1. Department of Radiological SciencesUCLA School of Medicine Los Angeles 90095–17215 California USA
2. Department of RadiologyCollege of Physicians & Surgeons of Columbia University New York 10032 New York USA
3. Department of PhysicsUniversity of Dallas Dallas 75062 Texas USA
4. Department of AnesthesiologyCollege of Physicians & Surgeons of Columbia University New York 10032 New York USA
5. Department of NeurosurgeryCollege of Physicians & Surgeons of Columbia University New York 10032 New York USA
6. Department of Electrical EngineeringColumbia University New York 10027 New York USA