms. The overall accuracy was 81%. Normalized rCBV, choline, NAA and lipid contents and Chol/cr and NAA/cr were statistically different between low and high grade neoplasms (p < 0.001).

Conclusion

MR perfusion and spectroscopic results provided information that were predictive of the outcome of radiosurgery in this patient pool, increased the diagnostic accuracy of conventional MRI in defining tumor type and grade and may play an important role in pre-therapeutic planning for radiosurgery.