AMBIGUOUS MR FINDINGS IN GLIOBLASTOMA REVISION OF 4 CASES FOCUSING ON DIFFUSION WEIGHTED IMAGING.

We collect 4 patients with glioblastoma showing unclear clinical presen- tation and ambiguous MRI findings; careful revision of follow-up imag- ing suggested DWI changes as the more specific tool to predict the pres- ence of underlying tumor tissue. Methods retrospective MR imaging review of 4 patients with biopsy proven diag- nosis of glioblastoma. All patients accessed Emergency Department with secondary generalized seizures. MRI examinations were performed in acute setting with different clinical orientation: ischemia, status epilepticus and encephalitis. Follow-up was scheduled after 1 month (4/ 4) and after 3 months (3/4). All MRI protocols include T2w FLAIR, DWI and post-contrast T1w images. Results&Discussion Although all glioblastomas demonstrate changes on T2 FLAIR and DW imaging before presenting rim enhancing core, DWI is more specific to predict the center core of the tumor. In each case glioblastoma apparently develops from non enhancing DWI hyperintense areas; these areas do not correspond to an evident restriction on ADC map, even if diffusivity is reduced compared to previous MR imaging and to the perilesional tissue. Actually, ADC values correlate inversely to cellular proliferation in spec- imen and in vivo acquisition; DWI changes is a powerful tool to identify proliferating tumor cells regardless of ischemic changes due to tumor neoangiogenesis. Conclusion In our experience non enhancing hyperintense areas on DWI could pre- dict the site of tumor core; DWI changes should be carefully evaluated and reported when considering unclear clinical cases with ambiguous MR findings