Image-guided surgery: from X-rays to virtual reality

Since the discovery of X-rays, medical imaging has played a major role in the guidance of surgical procedures. While medical imaging began with simple X-ray plates to indicate the presence of foreign objects within the human body, the advent of the computer has been a major factor in the recent development of this field. Imaging techniques have grown greatly in their sophistication and can now provide the surgeon with high quality three-dimensional images depicting not only the normal anatomy and pathology, but also vascularity and function. One key factor in the advances in Image-Guided Surgery (IGS) is the ability not only to register images derived from the various imaging modalities amongst themselves, but also to register them to the patient. The other crucial aspect of IGS is the ability to track instruments in real time during the procedure, and to portray them as part of a realistic model of the operative volume. Stereoscopic and virtual-reality techniques can usefully enhance the visualization process. IGS nevertheless relies heavily on the assumption that the images acquired prior to surgery, and upon which the surgical guidance is based, accurately represent the morphology of the tissue during the surgical procedure. In many instances this assumption is invalid, and intra-operative real-time imaging, using interventional MRI, Ultrasound, and electrophysiological recordings are often employed to overcome this limitation. Although now in extensive clinical use, IGS is often currently perceived as an intrusion into the operating room. It must evolve towards becoming a routine surgical tool, but this will only happen if natural and intuitive human interfaces are developed for these systems.     

Rapid acquisition of Raman spectral maps through minimal sampling: applications in tissue imaging

A method is presented for acquiring high‐spatial‐resolution spectral maps, in particular for Raman micro‐spectroscopy (RMS), by selectively sampling the spatial features of interest and interpolating the results. This method achieves up to 30 times reduction in the sampling time compared to raster‐scanning, the resulting images have excellent correlation with conventional histopathological staining, and are achieved with sufficient spectral signal‐to‐noise ratio to identify individual tissue structures. The benefits of this selective sampling method are not limited to tissue imaging however; it is expected that the method may be applied to other techniques which employ point‐by‐point mapping of large substrates. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel in vivo Cerenkov luminescence image‐guided surgery on primary and metastatic colorectal cancer

Intraoperative Cerenkov luminescence imaging (CLI) can effectively improve the performance of tumor surgery. Nevertheless, the existing approaches are still unsatisfying to the clinical demands of open surgery. This study develops a novel intraoperative in vivo CLI approach to investigate the potential and value of Cerenkov luminescence (CL) image‐guided surgery. A system characterized with high sensitivity (19.61 kBq mL^{?1 18}F‐FDG) and desirable spatial resolution (88.34 μm) is developed. CL image‐guided surgery is performed on colorectal cancer (CRC) models of mice and swine. Tumor surgery is guided by the static CL images, and the resection quality is evaluated quantitatively and contrasted with other imaging modalities exemplified by bioluminescence imaging (BLI). The in vivo results demonstrated the effectiveness of the proposed intraoperative CLI approach for removing primary and metastatic CRC. Safety of performing in vivo CL image‐guided surgery is verified as well through radiation measurements of related staffs. Overall, the developed intraoperative in vivo CLI approach can efficiently improve the cancer treatment.     

From Rhetoric to Reality: Using Specific Environmental Concerns to Identify Critical Sustainability Issues

Natural resource managers, environmental interest groups, and public agencies are interested in appropriate, identifiable, and measurable indicators of sustainability. At the same time, public agencies, including natural resource management agencies, are attempting to identify research and management priorities that address major environmental concerns at local and broad scales. The Identify the Specifics approach, described here, uses local (ecodistrict or smaller) ecological/biological “experts' ” knowledge to identify and prioritize the local natural resources of concern (commonly species), associated management practices and ecosystems to form a concern matrix. Local ecological/biological concerns form the environmental base of a broader-scale (ecoregion/ecozone) concern matrix. This matrix identifies similarities and differences among local matrices and appropriate components for promotion to broader scales. Scale-specific matrices identify appropriate local, regional, and broader-scale indicators to monitor and assess, and provide public agencies with direction for documenting effects of management and identifying where research is needed. This approach can provide industries, public agencies, environmental interest groups, and governments with ecosystem-based, prioritized information for balancing social, economic, and ecological concerns on public and private lands. Received 22 July 1997; accepted 7 January 1998.     

Creating the Future of Applied Psychophysiology and Biofeedback: From Fantasy to Reality

AAPB and its membership are faced with a number of giant challenges, including but not limited to: (1) the cost savings efforts of third-party payors and managed care organizations; (2) the lack of public awareness of biofeedback and its usefulness; and (3) the lack of sufficient research data on both the effectiveness and efficacy of biofeedback. In spite of these challenges, there are windows of opportunity that have been or which could be created to move biofeedback further into the realm of conventional treatment. We must focus our efforts on working together to: (1) create strategic plans for creating the future of applied psychophysiology and biofeedback; (2) educate all decision makers, including the general public; (3) establish better relationships with other professionals with common interests; (4) conduct more efficacy and effectiveness research; and (5) create a demand for our services so that the public will be more willing to pay for our services out of their own pocket. In order for this to happen, we must stop fighting with each other and direct our energies to productive activities that can change fantasies into realities.     

Weak biophoton emission after laser surgery application in soft tissues: Analysis of the optical features

Nowadays, laser scalpels are commonly used in surgery, replacing the traditional surgical scalpels for several applications involving cutting or ablating living biological tissue. Laser scalpels are generally used to concentrate light energy in a very small‐sized area; light energy is then converted in heat by the tissues. In other cases, the fiber glass tip of the laser scalpel is heated to high temperature and used to cut the tissues. Depending on the temperature reached in the irradiated area, different effects are visible in the tissues. In this study, we report the discovery and characterization of the light emitted by soft mammalian biological tissues from seconds to hours after laser surgery application. A laser diode (with hot fiber glass tip) working at 808 nm and commercially available for medical and dentistry applications was used. The irradiated tissues (red meat, chicken breast and fat) showed light emission in the visible range, well detectable with a commercial charge coupled device (CCD) camera. The time decay of the light emission, the laser power effects and the spectral features in the range 500 to 840 nm in the different tissues are here reported.      

AI applications to medical images: From machine learning to deep learning

PurposeArtificial intelligence (AI) models are playing an increasing role in biomedical research and healthcare services. This review focuses on challenges points to be clarified about how to develop AI applications as clinical decision support systems in the real-world context.MethodsA narrative review has been performed including a critical assessment of articles published between 1989 and 2021 that guided challenging sections.ResultsWe first illustrate the architectural characteristics of machine learning (ML)/radiomics and deep learning (DL) approaches. For ML/radiomics, the phases of feature selection and of training, validation, and testing are described. DL models are presented as multi-layered artificial/convolutional neural networks, allowing us to directly process images. The data curation section includes technical steps such as image labelling, image annotation (with segmentation as a crucial step in radiomics), data harmonization (enabling compensation for differences in imaging protocols that typically generate noise in non-AI imaging studies) and federated learning. Thereafter, we dedicate specific sections to: sample size calculation, considering multiple testing in AI approaches; procedures for data augmentation to work with limited and unbalanced datasets; and the interpretability of AI models (the so-called black box issue). Pros and cons for choosing ML versus DL to implement AI applications to medical imaging are finally presented in a synoptic way.ConclusionsBiomedicine and healthcare systems are one of the most important fields for AI applications and medical imaging is probably the most suitable and promising domain. Clarification of specific challenging points facilitates the development of such systems and their translation to clinical practice.     

Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

Visualization of cell migration during chemotaxis using spectral domain optical coherence tomography (OCT) requires non‐standard processing techniques. Stripe artefacts and camera noise floor present in OCT data prevent detailed computer‐assisted reconstruction and quantification of cell locomotion. Furthermore, imaging artefacts lead to unreliable results in automated texture based cell analysis. Here we characterize three pronounced artefacts that become visible when imaging sample structures with high dynamic range, e.g. cultured cells: (i) time‐varying fixed‐pattern noise; (ii) stripe artefacts generated by background estimation using tomogram averaging; (iii) image modulations due to spectral shaping. We evaluate techniques to minimize the above mentioned artefacts using an 800 nm optical coherence microscope. Effect of artefact reduction is shown exemplarily on two cell cultures, i.e. Dictyostelium on nitrocellulose substrate, and retinal ganglion cells (RGC‐5) cultured on a glass coverslip. Retinal imaging also profits from the proposed processing techniques. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

From analog to digital: exploring cell dynamics with single quantum dots

Semiconductor quantum dots (QDs) have emerged as new fluorescent probes for biology. When combined with ultrasensitive optical techniques, they allow motions of individual biomolecules to be tracked in live cells with high signal-to-noise and over unprecedented durations. Single QD imaging readily offers a powerful tool to investigate the organization in cell membranes. Altogether QDs will contribute to more advanced biological imaging and enable new studies on the dynamics of cellular processes.Robert Feulgen Lecture 2005 presented at the Joint Meeting of the Society for Histochemistry and The Histochemical Society in Noordwijkerhout, The Netherlands     

Cryo-EM image alignment: From pair-wise to joint with deep unsupervised difference learning

Cryo-electron microscopy (cryo-EM) single-particle analysis is a revolutionary imaging technique to resolve and visualize biomacromolecules. Image alignment in cryo-EM is an important and basic step to improve the precision of the image distance calculation. However, it is a very challenging task due to high noise and low signal-to-noise ratio. Therefore, we propose a new deep unsupervised difference learning (UDL) strategy with novel pseudo-label guided learning network architecture and apply it to pair-wise image alignment in cryo-EM. The training framework is fully unsupervised. Furthermore, a variant of UDL called joint UDL (JUDL), is also proposed, which is capable of utilizing the similarity information of the whole dataset and thus further increase the alignment precision. Assessments on both real-world and synthetic cryo-EM single-particle image datasets suggest the new unsupervised joint alignment method can achieve more accurate alignment results. Our method is highly efficient by taking advantages of GPU devices. The source code of our methods is publicly available at “http://www.csbio.sjtu.edu.cn/bioinf/JointUDL/” for academic use.     

Behavioural responses of juvenile Steller sea lions to abdominal surgery: Developing an assessment of post-operative pain

Marking and tracking of marine mammals is required to gain a better understanding of life history traits; however, some marking procedures used are likely painful. Recent technological advances include intra-abdominally implanted archival telemetry devices for the life-long monitoring of individual animals. No research to date has assessed any aspect of post-operative pain in marine mammals. This study specifically evaluated behavioural responses in nine juvenile Steller sea lions to the abdominal surgery required for insertion of telemetry devices. Behaviours predicted to reflect post-operative pain, including posture and body movements, were assessed during 3-day pre-, 3-day post-, and days 10–12 post-surgery. The proportion of time sea lions spent on land standing increased from 0.00 to 0.07 and then decreased to 0.04, for pre-, post-, and late post-surgery respectively. Similarly, the proportion of land time spent with the back arched increased from 0.01 to 0.57, and then decreased to 0.33. The time sea lions spent on land with pressure on their ventral side while sitting or lying down declined from 1.0 pre-surgery to 0.17 post-surgery, and increased to 0.20 late post-surgery. The time sea lions spent in locomotion on land and in the water decreased from 0.05 in pre-surgery to 0.01 post-surgery, and returned to 0.06 by late post-surgery. These results suggest that behaviours such as back arch, standing, time spent with pressure on the ventral side, and locomotion may be useful in the assessment of pain following abdominal surgery in sea lions. The presence of these behaviours and their persistence for up to 12 days after surgery suggest that more work is required to further develop safe and effective analgesic methods for this procedure.     

Ground monitoring the light–shadow windows of a tree canopy to yield canopy light interception and morphological traits

Monitoring the light–shadow windows of a tree via a grid system on the ground was performed on sunny summer days at high spatial resolution using a custom‐built, inexpensive scanner. The measurements were taken with two goals: (1) to quickly and remotely quantify the overall, short‐wave solar radiation (300–1100 nm) intercepted by the tree canopy, and (2) to yield such crown geometric traits as shape, size and the number of theoretical canopy leaf layers (leaf layer index, LLI) in relation to the section orthogonal to sunbeam direction (sun window). The ground readings at each measurement over the day were used to project a digitized shadow image. Image processing was applied and the intercepted radiation was calculated as the difference from the corresponding incoming radiation above the canopy. Tree‐crown size and shape were profiled via computer imaging by analysing the different shadow images acquired at the various solar positions during the day. It is notable that these combined images yielded the crown features without having to parameterize such canopy characteristics as foliage extension and spatial distribution.     

Neural network model of the primary visual cortex: From functional architecture to lateral connectivity and back

The role of intrinsic cortical dynamics is a debatable issue. A recent optical imaging study (Kenet et al., 2003) found that activity patterns similar to orientation maps (OMs), emerge in the primary visual cortex (V1) even in the absence of sensory input, suggesting an intrinsic mechanism of OM activation. To better understand these results and shed light on the intrinsic V1 processing, we suggest a neural network model in which OMs are encoded by the intrinsic lateral connections. The proposed connectivity pattern depends on the preferred orientation and, unlike previous models, on the degree of orientation selectivity of the interconnected neurons. We prove that the network has a ring attractor composed of an approximated version of the OMs. Consequently, OMs emerge spontaneously when the network is presented with an unstructured noisy input. Simulations show that the model can be applied to experimental data and generate realistic OMs. We study a variation of the model with spatially restricted connections, and show that it gives rise to states composed of several OMs. We hypothesize that these states can represent local properties of the visual scene. Action Editor: Jonathan D. Victor     

From Voxels to Knowledge: A Practical Guide to the Segmentation of Complex Electron Microscopy 3D-Data

Modern 3D electron microscopy approaches have recently allowed unprecedented insight into the 3D ultrastructural organization of cells and tissues, enabling the visualization of large macromolecular machines, such as adhesion complexes, as well as higher-order structures, such as the cytoskeleton and cellular organelles in their respective cell and tissue context. Given the inherent complexity of cellular volumes, it is essential to first extract the features of interest in order to allow visualization, quantification, and therefore comprehension of their 3D organization. Each data set is defined by distinct characteristics, e.g., signal-to-noise ratio, crispness (sharpness) of the data, heterogeneity of its features, crowdedness of features, presence or absence of characteristic shapes that allow for easy identification, and the percentage of the entire volume that a specific region of interest occupies. All these characteristics need to be considered when deciding on which approach to take for segmentation.The six different 3D ultrastructural data sets presented were obtained by three different imaging approaches: resin embedded stained electron tomography, focused ion beam- and serial block face- scanning electron microscopy (FIB-SEM, SBF-SEM) of mildly stained and heavily stained samples, respectively. For these data sets, four different segmentation approaches have been applied: (1) fully manual model building followed solely by visualization of the model, (2) manual tracing segmentation of the data followed by surface rendering, (3) semi-automated approaches followed by surface rendering, or (4) automated custom-designed segmentation algorithms followed by surface rendering and quantitative analysis. Depending on the combination of data set characteristics, it was found that typically one of these four categorical approaches outperforms the others, but depending on the exact sequence of criteria, more than one approach may be successful. Based on these data, we propose a triage scheme that categorizes both objective data set characteristics and subjective personal criteria for the analysis of the different data sets.     

Computer-aided hepatic tumour ablation: requirements and preliminary results

Surgical resection of hepatic tumours is not always possible, since it depends on different factors, among which their location inside the liver functional segments. Alternative techniques consist in local use of chemical or physical agents to destroy the tumour. Radio frequency and cryosurgical ablations are examples of such alternative techniques that may be performed percutaneously. This requires a precise localisation of the tumour placement during ablation. Computer-assisted surgery tools may be used in conjunction with these new ablation techniques to improve the therapeutic efficiency, whilst they benefit from minimal invasiveness. This paper introduces the principles of a system for computer-assisted hepatic tumour ablation and describes preliminary experiments focusing on data registration evaluation. To keep close to conventional protocols, we consider registration of pre-operative CT or MRI data to intra-operative echographic data.     

Matching a surface to a given sectional curve

We describe an algorithm to position a rigid surface so as to make its cross-section by a given plane match a given curve in that plane, a problem relevant to model-based medical imaging. After building an atlas of cross-sections of the surface and searching it for a best position to start from, each iteration of the algorithm (1) determines a vector field along the intersection curve that will improve its matching with the target curve, and (2) computes and applies a small displacement of the surface whose effect on the intersection will approximate best the required vector field. Computations use least-square techniques, an exponential formula for Lie groups of transformations, and generic properties of cross-sections. Experiments with an implementation are reported and theoretical tools for justifying and improving the algorithm, some of them based on Catastrophe Theory, are outlined.     

Modeling the nuclear magnetic resonance behavior of lung: From electrical engineering to critical care medicine

The present article reviews the basic principles of a new approach to the characterization of pulmonary disease. This approach is based on the unique nuclear magnetic resonance (NMR) properties of the lung and combines experimental measurements (using specially developed NMR techniques) with theoretical simulations. The NMR signal from inflated lungs decays very rapidly compared with the signal from completely collapsed (airless) lungs. This phenomenon is due to the presence of internal magnetic field inhomogeneity produced by the alveolar air–tissue interface (because air and water have different magnetic susceptibilities). The air–tissue interface effects can be detected and quantified by magnetic resonance imaging (MRI) techniques using temporally symmetric and asymmetric spin‐echo sequences. Theoretical models developed to explain the internal (tissue‐induced) magnetic field inhomogeneity in aerated lungs predict the NMR lung behavior as a function of various technical and physiological factors (e.g., the level of lung inflation) and simulate the effects of various lung disorders (in particular, pulmonary edema) on this behavior. Good agreement has been observed between the predictions obtained from the mathematical models and the results of experimental NMR measurements in normal and diseased lungs. Our theoretical and experimental data have important pathophysiological and clinical implications, especially with respect to the characterization of acute lung disease (e.g., pulmonary edema) and the management of critically ill patients. Bioelectromagnetics 20:110–119, 1999. © 1999 Wiley‐Liss, Inc.     

Evaluation of low-level laser at auriculotherapy points to reduce postoperative pain in inferior third molar surgery: study protocol for a randomized controlled trial

BackgroundA comfortable postoperative return to daily activities has increased the need to control inflammation after third molar surgery. Anti-inflammatory drugs and analgesics are not exempt from adverse effects such as allergies and chronic gastritis, and they are not without cost. The association between low-level laser and auricular acupuncture can be an alternative when conventional drugs are contraindicated. Among its advantages, we can mention the low risk of side effects, low cost and simplicity of application. The objective of this study is to evaluate the efficiency of low-level laser at auriculotherapy points in reducing postoperative pain in lower third molar surgery.Methods/designNinety bilateral, symmetrical lower third molar surgeries will be performed in 45 healthy patients. Each patient will be their own control, through a split-mouth crossover study. One side of the mouth will be randomly chosen and, immediately after surgery, will be treated with low-level laser. After 21 days, the contralateral side will be operated on with low-level laser simulation used postoperatively. This regimen (laser application or not) will be repeated at 24 and 48 h after surgery. All patients will be requested to take analgesics (acetaminophen) if they have pain, i.e. in case of pain. Neither the surgeon nor the patients will know the assigned treatment. The primary variable will be postoperative pain assessed using a Visual Analog Scale, and the secondary variables will be trismus, edema, local temperature, dysphagia, presence of infection and painkiller ingestion. These variables will be assessed at baseline, 24 h, 48 h and 7 days after surgery. Blood samples for systemic inflammatory cytokine (TNF-α, IL-1, IL-6 and IL-8) analysis will be assessed at baseline and 24 h after surgery.DiscussionSome authors believe that using a wavelength of 633 to 670 nm is a good option for laser therapy in the field of acupuncture. This wavelength can penetrate biological tissue to a depth of about 3 mm. However, for auriculotherapy points, the stimulus (mustard seeds, needles 1 to 2.5 mm) does not penetrate so deeply. For this reason, we chose a laser wavelength of 660 nm (red wavelength).

Trial registration

ClinicalTrials.gov Identifier: NCT02657174, registered on 11 January 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1540-9) contains supplementary material, which is available to authorized users.     

Dementia: Alzheimer pathology and vascular factors: From mutually exclusive to interaction

Alzheimer's disease (AD) is the most common type of dementia. Both its incidence and prevalence are expected to increase exponentially as populations' age worldwide. Despite impressive efforts of research worldwide, neither cure nor effective preventive strategy is available for this devastating disease. Currently there are several hypotheses on what causes AD, with the amyloid hypothesis being the most investigated and accepted hypothesis over the past 20 years. However the exact role of amyloid-β in the onset and progression of AD is not yet fully understood, and even the validity of the amyloid hypothesis itself is still being discussed. This debate is fuelled by the vascular hypothesis, as increasing epidemiological, neuroimaging, pathological, pharmacotherapeutic and clinical studies suggest that vascular pathology plays a key role in the onset and progression of AD. We here will discuss arguments in favor and limitations of both hypotheses within the framework of available literature, but also provide arguments for convergence of both hypotheses.Finally we propose approaches that may aid in unraveling the etiology and treatment of AD. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.