Deep Learning for Cranioplasty in Clinical Practice: Going from Synthetic to Real Patient Data

• https://www.sciencedirect.com/science/article/abs/pii/S0010482521005606?via%3Dihub

Cranioplasty; Skull Reconstruction; Cranial Implant Design; 3D Convolutional Neural Networks

Correct virtual reconstruction of a de- fective skull is a prerequisite for successful cranioplasty and its automatization has the potential for accelerat- ing and standardizing the clinical workflow. This work provides a deep learning-based method for the recon- struction of a skull shape and cranial implant design on clinical data of patients indicated for cranioplasty. The method is based on a cascade of multi-branch vol- umetric CNNs that enables simultaneous training on two different types of cranioplasty ground-truth data: the skull patch, which represents the exact shape of the missing part of the original skull, and which can be eas- ily created artificially from healthy skulls, and expert- designed cranial implant shapes that are much harder to acquire. The proposed method reaches an average surface distance of the reconstructed skull patches of 0.67 mm on a clinical test set of 75 defective skulls. It also achieves a 12% reduction of a newly proposed de- fect border Gaussian curvature error metric, compared to a baseline model trained on synthetic data only. Ad- ditionally, it produces directly 3D printable cranial im- plant shapes with a Dice coefficient 0.88 and a surface error of 0.65 mm. The outputs of the proposed skull reconstruction method reach good quality and can be considered for use in semi- or fully automatic clinical cranial implant design workflows.