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Abstract Details

Unifying Variability in T2-FLAIR Mismatch Sign for Diagnosing IDH-mutant Astrocytomas and Characterizing Evolution After Treatment
Neuro-oncology
P2 - Poster Session 2 (8:00 AM-9:00 AM)
13-001

To explore the T2-FLAIR mismatch sign (T2FM) by evaluating its appearance, further characterizing tumors which display it, and describing its evolution over time.
T2FM is a recently described imaging sign which demonstrates high predictive value for isocitrate dehydrogenase (IDH) mutant astrocytomas, helping facilitate early diagnosis and treatment planning. It consists of a hyperintense, homogenous signal on T2 but hypointense signal on FLAIR (‘mismatch’) with surrounding FLAIR hyperintense rim. There remains controversy on how best to define it, limiting clinical application.
Medical records from 64 patients with astrocytomas were assessed for age at diagnosis, sex, WHO grade, molecular status, seizure history, tumor characteristics on pre-treatment CT, MRI, and pathology, documentation of T2FM, treatment course, and changes in tumor appearance over time. Cases were divided into those meeting “classic” criteria (homogenous T2/FLAIR mismatch with rim), those considered “geographic” (heterogeneous T2/FLAIR signal with rim), and those which were negative (no T2/FLAIR mismatch or rim). Groups were compared using Chi square and qualitative analyses.
Including “geographic” tumors increased T2FM sensitivity 30% among astrocytomas without decreased specificity for IDH mutation. Tumors with T2FM characteristics were more cystic, less enhancing, and affected younger patients. T2FM persisted following subtotal resection and disappeared after radiation, persisted in 5/8 recurrent tumors, and was identified in some IDH mutant tumors with higher grade characteristics.  
The presence of a hyperintense FLAIR rim, with any degree of T2/FLAIR mismatch, is a reliable indicator of IDH mutation among astrocytomas. Tumors with a FLAIR rim are more cystic and this may lend to their appearance on MRI. T2FM displays characteristic changes after radiation and may be seen in high grade gliomas.
Authors/Disclosures
Patrick Throckmorton
PRESENTER 		No disclosure on file
Jerome J. Graber, MD, MPH, FÂ鶹´«Ã½Ó³»­ (University of Washington) Dr. Graber has received personal compensation for serving as an employee of Binaytara Foundation. Dr. Graber has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Â鶹´«Ã½Ó³»­. Dr. Graber has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Dickie McCamey Attorneys at Law. Dr. Graber has a non-compensated relationship as a Editorial Board member with Neuro-Oncology: Practice, published by Oxford that is relevant to Â鶹´«Ã½Ó³»­ interests or activities. Dr. Graber has a non-compensated relationship as a Editorial Board Member with Journal of Pain and Symptom Management that is relevant to Â鶹´«Ã½Ó³»­ interests or activities. Dr. Graber has a non-compensated relationship as a Board of Directors with American Society of Neuroimaging that is relevant to Â鶹´«Ã½Ó³»­ interests or activities. Dr. Graber has a non-compensated relationship as a Board of Directors and Certification Exam Committee Member with United Council of Neurological Subspecialties that is relevant to Â鶹´«Ã½Ó³»­ interests or activities. Dr. Graber has a non-compensated relationship as a Question of the Day 'app' committee and NeuroSAE and Continuum with Â鶹´«Ã½Ó³»­ that is relevant to Â鶹´«Ã½Ó³»­ interests or activities. Dr. Graber has a non-compensated relationship as a Editorial Board Member with Practical Neurology (BMC) that is relevant to Â鶹´«Ã½Ó³»­ interests or activities.