On accuracy of personalized 3D-printed MRI-based models of brain arteries

Possibilities of constructing an anatomically correct and accurate geometric model of brain blood vessels basing on clinical 1.5T magnetic resonance images are explored. A high-resolution ToF MR image (0.49 mm3 voxel) was used to build a reference geometric model of selected real-brain arteries. This model was STL-described and 3D printed using a photopolymer material. The printed phantom was submerged in water and scanned using a low-resolution clinical MR system (0.33×0.33×2.2 mm). Level-set segmentation of the obtained T2 images showed significant staircase effect. After T2 image resampling to 0.33mm3 voxel size, the model walls become smoother, but thin branches were still missing. A Frangi filtering-based, smooth centerline-radius vessel branches description was then developed to achieve their correct reconstruction with subvoxel accuracy. Challenges of MRI acquisition of 3D printed models are discussed.