Intraclass Correlations of Measured Magnetic Resonance Imaging Volumes of Laser Interstitial Thermal Therapy-Treated High-Grade Gliomas

Background and objectives: Laser interstitial thermal therapy (LITT) is a minimally invasive therapeutic option for the treatment of brain tumors. Previous studies have quantitatively followed the ablated volumes of high-grade gliomas. Reported treatment volumes range from 28% to 100%, with no reported interobserver analysis. Because these volumes are subjectively measured, it is necessary to establish concordance between clinicians.

Study design/materials and methods: Utilizing Brainlab tumor analysis software (Brainlab, Munich, Germany), five physician users traced out tumor volumes slice-by-slice on 10 treated tumors in eight patients. The participants were briefed with specific instructions and a demonstration on how to trace the enhancing borders of the tumor slice-by-slice. Volumes automatically calculated by the Brainlab software included preoperative, intraoperative ablation and postoperative enhancing volumes. Data regarding size, cystic appearance, pathology, previous surgery, and demographics were included.

Results: The intraclass correlation coefficient (ICC) for preoperative, intraoperative, and postoperative volumes was 0.92 (95% confidence interval, [CI] 0.81-0.97), 0.90 (0.77-0.96), and 0.89 (0.74-0.96), respectively. The overall ICC was 0.72 (0.50-0.87). ICC comparisons were also made for each pair of readers (neuroradiologist, neuro-oncologist, senior neurosurgery resident, neurosurgery junior resident) which resulted in pretreatment ICC scores of 0.97, 0.91, 0.66, 0.94; intratreatment scores of 0.97, 0.78, 0.90, 0.96; and posttreatment scores of 0.96, 0.81, 0.89, and 0.87. A Bland-Altman plot was also used to assess the differences in volumes.

Conclusions: The ICC gives a composite of the consistency of measurements made by multiple observers measuring the same quantity. The overall ICC of 0.72 means there is good correlation between observers in our study between measured volumes. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.