AIM To evaluate brain metastases volume control capabilities of stereotactic radiosurgery(SRS) through serial magnetic resonance(MR) imaging follow-up. METHODS MR examinations of 54 brain metastases in 31 patients before and after SRS were reviewed. Patients were included in this study if they had a pre-treatment MR examination and serial follow-up MR examinations at 6 wk, 9 wk, 12 wk, and 12 mo after SRS. The metastasis volume change was categorized at each follow-up as increased(> 20% of the initial volume), stable(± 20% of the initial volume) or decreased(< 20% of the initial volume). RESULTS A local tumor control with a significant(P < 0.05) volume decrease was observed in 25 metastases at 6-wk follow-up. Not significant volume change was observed in 23 metastases and a significant volume increase was observed in 6 metastases. At 9-wk followup, 15 out of 25 metastases that decreased in size at 6 wk had a transient tumor volume increase, followed by tumor regression at 12 wk. At 12-wk follow-up there was a significant reduction in volume in 45 metastases, and a significant volume increase in 4 metastases. At 12-mo follow-up, 19 metastases increased significantly in size(up to 41% of the initial volume). Volume tumor reduction was correlated to histopathologic subtype.CONCLUSION SRS provided an effective local brain metastases volume control that was demonstrated at follow-up MR imaging. AIM To evaluate brain metastases volume control capabilities of stereotactic radiosurgery (SRS) through serial magnetic resonance (MR) imaging follow-up. METHODS MR examinations of 54 brain metastases in 31 patients before and after SRS were reviewed. Patients were included in this study if they had a pre-treatment of MR examination and serial follow-up MR examinations at 6 wk, 9 wk, 12 wk, and 12 months after SRS. The metastasis volume change was categorized at each follow-up as increased (> 20% of the RESULTS A local tumor control with a significant (P <0.05) volume decrease was observed in 25 metastases at 6-wk (<20% of the initial volume) follow-up. Not significant volume change was observed in 23 metastases and a significant volume increase was observed in 6 metastases. At 9-wk followup, 15 out of 25 metastases that decreased in size at 6 wk had a transient tumor volume increase, followed by tumor regression at 12 wk. At 12 -wk follow-up there was a significant reduction in volume in 45 metastases, and a significant volume increase in 4 metastases. At 12-mo follow-up, 19 metastases greatly significantly in size (up to 41% of the initial volume). Volume tumor reduction was correlated to histopathologic subtype. CONCLUSION SRS provided an effective local brain metastases volume control that was demonstrated at follow-up MR imaging.