Inter-Rater Reliability of RANO2 Criteria in Assessing Tumor Response in Low-Grade Gliomas Treated With and Without Radiation

Motivation: The value of updated RANO2 criteria for assessing tumor response in low-grade gliomas (LGG), especially in post-radiation therapy (RT) setting is unknown. Goal(s): To evaluate the accuracy and inter-rater reliability (IRR) of the RANO2 criteria in LGG patients with and without RT. Approach: Retrospective analysis of 26 LGGs by three readers to measure IRR and accuracy compared to ground truth. Results: RANO2 demonstrates excellent IRR in without-RT (Intraclass correlation coefficient, ICC = 0.986) but moderate in post-RT (ICC = 0.516) LGGs. Accuracy is higher with the use of baseline scans compared to immediate priors in post RT cases (AUC 0.9 vs 0.6, respectively). Impact: This research highlights the challenges of implementing RANO2 criteria in post-treatment LGG monitoring. The lower IRR in the post-radiation setting and lower accuracy in the absence of baseline scans emphasize the need for an alternative imaging approach beyond RANO2.