1. 1Department of Radiology, School of Medicine, Stanford University, Stanford, California, USA
2. 2Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
3. 3Department of Small Animal Clinical Sciences, Texas A&M University, College Station, Texas, USA
4. 4Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA; email: hoyt@tamu.edu