Our second study of the research blog looks at the field of robotics in interventional radiology (1).
Objective: The study aimed to evaluate the accuracy of an optically tracked robotic device (Micromate) for CT-guided needle placements in a controlled phantom setting.
Methods:
Experimental Setup: The study used a gelatin-filled plexiglass phantom with conically shaped targets. A total of 240 needle punctures were performed using the Micromate robotic guidance system, assessing accuracy at three different CT slice thicknesses (1, 3, and 5 mm).
Accuracy Assessment: Accuracy was measured in terms of the Euclidean distance (ED) between the needle tip and target and the normal distance (ND) between the needle path and the target. The evaluation also considered the impact of CT slice thickness and target depth on accuracy.
Procedural Time: The time taken for planning and needle positioning was recorded.
Results:
The Micromate system achieved a mean ND of 1.34 mm and ED of 2.1 mm for the thinnest CT slice thickness (1 mm), demonstrating high precision. Accuracy decreased as slice thickness increased, with significant differences observed between 1 mm, 3 mm, and 5 mm slices.
There was no significant impact of target depth on accuracy.
The average time required for trajectory planning and needle positioning was 42 seconds and 64 seconds, respectively.
Conclusion: The Micromate system achieved satisfactory accuracy in ex vivo conditions, particularly at lower CT slice thicknesses, and shows potential for improving needle placement accuracy in clinical settings.
Strengths of the paper:
Detailed Accuracy Metrics: The use of multiple accuracy measures (ED and ND) provides a detailed evaluation of the system's performance.
Focus on Practical Applications: The study highlights the system's potential benefits in clinical settings, particularly its ability to reduce manual repositioning and improve targeting accuracy.
Limitations of the paper:
Limited Clinical Translation: The study was conducted in a phantom setting, which does not perfectly replicate the complexities of human anatomy, such as tissue heterogeneity and movement due to breathing.
Fixed Phantom Positioning: The setup required the phantom, robot, and camera to remain fixed, which is not fully representative of dynamic clinical environments where patient and equipment movement can affect performance.
Impact of Slice Thickness: Although the study found significant effects of slice thickness on accuracy, the 5 mm thickness showed outliers in results, suggesting that the system may struggle with coarser imaging, limiting its use in settings where fine resolution is unavailable.
Cost and Complexity: The discussion touched on the need to balance the accuracy benefits against the system's complexity and cost, but did not delve deeply into these practical barriers for broader clinical adoption.
Opportunities for Future Research:
Testing in clinical settings on human subjects is crucial to validate the system's effectiveness under real-world conditions.
Exploring the integration of respiratory compensation modules could address one of the key limitations identified in the study.
Comparative studies with other existing robotic systems would provide further insights into the relative advantages and disadvantages of the Micromate.
(1): Scharll, Y., Radojicic, N., Laimer, G., Schullian, P. and Bale, R., 2024. Puncture Accuracy of Robot-Assisted CT-Based Punctures in Interventional Radiology: An Ex Vivo Study. Diagnostics, 14(13), p.1371.
Overall, the paper provides a thorough initial evaluation of the Micromate system, with promising results that warrant further investigation in more complex and clinically relevant scenarios. Thank you for reading and see you next time on our research blog!
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