Img-10. magnetic resonance functional imaging biomarker for distinguishing high grade from low grade pediatric brain tumors

Abstract This study aims to show that the ratio between perfusion MRI (RCBV) and diffusion MRI (ADC - apparent diffusion coefficient) is more effective in distinguishing low-grade from high-grade pediatric brain tumors than either parameter (RCBV or ADC) alone. After IRB approval was obtained, an initial pilot prospective study was performed that included 38 patients (newborn - 18 years) (22 females and 16 males). All MRI exams were performed on a 1.5 T or 3.0 T scanner. Surgically resected tumors were classified as low grade (WHO I, II) or high grade (WHO III, IV). ROIs were selected using tumor boundaries delineated on the FLAIR sequence, excluding perilesional edema. Both standardized and normalized perfusion RCBV (sRCBV, nRCBV) as well as diffusion (ADC) mean values were acquired. Then sRCBV/ADC ratios were calculated. Statistical analysis included the Wilcoxon-Mann-Whitney t-test using an alpha=0.05 as the level of significance. The results of this preliminary study revealed that the sRCBV/ADC ratio calculations were more effective at separating high grade from low grade tumors than were RCBV or ADC values alone. As a result of this original pilot study, the calculated sRCBV/ADC ratio has occasionally been used as a clinical tool at our institution. In order to validate the results from this original pilot study, we have collected additional retrospective data to increase sample size. We plan to share the results of this additional data in order to validate that the sRCBV/ADC ratio is an easy-to-use imaging biomarker that can effectively separate high grade from low grade pediatric brain tumors. This information is useful for patient care in that it can potentially help predict prognosis which is essential for parental counseling, and potentially reduce the need for invasive tests and biopsies.