ABSTRACT
OBJECTIVE: A novel small form factor circular electrode array was designed specifically for electrical impedance tomography (EIT) based assessment of surgical margins during robot assisted radical prostatectomy (RARP). METHODS: The electrode array consists of 33 gold-plated electrodes arranged within a 9.5 mm diameter circular footprint on the end of a surgical probe that can be introduced through a standard 12 mm laparoscopic port used during RARP. The electrode array contains 8 larger, low-contact impedance outer electrodes dedicated for current drive and an internal grid of 25 smaller electrodes for simultaneous voltage measurement. Separating electrode geometry by function is designed to improve current delivery, speed, and resolution while reducing hardware requirements. RESULTS: Simulations demonstrated that 1 mm diameter hemispherical prostate cancer inclusions could be localized within regions of adipose and benign prostate tissue; 1.5 mm diameter inclusions were required for localization within muscle tissue. A 2.38 mm diameter aluminum rod in 0.2 S/m saline could be localized throughout the imaging domain with a position error of less than 2.5 mm for depths from the electrode array surface of up to 1.7 mm. Ex vivo tissue experiments with a bovine model demonstrate visual congruence of muscle and adipose tissue locations between the sample and reconstructed images. CONCLUSION: Simulation and experimental results indicate good detection and location of inclusions. SIGNIFICANCE: These results suggest the proposed electrode array design can provide sufficient accuracy in the detection and localization of prostate cancer against clinically relevant background tissues for use during RARP.
ABSTRACT
Infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are alarming in the clinical setting, as CRE isolates often exhibit resistance to most clinically-available antibiotics. Klebsiella pneumoniae carbapenemase (KPC) is the most common carbapenemase carried by CRE in North America and Europe, frequently detected in isolates of K. pneumoniae, Escherichia coli, and Enterobacter cloacae. Notably, KPC-expressing strains often arise from clonal lineages, with sequence type 258 (ST258) representing the dominant lineage in K. pneumoniae, ST131 in E. coli, and ST78 and ST171 in E. cloacae. Prior studies have demonstrated that carbapenem-resistant K. pneumoniae differs from carbapenem-susceptible K. pneumoniae at both the transcriptomic and soluble metabolomic levels. In the present study, we sought to determine whether carbapenem-resistant and carbapenem-susceptible isolates of K. pneumoniae, E. coli, and E. cloacae produce distinct volatile metabolic profiles. We were able to identify a volatile metabolic fingerprint that could discriminate between CRE and non-CRE with an area under the receiver operating characteristic curve (AUROC) as high as 0.912. Species-specific AUROCs were as high as 0.988 for K. pneumoniae and 1.000 for E. cloacae. Paradoxically, curing of KPC-expressing plasmids from a subset of K. pneumoniae isolates further accentuated the metabolic differences observed between ST258 and non-ST258.
