The relationship between Koos classification and ADC-post-contrast signal intensity values of vestibular schwannoma - A cross sectional study

Abstract

Aim: We aimed to determine the inter-observer reliability of the Koos classification and to evaluate its\rcorrelation with Apparent Diffusion Coefficiency (ADC) and post contrast signal intensity values.\rMethods: Vestibular schwannomas were retrospectively scanned from picture archiving and communication\rsystem over a 4-year period. Koos grade of tumor was assessed by two radiologists blinded to the clinical and\rpathological data. Cohen’s Kappa was used to analyse inter-observer agreement of Koos grade. The correlation\rbetween ADC, signal intensity measurements and Koos grade of tumors was analysed with Kendall’s tau b\rcorrelation coefficient.\rResults: Thirty three patients (21 females, mean age 52.6±16.6 years) with 34 vestibular schwannomas were\rincluded the study. The reliability analyses revealed excellent inter-observer agreement for ADC (ICC: 0.93,\r95% CI: 0.87-0.97, p<0.001) and signal intensity (ICC: 0.98, 95% CI: 0.96-0.99, p<0.001) measurements. The\rpercentage agreement for Koos grading was 97% (k= 0.96, p<0.001). A correlation was not found between the\rKoos grade and ADC (_?_b: 0.18). Also signal intensity remained similar between Koos grades (p=0.125). A\rsignificant difference was found for ADC values between Koos grades (p=0.039).\rConclusion: Koos classification is a practical and useful grading system with excellent inter-observer agreement\rfor vestibular schwannomas. ADC values differs significantly between the tumor grades, but ADC and post\rcontrast signal intensity values have no correlation with Koos grade.