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Introduction: Surgical corrections of fracture using fixation devices made from various alloys (stainless steel, cobalt-chromium alloys, and titanium) carry a risk of these alloys leaching into circulation, potentially causing undesired health effects. Hence, monitoring the levels of metal ions in the serum of postoperative patients with metal implants is mandated. Materials and Methods: Blood samples from seventy patients with orthopedic metal implants was collected after a minimum postoperative period of 1 year. The samples were subjected to triple acid digestion and serum levels of chromium and nickel were analyzed using inductively coupled plasma-mass spectrometry. Results: The concentration of chromium (0.13 ± 0.06 μg/L) and nickel (0.39 ± 0.28 μg/L) in serum was within the reference range (chromium: 0.05–0.15 μg/L; nickel: 0.05–1.0 μg/L). Although a relatively high variability in the concentration of nickel was observed compared to chromium. In a subgroup analysis, the concentrations of both metal ions were not influenced by either gender, age groups, site of intramedullary nail, or postoperative duration. Conclusion: The concentration of chromium and nickel in serum of patients with orthopedic metal implants was within the normal reference levels at over 1-year post implant. The concentration of these metal ions was not influenced by gender, age groups, site of intramedullary nail, or postoperative duration. [ABSTRACT FROM AUTHOR]

Porous metal implants are widely used in the field of orthopedics. However, there is urgent demand for a bottom-up design of orthopedic implants with low elastic modulus, favorable mechanical properties and biocompatibility. In this study, a controllable porous structure was designed by using Voronoi-Tessellation theory and parametric modeling method, and selective laser melting (SLM) was adopted to fabricate 316L stainless steel porous structure. The central composition design of the response surface methodology (RSM) was adopted to establish a mathematical model between elastic modulus (E), compressive strength (σ), porosity (Φ) and its structural parameters: Strut diameter (D), Irregularity (I), Number of seeds (N), and Unit distance (K). This model was validated by variance analysis and inspection indicators. The mathematical model was used to fabricate porous scaffolds with different irregularity (0.1-0.5) and porosity (40-80%), and the effects of irregularity and porosity on cell proliferation and differentiation were investigated. The results showed that the 316L stainless steel porous scaffolds fabricated by SLM have good biocompatibility. High porosity and high irregularity have positive effects on the proliferation and differentiation of osteoblasts, making it a suitable biomaterial for orthopedic implants. [ABSTRACT FROM AUTHOR]

The study investigated the dosimetric impact of an iterative metal artifact reduction (iMAR) tool on carbon ion therapy for pelvic cancer patients with hip prostheses. An anthropomorphic pelvic phantom with unilateral and bilateral hip prostheses was used to simulate pelvic cancer patients with metal implants. The raw data obtained from phantom CT scanning were reconstructed with a regular filtered back projection (FBP) algorithm and then corrected with iMAR. The phantom without hip prosthesis was also scanned and used as a reference ground truth (GT). The CT images of three prostate and four sarcoma patients with unilateral hip prosthesis were also reconstructed by FBP and iMAR algorithm and compared. iMAR algorithm reduced the metal artifacts and the maximum WEPL deviation in phantom images from −19.1 to −0.4 mm. However, the CT numbers cannot be retrieved using iMAR for periprosthetic bone materials, eventually leading to a WEPL deviation of −3.6 mm. The use of iMAR improved large discrepancies in DVHs of PTVs and the gamma index between FBP and GT images but increased the difference in the bladder DVH for bilateral hip prostheses due to newly introduced artifacts. In the patient study, the discrepancies of dose distribution were small on iMAR images when compared with FBP images for most cases, except for two sarcoma cases where gamma analysis failed and dose coverage in 98% of the PTV maximally reduced due to large volume of dark metal artifacts. iMAR reduced the metal artifacts and improved dose distribution accuracy in carbon ion radiotherapy for pelvic cancer. However, the residual and newly introduced artifacts, especially with bilateral hip prostheses, may potentially increase WEPL inaccuracy and dose uncertainty. The use of iMAR has the potential to improve carbon ion treatment planning of pelvic cancer but should be used with caution. [ABSTRACT FROM AUTHOR]

Featured Application: Tunable bioactive and bioresorbable metal implants. Magnesium and its alloys are not normally used as bioresorbable temporary implants due to their high and uncontrolled degradation rate in a physiological liquid environment. The improvement of corrosion resistance to simulated body fluids (SBF) of a magnesium alloy (AZ31) coated with poly-β-hydroxybutyrate (PHB) was investigated. Scanning electron microscopy, Fourier transform infrared spectrometer, and contact angle measurements were used to characterize surface morphology, material composition, and wettability, respectively. pH modification of the SBF corroding medium, mass of Mg2+ ions released, weight loss of the samples exposed to the SBF solution, and electrochemical experiments were used to describe the corrosion process and its kinetics. The material's biocompatibility was described by evaluating the effect of corrosion by products collected in the SBF equilibrating solution on hemolysis ratio, cytotoxicity, nitric oxide (NO), and total antioxidant capacity (T-AOC). The results showed that the PHB coating can diffusively control the degradation rate of magnesium alloy, improving its biocompatibility: the hemolysis rate of materials was lower than 5%, while in vitro human umbilical vein endothelial cell (HUVEC) compatibility experiments showed that PHB-coated Mg alloy promoted cell proliferation and had no effect on the NO content and that the T-AOC was enhanced compared with the normal group and bare AZ31 alloy. PHB-coated AZ31 magnesium alloy extraction fluids have a less toxic behavior due to the lower concentration of corrosion byproducts deriving from the diffusion control exerted by the PHB coating films both from the metal surface to the solution and vice versa. These findings provide more reference value for the selection of such systems as tunable bioresorbable prosthetic materials. [ABSTRACT FROM AUTHOR]

Featured Application: The problem caused by distal part disengagement is solved by implementing clamping through the yoke in the contact areas between the implant and the bone. Osteogenesis Imperfecta (IO) is a bone disease mainly characterized by the low bone density that produces common fractures in children around 0–7 years. The use of metal implants is a typical treatment of this disease. The intramedullary telescopic nail (ITN) was inspired by the progressive growth in the long bones such as the femur or humerus during children's aging. This work shows an experimental assessment of the ITN's, focusing on their fixation; the proposed improvements in the design of the intramedullary nail studied include the separation of the element into two parts for telescopic enlargement, minimal invasive fixation through the distal anchorage, and the double auto-drilled end for fixation on the distal and proximal section of the bone. The samples were manufactured in 316 L steel and mounted on specialized jaws to replicate the implants' boundary conditions. The experimental test was repeated three times to report the intramedullary telescopic nail's behavior at three lengths. The results show that the device supports only 79.06 N when not at extension length. However, if the device is extended 150% it will support 46.87 N which suggests that intramedullary telescopic nails can only increase by 25% of their original length before they fail. [ABSTRACT FROM AUTHOR]

BACKGROUND: Three-dimensional (3D) printing technology has been applied to fabricate the personalized metallic biomaterials with low elastic modulus, low cost and precision, aiming at overcoming the defects of the biomaterials fabricated by the traditional technology. OJECTIVE: To summarize the development of metallic biomaterials fabricated by the 3D printing technology. METHODS: The articles were searched by using the databases of PubMed and CNKI. The key words were “metallic biomaterials, metallic 3D printing technology, surgical implants, oral application and cardiovascular devices” in Chinese and in English. As a result, 92 articles were applied after reading and analyzing the title and abstract of the articles published between June 2010 and June 2020. RESULTS AND CONCLUSION: In biomedical applications, metallic 3D printing technology can be divided into two categories: powder bed selective melting and directional energy deposition. Metallic 3D printing enables mass production of metal implants with complex geometric shapes and internal structures, as well as customized medical implant production that meets the needs of specific patients. Faced with many metallic printing technologies, it is necessary to choose a suitable additive manufacturing process according to the complexity and different design of materials. At present, 3D printing of metallic biomaterials such as titanium and cobalt-chromium alloys has made substantial progress, and has been used in clinical orthopedics, dentistry and vascular surgery. Research on 3D printing metal biomaterials based on magnesium and iron is still carried on. [ABSTRACT FROM AUTHOR]

In this study, a new nanoscale U-shaped tunnel field-effect transistor (US TFET) structure is proposed. In order to start the design process, the drain region of the conventional US TFET is divided into two distinct parts with N+ and N- doping which is named the drain doping engineering (DDE). It is considered that the tunneling barrier at the channel-drain junction is increased and consequently the ambipolar current is decreased considerably. To continue the design process, the dual work function (DW) in the DDE-US TFET has been used to ameliorate the DC characteristics and the cutoff frequency. Moreover, we have used the metal implant (MI) in the source-side oxide of DDE-DW-US TFET as a technique to improve the device for high-frequency and low-power applications. The 2-D TCAD simulation results not only indicate the superiority of the proposed structure (DDE-DW-MI-US TFET) compared to others in terms of the highfrequency performance, but also illustrate the improvement of the DC parameters. Finally, the proposed device has been investigated by increasing the length of implanted metal in the source-side oxide. It is found that selecting the appropriate length contributes significantly to improve high-frequency performance. [ABSTRACT FROM AUTHOR]

In dental cone-beam computed tomography (CBCT), the image quality often degrades when patients have metallic objects such as metal implants and/or metal prostheses. Metal artifacts typically appear as streaks and shadows in the reconstructed CT images, limiting their clinical usefulness. Although various metal artifact reduction (MAR) methods are used in dental CBCT, no algorithm that can robustly remove metal artifacts has been universally accepted. Recent research has explored the potential benefits of using of a photon-counting detector (PCD) to advance enhanced MAR. PCD can classify x-ray photons into several different energy bins, allowing for more precise measurements of x-ray attenuation. Therefore, in this study, we propose a new MAR method based on the use of a PCD, named the high-energy trace normalized-MAR (HT-NMAR) algorithm, to ensure improved image quality. The proposed MAR algorithm consists of three main steps: 1) Segmentation of the metal trace using a high-energy binned sinogram, 2) Generation of a residual artifact-reduced prior, 3) Sinogram completion with the segmented metal trace and the prior, followed by CBCT reconstruction. We conducted a simulation on a numerical head phantom with metal inserts using a PCD simulation toolkit to demonstrate its efficacy. Our simulation study indicates that the proposed MAR method considerably reduces metal artifacts in CBCT and shows a better image performance than other existing MAR methods in reducing streak artifacts without any contrast anomaly. • High-energy trace normalized-MAR (HT-NMAR), a new MAR method based on the use of a PCD, is proposed. • Dental CBCT's image quality degrades with metallic objects, hindering clinical usefulness. • The proposed high-energy trace normalized-MAR (HT-NMAR) algorithm uses PCD for improved image quality. • Simulation study shows the proposed MAR method considerably reduces metal artifacts and outperforms other methods. [ABSTRACT FROM AUTHOR]

Computed Tomography (CT) is essential for precise medical diagnostics, yet metal implants often induce disruptive image artifacts. Metal Artifact Reduction (MAR) algorithms have emerged to enhance CT image quality by mitigating these artifacts. This review emphasizes the significance of quantifying MAR algorithms, details common quantification metrics, and presents findings from diverse CT scanner studies. MAR techniques effectively reduce metal artifacts and enhance CT imaging. Metrics like noise levels, Contrast-to-Noise ratio (CNR), CT number accuracy, and Metal Artifact Index (MAI) quantify their efficacy. Varied CT scanner experiments with diverse metal implants display improved CT number accuracy, noise reduction, and artifact management through MAR algorithms. However, secondary artifacts and altered metal size accuracy are potential drawbacks that need attention. Deep Learning-based Reconstruction (DLR) is an expanding approach using Artificial Intelligence (AI) for CT image reconstruction. DLR generates low-dose CT images with high spatial resolution. Recent clinical deployments highlight DLR's potential in generating low-noise, texture-rich images, and superior artifact reduction. Moreover, DLR techniques exhibit promise in addressing beam hardening artifacts. While MAR algorithms have revolutionized CT imaging, DLR techniques are emerging as potential alternatives. Current DLR implementations like TrueFidelity and Advanced Intelligent Clear-IQ Engine (AiCE) demonstrate promising outcomes. However, challenges in implementation and machine learning model reliability require further exploration. In conclusion, MAR algorithms enhance CT imaging quality by rectifying artifacts near metal implants, while DLR methods offer a promising path for radiation dose reduction and image refinement. Combining both approaches might pave the way for future CT imaging advancements. • Improvement of image quality and reduction of metal artifacts in CT scans reconstructed with MAR algorithms. • Introduction of new or secondary artifacts in CT scans reconstructed with MAR algorithms. • Underestimation of the implant metal size in CT scans reconstructed with MAR algorithms. • DLR algorithm mitigates the limitations of the MAR algorithms. • Combining both approaches might pave the way for future CT imaging advancements. [ABSTRACT FROM AUTHOR]

This article, titled "Metal Implant Allergy: The Diagnostic Utility of Skin Patch Testing," discusses the adverse reaction of the body's immune system to certain metals used in medical implants. The condition, known as metal implant allergy or metal hypersensitivity, is a growing concern for healthcare practitioners and patients. The article explores the diagnostic process for metal implant allergy, which often involves patch testing. The study conducted by Mark and colleagues at Albany Medical Center evaluated the utility of patch testing in patients with metal implant allergy. The article acknowledges the limitations of the study and suggests that larger prospective studies are needed to further analyze the effectiveness of patch testing in preoperative decision-making. [Extracted from the article]

[Display omitted] • To enhance the mechanical and biological performance of the implant, we integrated equine bone into titanium and 3D printed it using an SLM-based method. • The titanium/equine bone composite can prevent stress shielding when implanted in bone compared to titanium. • Equine bone integration provides superior biological performance of the implant. • Integration of equine bone provides superior biological performance of the implant, which can induce excellent bone regeneration. • Implants containing equine bone suppress unnecessary inflammatory reactions when interacting with bone. Although titanium-based metal implants have become a game changer in dental and orthopedic therapies, they still have several problems such as late osseointegration and immune response. In this study, we present a novel strategy to develop Ti6Al4V-based implants embedded with biogenic hydroxyapatite derived from equine bone to overcome these problems. A selective laser melting technique was employed for facile fabrication with flexible fusing feedstock and regular uniform distribution of equine bone. The physicochemical characteristics, cell attachment and proliferation, osteogenic differentiation, osseointegration, inflammatory response, and metabolomics of the developed Ti6Al4V/equine bone composite were then investigated. The Ti6Al4V-based composite integrated with equine bone at a certain concentration has improved the crystalline structure (β-Ti) suitable for implantation and exhibited higher hydrophilicity and protein adsorption. They significantly promoted cell attachment, osteogenic differentiation, and anti-inflammatory effects in vitro. In vivo study confirmed the osseointegration and alleviated inflammatory responses. Furthermore, the Ti6Al4V-based implants integrated with equine bone significantly reduced metabolites associated with inflammatory responses both in vitro and in vivo. The observed reduction in inflammatory responses suggests a subsequent promotion of osteogenesis. These promising results position the Ti6Al4V-based implant integrated with equine bone as a potential candidate for replacing conventional dental and orthopedic implants. [ABSTRACT FROM AUTHOR]

Metal alloy microstructure plays a crucial role in corrosion associated with total hip replacement (THR). THR is a prominent strategy that uses metal implants such as cobalt-chromium-molybdenum (CoCrMo) alloys due to their advantageous biological and mechanical properties. Despite all benefits, these implants undergo corrosion and wear processes in-vivo in a synergistic manner called tribocorrosion. Also, the implant retrieval findings reported that fretting corrosion occurred in-vivo , evidenced by the damage patterns that appeared on the THR junction interfaces. There is no scientific data on the studies reporting the fretting corrosion patterns of CoCrMo microstructures in the presence of specific biological treatments to date. In the current study, Flat-on-flat fretting corrosion set-up was customized and used to study the tribocorrosion patterns of fretting corrosion to understand the role of alloy microstructure. Alloy microstructural differences were created with the implant stock metal's longitudinal and transverse cutting orientations. As a result, the transverse created the non-banded, homogenous microstructure, whereas the longitudinal cut resulted in the banded, non-homogenous microstructure on the surface of the alloy (in this manuscript, the terms homogenous and banded were used). The induced currents were monitored using a three-electrode system. Three different types of electrolytes were utilized to study the fretting corrosion patterns with both homogeneous and banded microstructures: 1. Control media 2. Spent media (the macrophage cell cultured media) 3. Challenged media (media collected after the macrophage was treated with CoCrMo particles). From the electrochemical results, in the potentiostat conditions, the banded group exhibited a higher induced current in both challenged and spent electrolyte environments than in control due to the synergistic activity of CoCrMo particles and macrophage demonstrating more corrosion loss. Additionally, both Bode and Nyquist plots reported a clear difference between the banded and homogeneous microstructure, especially with challenged electrolytes becoming more corrosion-resistant post-fretting than pre-fretting results. The banded microstructure showed a unique shape of the fretting loop, which may be due to tribochemical reactions. Therefore, from the electrochemical, mechanical, and surface analysis data results, the transverse/homogenous/non-banded alloy microstructure groups show a higher resistance to fretting-corrosion damage. [ABSTRACT FROM AUTHOR]

Metal implants are widely used in orthopedics and can improve the quality of life of injured and diseased patients. However, many metal implants activate the local host immune system and cause a persistent inflammatory response, which accounts for a proportion of hospital-acquired infections. In this review article, we focus on three commonly used alloys materials for implantation, following the development of alloy implant from stainless steel to cobalt-chromium to titanium alloys. Also, we summarize their clinical uses and their associated inflammatory responses and induced immune cell responses including T cells, B cells, macrophage, granulocyte, and natural killer cells. Finally, we discuss the use of new 3-dimensional printing technology for structural modification and coating with antibacterial agents to reduce alloy implantation-induced infection. A better understanding of the induced immune responses provides further information for clinicians and patients to consider the use of metal for surgery with alloy implantation. More importantly, the prediction of the possible inflammatory outcome after implantation can help us to redesign and modify the existing alloy materials for implantation to minimize the inflammation. [ABSTRACT FROM AUTHOR]

Computed tomography angiography (CTA) is one of the most important diagnosis techniques for various vascular diseases in clinic. However, metallic artifacts caused by metal implants and calcified plaques in more and more patients severely hinder its wide applications. Herein, we propose an improved metallic artifacts-free spectral CTA technique based on renal clearable bismuth chelate (Bi-DTPA dimeglumine) for the first time. Bi-DTPA dimeglumine owns the merits of ultra-simple synthetic process, approximately 100% of yield, large-scale production capability, good biocompatibility, and favorable renal clearable ability. More importantly, Bi-DTPA dimeglumine shows superior contrast-enhanced effect in CTA compared with clinical iohexol at a wide range of X-ray energies especially in higher X-ray energy. In rabbits' model with metallic transplants, Bi-DTPA dimeglumine assisted-spectral CTA can not only effectively mitigate metallic artifacts by reducing beam hardening effect under high X-ray energy, but also enables accurate delineation of vascular structure. Our proposed strategy opens a revolutionary way to solve the bottleneck problem of metallic artifacts in CTA examinations. [Display omitted] [ABSTRACT FROM AUTHOR]

It is widely recognized that innate macrophage immune reactions to implant debris are central to the inflammatory responses that drive biologic implant failure over the long term. Less common, adaptive lymphocyte immune reactions to implant debris, such as delayed type hypersensitivity (DTH), can also affect implant performance. It is unknown which key patient factors, if any, mediate these adaptive immune responses that potentiate particle/macrophage mediated osteolysis. The objective of this investigation was to determine to what degree known adaptive immune responses to metal implant debris can affect particle-induced osteolysis (PIO); and if this pathomechanism is dependent on: 1) innate immune danger signaling, i.e., NLRP3 inflammasome activity, 2) sex, and/or 3) age. We used an established murine calvaria model of PIO using male and female wild-type C57BL/6 vs. Caspase-1 deficient mice as well as young (12–16 weeks old) vs. aged (18–24 months old) female and male C57BL/6 mice. After induction of metal-DTH, and Cobalt-alloy particle (ASTM F-75, 0.4um median diameter) calvaria challenge, bone resorption was assessed using quantitative micro-computed tomography (micro-CT) analysis and immune responses were assessed by measuring paw inflammation, lymphocyte transformation test (LTT) reactivity and adaptive immune cytokines IFN-gamma and IL-17 (ELISA). Younger aged C57BL/6 female mice exhibited the highest rate and severity of metal sensitivity lymphocyte responses that also translated into higher PIO compared to any other experimental group. The absence of inflammasome/caspase-1 activity significantly suppressed DTH metal-reactivity and osteolysis in both male and female Caspase-1 deficient mice. These murine model results indicate that young female mice are more predisposed to metal-DTH augmented inflammatory responses to wear debris, which is highly influenced by active NLRP3 inflammasome/caspase-1 danger signaling. If these results are clinically meaningful for orthopedic patients, then younger female individuals should be appropriately assessed and followed for DTH derived peri-implant complications. [ABSTRACT FROM AUTHOR]

In x-ray CT imaging, the existence of metal in the imaging field of view deteriorates the quality of the reconstructed image. This is because rays penetrating dense metal implants are highly corrupted, causing huge inconsistency between projection data. The result appears as strong artifacts such as black and white streaks on the reconstructed image disturbing correct diagnosis. For several decades, there have been various trials to reduce metal artifacts for better image quality. As the computing power of computer processors became more powerful, more complex algorithms with improved performance have been introduced. For instance, the initially developed metal artifact reduction (MAR) algorithms based on simple sinogram interpolation were combined with computationally expensive iterative reconstruction techniques to pursue better image quality. Recently, even machine learning based techniques have been introduced, which require huge amounts of computations for training. In this paper, we introduce an image based novel MAR algorithm in which severe metal artifacts such as black shadings are detected by the proposed method in a straightforward manner based on a linear interpolation. To do that, a new concept of metal artifact classification is devised using linear interpolation in the virtual projection domain. The proposed method reduces severe artifacts very quickly and effectively and has good performance to keep the detailed body structure preserved. Results of qualitative and quantitative comparisons with other representative algorithms such as LIMAR and NMAR support the excellence of the proposed algorithm. Thanks to the nature of reducing artifacts in the image itself and its low computational cost, the proposed algorithm can function as an initial image generator for other MAR algorithms, as well as being integrated in the modalities under limited computation power such as mobile CT scanners. [ABSTRACT FROM AUTHOR]

Aim Of the Study: Some cancerous patients have hip prosthesis of metal elements when they undergo radiation therapy. Metal implants are a cause of metal artifacts in computed tomography (CT) images due to their higher density compared to normal tissues. The aim of this study is to evaluate the quantitative effects of metal artifacts on dose distribution of the pelvic region.Materials and Methods: Seven patients with metal implants in the pelvic region were scanned and CT images were exported to the Monaco treatment planning system. Based on the diagnosis of each patient, three-dimensional plans were implemented on CT images and dose distributions were extracted. At the next step, metal artifacts were contoured and electron densities of these new structures were modified to the extent of soft tissue. Finally, dose distributions and the differences were investigated by VeriSoft software.Results: The results of this study showed that if the electron density to metal artifacts is not assigned properly, it will increase the calculated monitor units (MUs) by almost 3.78 MUs/fraction which will significantly affect total dose distribution of treatment.Conclusion: For the precise implementation of the treatment and in order to minimize the systematic errors related to the calculated MUs, necessary corrections on the electron density of metal artifacts should be considered before the treatment planning. The issue will be more critical in advanced treatment modalities where dose escalation is needed. [ABSTRACT FROM AUTHOR]

Additive manufacturing has facilitated the fabrication of orthopedic metal implants with interconnected pores. Recent reports have indicated that a pore size of 600 μm is beneficial for material-induced osteogenesis. However, the complete removal of the metal powder from such small pores of implants is extremely difficult especially in electron beam melting (EBM). We therefore developed a new type of Ti-6Al-4V implant with lattice-shaped interconnected pores measuring 880–1400 μm, which allowed for the easy removal of metal powder. This implant was fabricated by EBM and treated with NaOH, CaCl2, heat, and water (ACaHW treatment) to render the metal surface bioactivity. In the present study, the mechanical and chemical property of the implants and the biocompatibility were evaluated. The SEM and micro-CT images demonstrated the 3D interconnectivity of the porous structures. The average porosity of the porous titanium implant was 57.5%. The implant showed maximum compressive load of 78.9 MPa and Young's modulus of 3.57 GPa which matches that of human cortical bone. ACaHW treatment of the porous Ti-6Al-4V implants induced apatite formation in simulated body fluid in vitro. The ACaHW-treated porous implants harvested from rabbit femoral bone showed direct bonding of bone to the metal surface without interposition of fibrous tissue. The porous ACaHW-treated implant had a higher affinity to the bone than the untreated one. The mechanical strength of implant fixation assessed using the push-out test was significantly higher in the ACaHW-treated implant than in untreated one. FE-SEM analysis and EDX mapping after push-out test of solid implants showed a lot of bone tissue patches on the surface of the ACaHW-treated implant. These results suggest that the new ACaHW-treated Ti-6Al-4V implant with lattice-shaped interconnected pores is a superior alternative to conventional materials for medical application. [ABSTRACT FROM AUTHOR]

Purpose: To develop a rapid and accurate MRI phase‐unwrapping technique for challenging phase topographies encountered at high magnetic fields, around metal implants, or postoperative cavities, which is sufficiently fast to be applied to large‐group studies including Quantitative Susceptibility Mapping and functional MRI (with phase‐based distortion correction). Methods: The proposed path‐following phase‐unwrapping algorithm, ROMEO, estimates the coherence of the signal both in space—using MRI magnitude and phase information—and over time, assuming approximately linear temporal phase evolution. This information is combined to form a quality map that guides the unwrapping along a 3D path through the object using a computationally efficient minimum spanning tree algorithm. ROMEO was tested against the two most commonly used exact phase‐unwrapping methods, PRELUDE and BEST PATH, in simulated topographies and at several field strengths: in 3T and 7T in vivo human head images and 9.4T ex vivo rat head images. Results: ROMEO was more reliable than PRELUDE and BEST PATH, yielding unwrapping results with excellent temporal stability for multi‐echo or multi‐time‐point data. It does not require image masking and delivers results within seconds, even in large, highly wrapped multi‐echo data sets (eg, 9 seconds for a 7T head data set with 31 echoes and a 208 × 208 × 96 matrix size). Conclusion: Overall, ROMEO was both faster and more accurate than PRELUDE and BEST PATH, delivering exact results within seconds, which is well below typical image acquisition times, enabling potential on‐console application. [ABSTRACT FROM AUTHOR]

Brain imaging technology is an important means to study brain diseases. The commonly used brain imaging technologies are fMRI and EEG. Clinical practice has shown that although fMRI is superior to EEG in observing the anatomical details of some diseases that are difficult to diagnose, its costs are prohibitive. In particular, more and more patients who use metal implants cannot use this technology. In contrast, EEG technology is easier to implement. Therefore, to break through the limitations of fMRI technology, we propose a brain imaging modality transfer framework, namely BMT-GAN, based on a generative adversarial network. The framework introduces a new non-adversarial loss to reduce the perception and style difference between input and output images. It also realizes the conversion from EEG modality data to fMRI modality data and provides comprehensive reference information of EEG and fMRI for radiologists. Finally, a qualitative and quantitative comparison with the existing GAN-based brain imaging modality transfer approaches demonstrates the superiority of our framework. [ABSTRACT FROM AUTHOR]

To meet the personalized demands of different bone tissues in regard of the mechanical properties of titanium alloy implants and solve the problem of stress shielding, this paper studies TC4 and thereby proposes a design method of porous titanium alloy based on meta-structure for additive manufacturing. In this paper, the construction method of the meta-structure is illustrated, and the relationship model between the meta-structure and the key mechanical properties of metal implants is established. This paper determines certain relevant parameters in the model through simulation method, verifies the correctness of the model through additive manufacturing experiment, and proposes two construction methods of porous titanium alloy based on meta-structure, thus providing a systematic and quantitative solution for the design of porous structure of titanium alloy for implants. [ABSTRACT FROM AUTHOR]

Purpose: The presence of metal implants may reduce angiographic image quality due to automated beam adjustments. Digital variance angiography (DVA) is reported to be superior to digital subtraction angiography (DSA) with increased contrast-to-noise ratio (CNR) and better image quality. The aim of the study was to evaluate whether DVA could counterbalance the image quality impairment of lower-limb angiographies with metal implants. Materials and Methods: From November 2019 to January 2020, 85 raw lower-limb iodine contrast angiograms of 12 patients with metal implants were processed retrospectively with DVA analyses. For objective comparison, CNR of DSA and DVA images was calculated and the ratio CNRDVA/CNRDSA was determined. Visual image quality was evaluated in a paired comparison and by a five-grade Likert scale by three experienced radiologists. Results: The CNR was calculated and compared in 1252 regions of interest in 37 image pairs containing metal implants. The median ratio of CNRDVA/CNRDSA was 1.84 with an interquartile range of 1.35–2.32. Paired comparison resulted in 84.5% in favour of DVA with an interrater agreement of 83.2% (Fleiss κ 0.454, p < 0.001). The overall image quality scores for DSA and DVA were 3.64 ± 0.08 and 4.43 ± 0.06, respectively (p < 0.001, Wilcoxon signed-rank test) with consistently higher individual ratings for DVA. Conclusion: Our small-sample pilot study shows that DVA provides significantly improved image quality in lower-limb angiography with metal implants, compared to DSA imaging. The improved CNR suggest that this approach could reduce radiation exposure for lower-limb angiography with metal implants. Level of Evidence: Level 4, case studies [ABSTRACT FROM AUTHOR]

The presence of artificial implants complicates the delivery of proton therapy due to inaccurate characterization of both the implant and the surrounding tissues. In this work, we describe a method to characterize implant and human tissue mimicking materials in terms of relative stopping power (RSP) using a novel proton counting detector. Each proton is tracked by directly measuring the deposited energy along the proton track using a fast, pixelated spectral detector AdvaPIX-TPX3 (TPX3). We considered three scenarios to characterize the RSPs. First, in-air measurements were made in the presence of metal rods (Al, Ti and CoCr) and bone. Then, measurements of energy perturbations in the presence of metal implants and bone in an anthropomorphic phantom were performed. Finally, sampling of cumulative stopping power (CSP) of the phantom were made at different locations of the anthropomorphic phantom. CSP and RSP information were extracted from energy spectra at each beam path. To quantify the RSP of metal rods we used the shift in the most probable energy (MPE) of CSP from the reference CSP without a rod. Overall, the RSPs were determined as 1.48, 2.06, 3.08, and 5.53 from in-air measurements; 1.44, 1.97, 2.98, and 5.44 from in-phantom measurements, for bone, Al, Ti and CoCr, respectively. Additionally, we sampled CSP for multiple paths of the anthropomorphic phantom ranging from 18.63 to 25.23 cm deriving RSP of soft tissues and bones in agreement within 1.6% of TOPAS simulations. Using minimum error of these multiple CSP, optimal mass densities were derived for soft tissue and bone and they are within 1% of vendor-provided nominal densities. The preliminary data obtained indicates the proposed novel method can be used for the validation of material and density maps, required by proton Monte Carlo Dose calculation, provided by competing multi-energy computed tomography and metal artifact reduction techniques. [ABSTRACT FROM AUTHOR]

Background: SPECT-CT using radiolabeled phosphonates is considered a standard for assessing bone metabolism (e.g., in patients with osteoarthritis of knee joints). However, SPECT can be influenced by metal artifacts in CT caused by endoprostheses affecting attenuation correction. The current study examined the effects of metal artifacts in CT of a specific endoprosthesis design on quantitative hybrid SPECT-CT imaging. The implant was positioned inside a phantom homogenously filled with activity (955 MBq 99mTc). CT imaging was performed for different X-ray tube currents (I = 10, 40, 125 mA) and table pitches (p = 0.562 and 1.375). X-ray tube voltage (U = 120 kVp) and primary collimation (16 × 0.625 mm) were kept constant for all scans. The CT reconstruction was performed with five different reconstruction kernels (slice thickness, 1.25 mm and 3.75 mm, each 512 × 512 matrix). Effects from metal artifacts were analyzed for different CT scans and reconstruction protocols. ROI analysis of CT and SPECT data was performed for two slice positions/volumes representing the typical locations for target structures relative to the prosthesis (e.g., femur and tibia). A reference region (homogenous activity concentration without influence from metal artifacts) was analyzed for comparison. Results: Significant effects caused by CT metal artifacts on attenuation-corrected SPECT were observed for the different slice positions, reconstructed slice thicknesses of CT data, and pitch and CT-reconstruction kernels used (all, p < 0.0001). Based on the optimization, a set of three protocols was identified minimizing the effect of CT metal artifacts on SPECT data. Regarding the reference region, the activity concentration in the anatomically correlated volume was underestimated by 8.9–10.1%. A slight inhomogeneity of the reconstructed activity concentration was detected inside the regions with a median up to 0.81% (p < 0.0001). Using an X-ray tube current of 40 mA showed the best result, balancing quantification and CT exposure. Conclusion: The results of this study demonstrate the need for the evaluation of SPECT-CT protocols in prosthesis imaging. Phantom experiments demonstrated the possibility for quantitative SPECT-CT of bone turnover in a specific prosthesis design. Meanwhile, a systematic bias caused by metal implants on quantitative SPECT data has to be considered. [ABSTRACT FROM AUTHOR]

As two different modalities of medical images, Magnetic Resonance (MR) and Computer Tomography (CT), provide mutually-complementary information to doctors in clinical applications. However, to obtain both images sometimes is cost-consuming and unavailable, particularly for special populations. For example, patients with metal implants are not suitable for MR scanning. Also, it is probably infeasible to acquire multi-contrast MR images during once clinical scanning. In this context, to synthesize needed MR images for patients whose CT images are available becomes valuable. To this end, we present a novel generative network, called CAE-ACGAN, which incorporates the advantages of Variational Auto-Encoder (VAE) and Generative Adversarial Network (GAN) with an auxiliary discriminative classifier network. We apply this network to synthesize multi-contrast MR images from single CT and conduct experiments on brain datasets. Our main contributions can be summarized as follows: 1)We alleviate the problems of images blurriness and mode collapse by integrating the advantages of VAE and GAN; 2) We solve the complicated cross-domain, multi-contrast MR synthesis task using the proposed network; 3) The technique of random-extraction-patches is used to lower the limit of insufficient training data, enabling to obtain promising results even with limited available data; 4) By comparing with other typical networks, we are able to yield nearer-real, higher-quality synthetic MR images, demonstrating the effectiveness and stability of our proposed network. [ABSTRACT FROM AUTHOR]

Photopharmacology, which uses chemical photoswitches for the optical manipulation of biological process, holds immense potential for neuroscience and clinical medicine due to its high specificity, fast response, and versatility. However, enabling photopharmacology in living subjects has been an arduous undertaking mainly because of limitations of the available tools. Conventional approaches to drug delivery and photostimulation involve the use of bulky, rigid, and tethered implants in the form of metal cannulas and optical fibers. These prevent highly precise, spatially matching stimulation with drugs and light, aggravates adverse tissue responses, and causes undue stress in the freely‐moving subject. Recent advances in materials science and device engineering have led to the development of miniaturized, standalone multimodal implants referred to as "optofluidic" devices, which allow wireless delivery of both light and drugs. Herein, we review state‐of‐the‐art wireless optofluidic systems, which can open up new horizons for in vivo photopharmacology, and discuss future directions for further technology developments. [ABSTRACT FROM AUTHOR]

Background: Cone-beam computed tomography (CBCT) has become an increasingly important medical imaging modality in orthopedic operating rooms. Metal implants and related image artifacts create challenges for image quality optimization in CBCT. The purpose of this study was to develop a robust and quantitative method for the comprehensive determination of metal artifacts in novel CBCT applications. Methods: The image quality of an O-arm CBCT device was assessed with an anthropomorphic pelvis phantom in the presence of metal implants. Three different kilovoltage and two different exposure settings were used to scan the phantom both with and without the presence of metal rods. Results: The amount of metal artifact was related to the applied CBCT imaging protocol parameters. The size of the artifact was moderate with all imaging settings. The highest applied kilovoltage and exposure level distinctly increased artifact severity. Conclusions: The developed method offers a practical and robust way to quantify metal artifacts in CBCT. Changes in imaging parameters may have nonlinear effects on image quality which are not anticipated based on physics. [ABSTRACT FROM AUTHOR]

The many types of material currently used to treat bone injuries (caused by various reasons) have undergone changes over time. From the initial metal implants of stainless steel or titanium to those made of ceramics and polymers (which are now widely used), each material has its own advantages, disadvantages, and suitable uses. Artificial bone material needs to be selected according to the different stress conditions of the body part in which it will be used, and the characteristics of the different materials need to be studied before a reasonable selection of the material can be made. This article reviews the artificial bone materials that have been studied so far, including metals, inorganic nonmetallic materials, polymers, and composites. Their advantages, disadvantages, and development status undergo comprehensive analysis, and the basis for future material selection is provided. An examination of publications shows that the future trend in developing bone materials for treating bone defects is to combine the above-mentioned materials with growth factors and bioactive proteins. This article may be helpful for choosing the right materials. [ABSTRACT FROM AUTHOR]

Magnetic hyperthermia therapy (MHT) is able to ablate tumors using an alternating magnetic field (AMF) to heat up magnetocaloric agents (e.g. magnetic nanoparticles) administered into the tumors. For clinical applications, there is still a demand to find new magnetocaloric agents with strong AMF-induced heating performance and excellent biocompatibility. As a kind of biocompatible and biodegradable material, magnesium (Mg) and its alloys have been extensively used in the clinic as an implant metal. Herein, we discovered that the eddy thermal effect of the magnesium alloy (MgA) could be employed for MHT to effectively ablate tumors. Under low-field-intensity AMFs, MgA rods could be rapidly heated, resulting in a temperature increase in nearby tissues. Such AMF-induced eddy thermal heating of MgA could not only be used to kill tumor cells in vitro , but also be employed for effective and accurate ablation of tumors in vivo. In addition to killing tumors in mice, we further demonstrated that VX2 tumors of much larger sizes growing in rabbits after implantation of MgA rods could also be eliminated after exposure to an AMF, illustrating the ability of MgA-based MHT to kill large-sized tumors. Moreover, the implanted MgA rods showed excellent biocompatibility and ∼20% of their mass was degraded within three months. Our work thus discovered for the first time that non-magnetic biodegradable MgA, an extensively used implant metal in clinic, could be used for effective magnetic thermal ablation of tumors under a low-field-intensity AMF. Such a strategy could be readily translated into clinical use. [ABSTRACT FROM AUTHOR]

Objective: To evaluate a new adaptive iterative metal artifact reduction algorithm (AiMAR) in whole-body low-dose CT (WBLDCT) skeletal survey examinations. Methods: Projection data were retrospectively obtained from 25 clinical WBLDCT skeletal survey patients, each with two types of metal implants. Images were reconstructed with bone and soft tissue kernels using four settings—original and AiMAR with strengths of 2, 4, and 5. All images were anonymized and randomized for a reader study, where three musculoskeletal radiologists independently determined the overall ranking of all series based on diagnostic quality, and local scoring of metal artifact and anatomy visualization for each implant. Quantitative image noise analysis was performed in areas close to the implants. Intraclass correlation coefficients (ICC) and Krippendorff's alpha were computed for inter-rater reliability. Results: AiMAR 4 was ranked the highest for 64.3% of the series across eight types of implants. For local scoring task, AiMAR 4 showed better metal artifact and anatomy visualization than the original and AiMAR 2. AiMAR 4 was comparable in anatomy visualization but inferior to AiMAR 5 in metal artifact scores. AiMAR 4 led to 56.3% noise reduction around the implant areas compared with the original images, and AiMAR 5 68.1% but also resulted in anatomy blurring in 40% of the implants. ICC and Krippendorff's alpha revealed at least substantial reliability in the local scores among the readers. Conclusions: AiMAR was evaluated in WBLDCT skeletal surveys. AiMAR 4 demonstrated the highest overall quality ranking and improved local scores with noise reduction around implant areas. [ABSTRACT FROM AUTHOR]

The dynamics of changes in the crystal structure and in the elemental and chemical composition of Si surface layers implanted with Na+, Rb+, and Cs+ ions in the process of stepwise annealing under different temperature conditions has been studied. It is shown that, on the surface implanted with Na+ ions, a NaSi2 film is formed after annealing it at a temperature of T = 900 K, a single-layer NaSi2 coating is formed at T = 1000 K and the surface and near-surface Si layers are completely cleansed of the atoms of the alloying element, oxygen, and carbon at T = 1100 K. [ABSTRACT FROM AUTHOR]

In this paper, we introduce three new structures of a cylindrical gate-all-around nanowire (NW) field-effect transistor (FET) to achieve negative differential resistance (NDR) and negative transconductance (NTC) behaviors. In the first structure, only one metal is implanted in the channel near the drain of the dual-material cylindrical gate-all-around NWFET based on the energy band profile modulation to obtain the NDR behavior. To achieve NTC behavior, another metal is implanted in the channel near the source; therefore, the second structure has both the NDR and NTC behaviors. In the final structure, the use of a triple-metal gate is proposed to improve the peak-to-valley current ratio. The NTC behavior occurs when the increase in VGS creates a positive lateral electric field in the channel, which causes the potential barrier tunneling (PBT) to decrease. The cause of the positive electric field formation is the cavity in the channel's potential barrier due to implanted metals. Furthermore, by increasing VDS, the high electron scattering caused by the high electric field at the beginning of the drain region is increased and causes the electron drift velocity and IDS to decrease. Consequently, the NDR behavior is achieved. The structures are carefully simulated using numerical simulation based on non-local tunneling, and also the transfer characteristics (IDS − VGS) and the output characteristics (IDS − VDS) are attentively analyzed and examined. [ABSTRACT FROM AUTHOR]

Periprosthetic joint infection of total knee arthroplasties represents a major challenge to the field of orthopedic surgery. These infections are commonly associated with antibiotic‐tolerant Staphylococcus aureus biofilms. Engineered cationic amphipathic peptide WLBU2 has shown the ability to kill antibiotic‐resistant pathogens and drug‐tolerant bacterial biofilms. The novelty of using WLBU2 during the direct irrigation and debridement of periprosthetic joint infections led our group to investigate the optimal washout conditions for treatment of S. aureus biofilms. S. aureus mature biofilms were grown on metal implant material and treated with WLBU2 dissolved in differing irrigation solvents. Mature biofilms were treated both in vitro as well as in a periprosthetic joint infection murine model. WLBU2 activity against S. aureus biofilms was increased when dissolved in diphosphate‐buffered saline (dPBS) with pH of 7.0 compared with normal saline with pH of 5.5. WLBU2 activity was decreased in acidic dPBS and increased in alkaline dPBS. WLBU2 activity could be decreased in hypertonic dPBS and increased in hypotonic dPBS. WLBU2 dissolved in less acidic dPBS displayed increased efficacy in treating periprosthetic joint infection (PJI) implants ex vivo. WLBU2 demonstrated the ability to eliminate PJI associated S. aureus biofilms on arthroplasty material. The efficacy of engineered cationic amphipathic peptide WLBU2 for intraoperative elimination of S. aureus biofilms can be further optimized when kept in a less acidic and more physiologic pH adjusted saline. Understanding optimal physical washout conditions are vital for the success of WLBU2 in treating S. aureus biofilms in PJI clinical trials going forward. [ABSTRACT FROM AUTHOR]

Metal artifacts commonly appear in computed tomography (CT) images of the patient body with metal implants and can affect disease diagnosis. Known deep learning and traditional metal trace restoring methods did not effectively restore details and sinogram consistency information in X-ray CT sinograms, hence often causing considerable secondary artifacts in CT images. In this paper, we propose a new cross-domain metal trace restoring network which promotes sinogram consistency while reducing metal artifacts and recovering tissue details in CT images. Our new approach includes a cross-domain procedure that ensures information exchange between the image domain and the sinogram domain in order to help them promote and complement each other. Under this cross-domain structure, we develop a hierarchical analytic network (HAN) to recover fine details of metal trace, and utilize the perceptual loss to guide HAN to concentrate on the absorption of sinogram consistency information of metal trace. To allow our entire cross-domain network to be trained end-to-end efficiently and reduce the graphic memory usage and time cost, we propose effective and differentiable forward projection (FP) and filtered back-projection (FBP) layers based on FP and FBP algorithms. We use both simulated and clinical datasets in three different clinical scenarios to evaluate our proposed network’s practicality and universality. Both quantitative and qualitative evaluation results show that our new network outperforms state-of-the-art metal artifact reduction methods. In addition, the elapsed time analysis shows that our proposed method meets the clinical time requirement. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) are of great interest because of their ultrahigh activity and selectivity. However, it is difficult to construct model SACs according to a general synthetic method, and therefore, discerning differences in activity of diverse single‐atom catalysts is not straightforward. Herein, a general strategy for synthesis of single‐atom metals implanted in N‐doped carbon (M1‐N‐C; M=Fe, Co, Ni and Cu) has been developed starting from multivariate metal–organic frameworks (MOFs). The M1‐N‐C catalysts, featuring identical chemical environments and supports, provided an ideal platform for differentiating the activity of single‐atom metal species. When employed in electrocatalytic CO2 reduction, Ni1‐N‐C exhibited a very high CO Faradaic efficiency (FE) up to 96.8 % that far surpassed Fe1‐, Co1‐ and Cu1‐N‐C. Remarkably, the best‐performer, Ni1‐N‐C, even demonstrated excellent CO FE at low CO2 pressures, thereby representing a promising opportunity for the direct use of dilute CO2 feedstock. [ABSTRACT FROM AUTHOR]

Infections related to orthopedic procedures are considered particularly severe when implantation materials are used, because effective treatments for biofilm removal are lacking. In this study, the relatively new approach for infection control by using an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser was tested. This laser vaporizes all water containing cells in a very effective, precise, and predictable manner and results in only minimal thermal damage. For preliminary testing, 42 steel plates and 42 pins were seeded with mixed cultures. First, the minimally necessary laser energy for biofilm removal was determined. Subsequently, the effectiveness of biofilm removal with the Er:YAG laser and the cleansing of the metal implants with octenidine‐soaked gauze was compared. Then, we compared the effectiveness of biofilm removal on 207 steel pins from 41 patients directly after explantation. Sonication and scanning electron microscopy were used for analysis. Laser fluences exceeding 2.8 J/cm2 caused a complete extinction of all living cells by a single‐laser impulse. Cleansing with octenidine‐soaked gauze and irradiation with the Er:YAG laser are both thoroughly effective when applied to seeded pins. In contrast, when explanted pins with fully developed biofilms were analyzed, we found a significant advantage of the laser procedure. The Er:YAG laser offers a secure, complete, and nontoxic eradication of all kinds of pathogens from metal implants without damaging the implant and without the possible development of resistance. The precise noncontact removal of adjacent tissue is a decisive advantage over conventional disinfectants. Therefore, laser irradiation could become a valuable method in every debridement, antibiotics, and implant retention procedure. [ABSTRACT FROM AUTHOR]

Purpose: Metal implants in the patient's body can generate severe metal artifacts in x‐ray computed tomography (CT) images. These artifacts may cover the tissues around the metal implants in CT images and even corrupt the tissue regions, thus affecting disease diagnosis using these images. Previous deep learning metal trace inpainting methods used both valid pixels of uncorrupted areas and invalid pixels of corrupted areas to patch metal trace (i.e., the holes of removed metal‐corrupted regions). Such methods cannot recover fine details well and often suffer information mismatch due to interference of invalid pixels, thus incurring considerable secondary artifacts. In this paper, we develop a new irregular metal trace inpainting network for reducing metal artifacts. Methods: We develop a new deep learning network to patch irregular metal trace in metal‐corrupted sinograms to reduce metal artifacts for isometric fan‐beam CT. Our new method patches irregular metal trace in CT sinograms using only valid pixels, avoiding interference from invalid pixels. Furthermore, to enable the inpainting network to recover as many details as possible, we design an auxiliary inpainting network to suppress the probable secondary artifacts in CT images to assist fine detail restoration. The image produced by the auxiliary network is then projected onto a sinogram via a forward projection (FP) algorithm and is fused with the sinogram predicted by the inpainting network in order to predict the final recovered sinogram. Our entire network is trained end‐to‐end to extract cross‐domain information between the sinogram domain and CT image domain. Results: We compare our proposed method with two traditional and four deep learning‐based metal trace inpainting methods, and with an iterative reconstruction method on four datasets: dental fillings (panoramic and local perspectives), hip prostheses, and spine fixations. We use both quantitative and qualitative indices to evaluate our method, and the analyses suggest that our method reduces the most metal artifacts and produces the best quality CT images. Additionally, our proposed method takes 0.1512 s on average to process a CT slice, which meets the clinical requirement. Conclusions: This paper proposes a new deep learning network to patch irregular metal trace in corrupted sinograms to reduce metal artifacts. Our method restores more fine details in irregular metal trace and has a superior capability on metal artifact reduction compared with state‐of‐the‐art methods. [ABSTRACT FROM AUTHOR]

Introduction: The image quality of computed tomography (CT) can be seriously lowered by metal implants of patients. These implants are known to exert a significant impact on diagnostic accuracy due to artifacts. The current study aimed to assess the usefulness of Metal Artifact Reduction (MAR) software in the reduction of metal artifacts, in comparison to iterative reconstruction algorithm (IDREAM). Material and Methods: Water phantom with raw chicken leg underwent CT scan (Sinovision, Insitum 16) before (reference group (GPref) and after metal implantation: ((GPA (IDREAM without MAR) and GPB (IDREAM with MAR)). A total number of 30 patients [GP1 (instrumented spine (n=15)), GP2 (Brain clips (n=15))] underwent CT scan (Sinovision ,Insitum 16). GP1 and GP2 were reconstructed using two procedures including IDREAM without MAR vs. 2: IDREAM with MAR. All images were evaluated using subjective and quantitative assessment. Results: In subjective image quality assessment, the scores of MAR images were higher than IDREAM images (P<0.05) as indicated by four radiologists. The absolute CT difference (CT) and Artifact index (AI) demonstrated that MAR appeared to be superior for the reduction of metal artifacts (P<0.05). Conclusion: As evidenced by the obtained results, MAR software can be efficiently used for metal artifact reduction in computed tomography (instrumental spine and brain clips). [ABSTRACT FROM AUTHOR]