Fig 1.
Optical MPT system with interventional tool for real-time guidance.
(A) The MR-compatible tracking camera detects the position and orientation of a planar MPT marker shown in. (B) For real time needle guidance four MPT markers were rigidly attached to a ceramic needle with a dedicated holding device.
Fig 2.
Overview of the software implementation.
The real-time position of the MPT marker was continuously sent to the MRI Host in the control room. Based on it, the modified GRE sequence automatically aligned the imaging planes along the needle further utilizing the calibration information of the needle as well as the cross-calibration between the MRI and the optical tracking system. Additionally, a graphical overlay was produced. The resulting images of the needle guidance were sent in real-time towards the in-room monitor in the scanner room.
Fig 3.
Schematic drawing of the real-time needle guidance with the MPT system.
Two perpendicular imaging planes were aligned along the needle trajectory and centered at the needle tip. The additional graphical overlay contains information about the 3D distance between the needle tip and the predefined target as well as the 2D distance of
.
Fig 4.
Experimental setup of the user study.
A schematic drawing of the experimental setup is given in (A). The image (B) shows the real setup during the hands-on user study.
Fig 5.
Real-time needle guidance with the MPT system during the user study.
(A) The display of the in-room monitor presents images of the real-time needle guidance sequence during the user study together with its graphical overlay. (B) The present MRI image was extracted from one high-resolution dataset. The colored dots mark the detected real needle tip position (red dot) and the predefined target (blue dot).
Table 1.
Results of the hands-on user study with the MPT system.