A miniature accelerometer-based guidance device for percutaneous computed tomography-guided punctures

Purpose: Percutaneous punctures are often performed under computed tomography (CT) guidance using a freehand method. Especially in challenging cases, initial accuracy of the needle placement is highly dependent on the radiologist’s experience. Thus, a miniature lightweight guidance device was developed which is capable of assisting a radiologist during the needle placement process.Methods: The device utilizes an accelerometer to measure the needle’s tilt by calculating a set of orientation angles. This set can be matched with the coordinate system of the CT imaging software during a simple alignment process. After that, the needle’s orientation can be expressed in terms of projected angles in the axial and sagittal planes. The accuracy of the device was evaluated in a phantom study, and initial clinical trials were carried out performing facet joint punctures in a swine cadaver.Results: The sensor was embedded in a cube with dimensions of 2cm×2cm×2cm and a total weight of about 11 g which can be attached to the puncture needle at its rear end or handgrip. A graphical user interface (GUÌ) has been created offering visual real-time orientation guidance. Results of the phantom experiments showed differences between planned target and performed puncture angles of 0.^96∘±0.^76∘ for in-plane and 1.^78∘±1.^37∘ for out-of-plane punctures.Conclusion:  The results of the phantom and ex vivo study suggest that the device is useful to assist a radiologist in CT-guided percutaneous punctures and helps navigating the needle with high precision.