NIMG-69: THE IMPACT OF MRI PERFUSION IMAGING IN THE DIFFERENTIATION OF PROGRESSION AND PSEUDOPROGRESSION IN PATIENTS WITH GLIOBLASTOMA

INTRODUCTION: Glioblastoma multiforme (GBM) is the most malignant astrocytic tumor with dismal prognosis despite extensive treatment. Combined radio-chemotherapy as part of the standardized treatment plan may induce pseudoprogression, defined as an increase of contrast-enhancement and/or edema on MRI without true tumor progression. There are no established reliable criteria for the differentiation of true tumor progression (Pr) from pseudoprogression (PsP) by means of conventional MRI. However, this early differentiation would enable clinicians to timely change the treatment plan. OBJECTIVE: The objective of this study was to examine the role of dynamic susceptibility contrast-enhanced MR-perfusion in the differentiation of progression and pseudoprogression in a cohort of patients with GBM. METHODS: Between 10/2007 and 03/2013 we retrospectively examined 49 patients. Diagnosis of progression (n = 28) or pseudoprogression (n = 21) was determined by histopathology or clinical/MRI-follow-up. Data analysis was performed with Olea Sphere (OleaMedical®) software. After co-registration of MRI sequences a perfusion map was automatically calculated and corrected for leakage effect, permeability, background-segmentation and motion-artifacts. The perfusion map was merged with the volume segmentation image to get a mean value of CBV for the contrast enhanced tumor volume (rCBV). RESULTS: The median overall survival in our patients with PsP was 29 months and in those with Ps 19 month. The median volume of the contrast-enhancing lesion was similar in both groups (Pr:17.0 (0.85-136.8) vs. PsP:17.1 (2.1-51.5)). The mean rCBV was higher in patients with Pr 3.6 (0.80-6.45) than in PsP 3.1 (1.35-5.03), however, did not reach statistical significance due to variances of rCBV within the groups (p = 0.235; 95% CI 0.34-1.35). CONCLUSION: The retrospective analysis of rCBV in our patient cohort could not differentiate between patients with true progression and pseudoprogression. Further prospective analysis with larger patient cohorts and histological verification are required.