Bi-Directional Micro-Coil Electromagnetic Tracking for Vertebral Pose Accuracy
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Solution Overview
Problem
Existing electromagnetic (EM) navigation systems face challenges in accurately tracking the pose of vertebrae during spinal corrective surgery due to magnetic and conductive distortions caused by ferromagnetic materials and surgical instruments, which limit navigation volume and range.
Innovation Solution
A combined inverted-direction and bi-directional EM navigation system using micro-coil transmitters/receivers and spread-spectrum signaling to reduce distortions, allowing for precise tracking of vertebrae by minimizing magnetic and conductive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard EM navigation systems use macro-coil transmitters and mini-coil receivers, then navigation volume and range are covered, but magnetic and conductive distortions from ferromagnetic materials and surgical instruments significantly degrade tracking accuracy
Solution Approach 1:
The patent inverts the traditional EM navigation architecture by using micro-coils as transmitters and macro-coils as receivers. This reversal allows the system to operate in a regime where micro-coils generate localized fields that are less susceptible to distant ferromagnetic distortions, while the macro-coil receivers detect these fields with high sensitivity. The inversion fundamentally changes how the system interacts with distorting materials in the surgical field.
Solution Approach 2:
The patent changes key parameters of the EM system including coil sizes (from macro-transmitter/mini-receiver to micro-transmitter/macro-receiver), operating frequencies (100-1000 kHz range), and field strengths. These parameter changes enable the system to achieve better precision by operating in a frequency and field strength regime that is less affected by conductive and magnetic distortions from surgical instruments and ferromagnetic materials.
2Measurement precision
If micro-coil transmitters are used to reduce distortions, then tracking precision is improved, but navigation volume and range are reduced
Solution Approach 1:
The patent makes the EM navigation system multi-functional by enabling both high-precision localized tracking (through micro-coil transmitters) and extended navigation volume (through multiple macro-coil receivers positioned strategically). The system can adapt its configuration to serve different functional requirements within the same surgical procedure, achieving both precision and coverage.
Solution Approach 2:
The patent extends navigation volume by adding spatial dimensions to the receiver array configuration. Multiple macro-coil receivers are positioned at different locations and orientations around the patient, creating a three-dimensional detection network that expands the effective navigation volume while maintaining precision through the micro-coil transmitter architecture.
3Ease of operation
If ferromagnetic materials and surgical instruments are present in the surgical field, then surgical procedures can be performed, but magnetic distortions limit navigation range and accuracy
Solution Approach 1:
The patent converts the harmful effect of ferromagnetic materials and surgical instruments into a beneficial configuration by using micro-coil transmitters that operate at frequencies and field strengths where these materials have reduced distorting effects. The system design acknowledges the presence of surgical instruments and ferromagnetic materials while operating in a regime where their harmful magnetic and conductive distortions are minimized, effectively converting the surgical environment from a source of interference to an acceptable operating condition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system significantly reduces distortions while maintaining a clinically relevant navigation volume and range, enabling accurate real-time tracking of vertebrae positions and orientations during spinal surgery.
Implementation Method 1
Each micro-coil is configured to generate a distinct electromagnetic field
Implementation Method 2
neighboring micro-coils and receiving coils detect field components of each electromagnetic field
Data Source
AI summary
Tracking a pose of a portion of an anatomical structure using an electromagnetic navigation system may comprise generating a signal. The generated signal is configured to cause bi-directional micro coils of a bi-directional coil array to generate an electromagnetic field at each bi-directional micro coil in response to receiving the generated signal. Each of the bi-directional micro coils is also coupled to a portion of a tracked structure. At least one of the generated electromagnetic fields is configured to be detected by at least one neighboring bi-directional micro coil and at least one receiving coil of a receiving coil array. A pose of a particular bi-directional micro coil of the bi-directional micro coils associated with the at least one generated magnetic field is determined based on detecting the at least one generated magnetic field at the at least one neighboring bi-directional micro coil and the at least one receiving coil.