We assessed whether a new method of quantifying therapeutic-associated hemodynamic alterations may help to distinguish pseudoprogression from true progression in patients with high grade glioma. Patients from a prospective IRB-approved trial with high grade glioma received concurrent chemoradiation. Relative cerebral blood volume (rCBV) and blood flow (rCBF) maps were acquired prior and at week 3 mid-treatment. Pseudoprogression was defined as imaging changes 1-3 months after chemoradiation that mimic tumor progression but stabilized or improved without change in treatment or for which resection revealed radiation effects only. Clinical and conventional MR parameters, including average percent change of rCBV and CBF, were evaluated as potential predictors of pseudoprogression. Parametric response map (PRM), an innovative, voxel-by-voxel method of image analysis, was also performed. Median radiation dose was 72 Gy (range: 60-81). Of 27 patients, stable disease/partial response was noted in 13 and apparent progression in 14. Adjuvant temozolomide was continued in all patients. Pseudoprogression occurred in 6 patients. Based upon PRM analysis, a significant portion of the tumor volume had reduced rCBV (PRMrCBV) at week 3 in patients with progressive disease compared to those with pseudoprogression (p<0.01). In contrast, change in average percent rCBV or rCBF, MR tumor volume changes, age, extent of resection, and RTOG RPA classification did not distinguish progression from pseudoprogression. PRMrCBV at week 3 during chemoradiation is a potential early imaging biomarker of response that may be helpful in distinguishing pseudoprogression from true progression in glioma patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2698.