Accuracy of Central Neuro-Imaging Review of DIPG Compared with Histopathology in the International DIPG Registry.

Abstract

BACKGROUND\nDiffuse intrinsic pontine glioma (DIPG) remains a clinico-radiologic diagnosis without routine tissue acquisition. Reliable imaging distinction between DIPG and other pontine tumors with potentially more favorable prognoses and treatment considerations is essential.\n\n\nMETHODS\nCases submitted to the International DIPG registry (IDIPGR) with histopathologic and/or radiologic data were analyzed. Central imaging review was performed on diagnostic brain MRIs (if available) by two neuro-radiologists. Imaging features suggestive of alternative diagnoses included non-pontine origin, <50% pontine involvement, focally exophytic morphology, sharply-defined margins, and/or marked diffusion restriction throughout.\n\n\nRESULTS\nAmong 286 patients with pathology from biopsy and/or autopsy, 23 (8%) had histologic diagnoses inconsistent with DIPG, most commonly non-diffuse low-grade gliomas and embryonal tumors. Among 569 patients with centrally-reviewed diagnostic MRIs, 40 (7%) were classified as non-DIPG, alternative diagnosis suspected. The combined analysis included 151 patients with both histopathology and centrally-reviewed MRI. Of 77 patients with imaging classified as characteristic of DIPG, 76 (99%) had histopathologic diagnoses consistent with DIPG (infiltrating grade II-IV gliomas). Of 57 patients classified as likely DIPG with some unusual imaging features, 55 (96%) had histopathologic diagnoses consistent with DIPG. Of 17 patients with imaging features suggestive of an alternative diagnosis, eight (47%) had histopathologic diagnoses inconsistent with DIPG (remaining patients were excluded due to non-pontine tumor origin). Association between central neuro-imaging review impression and histopathology was significant (p<0.001), and central neuro-imaging impression was prognostic of overall survival.\n\n\nCONCLUSIONS\nThe accuracy and important role of central neuro-imaging review in confirming the diagnosis of DIPG is demonstrated.