Background: As a non-contact, non-invasive medical imaging technique, magnetic induction tomography (MIT) can measure the conductivity distribution inside the human body. Numerical calculation and physical phantom tests have showed the accuracy of MIT in principle. However, very few human studies have limited the development and application. At the key stage before clinical trials, animal experiment will be an effective method to verify the feasibility of in vivo detection the conductivity variation inside of biological body.
Methods: An abdominal subcutaneous injection rabbit model was used to simulate the local conductivity perturbation by injecting a 0.9% NaCl solution along with in vitro heparinized blood step by step. An insulated and sliding operation console was built to carry out the animal tests. An improved 16-channel MIT data acquisition system was used to record the data at 13.56 MHz and 4 seconds per frame. A series of time-difference reconstructed images, relative to non-injection, were obtained by the regularized Newton-Raphson algorithm for every 3 mL of injection.
Results: 15 rabbits were divided by two groups. Six rabbits were injected with 0.9% NaCl solution and nine rabbits were injected with the in vitro heparinized blood. The target with an increased conductivity distribution can clearly be observed in all the reconstructed images. The maximum target value in each image increased with the injection dosage. The slopes of the regressive line for the mean of maximum target value in two groups were statistically different.
Conclusion: Local conductivity perturbation inside of the rabbits is able to be reconstructed. The position and conductivity difference relative to the surrounding tissue of the target can be reflected correctly. This preliminary rabbit test shows the feasibility of the in vivo application for MIT and will be the basis for further animal tests and clinical trials in the future.