NI-17 NEW ASSESSMENT FOR FLAIR ABNORMALITY AREA OF GLIOMA USING APT IMAGING

Background In glioma, decision of infiltrating margin in extensive FLAIR hyperintensity area around enhanced area and only FLAIR hyperintensity without enhanced is difficult. For deciding this margin, there are some useful reports using perfusion imaging, diffusion-weighted imaging and PET. Recently, there are some reports that amide proton transfer (APT) imaging is useful for assessment for tumor invasion. In this study, we assessed FLAIR hyperintensity area in gliomas using APT imaging and discussed about pattern of APT signal intensity (SI). Methods For patients with glioblastoma (GBM) and oligodendroglioma (OL: IDH-mutant and 1p/19q-codeleted), APT imaging was performed. Gadolinium T1WI, FLAIR and apparent diffusion coefficient (ADC) were performed for tumor invasion and edema. Areas of these sequences were compared with APT hyperintensity and APT and ADC were determined the quantity by SI. Results 37 sections from 10 GBM and 5 OL patients were assessed. Areas of differences between FLAIR and APT hyperintensity was significantly different between GBM and OL (p = 0.0142). SIs of the hyperintensity area between GBM and OL were different on ADC and APT SIs (ADC: p = 0.0267 / APT: p = 0.055). On GBM, hyperintensity area of APT imaging showed a correlation with hyperintensity area of FLAIR (R2 = 0.600, p < 0.0001). On OL, hyperintensity area of APT imaging showed a strong correlation with hyperintensity area of FLAIR (R2 = 0.806, p < 0.0001), and ADC SI showed correlation with APT SI (R2 = 0.675, p = 0.0019). Conclusions FLAIR hyperintensity area of GBM and OL, APT imaging showed different distribution. In FLAIR hyperintensity area of GBM with various phenomenon, APT imaging may indicate increasing area of tumor cell and reactive cells. Furthermore, mismatch between FLAIR and APT hyperintensity area may be useful for differentiation for glioma subtypes.