? Magnetic Resonance Spectroscopic Imaging (MRSI) is an in vivo molecular imaging technique that has been proposed for defining tumor burden for patients with gliomas. The current funding cycle has demonstrated that MRSI is superior to conventional MR imaging for predicting outcome and following response to Gamma Knife Radiosurgery (GK-RS) in recurrent gliomas. The objective in the next funding cycle is to make this technology more generally applicable by investigating the application of MRSI to the evaluation of fractionated radiation therapy. This treatment is used as a follow-up to surgical resection for almost all newly diagnosed malignant gliomas. New approaches such as Intensity Modulated Radiation Therapy (IMRT) have made it possible to treat irregular 3-D volumes accurately and reproducibly in a highly conformal manner. Critical factors for realizing the potential of IMRT and for understanding its limitations are the ability to determine whether treatment failure is due to inadequate targeting or to an intrinsic lack of sensitivity to radiation. This represents a complex problem in gliomas because of the heterogeneity of the lesion and the spatial variations in radiation dose to the tumor and surrounding brain tissue.
Specific Aim 1 will address the optimization of data acquisition and reconstruction parameters. This will include the investigation of the use of a 3T MR scanner rather the standard 1.5T clinical system for obtaining the anatomic and metabolic data.
Specific Aim 2 will involve the development of algorithms for quantitative analysis of the MRSI data and correlation with serial MR images. The final Specific Aim will apply the new technology to the serial evaluation of 60 patients with malignant gliomas who are being treated at UCSF with fractionated radiation therapy. Using the MRSI data to guide and evaluate such focal therapy is expected to have a major impact upon treatment effectiveness and ultimately upon patient outcome. ? ?
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