Out of distribution detection for intra-operative functional imaging

Multispectral optical imaging is becoming a key tool in the operating room. Recent research has shown that machine learning algorithms can be used to convert pixel-wise reflectance measurements to tissue parameters, such as oxygenation. However, the accuracy of these algorithms can only be guaranteed if the spectra acquired during surgery match the ones seen during training. It is therefore of great interest to detect so-called out of distribution (OoD) spectra to prevent the algorithm from presenting spurious results. In this paper we present an information theory based approach to OoD detection based on the widely applicable information criterion (WAIC). Our work builds upon recent methodology related to invertible neural networks (INN). Specifically, we make use of an ensemble of INNs as we need their tractable Jacobians in order to compute the WAIC. Comprehensive experiments with in silico, and in vivo multispectral imaging data indicate that our approach is well-suited for OoD detection. Our method could thus be an important step towards reliable functional imaging in the operating room.Comment: The final authenticated version is available online at https://doi.org/10.1007/978-3-030-32689-0_

Computer- and robot-assisted Medical Intervention

Medical robotics includes assistive devices used by the physician in order to make his/her diagnostic or therapeutic practices easier and more efficient. This chapter focuses on such systems. It introduces the general field of Computer-Assisted Medical Interventions, its aims, its different components and describes the place of robots in that context. The evolutions in terms of general design and control paradigms in the development of medical robots are presented and issues specific to that application domain are discussed. A view of existing systems, on-going developments and future trends is given. A case-study is detailed. Other types of robotic help in the medical environment (such as for assisting a handicapped person, for rehabilitation of a patient or for replacement of some damaged/suppressed limbs or organs) are out of the scope of this chapter.Comment: Handbook of Automation, Shimon Nof (Ed.) (2009) 000-00

β-adrenergic-mediated dynamic augmentation of sarcolemmal CaV 1.2 clustering and co-operativity in ventricular myocytes.

Key pointsPrevailing dogma holds that activation of the β-adrenergic receptor/cAMP/protein kinase A signalling pathway leads to enhanced L-type CaV 1.2 channel activity, resulting in increased Ca2+ influx into ventricular myocytes and a positive inotropic response. However, the full mechanistic and molecular details underlying this phenomenon are incompletely understood. CaV 1.2 channel clusters decorate T-tubule sarcolemmas of ventricular myocytes. Within clusters, nanometer proximity between channels permits Ca2+ -dependent co-operative gating behaviour mediated by physical interactions between adjacent channel C-terminal tails. We report that stimulation of cardiomyocytes with isoproterenol, evokes dynamic, protein kinase A-dependent augmentation of CaV 1.2 channel abundance along cardiomyocyte T-tubules, resulting in the appearance of channel 'super-clusters', and enhanced channel co-operativity that amplifies Ca2+ influx. On the basis of these data, we suggest a new model in which a sub-sarcolemmal pool of pre-synthesized CaV 1.2 channels resides in cardiomyocytes and can be mobilized to the membrane in times of high haemodynamic or metabolic demand, to tune excitation-contraction coupling.AbstractVoltage-dependent L-type CaV 1.2 channels play an indispensable role in cardiac excitation-contraction coupling. Activation of the β-adrenergic receptor (βAR)/cAMP/protein kinase A (PKA) signalling pathway leads to enhanced CaV 1.2 activity, resulting in increased Ca2+ influx into ventricular myocytes and a positive inotropic response. CaV 1.2 channels exhibit a clustered distribution along the T-tubule sarcolemma of ventricular myocytes where nanometer proximity between channels permits Ca2+ -dependent co-operative gating behaviour mediated by dynamic, physical, allosteric interactions between adjacent channel C-terminal tails. This amplifies Ca2+ influx and augments myocyte Ca2+ transient and contraction amplitudes. We investigated whether βAR signalling could alter CaV 1.2 channel clustering to facilitate co-operative channel interactions and elevate Ca2+ influx in ventricular myocytes. Bimolecular fluorescence complementation experiments reveal that the βAR agonist, isoproterenol (ISO), promotes enhanced CaV 1.2-CaV 1.2 physical interactions. Super-resolution nanoscopy and dynamic channel tracking indicate that these interactions are expedited by enhanced spatial proximity between channels, resulting in the appearance of CaV 1.2 'super-clusters' along the z-lines of ISO-stimulated cardiomyocytes. The mechanism that leads to super-cluster formation involves rapid, dynamic augmentation of sarcolemmal CaV 1.2 channel abundance after ISO application. Optical and electrophysiological single channel recordings confirm that these newly inserted channels are functional and contribute to overt co-operative gating behaviour of CaV 1.2 channels in ISO stimulated myocytes. The results of the present study reveal a new facet of βAR-mediated regulation of CaV 1.2 channels in the heart and support the novel concept that a pre-synthesized pool of sub-sarcolemmal CaV 1.2 channel-containing vesicles/endosomes resides in cardiomyocytes and can be mobilized to the sarcolemma to tune excitation-contraction coupling to meet metabolic and/or haemodynamic demands

Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery

One of the main challenges for computer-assisted surgery (CAS) is to determine the intra-opera- tive morphology and motion of soft-tissues. This information is prerequisite to the registration of multi-modal patient-specific data for enhancing the surgeon’s navigation capabilites by observ- ing beyond exposed tissue surfaces and for providing intelligent control of robotic-assisted in- struments. In minimally invasive surgery (MIS), optical techniques are an increasingly attractive approach for in vivo 3D reconstruction of the soft-tissue surface geometry. This paper reviews the state-of-the-art methods for optical intra-operative 3D reconstruction in laparoscopic surgery and discusses the technical challenges and future perspectives towards clinical translation. With the recent paradigm shift of surgical practice towards MIS and new developments in 3D opti- cal imaging, this is a timely discussion about technologies that could facilitate complex CAS procedures in dynamic and deformable anatomical regions

Getting the best outcomes from epilepsy surgery.

Neurosurgery is an underutilized treatment that can potentially cure drug-refractory epilepsy. Careful, multidisciplinary presurgical evaluation is vital for selecting patients and to ensure optimal outcomes. Advances in neuroimaging have improved diagnosis and guided surgical intervention. Invasive electroencephalography allows the evaluation of complex patients who would otherwise not be candidates for neurosurgery. We review the current state of the assessment and selection of patients and consider established and novel surgical procedures and associated outcome data. We aim to dispel myths that may inhibit physicians from referring and patients from considering neurosurgical intervention for drug-refractory focal epilepsies. Ann Neurol 2018;83:676-690

Episodic memory retrieval, parietal cortex, and the default mode network: Functional and topographic analyses

The default mode network (DMN) is often considered a functionally homogeneous system that is broadly associated with internally directed cognition (e.g., episodic memory, theory of mind, self-evaluation). However, few studies have examined how this network interacts with other networks during putative default processes such as episodic memory retrieval. Using functional magnetic resonance imaging, we investigated the topography and response profile of human parietal regions inside and outside the DMN, independently defined using task-evoked deactivations and resting-state functional connectivity, during episodic memory retrieval. Memory retrieval activated posterior nodes of the DMN, particularly the angular gyrus, but also more anterior and dorsal parietal regions that were anatomically separate from the DMN. The two sets of parietal regions showed different resting-state functional connectivity and response profiles. During memory retrieval, responses in DMN regions peaked sooner than non-DMN regions, which in turn showed responses that were sustained until a final memory judgment was reached. Moreover, a parahippocampal region that showed strong resting-state connectivity with parietal DMN regions also exhibited a pattern of task-evoked activity similar to that exhibited by DMN regions. These results suggest that DMN parietal regions directly supported memory retrieval, whereas non-DMN parietal regions were more involved in postretrieval processes such as memory-based decision making. Finally, a robust functional dissociation within the DMN was observed. Whereas angular gyrus and posterior cingulate/precuneus were significantly activated during memory retrieval, an anterior DMN node in medial prefrontal cortex was strongly deactivated. This latter finding demonstrates functional heterogeneity rather than homogeneity within the DMN during episodic memory retrieval

Advances in ENT imaging

Over the last ten years or so radiology has shown dramatic technological developments especially in cross sectional imaging and the investigation and management of the complex ENT patient has benefitted enormously. Plain radiographs are being utilised less and less as their limitations are becoming more apparent and various studies have shown for example a 75% discrepancy between plain sinus radiographs and coronal sinus CT in children1,2 . The incorporation of small and flexible ultrasound transducers with high-resolution imaging into the tips of endoluminal catheters has allowed good quality endoluminal ultrasound. Recently endolaryngeal ultrasound has been clinically evaluated in 38 patients with a variety of laryngeal pathology including vocal fold polyps, laryngeal cysts, chronic laryngitis, epithelial dysplasia and cancer 5 . Using this technique tumour size and infiltration could be measured and involvement of the thyroid cartilage or anterior commissure could be visualised. Not surprisingly it was not able to detect any specific changes in the sonographic picture of patients suffering from chronic laryngitis, epithelial dysplasia or microinvasive cancer. Although these results are encouraging, its relative lack of availability will result in it only having a limited role in evaluating laryngeal pathology.peer-reviewe

Full Issue: Volume 13, Issue 1 - Winter 2018

Full Issue: Volume 13, Issue 1 - Winter 201