[1] UNIV PITTSBURGH, DEPT NEUROL SURG, PITTSBURGH, PA 15261 USA
[2] UNIV PITTSBURGH, DEPT ANESTHESIOL, PITTSBURGH, PA 15261 USA
[3] UNIV PITTSBURGH, DEPT RADIAT HLTH, PITTSBURGH, PA 15261 USA
[4] UNIV PITTSBURGH, DEPT RADIOL, PITTSBURGH, PA 15261 USA
[5] UNIV PITTSBURGH, DEPT NEUROL, PITTSBURGH, PA 15261 USA
[6] CASE WESTERN RESERVE UNIV, DIV CRIT CARE MED, CLEVELAND, OH 44106 USA
[7] MONTEFIORE HOSP, SURG RES LAB, PITTSBURGH, PA 15213 USA