Current Reconstruction Techniques Research Articles

Comparison of a Novel Anatomic Technique and the Docking Technique for Medial Ulnar Collateral Ligament Reconstruction

Background: Current reconstruction techniques do not re-create the distal ulnar collateral ligament (UCL) insertion. Reconstructing the distal extension of the anterior band ulnar footprint may increase elbow stability and resistance against valgus stress after UCL reconstruction (UCLR). Purpose/Hypothesis: The purpose was to test a new technique for UCLR, a modification of the docking technique, aimed at re-creating the distal ulnar footprint anatomy of the anterior band. We hypothesize that this novel “anatomic” technique will provide greater resistance to valgus stress after UCLR when compared with the docking technique. Study Design: Descriptive laboratory study. Methods: Eighteen unpaired cadaveric arms were dissected to capsuloligamentous elbow structures and potted. With use of a servohydraulic load frame, 5 Nċm of valgus stress was placed on the UCL-intact elbows at 30°, 60°, 90°, and 120° of flexion. UCLR was performed on each elbow, randomized to either the docking technique or the anatomic technique. After UCLR, the elbow was again tested at 30°, 60°, 90°, and 120° of flexion. Ulnohumeral joint gapping was calculated using a 3-dimensional motion capture system applied to markers attached to the ulna and humerus. Differences in gapping among the intact state and docking and anatomic techniques were compared using a 2-way analysis of variance with significance set to P < .05. Results: There was no significant difference in gapping between the anatomic and docking technique groups regardless of elbow flexion angle. All reconstructed groups showed increased gapping relative to intact, but all increases were below the clinically relevant level of 1 mm. Conclusion: Ulnohumeral joint gapping and resistance to valgus stress were similar between the anatomic technique and the docking technique for UCLR. Clinical Relevance: This study provides evidence that the anatomic technique is a viable alternative UCLR method as compared with the docking technique in a cadaveric model.

Current concepts in microsurgical soft tissue reconstruction of lower extremity trauma in a single-vessel extremity

Advancements in microsurgical techniques have allowed for the salvage of extremities that would otherwise be amputated. Despite these improvements, mangling injuries of the lower extremity with concomitant open fracture continue to present a challenge for reconstructive surgeons. These injuries are further complicated by circumstances in which a single vessel is perfusing the foot after trauma (Gustilo 3C injuries). Although the foot may remain perfused in this instance, free flap coverage of open fractures with concomitant vascular injury requires careful planning to maintain a viable foot. The surgeon must adapt surgical plans based on both preoperative and intraoperative findings. In this review, we discuss current concepts and reconstructive techniques for performing free flap reconstruction in single-vessel lower extremities.

Digital Implementation of Single Current Sensor-Based IPMSM Drive With Sampling Error Delay Compensation

Single current sensor-based three-phase drives are gaining huge interest from industries for sensitivity mismatch issues and cost reduction. However, the current sampling error caused by multiple sampling points during current reconstruction from various single current sensor (SCS) topologies led to increase in speed fluctuation and torque ripple. In this paper, a computationally efficient and accurate model-based sampling error compensation scheme based on a new SCS with double branch current sampling technique is proposed for an interior permanent magnet synchronous motor (IPMSM) drive. In order to improve of current reconstruction precision, the compensation strategy includes rotor angle compensation of IPMSM and dead-time effect mitigation for reduction of non-ideal behavior of inverter, which does not require major computation. Also, dc-link voltage utilization is improved significantly without any external dc-link control. The efficacy of the proposed compensation strategy is verified by an experimental setup consisting of 1.5 kW IPMSM drive, which shows the effectiveness of proposed current reconstruction technique from SCS by reducing current sampling error with minimum computational burden.

Biomechanical Comparison of Anatomic Restoration of the Ulnar Footprint vs Traditional Ulnar Tunnels in Ulnar Collateral Ligament Reconstruction

Background: Current techniques for ulnar collateral ligament (UCL) reconstruction do not reproduce the anatomic ulnar footprint of the UCL. The purpose of this study was to describe a novel UCL reconstruction technique that utilizes proximal-to-distal ulnar bone tunnels to better re-create the anatomy of the UCL and to compare the biomechanical profile at time zero among this technique, the native UCL, and the traditional docking technique. Hypothesis: The biomechanical profile of the anatomic technique is similar to the native UCL and traditional docking technique. Study Design: Controlled laboratory study. Methods: Ten matched cadaveric elbows were potted with the forearm in neutral rotation. The palmaris longus tendon graft was harvested, and bones were sectioned 14 cm proximal and distal to the elbow joint. Specimen testing included (1) native UCL testing performed at 90° of flexion with 0.5 N·m of valgus moment preload, (2) cyclic loading from 0.5 to 5 N·m of valgus moment for 1000 cycles at 1 Hz, and (3) load to failure at 0.2 mm/s. Elbows then underwent UCL reconstruction with 1 elbow of each pair receiving the classic docking technique using either anatomic (proximal to distal) or traditional (anterior to posterior) tunnel locations. Specimen testing was then repeated as described. Results: There were no differences in maximum load at failure between the anatomic and traditional tunnel location techniques (mean ± SD, 34.90 ± 10.65 vs 37.28 ± 14.26 N·m; P = .644) or when including the native UCL (45.83 ± 17.03 N·m; P = .099). Additionally, there were no differences in valgus angle after 1000 cycles across the anatomic technique (4.58°± 1.47°), traditional technique (4.08°± 1.28°), and native UCL (4.07°± 1.99°). The anatomic group and the native UCL had similar valgus angles at failure (24.13°± 5.86° vs 20.13°± 5.70°; P = .083), while the traditional group had a higher valgus angle at failure when compared with the native UCL (24.88°± 6.18° vs 19.44°± 5.86°; P = .015). Conclusion: In this cadaveric model, UCL reconstruction with the docking technique utilizing proximal-to-distal ulnar tunnels better restored the ulnar footprint while providing valgus stability comparable with reconstruction with the docking technique using traditional anterior-to-posterior ulnar tunnel locations. These results suggest that utilization of the anatomic tunnel location in UCL reconstruction has similar biomechanical properties to the traditional method at the time of initial fixation (ie, not accounting for healing after reconstruction in vivo) while keeping the ulnar tunnels farther from the ulnar nerve. Further studies are warranted to determine if an anatomically based UCL reconstruction results in differing outcomes than traditional reconstruction techniques. Clinical Relevance: Current UCL reconstruction techniques do not accurately re-create the ulnar UCL footprint. The UCL is a dynamic constraint to valgus loads at the elbow, and a more anatomic reconstruction may afford more natural joint kinematics. This more anatomic technique performs similarly to the traditional docking technique at time zero, and the results of this study may offer a starting point for future in vivo studies.

Reconstructive surgery of the scrotum: a systematic review.

The term scrotoplasty embraces several techniques which aim to restore a normal scrotal appearance and function. We provide here a quick reference tool to allow the urologist to select the appropriate surgical strategy among the several available options. A comprehensive research was carried out on MEDLINE/PubMed to identify relevant studies concerning this topic, including a range of key words, e.g., scrotoplasty, ventral phalloplasty, scrotal reconstruction, scrotomegaly, penoscrotal web, scrotal lifting, scrotal reduction, scrotectomy, scrotal lymphoedema. Scrotal skin defects may be related with Fournier's gangrene, traumatic events, and surgery for genital cancers or peno-scrotal lymphoedema. The reconstructive management of these conditions is relatively reproducible in the hands of experienced urologists, if aware of the basics of scrotal surgery. Primary tension-free wound closure and local pedicled flaps typically allow optimal surgical outcomes for repairing most of these scrotal defects, with split-thickness skin grafts (STSGs) and/or distant flaps being required only when dealing with extensive skin losses. The demand for genitals' aesthetic surgery among adults is on the increase recently. Although the scientific evidence regarding this topic is scarce, reduction scrotoplasty and peno-scrotal webbing correction techniques are easy, safe and effective solutions to improve genital cosmesis, being carried out in isolation or in combination with penile prosthesis implantation. More robust scientific evidence is needed to achieve a uniformed consensus regarding the optimal surgical management in this broad field, and surgical innovation should continue to refine current reconstructive techniques.

Systemic Venous Reconstructions During Pediatric Heart Transplantation.

Congenital heart disease continues to be an important indication for pediatric heart transplantation (HT) and is often complicated by systemic venous anomalies. The need for reconstruction, surgical technique used, as well as the outcomes of these have limited documentation. Descriptive, retrospective study of patients transplanted at Emory University between 2006 and 2017. We reviewed surgical data, follow-up, and interventions for patients necessitating venous reconstruction during transplantation. A total of 179 transplants were performed during the time period of which 74 (41%) required systemic venous reconstruction. Mean age at transplant was 6.3 (±6.16) years, and 74.3% of these patients carried a diagnosis of single ventricle; 51 (68.9%) of 74 patients required pulmonary artery reconstruction at the time of HT. Forty patients required superior vena caval reconstruction, while 22 patients required inferior vena caval reconstruction due to prior palliation or anomaly. Venous anomalies along with other anatomic features necessitated biatrial transplantation in four patients. Posttransplant evaluation revealed systemic venous stenosis in 14 (18.9%) of 74 patients. Eight (10.8%) patients required 12 interventions for the systemic veins. Patients with bilateral Glenn anastomosis prior to transplant were at high risk for the development of stenosis and needing interventions. Systemic venous complications were uncommon in those with native systemic veins without Glenn or Fontan procedure. Systemic venous reconstruction needs are high in pediatric HT. Posttransplant stenosis and the need for interventions are relatively common. Current techniques for systemic venous reconstruction for complex congenital heart disease patients may deserve further review to optimize these outcomes.

The Injured Shoulder in High-Level Male Gymnasts, Part 2: Can Athletes Return to Competition After Surgery?

Background:The results of surgical treatment of shoulder injuries in high-level male gymnasts have not yet been documented.Purpose:To evaluate the functional and subjective results after surgical treatment of shoulder injuries in high-level gymnasts and the possibilities to return to sport at the same level.Study Design:Case series; Level of evidence, 4.Methods:Over a 20-year period (1994-2014), 23 high-level male gymnasts (26 shoulders) underwent surgery by a single experienced shoulder surgeon. At the time of surgery, 7 gymnasts competed at the international level, 12 at the national elite level, and 4 at the regional level. According to symptoms and anatomic lesions, the shoulders were classified into 2 groups: painful shoulders (n = 11) and unstable shoulders (n = 15). Fifteen capsulolabral repairs, 10 cuff debridements, 1 cuff repair, 4 SLAP (superior labral anterior and posterior) repairs, and 8 suprapectoral biceps tenodesis were performed. Twelve shoulders (46%) had >1 procedure performed. Outcomes assessment was performed by an independent observer at a mean of 5 years (range, 2-15 years) postoperatively. In addition, patients completed the Subjective Shoulder Value (range, 0%-100%).Results:After shoulder surgery, 21 (91%) of the 23 gymnasts returned to competitive gymnastics, and 20 gymnasts (87%) regained their preinjury level of sport. All international-level gymnasts returned to their preinjury level of sport. Three athletes (13%) underwent revision surgery, and 1 athlete (4%) ended his career without returning to competition. The postoperative period before resumption of competitive gymnastics was 9 ± 3.5 months (mean ± SD). Of the 15 gymnasts treated for shoulder instability with arthroscopic stabilization, 12 were able to return to their previous level of sport. All 8 gymnasts who had arthroscopic biceps tenodesis were able to return to their previous level of sport, as opposed to only 2 of 4 gymnasts treated with SLAP repair. The gymnastics-specific Subjective Shoulder Value score was 80% ± 11%.Conclusion:Most gymnasts who required surgical treatment for a shoulder injury were able to return to competition at their previous level, although there was a considerable postoperative recovery period. Current arthroscopic reconstruction techniques were effective for treating structural lesions and allowing return to high-level gymnastics.

Abdominal Wall Expanding System. Intraoperative Abdominal Wall Expansion as a Technique to Repair Giant Incisional Hernia and Laparostoma. New and Long-Term Results From a Three-Center Feasibility Study.

The abdominal wall expanding system (AWEX) was first applied in 2012 and published in 2017. This novel technique was developed to reconstruct complex incisional hernias and residual skin-grafted laparostoma after treatment of an open abdomen, when primary midline closure was impossible. The main aim was the anatomical reconstruction of the abdominal wall and the avoidance of dissecting techniques (component separation). Between 2012 and 2019, 33 patients underwent AWEX hernia repair in three certified hernia centers. The retracted abdominal wall was stretched with the AWEX system intraoperatively for approximately 30min. Hernia size was measured preoperatively, on CT, and intraoperatively. The gain in length on the lateral abdominal wall (decrease in width of the defect) after stretching and any residual midline gap were determined in the OR. 33 patients underwent AWEX procedures. Six cases were evaluated separately because of additional procedures (TAR, four cases) and preoperative application of botulinum toxin (two cases). The median (95% confidence interval) measured width of hernia defects was 13 (12-16) cm, the median gain in length on the lateral abdominal wall was 12 (10-15) cm. After median follow-up of 29 (12-54) months, one recurrence from the broken mesh was observed. No method-related complications occurred. Based on the 2017 and current results, the AWEX system represents an alternative or supplemental procedure to current techniques for complex abdominal wall reconstruction. The system proved again to be time-saving, safe, effective, and easy to learn. Further studies with enhanced technology are in progress.

Transpatellar bone tunnels perforating the lateral or anterior cortex increase the risk of patellar fracture in MPFL reconstruction: a finite element analysis and survey of the International Patellofemoral Study Group.

(1) To determine applied patellar drilling techniques for medial patellofemoral ligament (MPFL) reconstruction among members of the International Patellofemoral Study Group (IPSG) and (2) to evaluate the risk of patellar fracture for various patellar bone tunnel locations based on a finite element analysis (FEA) model. In the first part of the study, an online survey on current MPFL reconstruction techniques was conducted among members of the IPSG. In the second part of the study, a three-dimensional FEA model of a healthy knee joint was created using a computed tomography scan. Patient-specific bone density was integrated into the patella, and cartilage of 3mm thickness was modeled for the patellofemoral joint. According to the survey's results, two different types of patellar bone tunnels (bone socket and transpatellar bone tunnel) were simulated. The risk of patellar fracture was evaluated based on the fracture risk volume (FRV) obtained from the FEA. Finite element analysis revealed that subchondral bone socket tunnel placement is associated with the lowest FRV but increased with an anterior offset (1-5mm). Transpatellar bone tunnels violating the lateral or anterior cortex showed a higher FRV compared to bone socket, with the highest values observed when the anterior cortex was penetrated. Violation of the anterior or lateral patellar cortex using transpatellar bone tunnels increased FRV compared to a subchondral patellar bone socket tunnel. In MPFL reconstruction, subchondral patellar bone socket tunnels should be considered for patellar graft fixation to avoid the risk of postoperative patellar fracture. Survey; Descriptive laboratory study/Level V.

Viability of acellular biologic graft for nipple-areolar complex reconstruction in a non-human primate model

Many of the > 3.5 million breast cancer survivors in the US have undergone breast reconstruction following mastectomy. Patients report that nipple-areolar complex (NAC) reconstruction is psychologically important, yet current reconstruction techniques commonly result in inadequate shape, symmetry, and nipple projection. Our team has developed an allogeneic acellular graft for NAC reconstruction (dcl-NAC) designed to be easy to engraft, lasting, and aesthetically pleasing. Here, dcl-NAC safety and host-mediated re-cellularization was assessed in a 6-week study in rhesus macaque non-human primates (NHPs). Human-derived dcl-NACs (n = 30) were engrafted on the dorsum of two adult male NHPs with each animal’s own nipples as controls (n = 4). Weight, complete blood counts, and metabolites were collected weekly. Grafts were removed at weeks 1, 3, or 6 post-engraftment for histology. The primary analysis evaluated health, re-epithelialization, and re-vascularization. Secondary analysis evaluated re-innervation. Weight, complete blood counts, and metabolites remained mostly within normal ranges. A new epidermal layer was observed to completely cover the dcl-NAC surface at week 6 (13–100% coverage, median 93.3%) with new vasculature comparable to controls at week 3 (p = 0.10). Nerves were identified in 75% of dcl-NACs (n = 9/12) at week 6. These data suggest that dcl-NAC is safe and supports host-mediated re-cellularization.

Tissue Engineering Auricular Cartilage: A Review of Auricular Cartilage Characteristics and Current Techniques for Auricular Reconstruction

Microtia and anotia are congenital auricular anomalies that negatively impact the psychosocial development of those affected. Because the auricular cartilage is a type of elastic cartilage that lacks regenerative capacity, any notable defect in its structure requires a surgical approach to reconstruct the auricle. While there are several reconstructive options available between alloplastic and prosthetic implants, autologous rib cartilage grafts remain the most commonly used treatment modality. Still, this widely used technique is accompanied by significant patient discomfort in a young child, and it carries additional risks secondary to the traumatic process of rib cartilage extraction, such as pneumothorax, chest wall deformities, and the final aesthetic results may not be ideal. To circumvent these limitations, tissue-engineering approaches have been employed to create a realistic-looking ear that mirrors the complex anatomy of the normal ear. This article provides an overall description of the ear’s anatomy and reviews the traditional management options for auricular reconstruction. The biochemical and biomechanical properties of human auricular cartilage are detailed as they relate to design criteria. In addition, a variety of cell sources, biocompatible scaffolds, scaffold-free techniques, mechanical and biological stimuli have been discussed. This review aims to identify knowledge gaps in the literature related to auricular cartilage characteristics and make recommendations to drive the field of auricular tissue engineering.

Artificial intelligence in medical imaging: implications for patient radiation safety.

Artificial intelligence, including deep learning, is currently revolutionising the field of medical imaging, with far reaching implications for almost every facet of diagnostic imaging, including patient radiation safety. This paper introduces basic concepts in deep learning and provides an overview of its recent history and its application in tomographic reconstruction as well as other applications in medical imaging to reduce patient radiation dose, as well as a brief description of previous tomographic reconstruction techniques. This review also describes the commonly used deep learning techniques as applied to tomographic reconstruction and draws parallels to current reconstruction techniques. Finally, this paper reviews some of the estimated dose reductions in CT and positron emission tomography in the recent literature enabled by deep learning, as well as some of the potential problems that may be encountered such as the obscuration of pathology, and highlights the need for additional clinical reader studies from the imaging community.

Acellular dermal matrices in breast reconstruction: a narrative review and institutional perspective

: Breast reconstruction after mastectomy is commonly undertaken in patients inappropriate for breast conserving surgery, women who are at high genetic risk for breast cancer or otherwise based on patient preference. Current breast reconstruction techniques are diverse and may involve the use of an autologous tissue flap, tissue expanders or definitive implants. Regardless of the technique used, the use of acellular dermal matrices (ADMs) has become increasingly prevalent. The increased uptake of ADMs has led to a paradigm shift in breast reconstruction. This has led to a proliferation of new products and materially contributed to increased rates of pre-pectoral reconstruction. Single-stage and two-stage breast reconstruction remain a contentious issue with increasing evidence justifying direct-to-implant reconstruction in well selected patients with ADMs. ADMs are able to provide solutions to a multitude of issues surrounding inadequate tissue coverage and support, such as implant rippling, implant migration and capsular contracture. This review outlines an overview of the history of ADMs, commonly used ADMs and addresses the evidence with respect to known complications of ADMs. A number of product alternatives to ADMs are explored and an analysis of materials and characteristics are also provided. Notwithstanding cheaper costs of manufacturing these products may offer comparable outcomes. Ultimately this narrative review provides an institutional insight into breast reconstruction in a high volume Australian centre routinely employing ADMs. Important adjuncts such as indocyanine green angiography (ICGA) and negative pressure wound therapy (NPWT) have enhanced outcomes in our practice facilitating the identification of patients likely to benefit from staged expander based reconstruction.

Protocol and Evaluation of 3D-Planned Microsurgical and Dental Implant Reconstruction of Maxillary Cleft Critical Size Defects in Adolescents and Young Adults.

Functional and esthetic final reconstruction of the cleft maxilla is still challenging. Current reconstructive and augmentation techniques do not provide sufficient bone and soft tissue support for the predictable rehabilitation with dental implants due to presence of maxillary bone critical size defects and soft tissue deficiency, scaring and poor vascularity. In this article the protocol for the use of 3D virtual surgical planning and microvascular tissue transfers for the reconstruction and rehabilitation of cleft maxilla is presented. Twenty-five patients (8 male/17 female) aged 14–41 years old with cleft-associated critical size defects were treated by 3D-virtual planned microvascular tissue transfers taken either from fibula, iliac crest, radial forearm, or medial femoral condyle. Follow-up lasted 1–5 years. No significant bone resorption (p > 0.005) nor volume loss of the graft was observed (p = 0.645). Patients received final permanent prosthetic reconstruction of the anterior maxilla based on 2–5 dental implants, depending on the defect severity. This is the first study presenting the use of virtual planning in the final restoration of the cleft maxilla with microvascular tissue transfers and dental implants. Presented protocol provide highly functional and aesthetic results.

Improved Three-Phase Current Reconstruction Technique for PMSM Drive With Current Prediction

In this article, we present an improved current reconstruction technique with current prediction for a permanent magnet synchronous motor drive system. In some conventional single current sensor techniques, current fluctuations occur at the sector-switching period (SSP) due to current holding between two adjacent sampling intervals, which can cause current distortion and introduce many current harmonics, especially when the motor speed is very high. Focusing on that, a current prediction method is proposed in this article to prevent the current fluctuation happening at SSP. The SSP is divided into two independent parts for the accurate calculation of the output voltage vector and the actual three-phase currents at SSP are determined on account of both the predicted <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis currents and the measurable ones. As a result, compared with the previous current-holding strategy, the current fluctuations can be fundamentally eliminated under the proposed method with less current harmonics introduced, further improving the control performance of the whole system. The accuracy and practicability of the proposed method are verified by the experimental results.

A Protocol for the Use of a Combined Microvascular Free Flap with Custom-Made 3D-Printed Total Temporomandibular Joint (TMJ) Prosthesis for Mandible Reconstruction in Children

Extended postoperative mandibular reconstructions due to orofacial disease involving the temporomandibular joint (TMJ) in immature patients remain a challenge as a result of ongoing growth, which is usually affected by the disease and treatment. Current reconstructive techniques based fully on alloplastic total joint replacement fail to meet fully the anatomical and functional requirements for the masticatory system and speech development. Fourteen children aged 12.6 ± 2.6 with tumors or congenital deformities affecting the mandible and TMJ were included in the study. Radical surgical treatment according to our own protocol was performed through microvascular anastomotic flap reconstruction of the soft tissues and bones, together with total TMJ custom replacements. Follow-up lasted 2–6 years. During the follow-up, increases in the mandible body (13% growth) and ramus (12% growth) were observed, both of which were related (p &lt; 0.001). This is the first report concerning the immediate reconstruction of the mandible with ramus and total TMJ in children and adolescents that combines a free vascularized graft and total individual prosthesis of the TMJ. The presented technique enabled optimal function of the TMJ, growth of the mandible, and further rehabilitation of the patients. The technique was demonstrated to be safe, reliable, and provide good functional and cosmetic outcomes.

CryoGAN: A New Reconstruction Paradigm for Single-Particle Cryo-EM Via Deep Adversarial Learning

We present CryoGAN, a new paradigm for single-particle cryo-electron microscopy (cryo-EM) reconstruction based on unsupervised deep adversarial learning. In single-particle cryo-EM, the structure of a biomolecule needs to be reconstructed from a large set of noisy tomographic projections with unknown orientations. Current reconstruction techniques are based on a marginalized maximum-likelihood formulation that requires calculations over the set of all possible poses for each projection image, a computationally demanding procedure. Our approach is to seek a 3D structure that has simulated projections that match the real data in a distributional sense, thereby sidestepping pose estimation or marginalization. We prove that, in an idealized mathematical model of cryo-EM, this approach results in recovery of the correct structure. Motivated by distribution matching, we propose CryoGAN, a specialized GAN that consists of a 3D structure, a cryo-EM physics simulator, and a discriminator neural network. During reconstruction, the 3D structure is optimized so that its projections obtained through the simulator resemble real data (to the discriminator). Simultaneously, the discriminator is trained to distinguish real projections from simulated projections. CryoGAN takes as input only real projection images and the distribution of the cryo-EM imaging parameters. It involves neither prior training nor an initial estimation of the 3D structure. CryoGAN currently achieves a 10.8 Å resolution on a realistic synthetic dataset. Preliminary results on experimental β-galactosidase and 80S ribosome data demonstrate the ability of CryoGAN to exploit data statistics under standard experimental imaging conditions. We believe that this paradigm opens the door to a family of novel likelihood-free algorithms for cryo-EM reconstruction.

The Use of Artificial Intelligence in Computed Tomography Image Reconstruction: A Systematic Review

Background Current image reconstruction techniques in computed tomography (CT) such as filtered back-projection (FBP) and iterative reconstruction (IR) have limited use in low-dose CT imaging due to poor image quality and reconstruction times not fit for clinical implementation. Hence, with the increasing need for radiation dose reductions in CT, the use of artificial intelligence (AI) in image reconstruction has been an area of growing interest. Aim The aim of this review is to examine the use of AI in CT image reconstruction and its effectiveness in enabling further dose reductions through improvements in image quality of low-dose CT images. Method A review of the literature from 2016 to 2020 was conducted using the databases Scopus, Ovid MEDLINE, and PubMed. A subsequent search of several well-known journals was performed to obtain additional information. After careful assessment, articles were excluded if they were not obtainable from the databases or not available in English. Results This review found that deep learning-based algorithms demonstrate promising results in improving the image quality of low-dose images through noise suppression, artefact reduction, and structure preservation in addition to optimising IR methods. Conclusion In conclusion, with the two AI-based CT systems currently in clinical use showing favourable benefits, it is expected that AI algorithms will continue to proliferate and enable significant dose reductions in CT imaging.

Phase Current Sensing Method Using Three Shunt Resistors to Eliminate Immeasurable Area in Voltage Vector Plane

This paper proposes a current sensing method to eliminate the immeasurable areas in three-phase inverters using the shunt resistors. Conventional shunt resistor-based current sensing methods have immeasurable areas in the voltage vector plane. Since motor control performance is degraded by the immeasurable area, various current reconstruction techniques have been proposed to expand the measurement range. Nevertheless, the software algorithm is quite complex, and the reconstruction ability is still unsatisfactory. In the proposed method, shunt resistors are located in series with the inverter output lines to obtain the motor phase currents. Both ends of the shunt resistors are at the high-potential as the dc-link voltage. High-potential voltages are lowered to the common-mode voltage level of the analog amplifier using voltage divider, and voltage drops across shunt resistors are detected by instrumentation amplifiers. Immeasurable areas are completely eliminated because phase currents can be detected directly through line shunt resistors. Simulations and experiments are carried out to verify the effectiveness of the proposed current sensing method.

Hybrid Three-Dimensional-Printed Ear Tissue Scaffold With Autologous Cartilage Mitigates Soft Tissue Complications.

To analyze the use of highly translatable three-dimensional (3D)-printed auricular scaffolds with and without novel cartilage tissue inserts in a rodent model. Preclinical rodent animal model. This prospective study assessed a single-stage 3D-printed auricular bioscaffold with or without porcine cartilage tissue inserts in an athymic rodent model. Digital Imaging and Communications in Medicine computed tomography images of a human auricle were segmented to create an external anatomic envelope filled with orthogonally interconnected spherical pores. Scaffolds with and without tissue inset sites were 3D printed by laser sintering bioresorbable polycaprolactone, then implanted subcutaneously in five rats for each group. Ten athymic rats were studied to a goal of 24 weeks postoperatively. Precise anatomic similarity and scaffold integrity were maintained in both scaffold conditions throughout experimentation with grossly visible tissue ingrowth and angiogenesis upon explantation. Cartilage-seeded scaffolds had relatively lower rates of nonsurgical site complications compared to unseeded scaffolds with relatively increased surgical site ulceration, though neither met statistical significance. Histology revealed robust soft tissue infiltration and vascularization in both seeded and unseeded scaffolds, and demonstrated impressive maintenance of viable cartilage in cartilage-seeded scaffolds. Radiology confirmed soft tissue infiltration in all scaffolds, and biomechanical modeling suggested amelioration of stress in scaffolds implanted with cartilage. A hybrid approach incorporating cartilage insets into 3D-printed bioscaffolds suggests enhanced clinical and histological outcomes. These data demonstrate the potential to integrate point-of-care tissue engineering techniques into 3D printing to generate alternatives to current reconstructive surgery techniques and avoid the demands of traditional tissue engineering. NA Laryngoscope, 131:1008-1015, 2021.