P15.14.A DIFFERENTIATE TREATMENT EFFECTS FROM DISEASE PROGRESSION IN TREATED BRAIN TUMOR: PROMISING RESULTS USING DELAYED CONTRAST MRI

Abstract BACKGROUND Treatment effects are reported in about 30% of treated glioma and brain metastases (BMs) characterized by increasing volume of contrast enhancing regions on MRI, similarly to tumor progression. Data interpretation are often difficult. The most methodology used to distinguish this 2 conditions is perfusion MRI; treatment effects are characterized by a decreased relative cerebral blood volume (rCBV) while persistent or progressive tumors by high rCBV. Limits of perfusion MRI are represented by overlap between two conditions, low spatial resolution, and presence of susceptibility artifacts. To overcome this crucial issue, encouraging results have been obtained using delayed contrast MRI that through contrast clearance analysis (CCA) allows to calculate high resolution maps called “treatment response assessment maps” (TRAMs). We prospectively evaluated patients with doubtful framework between treatment effects (TE) and tumor progression (TP) aiming to assess the ability of CCA in differentiate this two conditions in a cohort of treated brain tumor patients. MATERIAL AND METHODS Maps (TRAMS) were calculated through contrast clearance analysis (CCA) by subtracting ceT1MRI images acquired 5 minutes after contrast injection from images acquired at least 60-105 minutes after. Diagnosis of persistent tumors or disease progression was based on presence of contrast clearance (CC) region in blue, and treatment effects on contrast accumulation (CA) region in red. Data of CCA were compared to perfusion MRI. All images were uploaded, co-registered and elaborate into the image workstation of Brainlab. Whole tumor and enhancing tumor volumes were segmented and perfusion measures in area of signal alteration. TRAMs were generated and at last the calculation of effective volume of viable tumor tissue (CC region) and treatment-induced tissue changes within each lesion (CA region) have been calculated. RESULTS From February 2021 and November 2022, 62 patient (96 delayed-contrast-MRI) with doubtful framework between TE and TP underwent CCA and perfusion-MRI. Twenty-five treated for newly diagnosed glioma, 13 for recurrence, and 37 for BMs. Significantly increased rCBV value in CC regions compared to CA was observed (p=0.01). Patients with TP showed significantly greater CC that subjects with stable disease/partial response 33% vs 78% (p=0.01). TRAMs metric were in agreement with perfusion results. Greater accuracy of TRAMs compared to perfusion-MRI in discrim