MRI Features Can Predict 1p/19q Status in Intracranial Gliomas

Abstract

<h3>BACKGROUND AND PURPOSE:</h3> The 2016 revision of the <i>World Health Organization Classification of Tumors of the Central Nervous System</i> mandates codeletion of chromosomes 1p and 19q for the diagnosis of oligodendroglioma. We studied whether conventional MR imaging features could predict 1p/19q status. <h3>MATERIALS AND METHODS:</h3> Patients with previous 1p/19q testing were identified through pathology department records, typically performed on the basis of an oligodendroglial component on routine histology; 69 patients met the inclusion criteria. Preoperative imaging of patients with grade II or III gliomas was retrospectively assessed by 2 neuroradiologists, blinded to the 1p/19q status. Thirteen MR imaging features were first assessed in a small initial cohort (<i>n</i> = 10), after which the criteria were narrowed for the remaining patients as a validation cohort. <h3>RESULTS:</h3> There was 85% agreement between radiologists for the overall prediction of 1p/19q status in the validation cohort, with an accuracy of 84%. The presence of &gt;50% T2-FLAIR mismatch and calcification was found to be the most useful for predicting 1p/19q status. The &gt;50% T2-FLAIR mismatch variable was demonstrated in 14 tumors and had 100% specificity for identifying a noncodeleted tumor (<i>P</i> = .001), with 97% interobserver correlation. Calcification was visualized in 7 tumors, 6 of which were 1p/19q codeleted (specificity, 97%; <i>P</i> = .006), with 100% interobserver correlation. <h3>CONCLUSIONS:</h3> The presence of &gt;50% T2-FLAIR mismatch is highly predictive of a noncodeleted tumor, while calcifications suggest a 1p/19q codeleted tumor. If formal 1p/19q testing is not possible, a combined MR imaging–histologic assessment may improve the diagnostic accuracy over histology alone.