Search

The application of robotic puncture system in thoracic-abdominal puncture (TAP) surgery has been hindered by the undistinguished accuracy on account of the respiratory motion. In order to mitigate this challenge, a respiratory follow-up robotic system (RFRS) is designed for accurate surgical puncture. Notably, a control strategy on robotic puncture is proposed to compensate the tissue deformation under the effect of clinical respiration. With the real-time analysis of breathing motion, the movement of robotic arm is composed by follow-up compensation related to respiratory motion and insertion toward the target. An online target location model proposed here aims to restrict the surgical instrument overlapped with the planned target, increasing the accuracy, safety, flexibility, and agility of puncture procedures. Experimental results suggest that the presented system achieved outperforming accuracy, movement capabilities, and robustness. It is promising that the RFRS will be effective in TAP by analyzing breathing motion for tissue deformation compensation.

Object. Use a fluid-structure interaction (FSI) model to do a safety risk assessment of cervical spinal manipulative therapy (cSMT) for atherosclerosis to study the biomechanical changes of atherosclerosis plaque and the carotid artery (CA) lumen during the process of cSMT. Method. The FSI model, based on MRI data of an atherosclerosis patient, was used to simulate the deformations of the plaque and lumen during the process of two kinds of typical cSMT (the high-speed, low-amplitude spinal manipulation and the cervical rotatory manipulation). The biomechanical parameters were recorded, such as the highest wall shear stress (WSS), the maximum plaque wall stress (PWS), the wall tensile stress (Von mises stress, VWTS), and the strain. Result. The max_WSS was 33.77 kPa in the most extensive deformation. The highest WSS region on the plaque surface was also the highest PWS region. The max_PWS in a 12% stretch was 55.11 kPa, which was lower than the rupture threshold. The max_VWTS of the cap in 12% stretch which approached the fracture stress level was 116.75 kPa. Moreover, the vessel’s max_VWTS values in 10% and 12% stretch were 554.21 and 855.19 kPa. They were higher than the fracture threshold, which might cause media fracture. Meanwhile, the 7% stretched strain was 0.29, closed to the smallest experimental green strains at rupture. Conclusion. The carotid arteries’ higher stretch generated the higher stress level of the plaque. Cervical rotatory manipulation might cause plaque at a high risk of rupture in deformation after 12% stretch and more. Lower deformation of the plaque and artery caused by the high-speed, low-amplitude spinal manipulation might be safer.

Purpose To predict acute kidney injury (AKI) in a large intensive care unit (ICU) database. Materials and methods A total of 30,020 ICU admissions with 17,222 AKI episodes were extracted from the Medical Information Mart from Intensive Care (MIMIC)-III database. These were randomly divided into a training set and an independent testing set in a ratio of 4:1. Data pertaining to demographics, admission information, vital signs, laboratory tests, critical illness scores, medications, comorbidities, and intervention measures were collected. Logistic regression, random forest, LightGBM, XGBoost, and an ensemble model was used for early prediction of AKI occurrence and important feature extraction. The SHAP analysis was adopted to reveal the impact of prediction for each feature. Results The ensemble model had the best overall performance for predicting AKI before 24 h, 48 h and 72 h. The F1 values were 0.915, 0.893, and 0.878, respectively. AUCs were 0.923, 0.903, and 0.895, respectively. Conclusions Based on readily available electronic medical record (EMR) data, gradient boosting decision tree models are highly accurate at early AKI prediction in critically ill patients.

Precise craniotomy localization is essential in neurosurgical procedures, especially during the preoperative planning. The mainstream craniotomy localization method utilizing image-guided neurosurgery system (IGNS) or augmented reality (AR) navigation system require experienced neurosurgeons to point out the lesion margin by probe and draw the craniotomy manually on the patient's head according to cranial anatomy. However, improper manual operation and dither from the AR model will bring in errors about craniotomy localization. In addition, there is no specific standard to evaluate the accuracy of craniotomy. This paper attempts to propose a standardized interactive 3D method using orthogonal transformation to map the lesion onto the scalp model and generate a conformal virtual incision in real time. Considering clinical requirements, the incision can be amended by 3D interaction and margin modification. According to the IGNS and the virtual incision, an actual craniotomy will be located on the patient's head and the movement path of the probe will be recorded and evaluated by an indicator, which is presented as an evaluated standard to measure the error between virtual and actual craniotomies. After the experiment, an incision is drawn on a 3D printing phantom based on the generated virtual one. The results show that the proposed method can generate a lesion-consistent craniotomy according to the size of the lesion and the mapping angle and delineate the incision on the patient's head precisely under the IGNS.

There is a lot of numerical simulation on microwave ablation which studied the models of the microwave antennas (MA) design and thermal-dielectric properties of tissues. However, few studies focused on the efficient and accurate treatment planning to configure MA in various kinds of irregular tumor, especially irregular hepatic cancerous tissue (IHCT). This work proposed a modelling approach to analyzing the heating performance and thermal lesion of microwave ablation model with different MA inserting directions, inserting depth rates and powers. The specific absorption rate and thermal lesion results showed that the long axis of irregular tissue could be the better MA inserting direction, along which microwave power could be sent to ablate more IHCT. The MA inserting depth rate influenced the power absorption rate and axial thermal lesion of the MA axis under different powers. The temperature field of 60 \(^{\circ }\)C expanded when power gave rise on, which were proposed to predict the thermal lesion zone of IHCT. The results simulated microwave ablation with single MA on IHCT, and thus, the method could also be applied to treatment situations where multiple MAs or more complicated operation are required under image-guided surgical navigation.

Marker-based optical tracking systems (OTS) are widely used in clinical image-guided therapy. However, the emergence of ghost markers, which is caused by the mistaken recognition of markers and the incorrect correspondences between marker projections, may lead to tracking failures for these systems. Therefore, this paper proposes a strategy to prevent the emergence of ghost markers by identifying markers based on the features of their projections, finding the correspondences between marker projections based on the geometric information provided by markers, and fast-tracking markers in a 2D image between frames based on the sizes of their projections. Apart from validating its high robustness, the experimental results show that the proposed strategy can accurately recognize markers, correctly identify their correspondences, and meet the requirements of real-time tracking.

The rapid degradation of magnesium (Mg) based alloys has prevented their further use in orthopedic trauma fixation and vascular intervention, and therefore it is essential to investigate the corrosion mechanism for improving the corrosion resistance of these alloys. In this work, the effect of applied voltage on the surface morphology and the corrosion behavior of micro-arc oxidation (MAO) with different voltages were carried out to obtain biocompatible ceramic coatings on AZ31 Mg alloy. The effects of applied voltage on the surface morphology and the corrosion behavior of MAO samples in the simulated body fluid (SBF) were studied systematically. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were employed to characterize the morphologies and phase compositions of coating before and after corrosion. The results showed that corrosion resistance of the MAO coating obtained at 250 V was better than the others in SBF. The dense layer of MAO coating and the corrosion precipitation were the key factors for corrosion behavior. The corrosion of precipitation Mg(OH) 2 and the calcium phosphate (Ca–P) minerals on the surface of MAO coatings could enhance their corrosion resistance effectively. In addition, the mechanism of MAO coated Mg alloys was proposed.

Studies of cardiovascular system have been the hot point generally concerned as well as extraordinarily significant issue of bioscience. Because of the complexity of cardiovascular system, it is difficult to research the internal principle completely. Consequently, it is usual to study by modeling and simulation. In this article, the cardiovascular system model was established by using Matlab/Simulink. According to the functional test and the evaluation, the results of the model are highly similar to the clinical data, so it can be used widely to simulate various diseases and accidents. Based on the results, we mainly use the model to analyze the effective factors on pressure-volume loop of left ventricle, including preload, after-load and myocardial contractility. In a cardiac cycle, the pressure-volume (P-V) loop of left ventricle will always be in a series of dynamic changes. The pressure-volume relationship of left ventricle is a closed loop that could be used to evaluate the left ventricle's function. Preload, after-load and myocardial contractility always influence the cardiac outputs; the P-V loop will be changed as these factors change. The research focuses on the changes of these three factors and the corresponding changes of the P-V loop.

The purpose of the present study is to prepare a diatrizoate meglumine-loaded chitosan microsphere, which could be used to be investigated by ultrasonic imaging technique in vivo and would has water absorption swelling property to dredge the obstruction. Diatrizoate meglumine-loaded chitosan microspheres were prepared by crosslink emulsification process, to use chitosan acetic acid solution as aqueous phase, liquid paraffin as oil phase, Span80 and n-butyl alcohol as surfactant, glutaraldehyde solution as crosslink agent. The effect of ratio of diatrizoate meglumine (ratio of W), the ratio of aqueous to organic phase (W/O ratio), the ratio of Span80 to liquid paraffin and the time of crosslink process were optimized by the single factor experiment and response surface experiment. And the optimum prepared microspheres' appearance, distribution, diameter, zeta potential, thermal performance and release properties were measured and their swelling and development properties were observed. The diatrizoate meglumine-loaded chitosan microspheres had a good shape and uniform distribution by light microscope and transmission electron microscope, with average diameters of 1.53 μm and average zeta potential of −19.7 mV; the microspheres had a good sustained release property. And the swelling property of the diatrizoate megiumine-loaded chitosan microspheres varied in different conditions and developed clearly under the ultrasonic imaging technique. This study prepares a kind of diatrizoate meglumine-loaded chitosan microspheres, who can make the microspheres, develop and dredge the obstruction at the same time.

The adhesion of flowing cells to the vascular surface occurs in many physiological and pathological processes. The Parallel flow chamber (PFC) system is usually used to investigate this transport-dependent process. Understanding of the cells locomotion near the bottom, cells collision with the wall and the spatial distribution of the colliding particles in the chamber bottom should have useful in modeling of the cells adhesion and analyzing of the PFC biological experimental data. Here, with ADINA-F finite element analysis software, the collision events of small spherical particles pouring into inlet to PFC are numerically simulated for different wall shear stresses, 0.25, 0.5, 1, 2, 3 and 4dyn/cm2. And, by tracing the trajectory of the particles from the inlet to the bottom of flow chamber, the spatial distribution of the colliding particles in the PFC was predicted. The results show that, the collision events between the particles pouring into flow chamber and the flow chamber bottom decrease as increasing shear stress, the collision fraction of the particles is less than 12.5% under different shear conditions, and the front bench positions of the colliding particles are dependent on the initial position being released from inlet. The aim of our numerical simulation lies in give one some enlighten in the design of the flow chamber and the data analysis of flow chamber experiments.

the adhesion of flowing cells to the vascular surface in localized sites will occur in many physiological and pathological processes, such as inflammatory reaction, tumor metastasis, and thrombus formation. This transport dependent process depends not only on the specific interactions of adhesive molecules but also on the hemodynamics of blood flow. A theoretical model for binary adhesion of flowing cells is developed here for exploring the action and interplay of the factors, which may govern this process. Our numerical results show that, the hydrodynamic interaction of cells in flows may also be a dominating factor in the adhesion of flowing cells, especially in the case of too many cells having been tethered in surface. Similar to the increasing of the cellular on-rate, the more the upstream flowing cells, the larger the tethering rate of the flowing cells against flow direction. The spatial and temporal distributions of such adhesion are sensitive to both the cellular on-rate and the interaction of the crowding cells. This model may be also used in extracting the reaction kinetic information of flowing cells from flow chamber data.