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Recent research studies reported that the employment of wearable augmented reality (AR) systems such as head-mounted displays for the in situ visualisation of ultrasound (US) images can improve the outcomes of US-guided biopsies through reduced procedure completion times and improved accuracy. Here, the authors continue in the direction of recent developments and present the first AR system for guiding an in-depth tumour enucleation procedure under US guidance. The system features an innovative visualisation modality with cutting trajectories that 'sink' into the tissue according to the depth reached by the electric scalpel, tracked in real-time, and a virtual-to-virtual alignment between the scalpel's tip and the trajectory. The system has high accuracy in estimating the scalpel's tip position (mean depth error of 0.4 mm and mean radial error of 1.34 mm). Furthermore, we demonstrated with a preliminary user study that our system allowed us to successfully guide an in-depth tumour enucleation procedure (i.e. preserving the safety margin around the lesion)., Competing Interests: The authors declare no conflicts of interest., (© 2023 The Authors. Healthcare Technology Letters published by John Wiley & Sons Ltd on behalf of The Institution of Engineering and Technology.)

Background: Surgical simulation based on augmented reality (AR), mixing the benefits of physical and virtual simulation, represents a step forward in surgical training. However, available systems are unable to update the virtual anatomy following deformations impressed on actual anatomy., Methods: A proof-of-concept solution is described providing AR visualization of hidden deformable tubular structures using nitinol tubes sensorized with electromagnetic sensors. This system was tested in vitro on a setup comprised of sensorized cystic, left and right hepatic, and proper hepatic arteries. In the trial session, the surgeon deformed the tubular structures with surgical forceps in 10 positions., Results: The mean, standard deviation, and maximum misalignment between virtual and real arteries were 0.35, 0.22, and 0.99 mm, respectively., Conclusion: The alignment accuracy obtained demonstrates the feasibility of the approach, which can be adopted in advanced AR simulations, in particular as an aid to the identification and isolation of tubular structures. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: Magnetic endovascular navigation of wireless or soft-tethered endoluminal devices was recently proposed in the literature. This approach allows for innovative therapeutic procedures, but developing a real-time tracking strategy, compatible with magnetic dragging, is a challenging problem and is not yet solved., Methods: Two-dimensional (2D) imaging ultrasound (US)-based tracking algorithms applied to a platform for cardiovascular treatment, i.e. the MicroVAST platform, were implemented and tested for deriving the optimal strategy for tracking endovascular devices dragged by magnetic locomotion., Results: The algorithm, based on the combination of Shi-Tomasi features detector, Lucas-Kanade features tracking and watershed segmentation technique, was demonstrated to be the most reliable and accurate solution for the implementation of the tracking strategy of soft-tethered endoluminal devices., Conclusions: Our results encourage the development of US-based tracking algorithms for endoluminal devices in cardiovascular surgery, paving the way to a robust three-dimensional (3D) imaging US-based tracking strategy implementation. Copyright © 2014 John Wiley & Sons, Ltd., (Copyright © 2014 John Wiley & Sons, Ltd.)

Repetitions that are distributed (spaced) across time prompt enhancement of a memory-related event-related potential, compared to when repetitions are massed (contiguous). Here, we used fMRI to investigate neural enhancement and suppression effects during free viewing of natural scenes that were either novel or repeated four times with massed or distributed repetitions. Distributed repetition was uniquely associated with a repetition enhancement effect in a bilateral posterior parietal cluster that included the precuneus and posterior cingulate and which has previously been implicated in episodic memory retrieval. Unique to massed repetition, conversely, was enhancement in a right dorsolateral prefrontal cluster that has been implicated in short-term maintenance. Repetition suppression effects for both types of spacing were widespread in regions activated during novel picture processing. Taken together, the data are consistent with a hypothesis that distributed repetition prompts spontaneous retrieval of prior occurrences, whereas massed repetition prompts short-term maintenance of the episodic representation, due to contiguous presentation. These processing differences may mediate the classic spacing effect in learning and memory., (© 2014 Wiley Periodicals, Inc.)

Background: The da Vinci robotic surgical telemanipulator has been utilized in several surgical specialties for varied procedures, and the users' experiences have been widely published. To date, no detailed system technical analyses have been performed., Methods: A detailed review was performed of all publications and patents about the technical aspects of the da Vinci robotic system., Results: Published technical literature on the da Vinci system highlight strengths and weaknesses of the robot design. While the system facilitates complex surgical operations and has a low malfunction rate, the lack of haptic (especially tactile) feedback and collisions between the robotic arms remain the major limitations of the system. Accurate, preplanned positioning of access ports is essential., Conclusion: Knowledge of the technical aspects of the da Vinci robot is important for optimal use. We confirmed the excellent system functionality and ease of use for surgeons without an engineering background. Research and development of the surgical robot has been predominant in the literature. Future trends address robot miniaturization and intelligent control design., (Copyright © 2012 John Wiley & Sons, Ltd.)

Background: Currently, pedicle screws are positioned using a free-hand technique or under fluoroscopic guidance, with error in the range 10-40%, depending on the skill of the surgeon., Methods: After spine CT acquisition, each vertebra is segmented and the surgeon plans screw positioning in a virtual environment, then the template is designed around the chosen trajectories. This design is based on surgical and mechanical considerations to obtain an optimal solution to guarantee template stability, simple positioning and minimized intervention invasiveness. In vitro evaluation on synthetic spine models and ex vivo animal tests on porcine specimens were performed, with the insertion of 28 Kirschner wires., Results: During the in vitro tests, all the surgeons rendered positive evaluations regarding the device and considered template placement to be easy. Ex vivo tests were evaluated by CT examination, which showed that 96.5% of the Kirschner wires had been correctly inserted., Conclusions: The proposed solution is a promising, simple, highly precise, low-cost solution to safely performing posterior stabilization. Such a solution would be of interest even in hospitals in which a few spine interventions are performed per year, and for which it is not reasonable to purchase the equipment required for robotic or navigated approaches., (Copyright © 2012 John Wiley & Sons, Ltd.)

Background: The objective of this study was to assess the efficacy of (90)Y-DOTA-D-Phe1-Tyr3 octreotide ((90)Y-DOTATOC) therapy with a fixed activity of 2.56 GigaBequerels bimonthly in patients with advanced stage, well differentiated neuroendocrine carcinomas., Methods: In total, 38 patients were enrolled in this phase 2A protocol. All patients had gastroenteropancreatic neuroendocrine tumors in sharp clinical and radiologic progression despite previous surgery, chemotherapy, and biotherapy. Their survival rate after therapy with (90)Y-DOTATOC was compared with a chronologic control group of patients who had received biotherapy and chemotherapy and with results from a previous similar study. The progression-free survival rate after peptide receptor radionuclide therapy with (90)Y-DOTATOC was determined for all patients until they had documented disease progression according to Response Criteria in Solid Tumors, tumor-related death, or censoring., Results: Seventeen patients (43.6%) had a partial response, 10 patients (25.6%) had stable disease, and 11 patients (28.2%) had progressive disease. A statistically significant difference was observed (P < .001) between the response to (90)Y-DOTATOC treatment and the response to biotherapy with somatostatin analogs and chemotherapy and also between the current results and the results from a previous similar study (P < .05). At the time of the current evaluation with ongoing follow-up for 30 patients, the median progression-free survival was 22.3 months., Conclusions: The results from this phase 2 study indicated that the treatment of metastatic neuroendocrine tumors with fixed (90)Y-DOTATOC activity is useful and safe., (Copyright © 2011 American Cancer Society.)

Background: Computer-assisted surgery (CAS) systems are currently used in only a few surgical specialties: ear, nose and throat (ENT), neurosurgery and orthopaedics. Almost all of these systems have been developed as dedicated platforms and work on rigid anatomical structures. The development of augmented reality systems for intra-abdominal organs remains problematic because of the anatomical complexity of the human peritoneal cavity and especially because of the deformability of its organs. The aim of the present work was to develop and implement a highly modular platform (targeted for minimally invasive laparoscopic surgery) generally suitable for CAS, and to produce a prototype for demonstration of its potential clinical application and use in laparoscopic surgery., Methods: In this paper we outline details of a platform integrating several aspects of CAS and medical robotics into a modular open architecture: the EndoCAS navigator platform, which integrates all the functionalities necessary for provision of computer-based assistance to surgeons during all the management phases (diagnostic work-up, planning and intervention). A specific application for computer-assisted laparoscopic procedures has been developed on the basic modules of the platform. The system provides capabilities for three-dimensional (3D) surface model generation, 3D visualization, intra-operative registration, surgical guidance and robotic assistance during laparoscopic surgery. The description of specific modules and an account of the initial clinical experience with the system are reported., Results: We developed a common platform for computer assisted surgery and implemented a system for intraoperative laparoscopic navigation. The preliminary clinical trials and feedback from the surgeons on its use in laparoscopic surgery have been positive, although experience has been limited to date., Conclusions: We have successfully developed a system for computer-assisted technologies for use in laparoscopic surgery and demonstrated, by early clinical trials, that the introduction of these technologies in operative laparoscopy, even though they are not yet sufficiently accurate (from an engineering viewpoint) for surgical treatment of intra-abdominal disease, brings added benefits to the execution of interventions by surgeons and hence represents concrete on-going progress in interventional technology.

In this study, pulmonary MR angiography (MRA) using a tailored coil at 4 Tesla in conjunction with an intravenous injection of contrast agent is described. Three-dimensional gradient-echo images were obtained during the intravenous injection of 0.05, 0.1, and 0.2 mmol/kg body weight of gadodiamide to investigate the signal enhancement effect of the contrast agent in pulmonary arteries qualitatively and quantitatively. In the qualitative analysis, the subsegmental branches were visualized on every dose. In the quantitative analysis, the average contrast-to-noise ratios (CNRs) of the main pulmonary arteries increased in a dose-dependent manner. However, the CNRs of segmental arteries did not increase as the dose of contrast agent increased, as observed at 1.5 Tesla MRI. These observations demonstrate the feasibility of delineating the pulmonary vasculature using a contrast agent; however, our results also suggest possible high-field-related disabilities that need to be overcome before high-field (> or =4 Tesla) MRI can be used to full advantage., (Copyright 2001 Wiley-Liss, Inc.)

In studies of transmural myocardial function, acquisitions of high spatial and temporal resolution tagged cardiac images often exceed the practical time limit for breath-hold fast imaging techniques. Therefore, a dual cardiac-respiratory gating device has been constructed to acquire SPAMM-tagged cardiac MR images at or near end-expiration during spontaneous breathing, by providing an external trigger to a conventional MRI system. Combined cardiac and respiratory gating essentially eliminates the respiratory motion artifacts in tagged cardiac MR images. Compared to cardiac-gated images obtained during intermittent breath-holds, cardiac-respiratory gated images show improved tag-myocardium contrast due to magnetization recovery during inspiration.

A single integrated examination using regional measurements of perfusion from contrast-enhanced MRI and three-dimensional (3D) strain from tissue-tagged MRI was developed to differentiate infarcted myocardium from adjacent tissue with functional abnormalities. Ten dogs were studied at baseline and 10 days after a 2-hour occlusion of the left anterior descending coronary artery (LAD). Strain was determined using a 3D finite element model. Two-dimensional measurements of hypoenhancing regions were highly correlated with myocardial viability (r = 0.96). Signal intensity versus time curves obtained from contrast-enhanced MRI were used for quantitative perfusion analysis. The remote and adjacent noninfarcted tissue of the dogs with LAD occlusion, as well as the infarcted tissue, exhibited abnormal deformation patterns as compared to normal dogs (positive predictive value (PPV) of strain determination of infarction = 66%). Integration of contrast-enhanced MRI results with 3D strain analysis enabled the delineation of the myocardial infarction (PPV = 100%) from functionally compromised myocardium. This integrated cardiac examination shows promise for noninvasive serial assessment of potentially jeopardized noninfarcted myocardium to study the process of infarct remodeling and expansion.

Right ventricular (RV) regional function, in both normal and diseased states, is not well characterized. Using 1D MR myocardial tagging, RV and septal intramyocardial segmental shortening was noninvasively measured in ten healthy subjects and in seven patients with chronic pulmonary hypertension. The normal RV free wall regional shortening was not uniform. A pattern of increasing RV free wall short-axis shortening was found from the RV outflow tract to the RV apex, and a more complex pattern of RV free wall long-axis shortening was observed. Both regional short- and long-axis shortening were globally reduced in pulmonary hypertension patients, with the greatest decreases in the RV outflow tract and in the basal septal wall region. Regional RV function can be quantitatively evaluated using MR tagging to determine the impact of chronic pulmonary hypertension on RV performance.

Calculation of global cardiac function parameters has been validated using fast, segmented k-space, breath-hold, gradient-echo, magnetic resonance images. Images of phantoms, experimental animals, normal volunteers, and patients were acquired with a 1.5 T clinical scanner. Humans were imaged using two phased-array surface coils in multicoil mode. Myocardial contours were extracted using a new interactive, semi-automated method based on the active contour model method. Images were acquired in the short-axis orientation, and, using a new imaging and analysis strategy, in rotating plane long-axis orientations, to provide better definition of the valve planes and the apex, and also to reduce the number of slices (compared with the short-axis method) required to sample the whole heart. Validation was accomplished through calculation of the volumes of phantoms and left and right ventricular masses of animal hearts. Functional parameters from MRI were compared with those from echocardiograms and radionuclide angiograms in normal volunteers and patients, respectively.

The allopurinol challenge test was performed on 44 healthy subjects (28 children and 16 adolescents) in order to establish normal values of urinary orotic acid excretion following allopurinol ingestion in the paediatric population. The subjects were divided into three groups according to their age: 6 months to 6 years; 6 years to 10 years; and 10 years to 17 years. They were given 100 mg, 200 mg, or 300 mg of allopurinol, respectively (based on age) in a single oral dose. Maximum peak urinary orotic acid levels following ingestion of allopurinol were 13.0 (n = 14), 9.3 (n = 14), and 10.2 (n = 16) mumol/mmol creatinine in the three groups, respectively. In all children tested the peak orotic acid level was 3.1 +/- 2.7 mumol/mmol creatinine (mean +/- SD, n = 44). This allopurinol challenge test was also performed in six children with urea-cycle disorders, including five females with ornithine transcarbamylase (OTC) deficiency, all of whom demonstrated abnormally elevated levels of urinary orotic acid (peak levels of 26-134 mumol/mmol creatinine) following allopurinol ingestion.