Blood brain barrier (BBB) can be opened transiently by the cavitation effect with the assist of focused ultrasound (FUS) and microbubble (MB). A previous study proved that FUS-induced MR signal changes can monitor cavitation effect in in vitro phantom experiments. However, whether MR signal changes can reflect BBB opening levels in vivo remains uncertain. In this study, a cavitation index (CI) map was employed to evaluate MR signal changes during FUS sonication in in vivo experiments. We aim to examine the relationship between MR signal change and BBB opening levels by associating CI map with Gd-enhancement and Ktrans maps.