Non-Metallic MR-Guided Concentric Tube Robot for Intracerebral Hemorrhage Evacuation.

OBJECTIVE: We aim to develop and evaluate an MR-conditional concentric tube robot for intracerebral hemorrhage (ICH) evacuation. METHODS: We fabricated the concentric tube robot hardware with plastic tubes and customized pneumatic motors. The robot kinematic model was developed using a discretized piece-wise constant curvature (D-PCC) approach to account for variable curvature along the tube shape, and tube mechanics model was used to compensate torsional deflection of the inner tube. The MR-safe pneumatic motors were controlled using a variable gain PID algorithm. The robot hardware was validated in a series of bench-top and MRI experiments, and the robot's evacuation efficacy was tested in MR-guided phantom trials. RESULTS: The pneumatic motor was able to achieve a rotational accuracy of 0.32°±0.30° with the proposed variable gain PID control algorithm. The kinematic model provided a positional accuracy of the tube tip of 1.39 ± 0.54 mm. The robot was able to evacuate an initial 38.36 mL clot, leaving a residual hematoma of 8.14 mL after 5 minutes, well below the 15 mL guideline suggesting good post-ICH evacuation clinical outcomes. CONCLUSION: This robotic platform provides an effective method for MR-guided ICH evacuation. SIGNIFICANCE: ICH evacuation is feasible under MRI guidance using a plastic concentric tube, indicating potential feasibility in future live animal studies.

Validation of a novel path planner for stereotactic neurosurgical interventions-A retrospective clinical study.

BACKGROUND: The gold standard workflow for targeting structures in the brain involves manual path planning. This preoperative manual path planning is very time-intensive and laborious, especially when some outcome measures such as maximum ablation and penetration depth has to be optimised. METHODS: Our novel path planner generates an optimal path which maximises the hippocampus penetration and distance from critical structures using a precomputed cost map and a reward map. RESULTS: The average penetration ratio for 12 cases is 88.13 ± 23.23% for a resolution of 1° and a safety margin of 1 mm. Average run time for the path planner based on 1° resolution was 1.99 ± 0.68 min. CONCLUSIONS: Results show that the algorithm can generate safe and clinically relevant paths with a quantitative representation of the penetration depth and is faster than the average reported time for manual path planning.

Prevalence of Mendosal Suture Patency in Infants Up to the Age of 18 Months.

Background: The mendosal suture joins the interparietal and inferior portions of the occipital bone. Persistent patency of this suture can result in bathrocephaly, an abnormal occipital projection. This study aims to determine normal temporal fusion of the mendosal suture and cranial shape of the patients with persistent suture patency. Methods: A retrospective review of head CT scans in patients aged 0-18 months who presented to the emergency department between 2010 and 2020 was completed. Presence and patency of the mendosal suture were assessed. Cranial shape analysis was conducted in the cases that presented with 100% suture patency and age-matched controls. An exponential regression model was used to forecast the timing of suture fusion. Results: In total, 378 patients met inclusion criteria. Median age at imaging was 6.8 months (IQR 2.9, 11.6). Initiation of mendosal suture fusion was observed as early as 4 days of age and was completed in all instances except one by age 18 months. Most patients had either a complete or partial suture fusion (66.7% versus 30.7%, respectively), and 2.6% of patients had 100% suture patency. Cranial shape analysis demonstrated increased occipital projection in patients with 100% suture patency compared with their controls. Exponential regression model suggested that the mendosal suture closure begins prenatally and typically progresses to full closure at the age of 6 months. Conclusions: Prevalence of a patent mendosal suture was 2.6% overall. Mendosal suture fusion initiates in-utero and completes ex-utero within the first 18 months of life. Delayed closure results in greater occipital projection.