Brain T2 relaxometry can provide sensitive biomarkers for pathological tissue alterations, especially inflammation. But their acquisition is often 2D-based and typically comes with long acquisition times. To improve through-slice resolution while keeping a clinically feasible scan time, we propose a centric T2-prepared variable-density Cartesian spiral phyllotaxis FLASH sequence combined with a compressed sensing reconstruction. Phantom experiments and a preliminary in-vivo scan show that T2 values can be reliably measured in 3D with high resolution. Parameter dependencies are evaluated and an initial protocol optimisation yields an acquisition time of 8.48min for a 1x1x1.2mm3 whole-brain acquisition.