Dipole Field Navigation for targeted drug delivery

A new method for the navigation of therapeutic agents in the vascular network is introduced. This method, dubbed Dipole Field Navigation (DFN), is characterized by high directional gradients and a high magnetic field strength. The latter is used to bring magnetic therapeutic agents at saturation magnetization such that when combined with high directional gradients, effective navigation at any depths within the patient can be achieved. DFN does not have many of the constraints of gradient coil-based platforms, which include potential peripheral nerve stimulations, reduced directional changes and slew rates of the gradient fields, overheating of the coils, and high implementation cost. To achieve such specifications, soft ferromagnetic cores are positioned at specific locations inside the tunnel of a clinical MRI scanner providing a high uniform field of typically up to 3T, sufficient to bring both the cores and the therapeutic agents at full saturation magnetization. The field distortions created by the cores result in gradients exceeding 300 mT/m for whole body interventions. Hence, with such cores placed at specific locations, the resulting gradients would cause the therapeutic agents to follow a precise path in the vascular network towards the targeted region. In this paper, the fundamental theory of DFN with preliminary in vitro experimental results using one core in a 1.5T scanner confirms the potential of DFN for targeted drug delivery.