Radiogenomics Provides Insights into Gliomas Demonstrating Single-Arm 1p or 19q Deletion

Area of Science:

• Neuro-oncology
• Molecular diagnostics
• Radiology

Background:

• IDH-mutant gliomas are classified by 1p/19q status: codeleted (oligodendroglioma) or non-codeleted (astrocytoma).
• Single-arm 1p or 19q deletion (unideletion) is diagnosed as astrocytoma, but may represent unclassified codeleted tumors.
• This study investigates the imaging and survival characteristics of unideleted gliomas.

Purpose of the Study:

• To determine if unideleted IDH-mutant gliomas exhibit MR imaging features and patient survival consistent with astrocytomas or oligodendrogliomas.
• To assess the T2-FLAIR mismatch sign and calcifications as potential differentiators.
• To compare outcomes between unideleted, codeleted, and non-deleted gliomas.

Main Methods:

• Retrospective analysis of 121 IDH-mutant grade 2-3 gliomas with known 1p/19q status.
• Two neuroradiologists evaluated MR imaging for T2-FLAIR mismatch sign and calcifications.
• Comparison of imaging features and patient survival across different 1p/19q deletion groups.

Main Results:

• Unideleted tumors (12) showed the T2-FLAIR mismatch sign more frequently (33%) than codeleted tumors (0%), similar to non-deleted tumors (49%).
• Calcifications were less common in unideleted tumors (0%) compared to codeleted tumors (25%).
• Median survival for unideleted tumors (7.8 years) was similar to non-deleted tumors (8.5 years) but significantly shorter than codeleted tumors (not reached >12 years).

Conclusions:

• IDH-mutant gliomas with unideletion display MR imaging features and survival outcomes aligning with astrocytomas.
• These findings differentiate unideleted gliomas from 1p/19q-codeleted oligodendrogliomas.
• Unideletion status is a significant factor in classifying and predicting outcomes for IDH-mutant gliomas.