Diffusion-weighted imaging-gadolinium enhancement mismatch sign in diffuse midline glioma.

Background: Diffuse midline glioma (DMG), H3 K27M-mutant including diffuse intrinsic pontine glioma (DIPG) is a disease with dismal prognosis. We focused on diffusion-weighted imaging (DWI) and gadolinium enhanced T1WI (Gd), especially high intensity on DWI at non-enhanced lesion, i.e. DWI-Gd mismatch sign, to establish as an imaging biomarker of DMG patients.

Materials And Methods: Our institutional review board approved this retrospective study. Twenty-one patients diagnosed as DMG including DIPG at our institution between 2007 and 2020 were enrolled in this study. All patients underwent local radiotherapy of 54 Gy/30 fractions. We studied the relationship between imaging features including DWI-Gd mismatch sign and prognosis.

Results: DWI-Gd mismatch sign was found in 9 out of 21 DMG patients. Among different imaging characteristics, existence of high intensity on DWI (P = 0.0014), gadolinium enhancement (P = 0.00071) were the significant poor prognostic markers in DMG, which were consistent with the previous reports about DIPG. In our results, positive DWI-Gd mismatch sign was statistically strongest poor prognostic imaging biomarker, and patients with positive DWI-Gd mismatch sign had shorter OS compared to those with negative mismatch sign (9.9 months vs 18.6 months, P = 0.00062). DWI/Gd mismatch sign and intratumoral bleeding were more common in DMG at thalamus compared to DMG at pons/DIPG (P = 0.046 and P = 0.0017, respectively).

Conclusions: DWI-Gd mismatch sign may be an imaging biomarker for poor prognosis in DMG. (E-1601).