Optical and electromagnetic tracking guidance for hepatic interventions

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Abstract

The system hardware and software were verified, integrated, and validated as one unit. The function and workflow in an in vivo model were defined and the clinical trial in human liver biopsy continues as a translational clinical trial with IRB approval. A custom electromagnetic (EM) tracking biopsy platform was modified to include visualization and quantification of ICG fluorescence intensity signals, derived from either an ICG fluorescence probe (for in vivo detection) or and ICG optical point-of-care (POC) system (for ex vivo specimen). Feasibility was evaluated in i) abdomen phantom with 0.001mg/ ICG injected ii) a woodchuck HCC model (in vivo and ex vivo biopsy cores, as well as explanted liver tissue) with intravenous injected ICG 1 day prior to biopsy. ICG fluorescence signal and diagnostic accuracy were defined. During EM-tracked ICG probe needle guidance in the phantom, the mean error between the first ICG fluorescence signal and the peak ICG fluorescence signal was about 5mm. In vivo, the EM-ICG biopsy platform was successful in targeting 7 biopsy locations and obtaining 10 biopsy cores. ICG-probe fluorescence intensity signal on ex vivo normal and cancerous liver specimens was able to be differentiated in a point of care testing system (camera and filters in a box). EM tracked coaxial needle combined with an ICG probe provided simultaneous and real-time navigation with optical molecular imaging feedback during hepatic tumor biopsy. Direct assessment of the biopsy cores using an ICG-POC system could provide real-time imaging feedback on type and quality of the derived biopsy core. EM tracking was predominantly useful for gross navigation towards a specified target (such as an arterial enhancing LIRADS 5 lesion), whereas the optical system was most useful for "fine-tuning" or smaller adjustments of sample locations. This method of use is recruiting patients and is in process of being studied in the clinical trial which is IRB cleared and ongoing. We have completed 7 patients thus far with preliminary results quite promising for the ability to detect local cancer in the liver via a combined needle based optical and electromagnetic tracking approach. The regulatory pathway reflected the challenges of combining two novel systems in a drug and device, first in human study. Cytology point of care system results are in the process of being closely compared to in vivo signal results with ICG. Alternate designs that integrate FDA cleared EM tracking systems will be designed and deployed in the future.