HOW RELIABLE ARE OCCIPITAL ASYMMETRY MEASUREMENTS

In vivo occipital asymmetry (OA) measurements have been used to infer functional asymmetries such as language dominance. We investigated the degree of correlation between OA measurements derived by the same rat er from different scans of the same subject. We used magnetic resonanc e (MR) and computerized axial tomography (CT) to study correlations be tween MR:MR, CT:CT and CT:MR. The highest intrasubject correlation was for MR. MR (r =0.79). The CT:CT value was similar (r = 0.78) and the CT:MR correlation was slightly lower (r = 0.72). The findings indicate that the reliability of occipital asymmetry measurements is modest at best, setting a low ceiling on the valid use of this variable to infe r other indexes.