NIMG-52. UTILITY OF ARTERIAL SPIN LABELING (ASL) AND DYNAMIC SUSCEPTIBILITY CONTRAST (DSC) PERFUSION MRI IMAGING IN DISTINGUISHING PSEUDOPROGRESSION IN GLIOBLASTOMA

Abstract

Abstract Pseudoprogression is a radiographic phenomenon in which increase in post contrast enhancement can mimic tumor progression while actually representing treatment effect. This occurs in up to 30% of glioblastoma (GBM) patients, with higher rate in O6-methylguanine-DNA methyltransferase (MGMT) methylated patient, and may lead to premature discontinuation of therapy. Perfusion imaging, with either DSC and/or ASL can sometimes help differentiate between progression (Pr) versus pseudoprogression (PsPr) noninvasively. Between 2009-2019, we conducted a retrospective study of GBM patients diagnosed between 2009-2019 at Maine Medical Center who received standard of care (surgery/radiation/temozolomide), subsequently displayed changes concerning for progression (n=23) or pseudoprogression (n=3) within 12 months from completion of radiation, and who had a second resection for pathological assessment. Perfusion values were analyzed by assessing DSC ratios and grading ASL signal on MRI. 7/25 patients were MGMT methylated in the Pr group compared to 1/3 patients in the PsPr group. Both Pr and PsPr patients had similar mean DSC ratios (2.098 Pr and 2.200 PsPr, p = NS). Mean ASL grade was 2.4 for Pr patients versus 1.3 for PsPr patients, p = NS. ASL grades of 2 or higher had a sensitivity of 62% (95% CI [36, 83%]) and specificity of 33% (95% CI [6, 79%]) in distinguishing Pr from PsPr patients. DSC ratios of 1 or greater had a sensitivity of 96% (95% CI [80, 99%]) and specificity of 0% (95% CI [0, 66%]) for Pr versus PsPr patients. When both DSC ratios of 1 or greater and ASL grade of 2 or higher were combined, sensitivity remained high at 91% (95% CI [62, 98%]) with specificity of 0% (95% CI [0, 66%]). Despite the limited number of PsPr patients, results support the use of both DSC and ASL measurements to guide the determination of progression versus pseudoprogression in treated glioblastoma patients.