Relative cerebral blood volume measurements in intracranial mass lesions: interobserver and intraobserver reproducibility study

PURPOSE: To assess inter- and intraobserver reproducibility for different techniques of measuring relative cerebral blood volume (rCBV) in patients with intracranial mass lesions. MATERIALS AND METHODS: Three independent observers (neuroradiology fellows) who were blinded to the histopathologic diagnosis performed rCBV measurements in 50 patients with various intracranial mass lesions. Three different methods were compared. With method 1, placement of a single region of interest was guided by a color overlay map. With methods 2 and 3, the highest rCBV value and the mean of repeated rCBV measurements, respectively, were recorded. Calculations of the intraclass correlation coefficient, coefficient of variation (CV), and descriptive statistics were used to determine the levels of reproducibility. A multiple linear regression model was used to evaluate for possible explanatory factors for interobserver variance. RESULTS: Method 2 had, overall, the best reproducibility of all techniques, with an intraclass interobserver correlation coefficient of 0.71 (indicating good agreement), interobserver CV of 30%, and intraobserver CV in the range of 32%-41%. Measurement variations between observers correlated significantly (P