1. Department of Neurosurgery, University of Iowa Hospital and Clinics, Iowa City, Iowa, USA;
2. University of Iowa, Carver College of Medicine, Iowa City, Iowa, USA;
3. Department of Radiation Oncology, University of Iowa Hospital and Clinics, Iowa City, Iowa, USA;
4. Department of Pathology, University of Iowa Hospital and Clinics, Iowa City, Iowa, USA;
5. Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA