Traditional Reconstruction Techniques Research Articles

A feature-based convolutional neural network for reconstruction of interventional MRI.

Real-time interventional MRI (I-MRI) could help to visualize the position of the interventional feature, thus improving patient outcomes in MR-guided neurosurgery. In particular, in deep brain stimulation, real-time visualization of the intervention procedure using I-MRI could improve the accuracy of the electrode placement. However, the requirements of a high undersampling rate and fast reconstruction speed for real-time imaging pose a great challenge for reconstruction of the interventional images. Based on recent advances in deep learning (DL), we proposed a feature-based convolutional neural network (FbCNN) for reconstructing interventional images from golden-angle radially sampled data. The method was composed of two stages: (a) reconstruction of the interventional feature and (b) feature refinement and postprocessing. With only five radially sampled spokes, the interventional feature was reconstructed with a cascade CNN. The final interventional image was constructed with a refined feature and a fully sampled reference image. With a comparison of traditional reconstruction techniques and recent DL-based methods, it was shown that only FbCNN could reconstruct the interventional feature and the final interventional image. With a reconstruction time of ~ 500ms per frame and an acceleration factor of ~ 80, it was demonstrated that FbCNN had the potential for application in real-time I-MRI.

One-Step Triple-Layer Reconstruction of an Exposed Calvarium in a Patient With Radiated Tinea Capitis

Full-thickness large scalp defects with underlying exposed calvarium pose a significant reconstructive challenge. Traditional reconstructive techniques are usually not an option in patients with irradiated scalp with thin skin and reduced laxity.Dermal substitutes-based reconstruction techniques have been described in recent years. A common approach is the staged methodology, with the initial application of skin substitute followed by a split-thickness skin graft few weeks later; however, this method involves a prolonged period of local wound management prior to skin grafting and is often associated with complications that interfere with wound healing.This report describes a single-stage triple-layer technique for the reconstruction of a large scalp defect with exposed bone in a patient with a history of radiation treatment, using 3 turnover pericranial flaps in conjunction with a Matriderm dermal substitute and split-thickness skin graft. This immediate multilayered reconstruction provides a long-lasting structural and aesthetic outcome, with minimal donor site morbidity and reduced complications.

Arthroscopic Posterior Glenohumeral Capsular Augmentation With Gracilis Tendon Allograft

Recurrent shoulder instability complicated by capsular insufficiency due to underlying soft-tissue disorders or multiple prior failed surgical procedures poses a challenging surgical problem. Traditional capsulolabral soft-tissue reconstruction techniques are less effective in this setting, and bony procedures sacrifice normal anatomic relations. The described arthroscopic technique aims to prevent instability while maintaining range of motion through creation of a soft-tissue allograft “sling” augmenting the posterior glenohumeral capsule.

Algorithm for the reconstruction of dynamic objects in CT-scanning using optical flow

Computed Tomography is a powerful imaging technique that allows non-destructive visualisation of the interior of physical objects in different scientific areas. In traditional reconstruction techniques the object of interest is mostly considered to be static, which gives artefacts if the object is moving during the data acquisition. In this paper we present a method that, given only scan results of multiple successive scans, can estimate the motion and correct the CT-images for this motion assuming that the motion field is smooth over the complete domain using optical flow. The proposed method is validated on simulated scan data. The main contribution is that we show we can use the optical flow technique from imaging to correct CT-scan images for motion.

Prepectoral implant-based breast reconstruction: a joint consensus guide from UK, European and USA breast and plastic reconstructive surgeons.

Advances in implantable biologic and synthetic products over the last decade have enabled surgeons to replace traditional submuscular implant-based breast reconstruction techniques with a prepectoral or muscle-sparing technique. Prepectoral breast reconstruction is becoming increasingly popular among surgeons and patients due to the preservation of normal chest wall anatomy, with the restoration of body image with minimal morbidity. In this article, we have described a guide to prepectoral or muscle-sparing breast reconstruction with a particular emphasis on patient selection, technique and postoperative outcomes. Hence, a joint consensus guide from European and USA breast and plastic reconstructive surgeons has been agreed, and a crowd-writing method has been adopted to produce this guide.

Optimization of Reconstruction Accuracy of Anomaly Position Based on Stacked Auto-Encoder Neural Networks

The diffuse optical tomography (DOT) technique which uses the traditional linear iterative algorithm has the problems of slow calculation speed and low reconstruction imaging accuracy in the inverse problem reconstruction, which limits its clinical application and development. This paper proposes an inverse-problem solving technology based on a stacked auto-encoder (SAE) network to improve the reconstruction accuracy of anomaly position, size and absorption coefficient in tissues. The reconstruction accuracy of anomaly position, size and absorption coefficient obtained by the traditional algebraic reconstruction technique (ART) method and the SAE based method are experimentally compared. The experimental results show that the SAE based method achieves the prediction accuracy of anomaly position of 96.25%, thus improving the accuracy and shortening the reconstruction time compared with the traditional ART method. Accordingly, the proposed method provides a better solution to the problem of the inaccurate reconstruction of the position and size of the rapid DOT based positioning of anomalies.

Visible/Infrared Combined 3D Reconstruction Scheme Based on Nonrigid Registration of Multi-Modality Images With Mixed Features

When traditional 3D reconstruction techniques were used to reconstruct a scene with hidden and disguised heat source targets, the reconstructed scene could not contain these targets; thus, we could not recognize them. The disadvantages of such problems are particularly acute in the military and remote-sensing areas. For this application problem, the authors proposed a visible/infrared combined 3D reconstruction scheme. The 3D scene containing thermal radiation information could be reconstructed by fusing the data from RGB optical and infrared images combined with computer vision passive optical 3D scene reconstruction technique. Meanwhile, the authors proposed the nonrigid registration of multi-modality images with mixed features to solve the problem that the registration algorithm, which is widely used in traditional passive reconstruction technology, cannot accurately match visible and infrared images. Registration accuracy was improved by approximately 40%, experimental results showed that the visible/infrared combined 3D reconstruction scenes retain the visual reality of the traditional 3D reconstruction, and the hidden targets are highlighted in the scenes, which is conducive to the detection and recognition of interesting targets.

Reconstructive Science in Orthopedic Oncology.

Limb salvage is widely practiced as standard of care in most cases of extremity bone sarcoma. Allograft and endoprosthesis reconstructions are the most widely utilized modalities for the reconstruction of large segment defects, however complication rates remain high. Aseptic loosening and infection remain the most common modes of failure. Implant integration, soft-tissue function, and infection prevention are crucial for implant longevity and function. Macro and micro alterations in implant design are reviewed in this manuscript. Tissue engineering principles using nanoparticles, cell-based, and biological augments have been utilized to develop implant coatings that improve osseointegration and decrease infection. Similar techniques have been used to improve the interaction between soft tissues and implants. Tissue engineered constructs (TEC) used in combination with, or in place of, traditional reconstructive techniques may represent the next major advancement in orthopaedic oncology reconstructive science, although preclinical results have yet to achieve durable translation to the bedside.

An improved algebraic reconstruction technique for reconstructing tomographic gamma scanning image

Tomographic gamma scanning (TGS) is one of the most advanced non-destructive techniques for assaying the radioactive waste drum. When traditional algorithms are adopted to accurately reconstruct TGS images, the measurement data must be completely sampled by TGS system, which inevitably leads to a long-term assay. In order to save time, small number of data is measured by dividing the drum into several large voxels, which leads to inaccurate TGS images. In this work, an improved algebraic reconstruction technique (IART) is proposed to reconstruct TGS images. The total variation minimization method and the self-adaptive relaxation factor are applied to improve the iterative process of traditional algebraic reconstruction technique (ART). Experimental results show that this IART algorithm can accurately reconstruct TGS images simply based on small amount of measurement data. Compared with traditional technique, this method can reduce the mean square error and improve the signal-to-noise ratio of transmission images. And it can improve the positioning accuracy of radioisotope and the accuracy of reconstructed activity.

Endoscopic assisted suturectomy for primary craniosynostosis in infancy

Background: Multiple procedures have been used for the treatment of craniosynostosis, ranging from simple suturectomy to extensive calvarial vault remodeling. The optimal timing for surgery is still controversial. The goal of therapy is to provide adequate intracranial volume, in addition to an aesthetically almost normal skull shape. Endoscopic synostosis repair described in 1998 by Jimenez and Baron [1]. This technique allows for a less invasive method that can result in excellent longstanding reconstruction of the cranial skeleton. This method is a minimally invasive approach that has less morbidity involved with traditional reconstruction techniques. Aim: Evaluation of early endoscopic suturectomy and its impact on both neurological functions and cosmetic appearance of infants up to 6 months of age suffering primary craniosynostosis. Methodology: This is a prospective analytical study of 50 patients with primary non syndromic craniosynostosis either single suture or multiple sutures, up to sixth months of age; with evident of skull shape deformity and or manifestations of increase intracranial pressure. from; October 2009 to October 2016 were managed byendoscopic assisted suturectomy the approach of Jimenez and Baron, in both Neurosurgery Department Shebin Elkom teaching hospital and Neurosurgery Department in Elsahel teaching hospital. Clinical and radiological follow up for six months postoperative. Results: This is a prospective analytical study of 50 patients with primary craniosynostosis, 28 patients are male and 22 patients are female. The age of patients range from one and half months to sixth months. The majority of cases presented with deformity alone 68%. Other clinical presentations as manifestations of increased intracranial pressure, fits, and delayed milestones plus deformity was 20%, 8%, and 4% respectively. Estimated blood loss, the mean loss was 56cc, minimum 30cc, and maximum was 100cc, with stander deviation ±18cc.The minimum hospital stay was one day and maximum was three days.There is significant change of head shape and head circumference postoperatively this observed by highly significant P value in head circumference (< 0.001). Conclusion: Endoscopic assisted suturectomy is minimally invasive approach with a very narrow range of complications, very limited need to blood transfusion and if it occurs, it is small volume in relation to total volume. Very short ICU and hospital stay also decrease the economic load.

Cinematic rendering of pancreatic neoplasms: preliminary observations and opportunities

Pancreatic cancer is the third most common cause of cancer death and CT is the most commonly used modality for the initial evaluation of suspected pancreatic cancer. Post-processing of CT data into 2D multiplanar and 3D reconstructions has been shown to improve tumor visualization and assessment of tumor resectability compared to axial slices, and is considered the standard of care. Cinematic rendering is a new 3D-rendering technique that produces photorealistic images, and it has the potential to more accurately depict anatomic detail compared to traditional 3D reconstruction techniques. The purpose of this article is to describe the potential application of CR to imaging of pancreatic neoplasms. CR has the potential to improve visualization of subtle pancreatic neoplasms, differentiation of solid and cystic pancreatic neoplasms, assessment of local tumor extension and vascular invasion, and visualization of metastatic disease.

A hierarchical Bayesian method for vibration-based time domain force reconstruction problems

Traditional force reconstruction techniques require prior knowledge on the force nature to determine the regularization term. When such information is unavailable, the inappropriate term is easily chosen and the reconstruction result becomes unsatisfactory. In this paper, we propose a novel method to automatically determine the appropriate q as in ℓq regularization and reconstruct the force history. The method incorporates all to-be-determined variables such as the force history, precision parameters and q into a hierarchical Bayesian formulation. The posterior distributions of variables are evaluated by a Metropolis-within-Gibbs sampler. The point estimates of variables and their uncertainties are given. Simulations of a cantilever beam and a space truss under various loading conditions validate the proposed method in providing adaptive determination of q and better reconstruction performance than existing Bayesian methods.

A biomechanical modeling-guided simultaneous motion estimation and image reconstruction technique (SMEIR-Bio) for 4D-CBCT reconstruction

Reconstructing four-dimensional cone-beam computed tomography (4D-CBCT) images directly from respiratory phase-sorted traditional 3D-CBCT projections can capture target motion trajectory, reduce motion artifacts, and reduce imaging dose and time. However, the limited numbers of projections in each phase after phase-sorting decreases CBCT image quality under traditional reconstruction techniques. To address this problem, we developed a simultaneous motion estimation and image reconstruction (SMEIR) algorithm, an iterative method that can reconstruct higher quality 4D-CBCT images from limited projections using an inter-phase intensity-driven motion model. However, the accuracy of the intensity-driven motion model is limited in regions with fine details whose quality is degraded due to insufficient projection number, which consequently degrades the reconstructed image quality in corresponding regions. In this study, we developed a new 4D-CBCT reconstruction algorithm by introducing biomechanical modeling into SMEIR (SMEIR-Bio) to boost the accuracy of the motion model in regions with small fine structures. The biomechanical modeling uses tetrahedral meshes to model organs of interest and solves internal organ motion using tissue elasticity parameters and mesh boundary conditions. This physics-driven approach enhances the accuracy of solved motion in the organ’s fine structures regions. This study used 11 lung patient cases to evaluate the performance of SMEIR-Bio, making both qualitative and quantitative comparisons between SMEIR-Bio, SMEIR, and the algebraic reconstruction technique with total variation regularization (ART-TV). The reconstruction results suggest that SMEIR-Bio improves the motion model’s accuracy in regions containing small fine details, which consequently enhances the accuracy and quality of the reconstructed 4D-CBCT images.

Accounting for Microtubule Distortions in Cryo-EM Structures using Patch Refinements

Microtubules are dynamic, filamentous structures that are essential for many different cellular processes. These processes often rely on a number of microtubule associated proteins (MAPs) that either regulate or carry out these functions. Characterizing interactions between MAPs and microtubules is crucial to understanding of how these processes are carried out. Recent advances in cryo-electron microscopy have made observing interactions between microtubules and several different MAPs at near atomic resolution possible. However, the resolution of these structures is variable, depending on the MAP. Recent studies have shown that the microtubule lattice is flexible and different stabilizing drugs and MAPs affects this flexibility. These results suggest that distortions in the microtubule lattice are limiting overall resolution. Rather than aligning whole segments of microtubules (like in conventional microtubule reconstructions), we have developed a technique that aligns patches of tubulin. By subtracting the surrounding microtubule density and leaving a patch of tubulin dimers, each patch can be aligned independently from the bulk of the microtubule. We have tested this ‘patch refinement’ technique on a synthetically, distorted dataset. Using traditional reconstruction techniques yielded a low resolution structure, but upon application of the patch refinement technique, the resulting structure was nearly indistinguishable from an equivalent undistorted, synthetic dataset. The patch refinement method has also been applied to an experimental dataset that was resolved to >5Å using traditional methods. Following patch refinement, the resolution increased to <3.6Å. Using the alignment parameters following patch refinement, we were able to trace the path of individual protofilaments and observe distortions in the lattice. Further use and development of this technique will allow us to analyze microtubule distortions and work towards obtaining an atomic structure of a microtubule.

Open Anterior Skull Base Reconstruction: A Contemporary Review.

Skull base extirpative and reconstructive surgery has undergone significant changes due to technological and operative advances. While endoscopic resection and reconstruction will continue to advance skull base surgery for the foreseeable future, traditional open surgical approaches and reconstructive techniques are still contemporarily employed as best practices in certain tumors or patient-specific anatomical cases. Skull base surgeons should strive to maintain a working knowledge and technical skill set to manage these challenging cases where endoscopic techniques have previously failed, are insufficient from anatomical constraints, or tumor biology with margin control supersedes the more minimally invasive approach. This review focuses on the reconstructive techniques available to the open skull base surgeon as an adjunct to the endoscopic reconstructive options. Anatomic considerations, factors relating to the defect or patient, reconstructive options of nonvascular grafts, local and regional flaps, and free tissue transfer are outlined using the literature and author's experience. Future directions in virtual surgical planning and emerging technologies will continue to enhance open and endoscopic skull base surgeon's preparation, performance, and outcomes in this continually developing interdisciplinary field.

Reconstruction method for inversion problems in an acoustic tomography based temperature distribution measurement

In industrial areas, temperature distribution information provides a powerful data support for improving system efficiency, reducing pollutant emission, ensuring safety operation, etc. As a noninvasive measurement technology, acoustic tomography (AT) has been widely used to measure temperature distribution where the efficiency of the reconstruction algorithm is crucial for the reliability of the measurement results. Different from traditional reconstruction techniques, in this paper a two-phase reconstruction method is proposed to ameliorate the reconstruction accuracy (RA). In the first phase, the measurement domain is discretized by a coarse square grid to reduce the number of unknown variables to mitigate the ill-posed nature of the AT inverse problem. By taking into consideration the inaccuracy of the measured time-of-flight data, a new cost function is constructed to improve the robustness of the estimation, and a grey wolf optimizer is used to solve the proposed cost function to obtain the temperature distribution on the coarse grid. In the second phase, the Adaboost.RT based BP neural network algorithm is developed for predicting the temperature distribution on the refined grid in accordance with the temperature distribution data estimated in the first phase. Numerical simulations and experiment measurement results validate the superiority of the proposed reconstruction algorithm in improving the robustness and RA.

Bioengineered dermal substitutes for the management of traumatic periocular tissue loss

ABSTRACTPurpose: Traumatic periocular injuries occasionally result in significant soft tissue loss, for which there are limited management options that provide satisfactory cosmetic and functional outcomes. The authors describe the use of a bioengineered dermal substitute (Integra® Dermal Regeneration Template [DRT], Integra LifeSciences, Plainsboro, NJ) as an alternative to immediate flap reconstruction or skin grafting.Methods: Retrospective interventional case series of patients who underwent DRT placement for periocular tissue loss at the time of trauma. In each case, primary closure or immediate flap reconstruction was deemed impractical or undesirable due to the size and location of the primary and associated secondary defects. One to four weeks later, the outer silicone layer was removed and healing assessed. Additional reconstructive techniques were performed as needed.Results: Three patients were treated at Bascom Palmer Eye Institute and one at Byers Eye Institute at Stanford. The defects healed completely in two patients, and by 79.2% in a third, with no need for additional reconstructive surgery. In the remaining patient, the defect was significantly downsized by 56.1%, allowing for a simpler flap reconstruction.Conclusions: Bioengineered dermal substitutes should be considered as a viable alternative to traditional reconstructive techniques for large periocular defects resulting from trauma. The outer silicone layer prevents desiccation and serves as a protective barrier, while the inner collagen matrix organizes the growth of neo-dermis and minimizes wound contraction. The dimensions of cutaneous defects can therefore be reduced dramatically, potentially eliminating the need for skin grafting and/or reducing the ultimate complexity of flap reconstruction.

Reconstruction of Mandible: A Fully Digital Workflow From Visualized Iliac Bone Grafting to Implant Restoration

Although digital aids can help surgeons compensate for the shortcomings of traditional mandibular reconstruction techniques to perform surgery more precisely and effectively, the use of these digital techniques has often been fragmented, divided, and incomplete. This article describes the workflow of a fully digital mandibular reconstruction to explore the proper indications and discusses innovations based on the accuracy and effectiveness of digital techniques. A restoration-oriented mandibular reconstruction was performed by applying different digital techniques. Preoperative virtual surgery and rapid prototyping were used to aid the vascularized iliac bone graft surgery, which offered a solid basis for the ensuing treatment. Subsequently, implant rehabilitation was accomplished with the assistance of computer-assisted design and manufacture, laser treatment, and selective laser melting techniques. The workflow of the fully digital mandibular reconstruction successfully achieved a restoration-oriented treatment. These predictable, accurate, and effective digital techniques improved the consistency of pretreatment design and follow-up treatment. The treatment sequence achieved high predictability and reproducibility owing to the use of digital techniques. This study shows that a digital workflow can be predictable, accurate, and effective, which suggests that it could be a valid digital protocol for developing a treatment sequence for patients with jaw defects caused by trauma, congenital anomalies, or mandibular tumor resection.

Two stage management of Cierny-Mader type IV chronic osteomyelitis of the long bones

IntroductionCierny-Mader (C-M) type IV chronic osteomyelitis represents a complex clinical challenge with permeation of extensive bone and soft tissue involvement. Aggressive debridement through viable tissue margin includes en bloc resection improves the odds of eradication of infection, which creates large bone and soft tissue loss in treating this type of osteomyelitis. The potentially large defects increase reconstruction problems with traditional reconstruction technique. The newly staged induced membrane technique presents length-independent, potential as an alternative reconstruction method for segmental bone defects due to type IV chronic osteomyelitis. The purpose of this study was to assess the result and related factors of C-M type IV chronic osteomyelitis treated with staged methods of aggressive debridement and induced membrane technique. MethodsFrom January 2012 to January 2014, 36 consecutive adult patients of C-M type IV chronic osteomyelitis were treated by this staged method in our clinical center with a minimum of 2-years follow-up. The clinical and imaging results were retrospectively analyzed. ResultsFive patients had a second debridement and eight needed a local flap transfer to cover the wound in the first stage. Patients formed a mean of 5.5cm (range: 2–10.9) segmental bone defect; Sixteen patients had autograft and twenty had autograft mixed allograft in the second stage. The mean follow-up time was 29.5 months (range: 24–45). No patients required amputation. Bone union was achieved in all patients. Clinical eradication of osteomyelitis was achieved in 35 (97%) patients, 35 (97%) patients were able to walk independently, and 31patients (86%) returned to work. Patients returned to a mean of 82% (46.3%–100%) lower extremity function. Bone union time was not dependent on the length of bone defect, but associated with the infection site (p=0.005) and age (p=0.005). ConclusionsStaged methods of aggressive debridement and induced membrane technique seems to be a simple, reliable and effective for the treatment of C-M type IV chronic osteomyelitis. Advanced age and poor soft tissue envelope may have adverse affects and are relative contraindications. The combined assessment and management of such patients with a plastic surgeon are advocated.

A Biomechanical Modeling Guided CBCT Estimation Technique.

Two-dimensional-to-three-dimensional (2D-3D) deformation has emerged as a new technique to estimate cone-beam computed tomography (CBCT) images. The technique is based on deforming a prior high-quality 3D CT/CBCT image to form a new CBCT image, guided by limited-view 2D projections. The accuracy of this intensity-based technique, however, is often limited in low-contrast image regions with subtle intensity differences. The solved deformation vector fields (DVFs) can also be biomechanically unrealistic. To address these problems, we have developed a biomechanical modeling guided CBCT estimation technique (Bio-CBCT-est) by combining 2D-3D deformation with finite element analysis (FEA)-based biomechanical modeling of anatomical structures. Specifically, Bio-CBCT-est first extracts the 2D-3D deformation-generated displacement vectors at the high-contrast anatomical structure boundaries. The extracted surface deformation fields are subsequently used as the boundary conditions to drive structure-based FEA to correct and fine-tune the overall deformation fields, especially those at low-contrast regions within the structure. The resulting FEA-corrected deformation fields are then fed back into 2D-3D deformation to form an iterative loop, combining the benefits of intensity-based deformation and biomechanical modeling for CBCT estimation. Using eleven lung cancer patient cases, the accuracy of the Bio-CBCT-est technique has been compared to that of the 2D-3D deformation technique and the traditional CBCT reconstruction techniques. The accuracy was evaluated in the image domain, and also in the DVF domain through clinician-tracked lung landmarks.