Pre-procedural simulation for precision stent-assisted coiling of cerebral aneurysm

Fluid-structure interactions of peripheral arteries using a coupled in silico and in vitro approach

Vascular compliance is considered both a cause and a consequence of cardiovascular disease and a significant factor in the mid- and long-term patency of vascular grafts. However, the biomechanical effects of localised changes in compliance cannot be satisfactorily studied with the available medical imaging technologies or surgical simulation materials. To address this unmet need, we developed a coupled silico-vitro platform which allows for the validation of numerical fluid-structure interaction results as a numerical model and physical prototype. This numerical one-way and two-way fluid-structure interaction study is based on a three-dimensional computer model of an idealised femoral artery which is validated against patient measurements derived from the literature. The numerical results are then compared with experimental values collected from compliant arterial phantoms via direct pressurisation and ring tensile testing. Phantoms within a compliance range of 1.4-68.0%/100 mmHg were fabricated via additive manufacturing and silicone casting, then mechanically characterised via ring tensile testing and optical analysis under direct pressurisation with moderately statistically significant differences in measured compliance ranging between 10 and 20% for the two methods. One-way fluid-structure interaction coupling underestimated arterial wall compliance by up to 14.7% compared with two-way coupled models. Overall, Solaris™ (Smooth-On) matched the compliance range of the numerical and in vivo patient models most closely out of the tested silicone materials. Our approach is promising for vascular applications where mechanical compliance is especially important, such as the study of diseases which commonly affect arterial wall stiffness, such as atherosclerosis, and the model-based design, surgical training, and optimisation of vascular prostheses.

Development of a Pedicle Screw Fixation Simulation Model for Surgical Training Using a 3-Dimensional Printer

OBJECTIVE

Training surgeons in pedicle screw fixation (PSF) techniques during actual surgery is limited because of patient safety, complications, and surgical efficiency issues. Recent technical developments are leading the world to an era of personalized three-dimensional (3D) printing. This study aimed to evaluate the educational effect of using a 3D-printed spine model to train beginners in PSF techniques to improve screw accuracy and procedure time.

METHODS

Computed tomography (CT) scan data were used in a 3D printer to produce a life-size lumbar spine replica of L1-3 vertebrae. Four residents performed PSF thrice. Each resident performed 18 screw fixations on both sides (6 screws per trial). The time to complete the procedure and pedicle violation was recorded.

RESULTS

The average time for the 3 procedures was 42.1±2.9 minutes, 38.8±3.3 minutes, and 32.1±2.5 minutes, respectively. Furthermore, the average pedicle screw score for the 3 procedures was 13.0±0.8, 14.5±0.6, and 16.0±0.8, respectively. As the trial was repeated, the procedure time decreased and the accuracy of screw fixation tended to be more accurate.

CONCLUSIONS

It was possible to decrease the procedure time and increase accuracy through repeated training using the 3D-printed spine model. By implementing a 3Dprinted spine model based on the patient's actual CT data, surgeons can perform simulation surgery before the actual surgery. Therefore, this technology can be useful in educating residents to improve their surgical skills.

Usefulness of Preoperative Simulation Using a Stereolithographic 3D Printer in Cerebral Aneurysm Coil Embolization

Objective

We present a preoperative simulation of cerebral aneurysm coil embolization using a hollow model of cerebral blood vessels created by a stereolithography (SLA) 3D printer.

Case Presentation

The patient was a 66-year-old woman. During follow-up, coil embolization was planned for an expanding paraclinoid aneurysm. A hollow cerebral vascular model was created preoperatively using an SLA 3D printer. The catheter was malleable and inserted into the hollow model, which enabled the surgeons to confirm its movement, stability, and ease of insertion. In the surgical procedure, the catheter was easily inserted into the aneurysm without reshaping. The procedure was completed without stability problems.

Conclusion

The use of a hollow model of cerebral blood vessels was useful as a preoperative simulation and improved the safety of the procedure.

Advances in endovascular aneurysm management: coiling and adjunctive devices

Endovascular coil embolisation continues to evolve and remains a valid modality in managing ruptured and unruptured cerebral aneurysms. Technological advances in coil properties, adjunctive devices and interventional techniques continue to improve long-term aneurysm occlusion rates. This review elaborates on the latest advances in next-generation endovascular coils and adjunctive coiling techniques for treating cerebral aneurysms.