T2 mapping is a parametric imaging approach that provides quantification of T2-weighted images for a more accurate diagnosis of pathology. 2D multi-slice T2 estimation techniques cannot be used for thin slice isotropic imaging. To overcome this limitation, we present a T2 mapping technique using a 3D radial FSE pulse sequence with a variable flip angle scheme for optimal T2-weighting and T2 mapping within SAR constraints. Data is acquired in a stack-of-stars radial trajectory and T2 maps are reconstructed using model based iterative algorithms. The method is demonstrated in phantoms and in vivo brain and musculoskeletal imaging.