MRI-guided treatment of degenerative spinal diseases

MRI-guided lumbar spinal injections with body-mounted robotic system: cadaver studies

INTRODUCTION

This paper reports the system integration and cadaveric assessment of a body-mounted robotic system for MRI-guided lumbar spine injections. The system is developed to enable MR-guided interventions in closed bore magnet and avoid problems due to patient movement during cannula guidance.

MATERIAL AND METHODS

The robot is comprised by a lightweight and compact structure so that it can be mounted directly onto the lower back of a patient using straps. Therefore, it can minimize the influence of patient movement by moving with the patient. The MR-Conditional robot is integrated with an image-guided surgical planning workstation. A dedicated clinical workflow is created for the robot-assisted procedure to improve the conventional freehand MRI-guided procedure.

RESULTS

Cadaver studies were performed with both freehand and robot-assisted approaches to validate the feasibility of the clinical workflow and to assess the positioning accuracy of the robotic system. The experiment results demonstrate that the root mean square (RMS) error of the target position to be 2.57 ± 1.09 mm and of the insertion angle to be 2.17 ± 0.89°.

CONCLUSION

The robot-assisted approach is able to provide more accurate and reproducible cannula placements than the freehand procedure, as well as to reduce the number of insertion attempts.

MR compatible positioning device for guiding a focused ultrasound system for the treatment of brain deseases

BACKGROUND

A prototype magnetic resonance imaging (MRI)-compatible positioning device that navigates a high intensity focused ultrasound (HIFU) transducer is presented. The positioning device has three user-controlled degrees of freedom that allow access to brain targets using a lateral coupling approach. The positioning device can be used for the treatment of brain cancer (thermal mode ultrasound) or ischemic stroke (mechanical mode ultrasound).

MATERIALS AND METHODS

The positioning device incorporates only MRI compatible materials such as piezoelectric motors, ABS plastic, brass screws, and brass rack and pinion.

RESULT

The robot has the ability to accurately move the transducer thus creating overlapping lesions in rabbit brain in vivo. The registration and repeatability of the system was evaluated using tissues in vitro and gel phantom and was also tested in vivo in the brain of a rabbit.

CONCLUSION

A simple, cost effective, portable positioning device has been developed which can be used in virtually any clinical MRI scanner since it can be placed on the table of the MRI scanner. This system can be used to treat in the future patients with brain cancer and ischemic stroke.

An MRI-Compatible Surgical Robot for Precise Radiological Interventions

OBJECTIVE

A variety of medical robots have been developed in recent years. MRI, including MR angiography and morphological imaging, with its excellent soft-tissue contrast is attractive for the development of interventional MRI-guided therapies and operations. This paper presents a telerobotic device for use in CT- and/or MR-guided radiological interventions. A robotic device for precise needle insertion during MR-guided therapy of spinal diseases will be briefly described.

MATERIALS AND METHODS

Actuation of robots in an MRI environment is difficult due to the presence of strong magnetic fields. Therefore, the robot was constructed of nonmagnetic materials. The system frame was built from polyether ether ketone (PEEK) and fiber-reinforced epoxy, and actuated using ultrasonic and pneumatic motors. Completely MR-compatible sensors were developed for positioning control.

RESULTS

Accuracy evaluation procedures and phantom tests were performed, with the required accuracy of approximately 1 mm being achieved and no significant artifacts being caused by the robotic device during MR image acquisition.