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Ge S, Kumar N, Hallinan JTPD. Pedicle Screw Pseudofracture on Computed Tomography Secondary to Metal Artifact Reduction. Diagnostics (Basel) 2024; 14:108. [PMID: 38201417 PMCID: PMC10795680 DOI: 10.3390/diagnostics14010108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/20/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Metal artifact reduction (MAR) algorithms are commonly used in computed tomography (CT) scans where metal implants are involved. However, MAR algorithms also have the potential to create new artifacts in reconstructed images. We present a case of a screw pseudofracture due to MAR on CT.
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Affiliation(s)
- Shuliang Ge
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
| | - Naresh Kumar
- University Spine Centre, Department of Orthopaedic Surgery, National University Health System, 1E, Lower Kent Ridge Road, Singapore 119228, Singapore
| | - James Thomas Patrick Decourcy Hallinan
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
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2
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Li M, Zeng Y, Nie Y, Liao K, Pei F, Yang J, Xie H, Shen B. A high risk of postoperative periprosthetic femoral fracture in Dorr type C femurs: a retrospective cohort study with 10-year follow-up data and a preliminary monochromatic image analysis. Int J Surg 2024; 110:296-305. [PMID: 37830949 PMCID: PMC10793812 DOI: 10.1097/js9.0000000000000810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 09/18/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND The authors applied Anatomique Benoist Girard II (ABG II) stems for total hip arthroplasty in some Dorr type C femurs as early attempts. Here, the authors compared the long-term follow-up results between ABG II stems and the 'well-performing' Corail stems and their monochromatic images. METHODS Among 3214 primary total hip arthroplasty records, 43 short ABG II stems and 67 standard-length Corail stems implanted in Dorr type C femurs were eligible and enrolled in this retrospective cohort study, with a mean follow-up of 10.3 years. Revision rates, Harris hip scores, and radiologic signs were compared. Spectral CT scans from a representative sample were obtained, and monochromatic images were reconstructed. A quantitative method was developed to measure the volume of the gap around stems. Patient-specific finite element analysis was conducted to investigate the strains. RESULTS The revision rate of ABG II stems was significantly higher than that of Corail stems (21 vs. 3%, P <0.05). In the monochromatic images, fewer spot-weld signs (2.2 vs. 3.4, P <0.05) and wider gaps around stems (1.64 cm 3 vs. 0.13 cm 3 , P <0.05) were observed on average in the ABG II group. The mean maximum principal strains of the proximal femurs in the ABG II group were close to the yield strains and significantly larger than those in the Corail group (0.0052 vs. 0.0011, P <0.05). CONCLUSIONS There was a high risk of postoperative periprosthetic femoral fracture for ABG II stems in Dorr type C femurs. Monochromatic images provided some insight into the failure mechanism. LEVEL OF EVIDENCE III.
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Affiliation(s)
- Mingyang Li
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Yi Zeng
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Yong Nie
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Kai Liao
- Department of Radiology, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China
| | - Fuxing Pei
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Jing Yang
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Huiqi Xie
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
| | - Bin Shen
- Department of Orthopedic Surgery and Orthopedic Research Institute, West China Hospital
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3
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Dual-Energy Computed Tomography Applications to Reduce Metal Artifacts in Hip Prostheses: A Phantom Study. Diagnostics (Basel) 2022; 13:diagnostics13010050. [PMID: 36611342 PMCID: PMC9853491 DOI: 10.3390/diagnostics13010050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
Metal components of hip prostheses cause severe artifacts in CT images, influencing diagnostic accuracy. Metal artifact reduction (MAR) software and virtual monoenergetic reconstructions on dual-energy CT (DECT) systems are possible solutions that should be considered. In this study, we created a customized adjustable phantom to quantify the severity of artifacts on periprosthetic tissues (cortical and spongious bone, soft tissues) for hip prostheses. The severity of artifacts was classified by different thresholds of deviation from the CT numbers for reference objects not affected by artifacts. The in vitro setup was applied on four unilateral and three bilateral configurations of hip prostheses (made of titanium, cobalt, and stainless steel alloys) with a DECT system, changing the energy of virtual monoenergetic reconstructions, with and without MAR. The impact of these tools on the severity of artifacts was scored, looking for the best scan conditions for the different configurations. For titanium prostheses, the reconstruction at 110 keV, without MAR, always minimized the artifacts. For cobalt and stainless-steel prostheses, MAR should always be applied, while monoenergetic reconstruction alone did not show clear advantages. The available tools for reducing metal artifacts must therefore be applied depending on the examined prosthetic configuration.
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Park C, Lee SM, Seo JS, Kim TW, Rhee SJ, Jeong HS. Metal Artifact Reduction Dual-Energy CT as an Accurate and Reliable Method for Measuring Total Knee Arthroplasty Femoral Component Rotation Compared to Conventional CT. J Knee Surg 2022. [PMID: 35820433 DOI: 10.1055/s-0042-1748899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This article determines the accuracy and reliability of dual-energy computed tomography (DECT) with metal artifact reduction (MAR) in the evaluation of femoral component rotation after total knee arthroplasty (TKA), in comparison with conventional CT images. A total of 49 patients (mean age, 69 years; 42 women) who underwent TKA between January 2019 and March 2020 were retrospectively enrolled. Femoral component rotation, including the anatomic and surgical transepicondylar axes, was evaluated with preoperative conventional CT and postoperative conventional CT and DECT with MAR. Surgical femoral component rotation was also assessed as a reference standard. Accuracy was assessed using paired t-test, and inter- and intraobserver reliability using intraclass correlation coefficients (ICCs) based on postoperative conventional CT and DECT with MAR. Clinical outcomes were evaluated using the Knee Society objective and functional scores. Accuracy of femoral component rotation was not significantly different from that of surgical rotation with both conventional CT and DECT with MAR. However, inter- and intraobserver reliability were better for DECT with MAR (ICC: 0.953-0.966) than for conventional CT (ICC: 0.641-0.749). The Knee Society objective and functional scores improved 1 year postoperatively. CONCLUSION: DECT with MAR showed accurate and more reliable results than did conventional CT in the evaluation of femoral component rotation after TKA.
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Affiliation(s)
- Chankue Park
- Department of Radiology, Pusan National University - Yangsan Hospital, Yangsan, Korea.,Research Institute for Convergence of Biomedical Science and Technology, Pusan National University School of Medicine, Yangsan, Korea
| | - Sang-Min Lee
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University School of Medicine, Yangsan, Korea.,Department of Orthopaedic Surgery, Pusan National University - Yangsan Hospital, Yangsan, Korea
| | - Jae Seung Seo
- Department of Orthopaedic Surgery, Pusan National University - Yangsan Hospital, Yangsan, Korea
| | - Tae Woo Kim
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University School of Medicine, Yangsan, Korea.,Department of Orthopaedic Surgery, Pusan National University - Yangsan Hospital, Yangsan, Korea
| | - Seung Joon Rhee
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University School of Medicine, Yangsan, Korea.,Department of Orthopedic Surgery, Pusan National University Hospital, Busan, Korea
| | - Hee Seok Jeong
- Department of Radiology, Pusan National University - Yangsan Hospital, Yangsan, Korea.,Research Institute for Convergence of Biomedical Science and Technology, Pusan National University School of Medicine, Yangsan, Korea
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Kuah T, Vellayappan BA, Makmur A, Nair S, Song J, Tan JH, Kumar N, Quek ST, Hallinan JTPD. State-of-the-Art Imaging Techniques in Metastatic Spinal Cord Compression. Cancers (Basel) 2022; 14:3289. [PMID: 35805059 PMCID: PMC9265325 DOI: 10.3390/cancers14133289] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 12/23/2022] Open
Abstract
Metastatic Spinal Cord Compression (MSCC) is a debilitating complication in oncology patients. This narrative review discusses the strengths and limitations of various imaging modalities in diagnosing MSCC, the role of imaging in stereotactic body radiotherapy (SBRT) for MSCC treatment, and recent advances in deep learning (DL) tools for MSCC diagnosis. PubMed and Google Scholar databases were searched using targeted keywords. Studies were reviewed in consensus among the co-authors for their suitability before inclusion. MRI is the gold standard of imaging to diagnose MSCC with reported sensitivity and specificity of 93% and 97% respectively. CT Myelogram appears to have comparable sensitivity and specificity to contrast-enhanced MRI. Conventional CT has a lower diagnostic accuracy than MRI in MSCC diagnosis, but is helpful in emergent situations with limited access to MRI. Metal artifact reduction techniques for MRI and CT are continually being researched for patients with spinal implants. Imaging is crucial for SBRT treatment planning and three-dimensional positional verification of the treatment isocentre prior to SBRT delivery. Structural and functional MRI may be helpful in post-treatment surveillance. DL tools may improve detection of vertebral metastasis and reduce time to MSCC diagnosis. This enables earlier institution of definitive therapy for better outcomes.
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Affiliation(s)
- Tricia Kuah
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
| | - Balamurugan A. Vellayappan
- Department of Radiation Oncology, National University Cancer Institute Singapore, National University Hospital, Singapore 119074, Singapore;
| | - Andrew Makmur
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
| | - Shalini Nair
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
| | - Junda Song
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
| | - Jiong Hao Tan
- University Spine Centre, Department of Orthopaedic Surgery, National University Health System, 1E Lower Kent Ridge Road, Singapore 119228, Singapore; (J.H.T.); (N.K.)
| | - Naresh Kumar
- University Spine Centre, Department of Orthopaedic Surgery, National University Health System, 1E Lower Kent Ridge Road, Singapore 119228, Singapore; (J.H.T.); (N.K.)
| | - Swee Tian Quek
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
| | - James Thomas Patrick Decourcy Hallinan
- Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore; (A.M.); (S.N.); (J.S.); (S.T.Q.); (J.T.P.D.H.)
- Department of Diagnostic Radiology, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
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Schmidt TG, Sammut BA, Barber RF, Pan X, Sidky EY. Addressing CT metal artifacts using photon-counting detectors and one-step spectral CT image reconstruction. Med Phys 2022; 49:3021-3040. [PMID: 35318699 PMCID: PMC9353719 DOI: 10.1002/mp.15621] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 02/08/2022] [Accepted: 03/06/2022] [Indexed: 01/06/2023] Open
Abstract
PURPOSE The constrained one-step spectral CT image reconstruction (cOSSCIR) algorithm with a nonconvex alternating direction method of multipliers optimizer is proposed for addressing computed tomography (CT) metal artifacts caused by beam hardening, noise, and photon starvation. The quantitative performance of cOSSCIR is investigated through a series of photon-counting CT simulations. METHODS cOSSCIR directly estimates basis material maps from photon-counting data using a physics-based forward model that accounts for beam hardening. The cOSSCIR optimization framework places constraints on the basis maps, which we hypothesize will stabilize the decomposition and reduce streaks caused by noise and photon starvation. Another advantage of cOSSCIR is that the spectral data need not be registered, so that a ray can be used even if some energy window measurements are unavailable. Photon-counting CT acquisitions of a virtual pelvic phantom with low-contrast soft tissue texture and bilateral hip prostheses were simulated. Bone and water basis maps were estimated using the cOSSCIR algorithm and combined to form a virtual monoenergetic image for the evaluation of metal artifacts. The cOSSCIR images were compared to a "two-step" decomposition approach that first estimated basis sinograms using a maximum likelihood algorithm and then reconstructed basis maps using an iterative total variation constrained least-squares optimization (MLE+TVmin $_{\text{min}}$ ). Images were also compared to a nonspectral TVmin $_{\text{min}}$ reconstruction of the total number of counts detected for each ray with and without normalized metal artifact reduction (NMAR) applied. The simulated metal density was increased to investigate the effects of increasing photon starvation. The quantitative error and standard deviation in regions of the phantom were compared across the investigated algorithms. The ability of cOSSCIR to reproduce the soft-tissue texture, while reducing metal artifacts, was quantitatively evaluated. RESULTS Noiseless simulations demonstrated the convergence of the cOSSCIR and MLE+TVmin $_{\text{min}}$ algorithms to the correct basis maps in the presence of beam-hardening effects. When noise was simulated, cOSSCIR demonstrated a quantitative error of -1 HU, compared to 2 HU error for the MLE+TVmin $_{\text{min}}$ algorithm and -154 HU error for the nonspectral TVmin $_{\text{min}}$ +NMAR algorithm. For the cOSSCIR algorithm, the standard deviation in the central iodine region of interest was 20 HU, compared to 299 HU for the MLE+TVmin $_{\text{min}}$ algorithm, 41 HU for the MLE+TVmin $_{\text{min}}$ +Mask algorithm that excluded rays through metal, and 55 HU for the nonspectral TVmin $_{\text{min}}$ +NMAR algorithm. Increasing levels of photon starvation did not impact the bias or standard deviation of the cOSSCIR images. cOSSCIR was able to reproduce the soft-tissue texture when an appropriate regularization constraint value was selected. CONCLUSIONS By directly inverting photon-counting CT data into basis maps using an accurate physics-based forward model and a constrained optimization algorithm, cOSSCIR avoids metal artifacts due to beam hardening, noise, and photon starvation. The cOSSCIR algorithm demonstrated improved stability and accuracy compared to a two-step method of decomposition followed by reconstruction.
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Affiliation(s)
- Taly Gilat Schmidt
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Barbara A Sammut
- Department of Biomedical Engineering, Marquette University and Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | - Xiaochuan Pan
- Department of Radiology, University of Chicago, Chicago, Illinois, USA
| | - Emil Y Sidky
- Department of Radiology, University of Chicago, Chicago, Illinois, USA
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Ong N, Zailan I, Tandon A. Imaging update in arthroplasty. J Clin Orthop Trauma 2021; 23:101649. [PMID: 34777990 PMCID: PMC8577440 DOI: 10.1016/j.jcot.2021.101649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 10/12/2021] [Indexed: 11/20/2022] Open
Abstract
Imaging of metal implants has historically been difficult, regardless of the applied modality. The number of primary arthroplasties is increasing over the years. With it, we expect the number of symptomatic complications to increase as well. Acquiring accurate imaging for diagnosis and treatment planning for these cases is of paramount importance. Significant advancements have been made to reduce artifacts, leading to better imaging representation of arthroplasty. This review article would give a background on the current ways of imaging arthroplasty and metal implants, covering recent advances in imaging techniques.
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Affiliation(s)
| | | | - Ankit Tandon
- Tan Tock Seng Hospital, Singapore
- Corresponding author.
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Barreto I, Pepin E, Davis I, Dean C, Massini T, Rees J, Olguin C, Quails N, Correa N, Rill L, Arreola M. Comparison of metal artifact reduction using single-energy CT and dual-energy CT with various metallic implants in cadavers. Eur J Radiol 2020; 133:109357. [PMID: 33126172 DOI: 10.1016/j.ejrad.2020.109357] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/15/2020] [Accepted: 10/12/2020] [Indexed: 12/27/2022]
Abstract
OBJECTIVES The purpose of this study was to compare the effectiveness of metal artifact reduction using Single Energy Metal Artifact Reduction (SEMAR) and Dual Energy CT (DECT). MATERIALS AND METHODS Six cadavers containing metal implants in the head, neck, abdomen, pelvis, and extremities were scanned with Standard, SEMAR, and DECT protocols on a 320-slice CT scanner. Four specialized radiologists blinded to acquisition methods rated severity of metal artifacts, visualization of anatomic structures, diagnostic interpretation, and image preference with a 5-point grading scale. RESULTS Scores were significantly better for SEMAR than Standard images in the hip, knee, pelvis, abdomen, and maxillofacial scans (3.25 ± 0.88 versus 2.14 ± 0.93, p < 0.001). However, new reconstruction artifacts developed in SEMAR images that were not present in Standard images. Scores for severity of metal artifacts and visualization of smooth structures were significantly better for DECT than Standard images in the cervical spine (3.50±0.50 versus 2.0±0.58, p < 0.001) and was preferred over Standard images by one radiologist. In all other cases, radiologists preferred the Standard image over the DECT image due to increased image noise and reduced low-contrast resolution with DECT. In all cases, SEMAR was preferred over Standard and DECT images. CONCLUSION SEMAR was more effective at reducing metal artifacts than DECT. Radiologists should be aware of new artifacts and review both the original and SEMAR images. When the anatomy or implant is relatively small, DECT may be superior to SEMAR without additional artifacts. However, radiologist should be aware of a reduction in soft tissue contrast.
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Affiliation(s)
- Izabella Barreto
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Eric Pepin
- Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390, United States.
| | - Ivan Davis
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Cooper Dean
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Tara Massini
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - John Rees
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Catherine Olguin
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Nathan Quails
- Department of Radiology, Ohio State University Wexner Medical Center, 395 W 12th Ave 4th Fl, Columbus, OH 43210, United States.
| | - Nathalie Correa
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Lynn Rill
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
| | - Manuel Arreola
- Department of Radiology, College of Medicine, University of Florida, PO Box 100374, Gainesville, FL 32610-0374, United States.
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The Optimal Combination of Monochromatic and Metal Artifact Reconstruction Dual-energy CT to Evaluate Total Knee Replacement Arthroplasty. Eur J Radiol 2020; 132:109254. [PMID: 32956998 DOI: 10.1016/j.ejrad.2020.109254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/23/2020] [Accepted: 08/19/2020] [Indexed: 11/23/2022]
Abstract
PURPOSE To evaluate the effects of gemstone spectral imaging-metal artifact reduction (GSI-MAR) on different dual-energy CT monochromatic images for patients with total knee replacement arthroplasty (TKRA) and to identify an appropriate protocol for clinical practice. METHOD We enrolled 34 patients with TKRA. CT images were iteratively reconstructed with or without GSI-MAR at different energy levels (70, 95, 115, and 140 keV). Two radiologists evaluated the objective and subjective image qualities and MAR-related new artifacts at the femoral and tibial levels. For objective analysis, the mean CT number and image noise of the selected regions of interest in the bone and muscle were recorded. To quantitatively evaluate the performance of GSI-MAR, a structural similarity index (SSIM) was used. For subjective analysis, streak artifacts and diagnostic confidence in detecting periprosthetic complications were assessed. Objective and subjective indicators were compared among the image combinations. RESULTS In the femoral component, 140 keV monochromatic energy images with GSI-MAR showed the lowest mean CT number, image noise, SSIM value, and streak artifacts, and the best diagnostic confidence. In the tibial component, the image noise differed significantly, but the SSIM and subjective indicators were similar among the image combinations. MAR-related new artifacts were noted in 14.7% of images, and all of them were observed in only the femoral component. CONCLUSION GSI-MAR with higher-energy monochromatic images showed fewer metal artifacts and better visualization. We recommend 140 keV with GSI-MAR for improving image quality and 140 keV without GSI-MAR for identifying MAR-related new artifacts when evaluating TKRA.
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Combined use of virtual monochromatic images and projection-based metal artifact reduction methods in evaluation of total knee arthroplasty. Eur Radiol 2020; 30:5298-5307. [PMID: 32424592 DOI: 10.1007/s00330-020-06932-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/30/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVES To evaluate the effect of the combined use of virtual monochromatic imaging (VMI) and projection-based metal artifact reduction (PB-MAR) methods on further artifact reduction and image quality in total knee arthroplasty (TKA) patients. METHODS Fifty-seven knee joints from 36 patients who had a previous history of TKA for bilateral or unilateral knee joints were included in this study. Four sets of images were compared between non-MAR, PB-MAR, VMI, and VMI + PB-MAR. For quantitative analysis, the area, mean attenuation, artifact index (AI), and contrast-to-noise ratio (CNR) were calculated for each protocol. Regarding qualitative analysis, overall artifact and depiction of soft tissue and bony structure were compared using relative visual grading analysis. RESULTS In the femoral region, the VMI + PB-MAR protocol showed the best MAR performance in quantitative measures including area, mean attenuation, and AI (p < .001). However, MAR protocols with VMI showed significantly lower CNRs than did the protocols without VMI in the tibial region (p < .001). On qualitative analysis, VMI + PB-MAR also showed fewer overall artifacts than did the other two MAR protocols. Soft tissue was best depicted in VMI + PB-MAR protocol, and PB-MAR showed the best performance for the depiction of bony structure (p < .001). CONCLUSIONS The combined use of VMI and PB-MAR showed better MAR performance than did PB-MAR or VMI alone. In areas with severe metal artifacts, the VMI + PB-MAR and PB-MAR protocols were useful for the evaluation of soft tissue and bone structure, respectively. KEY POINTS • The combination of artifact reduction methods is effective in reducing metal artifacts in CT. • Soft tissue was best depicted in the combined protocol of projection- and dual-energy-based methods, and projection-based protocol showed the best performance for the depiction of bone structure in case of severe metal artifacts.
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Combined Dual-Energy and Single-Energy Metal Artifact Reduction Techniques Versus Single-Energy Techniques Alone for Lesion Detection Near an Arthroplasty. AJR Am J Roentgenol 2020; 215:425-432. [PMID: 32374668 DOI: 10.2214/ajr.19.22084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE. The purpose of this study was to compare a combined dual-energy CT (DECT) and single-energy CT (SECT) metal artifact reduction technique with a SECT metal artifact reduction technique for detecting lesions near an arthroplasty in a phantom model. MATERIALS AND METHODS. Two CT phantoms with a cobalt chromium sphere attached to a titanium rod, simulating an arthroplasty, within a background of soft-tissue attenuation containing spherical lesions (range, 10-20 mm) around the head and stem of different attenuations from the background (range of attenuation, 10-70 HU) were scanned with a single CT scanner individually (unilateral) and together (bilateral) with the following three dose-equivalent techniques: the currently used clinical protocol (140 kVp, 300 Reference mAs); 100 kVp; and DECT (100 kVp and 150 kVp with a tin filter). Three radiologists reviewed the datasets to identify lesions. Nonparametric AUC was estimated for each reader with each technique. Multireader ANOVA was performed to compare AUCs. Multiple-variable logistic regression analysis was used to identify factors affecting sensitivity and specificity. RESULTS. Accuracy was lower (p < 0.001) for the DECT 130-keV technique than for the 100-, 70-, and 140-kVp techniques. Sensitivity was higher with unilateral arthroplasties (p = 0.037), with greater contrast differences from background (p < 0.001), and with the SECT 100-kVp technique versus other techniques (p < 0.001). The difference in specificities of modalities was not statistically significant (p = 0.148). CONCLUSION. Combining DECT and SECT techniques does not provide additional benefits for lesion detection as opposed to using SECT alone.
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Lim P, Barber J, Sykes J. Evaluation of dual energy CT and iterative metal artefact reduction (iMAR) for artefact reduction in radiation therapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:1025-1032. [PMID: 31602593 DOI: 10.1007/s13246-019-00801-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/19/2019] [Accepted: 09/16/2019] [Indexed: 11/27/2022]
Abstract
Metal artefacts pose a common problem in single energy computed tomography (SECT) images used for radiotherapy. Virtual monoenergetic (VME) images constructed with dual energy computed tomography (DECT) scans can be used to reduce beam hardening artefacts. Dual energy metal artefact reduction is compared and combined with iterative metal artefact reduction (iMAR) to determine optimal imaging strategies for patients with metal prostheses. SECT and DECT scans were performed on a Siemens Somatom AS-64 Slice CT scanner. Images were acquired of a modified CIRS pelvis phantom with 6, 12, 20 mm diameter stainless steel rods and VME images reconstructed at 100, 120, 140 and 190 keV. These were post-reconstructed with and without the iMAR algorithm. Artefact reduction was measured using: (1) the change in Hounsfield Unit (HU) with and without metal artefact reduction (MAR) for 4 regions of interest; (2) the total number of artefact pixels, defined as pixels with a difference (between images with metal rod and without) exceeding a threshold; (3) the difference in the mean pixel intensity of the artefact pixels. DECT, SECT + iMAR and DECT + iMAR were compared. Both SECT + iMAR and DECT + iMAR offer successful MAR for phantom simulating unilateral hip prosthesis. DECT gives minimal artefact reduction over iMAR alone. Quantitative metrics are advantageous for MAR analysis but have limitations that leave room for metric development.
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Affiliation(s)
- P Lim
- School of Physics, University of Sydney, Sydney, Australia.
| | - J Barber
- School of Physics, University of Sydney, Sydney, Australia
- Radiation Oncology, Blacktown Hospital, Sydney West Cancer Network, Sydney, Australia
| | - J Sykes
- School of Physics, University of Sydney, Sydney, Australia
- Radiation Oncology, Blacktown Hospital, Sydney West Cancer Network, Sydney, Australia
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13
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Yun HH, Lim JT, Yang SH, Park PS. Occult periprosthetic femoral fractures occur frequently during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA. PLoS One 2019; 14:e0221731. [PMID: 31536499 PMCID: PMC6752856 DOI: 10.1371/journal.pone.0221731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/13/2019] [Indexed: 11/19/2022] Open
Abstract
The present study aimed to investigate the prevalence and clinical consequences of occult intra-operative periprosthetic femoral fractures in total hip arthroplasty (THA). Between 2012 and 2017, a total of 113 primary THAs were enrolled. The mean age of the patients was 66.4 ± 7.6 years. We assessed occult intra-operative periprosthetic femoral fractures with the use of computed tomography (CT) and risk factors, including age, sex, body mass index, diagnosis, stem size, and radiographic parameters of proximal femoral geometry were analyzed. We also assessed the differences in thigh pain and stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. Occult intra-operative periprosthetic femoral fractures were found in 13 of 113 hips (11.5%). In 9/13 (69.2%) of occult fractures, fracture lines were started from the region below the tip of the lesser trochanter. Six periprosthetic femoral fractures (5.3%) were found during the operation. Out of the five hips that had detected femoral fractures around the lesser trochanter intra-operatively, four hips (80%) showed concurrent occult fractures on different levels. The female sex (P = .01) and canal filling ratio at 7 cm below the tip of the lesser trochanter (P = .01) were significantly different between the patients with and without occult periprosthetic femoral fracture. The sex was significantly associated with an increased risk in predicting an occult intra-operative periprosthetic femoral fracture (odds ratio of male, 0.25 compared with the female; 95% CI, 0.08-0.85; p = .02). There was a significant difference in the incidence of thigh pain between occult fracture group and non-occult fracture group (P < .05). There were no significant differences in stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. All 13 cases of occult intra-operative periprosthetic femoral fractures were healed at the final follow-up. Occult periprosthetic femoral fractures are common during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA, that CT scans are helpful to identify them, and that these fractures do not adversely affect the implant's survival if a rigid fixation of the implants has been achieved.
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Affiliation(s)
- Ho Hyun Yun
- Department of Orthopaedic Surgery, Seoul Veterans Hospital, Seoul, South Korea
- * E-mail:
| | - Jung Taek Lim
- Department of Orthopaedic Surgery, Seoul Veterans Hospital, Seoul, South Korea
| | - Se-Hyun Yang
- Department of Orthopaedic Surgery, Seoul Veterans Hospital, Seoul, South Korea
| | - Phil Sun Park
- Department of Orthopaedic Surgery, Seoul Veterans Hospital, Seoul, South Korea
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14
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Katsura M, Sato J, Akahane M, Kunimatsu A, Abe O. Current and Novel Techniques for Metal Artifact Reduction at CT: Practical Guide for Radiologists. Radiographics 2018. [PMID: 29528826 DOI: 10.1148/rg.2018170102] [Citation(s) in RCA: 166] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Artifacts caused by metallic implants appear as dark and bright streaks at computed tomography (CT), which severely degrade the image quality and decrease the diagnostic value of the examination. When x-rays pass through a metal object, depending on its size and composition, different physical effects negatively affect the measurements in the detector, most notably the effects of photon starvation and beam hardening. To improve image quality and recover information about underlying structures, several artifact reduction methods have been introduced in modern CT systems. Projection-based metal artifact reduction (MAR) algorithms act in projection space and replace corrupted projections caused by metal with interpolation from neighboring uncorrupted projections. MAR algorithms primarily suppress artifacts that are due to photon starvation. The dual-energy CT technique is characterized by data acquisition at two different energy spectra. Dual-energy CT provides synthesized virtual monochromatic images at different photon energy (kiloelectron volt) levels, and virtual monochromatic images obtained at high kiloelectron volt levels are known to reduce the effects of beam hardening. In clinical practice, although MAR algorithms can be applied after image acquisition, the decision whether to apply dual-energy CT for the patient usually needs to be made before image acquisition. Radiologists should be more familiar with the clinical and technical features of each method and should be able to choose the optimal method according to the clinical situation. ©RSNA, 2018.
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Affiliation(s)
- Masaki Katsura
- From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.)
| | - Jiro Sato
- From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.)
| | - Masaaki Akahane
- From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.)
| | - Akira Kunimatsu
- From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.)
| | - Osamu Abe
- From the Department of Radiology, Graduate School of Medicine (M.K., J.S., O.A.), and the Department of Radiology, Institute of Medical Science (A.K.), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan; and the Department of Radiology, School of Medicine, International University of Health and Welfare, Chiba, Japan (M.A.)
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15
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Abstract
Dual-energy computed tomography (DECT) enables material decomposition and virtual monochromatic images by acquiring 2 different energy X-ray data sets. DECT can detect musculoskeletal pathologic conditions that CT alone cannot, and that would otherwise require MR imaging. In this review, the authors discuss several useful techniques and applications of DECT in musculoskeletal research: virtual monochromatic images, virtual noncalcium images, gout, iodine map, and tendons.
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Affiliation(s)
- Takeshi Fukuda
- Department of Radiology, The Jikei University School of Medicine, 3-19-18, Nishi-Shimbashi, Minato-ku, Tokyo 105-8471, Japan; Department of Radiology, Stony Brook Medicine, HSC Level 4, Room 120, Stony Brook, NY 11794, USA.
| | - Kunihiko Fukuda
- Centre for International Affairs, The Jikei University, 3-25-8, Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan
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16
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Wellenberg RHH, Hakvoort ET, Slump CH, Boomsma MF, Maas M, Streekstra GJ. Metal artifact reduction techniques in musculoskeletal CT-imaging. Eur J Radiol 2018; 107:60-69. [PMID: 30292274 DOI: 10.1016/j.ejrad.2018.08.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 07/02/2018] [Accepted: 08/11/2018] [Indexed: 01/02/2023]
Abstract
It is known that metal artifacts can be reduced by modifying standard acquisition and reconstruction, by modifying projection data and/or image data and by using virtual monochromatic imaging extracted from dual-energy CT. In this review we focus on the origin of metal artifacts, technical background of commercially available metal artifact reduction (MAR) algorithms and the value of dual-energy CT and MAR software for different metal hardware in current clinical practice. Virtual monochromatic imaging reduces beam-hardening artifacts, where metal artifact reduction software effectively reduces artifacts caused by extensive photon-starvation. Both techniques have their advantages and disadvantages, and the combination of both techniques is often but not always the best solution regarding metal artifact reduction. Advances in prosthetic imaging are reinforced by advances in prosthetic design. Providing implant specific information prior to scanning is important in order to adjust the metal artifact reduction approach, minimize artifacts and optimize image quality and diagnostic value of CT.
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Affiliation(s)
- R H H Wellenberg
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, location AMC, University of Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands; Department of Radiology, Isala, Zwolle, The Netherlands.
| | - E T Hakvoort
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, The Netherlands.
| | - C H Slump
- MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
| | - M F Boomsma
- Department of Radiology, Isala, Zwolle, The Netherlands.
| | - M Maas
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, location AMC, University of Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands.
| | - G J Streekstra
- Department of Biomedical Engineering and Physics, Amsterdam University Medical Center, location AMC, Amsterdam, The Netherlands.
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17
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Yue D, Fan Rong C, Ning C, Liang H, Ai Lian L, Ru Xin W, Ya Hong L. Reduction of metal artifacts from unilateral hip arthroplasty on dual-energy CT with metal artifact reduction software. Acta Radiol 2018; 59:853-860. [PMID: 28899125 DOI: 10.1177/0284185117731475] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background The evaluation of hip arthroplasty is a challenge in computed tomography (CT). The virtual monochromatic spectral (VMS) images with metal artifact reduction software (MARs) in spectral CT can reduce the artifacts and improve the image quality. Purpose To evaluate the effects of VMS images and MARs for metal artifact reduction in patients with unilateral hip arthroplasty. Material and Methods Thirty-five patients underwent dual-energy CT. Four sets of VMS images without MARs and four sets of VMS images with MARs were obtained. Artifact index (AI), CT number, and SD value were assessed at the periprosthetic region and the pelvic organs. The scores of two observers for different images and the inter-observer agreement were evaluated. Results The AIs in 120 and 140 keV images were significantly lower than those in 80 and 100 keV images. The AIs of the periprosthetic region in VMS images with MARs were significantly lower than those in VMS images without MARs, while the AIs of pelvic organs were not significantly different. VMS images with MARs improved the accuracy of CT numbers for the periprosthetic region. The inter-observer agreements were good for all the images. VMS images with MARs at 120 and 140 keV had higher subjective scores and could improve the image quality, leading to reliable diagnosis of prosthesis-related problems. Conclusion VMS images with MARs at 120 and 140 keV could significantly reduce the artifacts from hip arthroplasty and improve the image quality at the periprosthetic region but had no obvious advantage for pelvic organs.
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Affiliation(s)
- Dong Yue
- Department of Radiology, Cancer Hospital of China Medical University, LiaoNing Cancer Hospital, LiaoNing, PR China
| | - Cheng Fan Rong
- Department of Radiology, Cancer Hospital of China Medical University, LiaoNing Cancer Hospital, LiaoNing, PR China
- Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing, PR China
| | - Cai Ning
- Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing, PR China
| | - Hu Liang
- Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing, PR China
| | - Liu Ai Lian
- Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing, PR China
| | - Wang Ru Xin
- Department of Radiology, The First Affiliated Hospital of Dalian Medical University, LiaoNing, PR China
| | - Luo Ya Hong
- Department of Radiology, Cancer Hospital of China Medical University, LiaoNing Cancer Hospital, LiaoNing, PR China
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18
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Jeong J, Kim HJ, Oh E, Cha JG, Hwang J, Hong SS, Chang YW. Visibility of bony structures around hip prostheses in dual-energy CT: With or without metal artefact reduction software. J Med Imaging Radiat Oncol 2018; 62:634-641. [PMID: 29797407 DOI: 10.1111/1754-9485.12746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 04/18/2018] [Indexed: 02/03/2023]
Abstract
INTRODUCTION The development of dual-energy CT and metal artefact reduction software provides a further chance of reducing metal-related artefacts. However, there have been only a few studies regarding whether MARs practically affect visibility of structures around a metallic hip prosthesis on post-operative CT evaluation. METHODS Twenty-seven patients with 42 metallic hip prostheses underwent DECT. The datasets were reconstructed with 70, 90 and 110 keV with and without MARs. The areas were classified into 10 zones according to the reference zone. All the images were reviewed in terms of the severity of the beam-hardening artefacts, differentiation of the bony cortex and trabeculae and visualization of trabecular patterns with a three-point scale. The metallic screw diameter was measured in the acetabulum with 110 keV images. RESULTS The scores were the worst on 70 keV images without MARs [mean scores:1.84-4.22 (p < 0.001-1.000)]. The structures in zone II were best visualized on 110 keV (p < 0.001-0.011, mean scores: 2.86-5.22). In other zones, there is general similarity in mean scores whether applying MARs or not (p < 0.001-0.920). The mean diameter of the screw was 5.85 mm without MARs and 3.44 mm with MARs (mean reference diameter: 6.48 mm). CONCLUSION The 110 keV images without MARs are best for evaluating acetabular zone II. The visibility of the bony structures around the hip prosthesis is similar in the other zones with or without MARs regardless of keV. MARS may not be needed for the evaluation of the metallic hip prosthesis itself at sufficient high-energy levels; however, MARS still has a role in the evaluation of other soft tissues around the prosthesis.
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Affiliation(s)
- Jewon Jeong
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
| | - Hyun-Joo Kim
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
| | - Eunsun Oh
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
| | - Jang Gyu Cha
- Soonchunhyang University Bucheon Hospital, Wonmigu, Bucheonsi, Gyeonggido, South Korea
| | - Jiyoung Hwang
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
| | - Seong Sook Hong
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
| | - Yun Woo Chang
- Soonchunhyang University Seoul Hospital, Yongsangu, Seoul, South Korea
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19
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Zhou P, Zhang C, Gao Z, Cai W, Yan D, Wei Z. Evaluation of the Quality of CT Images Acquired with Smart Metal Artifact Reduction Software. Open Life Sci 2018; 13:155-162. [PMID: 33817081 PMCID: PMC7874696 DOI: 10.1515/biol-2018-0021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/12/2018] [Indexed: 11/21/2022] Open
Abstract
Objective To evaluate the practical effectiveness of smart metal artifact reduction (SMAR) in reducing artifacts caused by metallic implants. Methods Patients with metal implants underwent computed tomography (CT) examinations on high definition CT scanner, and the data were reconstructed with adaptive statistical iterative reconstruction (ASiR) with value weighted to 40% and smart metal artifact reduction (SMAR) technology. The comparison was assessed by both subjective and objective assessment between the two groups of images. In terms of subjective assessment, three radiologists evaluated image quality and assigned a score for visualization of anatomic structures in the critical areas of interest. Objectively, the absolute CT value of the difference (ΔCT) and artifacts index (AI) were adopted in this study for the quantitative assessment of metal artifacts. Results In subjective image quality assessment, three radiologists scored SMAR images higher than 40% ASiR images (P<0.01) and the result suggested that visualization of critical anatomic structures around the region of the metal object was significantly improved by using SMAR compared with 40% ASiR. The ΔCT and AI for quantitative assessment of metal artifacts showed that SMAR appeared to be superior for reducing metal artifacts (P<0.05) and indicated that this technical approach was more effective in improving the quality of CT images. Conclusion A variety of hardware (dental filling, embolization coil, instrumented spine, hip implant, knee implant) are processed with the SMAR algorithm to demonstrate good recovery of soft tissue around the metal. This artifact reduction allows for the clearer visualization of structures hidden underneath.
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Affiliation(s)
- Peng Zhou
- Department of Radiology, Jinan central hospital affiliated to Shandong University, Jinan, Shandong Province 250013, PR China
| | - Chunling Zhang
- Department of Radiology, Jinan central hospital affiliated to Shandong University, Jinan, Shandong Province 250013, PR China
| | - Zhen Gao
- Department of Radiology, Jinan central hospital affiliated to Shandong University, Jinan, Shandong Province 250013, PR China
| | - Wangshu Cai
- Department of Radiology, Jinan central hospital affiliated to Shandong University, Jinan, Shandong Province 250013, PR China
| | - Deyue Yan
- Department of Radiology, Jinan central hospital affiliated to Shandong University, Jinan, Shandong Province 250013, PR China
| | - Zhaolong Wei
- Department of Radiology, Jinan central hospital affiliated to Shandong University, 105 Jiefang road, Jinan, 250013, PR China
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20
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Wellenberg RHH, Donders JCE, Kloen P, Beenen LFM, Kleipool RP, Maas M, Streekstra GJ. Exploring metal artifact reduction using dual-energy CT with pre-metal and post-metal implant cadaver comparison: are implant specific protocols needed? Skeletal Radiol 2018; 47:839-845. [PMID: 28842739 PMCID: PMC5915501 DOI: 10.1007/s00256-017-2750-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/26/2017] [Accepted: 08/01/2017] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans. METHODS Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel tibia plate and a titanium intramedullary nail respectively. Virtual monochromatic images were analyzed from 70 to 190 keV. Region-of-interest (ROI), used to determine fluctuations and inaccuracies in CT numbers of soft tissues and bone, were placed in muscle, fat, cortical bone and intramedullary tibia canal. RESULTS The stainless-steel implant resulted in more pronounced metal artifacts compared to both titanium implants. CT number inaccuracies in 70 keV reference images were minimized at 130, 180 and 190 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Noise, measured as the standard deviation of pixels within a ROI, was minimized at 130, 150 and 140 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. CONCLUSION Tailoring dual-energy CT protocols using implant specific virtual monochromatic images minimizes fluctuations and inaccuracies in CT numbers in bone and soft tissues compared to non-metal reference scans.
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Affiliation(s)
| | - Johanna C. E. Donders
- Department of Orthopedic Surgery, AMC, Amsterdam, The Netherlands ,Orthopedic Trauma Service, Hospital for Special Surgery, New York, NY USA
| | - Peter Kloen
- Department of Orthopedic Surgery, AMC, Amsterdam, The Netherlands
| | - Ludo F. M. Beenen
- Department of Radiology, AMC, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | | | - Mario Maas
- Department of Radiology, AMC, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Geert J. Streekstra
- Department of Biomedical Engineering and Physics, AMC, Amsterdam, The Netherlands
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Dose Reduction With Dedicated CT Metal Artifact Reduction Algorithm: CT Phantom Study. AJR Am J Roentgenol 2017; 210:593-600. [PMID: 29231758 DOI: 10.2214/ajr.17.18544] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The objective of this study was to compare reader accuracy detecting lesions near hardware in a CT phantom model at different radiation exposures using an advanced metal artifact reduction (MAR) algorithm and standard filtered back projection (FBP) techniques and to determine if radiation exposure could be decreased using MAR without compromising lesion detectability. MATERIALS AND METHODS A CT phantom manufactured with spherical lesions of various sizes (10-20 mm) and attenuations (20-50 HU) embedded around cobalt-chromium spheres attached to titanium rods, simulating an arthroplasty, was scanned on a single CT scanner (FLASH, Siemens Healthcare) at 140 kVp and 0.6-mm collimation using clinical-dose (300 Quality Reference mAs [Siemens Healthcare]), low-dose (150 Quality Reference mAs), and high-dose (600 Quality Reference mAs) protocols. Images reconstructed with iterative MAR, advanced modeled iterative reconstruction (ADMIRE), and FBP with identical parameters were anonymized and independently reviewed by three radiologists. Accuracies for detecting lesions, measured as AUC, sensitivity, and specificity, were compared. RESULTS Accuracy using MAR was significantly higher than that using FBP at all exposures (p values ranged from < 0.001 to 0.021). Sensitivity was also higher for MAR than for FBP at all exposures. Specificity was very high for both reconstruction techniques at all exposures with no significant differences. Accuracy of low-dose MAR was higher than and not inferior to standard-dose and high-dose FBP. MAR was significantly more sensitive than FBP in detecting smaller lesions (p = 0.021) and lesions near high streak artifact (p < 0.001). CONCLUSION MAR improves reader accuracy to detect lesions near hardware and allows significant reductions in radiation exposure without compromising accuracy compared with FBP in a CT phantom model.
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Wellenberg R, Boomsma M, van Osch J, Vlassenbroek A, Milles J, Edens M, Streekstra G, Slump C, Maas M. Quantifying metal artefact reduction using virtual monochromatic dual-layer detector spectral CT imaging in unilateral and bilateral total hip prostheses. Eur J Radiol 2017; 88:61-70. [DOI: 10.1016/j.ejrad.2017.01.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 11/24/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
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Wang F, Zhang Y, Xue H, Han W, Yang X, Jin Z, Zwar R. Combined use of iterative reconstruction and monochromatic imaging in spinal fusion CT images. Acta Radiol 2017; 58:62-69. [PMID: 26917784 DOI: 10.1177/0284185116631182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 01/13/2016] [Indexed: 01/04/2023]
Abstract
BACKGROUND Spinal fusion surgery is an important procedure for treating spinal diseases and computed tomography (CT) is a critical tool for postoperative evaluation. However, CT image quality is considerably impaired by metal artifacts and image noise. PURPOSE To explore whether metal artifacts and image noise can be reduced by combining two technologies, adaptive statistical iterative reconstruction (ASIR) and monochromatic imaging generated by gemstone spectral imaging (GSI) dual-energy CT. MATERIAL AND METHODS A total of 51 patients with 318 spinal pedicle screws were prospectively scanned by dual-energy CT using fast kV-switching GSI between 80 and 140 kVp. Monochromatic GSI images at 110 keV were reconstructed either without or with various levels of ASIR (30%, 50%, 70%, and 100%). The quality of five sets of images was objectively and subjectively assessed. RESULTS With objective image quality assessment, metal artifacts decreased when increasing levels of ASIR were applied (P < 0.001). Moreover, adding ASIR to GSI also decreased image noise (P < 0.001) and improved the signal-to-noise ratio (P < 0.001). The subjective image quality analysis showed good inter-reader concordance, with intra-class correlation coefficients between 0.89 and 0.99. The visualization of peri-implant soft tissue was improved at higher ASIR levels (P < 0.001). CONCLUSION Combined use of ASIR and GSI decreased image noise and improved image quality in post-spinal fusion CT scans. Optimal results were achieved with ASIR levels ≥70%.
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Affiliation(s)
- Fengdan Wang
- Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China
| | - Yan Zhang
- Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China
| | - Huadan Xue
- Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China
| | - Wei Han
- Statistics Office, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, PR China
| | - Xianda Yang
- Department of Pathophysiology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, PR China
| | - Zhengyu Jin
- Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China
| | - Richard Zwar
- Department of Radiology, Austin Health, Victoria, Australia
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Liu J, Wang W, Zhao X, Shen Z, Shao W, Wang X, Li L, Wang B. The value of spectral imaging to reduce artefacts in the body after 125 I seed implantation. J Med Imaging Radiat Oncol 2016; 60:643-649. [PMID: 27612002 DOI: 10.1111/1754-9485.12504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 07/07/2016] [Indexed: 11/30/2022]
Abstract
INTRODUCTION To explore the value of gemstone spectral imaging (GSI) and metal artefact reduction sequence (MARs) to reduce the artefacts of metal seeds. METHODS Thirty-five patients with 125 I seed implantation in their abdomens underwent GSI CT. Six types of monochromatic images and the corresponding MARs images at 60-110 keV (interval of 10 keV) were reconstructed. The differences in the quality of the images of three imaging methods were subjectively assessed by three radiologists. Length of artefacts, the CT value and noise value of tissue adjacent to 125 I seeds, contrast-to-noise ratio (CNR), and artefact index (AI) were recorded. RESULTS The differences in subjective scoring were statistically significant (t = 10.87, P < 0.001). Images at 70 keV showed the best CNR (0.84 ± 0.17) of tissues adjacent to 125 I seeds, and received the highest subjective score (2.82 ± 0.18). Images at 80 keV had the lowest AI (70.67 ± 19.17). Images at 110 keV had the shortest artefact lengths. High-density metal artefacts in the MARs spectral images were reduced. The length of metal artefacts in images at 110 keV was shorter than that of the polychromatic images and MARs spectral images (t = 3.35, 3.89, P < 0.05). The difference in CNR between MARs spectral images and polychromatic images, and images at 70 keV was statistically significant (t = 3.57, 4.16, P < 0.01). CONCLUSIONS Gemstone spectral imaging technique can reduce metal artefacts of 125 I seeds effectively in CT images, and improve the quality of images, and improve the display of tissues adjacent to 125 I seeds after implantation. MARs technique cannot reduce the artefacts caused by radioactive seeds effectively.
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Affiliation(s)
- Jingang Liu
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China
| | - Wenjuan Wang
- Department of Radiology, Weifang People's Hospital, Weifang, China
| | - Xingsheng Zhao
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China
| | - Zhen Shen
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China
| | - Weiguang Shao
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China
| | - Xizhen Wang
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China.
| | - Lixin Li
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China
| | - Bin Wang
- Imaging Center of Affiliated Hospital, Weifang Medical University, Weifang, China. .,Department of Medical Imaging, Medical Imaging Research Institute, Binzhou Medical University, Yantai, China.
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Imaging of Arthroplasties: Improved Image Quality and Lesion Detection With Iterative Metal Artifact Reduction, a New CT Metal Artifact Reduction Technique. AJR Am J Roentgenol 2016; 207:378-85. [DOI: 10.2214/ajr.15.15850] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Andersson KM, Norrman E, Geijer H, Krauss W, Cao Y, Jendeberg J, Geijer M, Lidén M, Thunberg P. Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography. Br J Radiol 2016; 89:20150993. [DOI: 10.1259/bjr.20150993] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Abstract
OBJECTIVE Various strategies have been developed in the past to reduce the excessive effects of metal artifacts in computed tomography images. From straightforward sinogram inpainting-based methods to computationally expensive iterative methods, all have been successful in improving the image quality up to a certain degree. We propose a novel image-based metal artifact subtraction method that achieves a superior image quality and at the same time provides a quantitatively more accurate image. METHODS Our proposed method consists of prior image-based sinogram inpainting, metal sinogram extraction, and metal artifact image subtraction. Reconstructing the metal images from the extracted metal-contaminated portions in the sinogram yields a streaky image that eventually can be subtracted from the uncorrected image. The prior image is reconstructed from the sinogram that is free from the metal-contaminated portions by use of a total variation (TV) minimization algorithm, and the reconstructed prior image is fed into the forward projector so that the missing portions in the sinogram can be recovered. Image quality of the metal artifact-reduced images on selected areas was assessed by the structure similarity index for the simulated data and SD for the real dental data. RESULTS Simulation phantom studies showed higher structure similarity index values for the proposed metal artifact reduction (MAR) images than the standard MAR images. Thus, more artifact suppression was observed in proposed MAR images. In real dental phantom data study, lower SD values were calculated from the proposed MAR images. The findings in real human arm study were also consistent with the results in all phantom studies. Thus, compared with standard MAR images, lesser artifact intensity was exhibited by the proposed MAR images. CONCLUSIONS From the quantitative calculations, our proposed method has shown to be effective and superior to the conventional approach in both simulation and real dental phantom cases.
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Analysis of metal artifact reduction tools for dental hardware in CT scans of the oral cavity: kVp, iterative reconstruction, dual-energy CT, metal artifact reduction software: does it make a difference? Neuroradiology 2015; 57:841-9. [DOI: 10.1007/s00234-015-1537-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 04/20/2015] [Indexed: 10/23/2022]
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Metal artifact reduction: standard and advanced magnetic resonance and computed tomography techniques. Radiol Clin North Am 2015; 53:531-47. [PMID: 25953288 DOI: 10.1016/j.rcl.2014.12.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An increasing number of joint replacements are being performed in the United States. Patients undergoing these procedures can have various complications. Imaging is one of the primary means of diagnosing these complications. Cross-sectional imaging techniques, such as computed tomography (CT) and MR imaging, are more sensitive than radiographs for evaluating complications. The use of CT and MR imaging in patients with metallic implants is limited by the presence of artifacts. This review discusses the causes of metal artifacts on MR imaging and CT, contributing factors, and conventional and novel methods to reduce the effects of these artifacts on scans.
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