A system for endoscopic mechanically scanned localized proton MR and light-induced fluorescence emission spectroscopies.

Molecular and near-cellular modalities offer new opportunities in assessing living tissue in situ, and multimodality approaches, which offer complementary information, may lead to improved characterization of tissue pathophysiology benefiting diagnosis and focal therapy. However, many such modalities are limited by their low penetration through tissue, which has led to minimally invasive trans-cannula approaches to place the corresponding sensors locally at the area of interest. This work presents a system for performing localized fluorescence emission and proton magnetic resonance (MR) spectroscopies via endoscopic access. The in-house developed side-firing 1.9-mm wide dual-sensor integrates a three-fiber optical sensor for fluorescence emission optical spectroscopy and a 1-mm circular radiofrequency (RF) coil for localized MR proton spectroscopy. An MR-compatible manipulator was developed for carrying and mechanically translating the dual-sensor along a linear access channel. The hardware and software control of the system allows reconfigurable synchronization of the manipulator-assisted translation of the sensor, and MR and optical data collection. The manipulator serves as the mechanical link for the three modalities and MR images, MR spectra and optical spectra are inherently co-registered to the MR scanner coordinate system. These spectra were then used to generate spatio-spectral maps of the fluorophores and proton MR-signal sources in three-compartment phantoms with optically- and MR-visible, and distinguishable, materials. These data demonstrate a good spatial match between MR images, MR spectra and optical spectra along the scanned path. In addition to basic research, such a system may have clinical applications for assessing and characterizing cancer in situ, as well as guiding focal therapies.

Simulations and experimental demonstration of coupling molecular and macroscopic level modalities with a robotic manipulator.

Established and emerging molecular and cellular modalities, such as optical imaging and spectroscopy, offer new opportunities for assessing tissue pathophysiology in situ. A challenge with such applications is their limited tissue penetration and low sensitivity that can be addressed with trans-needle or trans-catheter access. In this work, we describe the use of an actuated manipulator to physically manipulate such sensors to scan an area of interest generating 1-D scans while registering them to a guiding modality. Simulations were performed for a miniature RF coil to determine the voxel size, and experimental studies were conducted using a miniature RF coil manipulated by the MR-compatible device. The experimental results on phantom studies show that potential diagnostic information can be collected by using this methodology. This system was pursued to address a critical limitation of emerging molecular and near-cellular modalities; the limited tissue penetration.

MR-based real time path planning for cardiac operations with transapical access.

Minimally invasive surgeries (MIS) have been perpetually evolving due to their potential high impact on improving patient management and overall cost effectiveness. Currently, MIS are further strengthened by the incorporation of magnetic resonance imaging (MRI) for amended visualization and high precision. Motivated by the fact that real-time MRI is emerging as a feasible modality especially for guiding interventions and surgeries in the beating heart; in this paper we introduce a real-time path planning algorithm for intracardiac procedures. Our approach creates a volumetric safety zone inside a beating heart and updates it on-the-fly using real-time MRI during the deployment of a robotic device. In order to prove the concept and assess the feasibility of the introduced method, a realistic operational scenario of transapical aortic valve replacement in a beating heart is chosen as the virtual case study.