Advances in Bone Joint Imaging-Metal Artifact Reduction

Role of WARP sequence magnetic resonance imaging with the removal of metal artifacts in the evaluation of lumbar adjacent

BACKGROUND

Posterior lumbar interbody fusion has good clinical results, but adjacent segment disease (ASD) affects its long-term efficacy. In patients with L4-5 fusion who were followed up for more than 10 years, the ASD incidence was 33.3%. Magnetic resonance imaging (MRI) is key for ASD diagnosis, but metal artifacts from internal fixation limit its use; therefore, removing the artifacts is crucial for ASD diagnosis and treatment.

AIM

To evaluate the value of WARP MRI for patients with lumbar ASD.

METHODS

In our hospital, the lumbar spines of patients with ASD were assessed via lumbar MRI, including conventional sequences and sequences for artifacts. A PACS workstation was used for image measurement, analysis, and assessment, which mainly included measurement of the internal fixation implant artifact area, evaluation of the visibility of the anatomical structures surrounding the implant, and diagnostic assessment of ASD in the section. Conventional MRI data sequences and artifacts to sequence the contrast analysis of the MRI data.

RESULTS

A total of 30 patients with ASD after lumbar fusion and internal fixation were included in the study; the patients included 13 male and 17 female patients and were aged 66.03 ± 5.83 years. The metal artifact area of the WARP T2-tirm sequence was significantly smaller than that of the conventional STIR sequence [(20.85 ± 6.27) cm² vs (50.56 ± 8.55) cm², P < 0.01]. The WARP T2-tirm sequence was observed around the implants, pedicles, intervertebral foramen, and vertebral bodies, and the conventional STIR sequence clearly displayed nerve roots within the intervertebral foramen. In all 30 patients, all adjacent segments of the WARP T2-tirm sequence could be clearly observed (above Grade 4), whereas it was difficult to observe these segments in the conventional STIR sequence due to the presence of more severe metal artifacts.

CONCLUSION

WARP sequences can significantly reduce the artifact area in the sagittal and cross-sectional images of titanium alloy spinal fixation, providing a good imaging reference for the diagnosis of ASD.

The Clinical Value of the MAR+ Metal Artifact Reduction Algorithm for Postoperative Assessment of Lumbar Internal Fixation

BACKGROUND

With the widespread use of lumbar pedicle screws for internal fixation, the morphology of the screws and the surrounding tissues should be evaluated. The metal artifact reduction (MAR) technique can reduce the artifacts caused by pedicle screws, improve the quality of computed tomography (CT) images after pedicle fixation, and provide more imaging information to the clinic.

PURPOSE

To explore whether the MAR+ method, a projection-based algorithm for correcting metal artifacts through multiple iterative operations, can reduce metal artifacts and have an impact on the structure of the surrounding metal.

MATERIALS AND METHODS

A total of 57 patients who underwent lumbar spine CT examination after lumbar internal fixation from January to December 2023 in our hospital were retrospectively enrolled. The CT images were reconstructed using MAR+ and non-MAR+ techniques and were subdivided into MAR+ and non-MAR+ groups. The CT number (in Hounsfield units) and the SD noise values of the spinal canal, vertebral body, psoas major muscle, and adjacent fat were measured in the 2 groups of CT images, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The subjective score was evaluated by two diagnostic radiologists using a double-blind method for image quality evaluation of the MAR+ group and the non-MAR+ group, and the image quality was classified on a 5-point scale. The rank-sum test was utilized to compare the subjective and objective scores of the 2 groups.

RESULTS

The SD values of the spinal canal (Z=-4.12, P<0.01), vertebral body (Z=-3.81, P<0.01), and psoas major muscle (Z=-3.87, P<0.01) in the MAR+ group were significantly lower than those in the non-MAR+ group (P<0.05). However, the SD values of the adjacent fat (Z=-2.03, P=0.42) in the MAR+ group, although smaller than those in the non-MAR+ group, were not statistically significant. The CNR values of vertebral canal (Z=-2.67, P=0.008) and fat (Z=-2.60, P=0.009) were higher in the MAR+ group than in the non-MAR+ group, whereas the CNR values of the vertebral body (Z=-6.74, P<0.01) in the MAR+ group were smaller than those in the non-MAR+ group, and the difference of all of them was statistically significant (P<0.05). Furthermore, for both CT and SNR values, the MAR group's values were all less than those of the non-MAR group and were statistically significant (P<0.05). The subjective scores of the measurement points were all higher in the MAR+ group than in the non-MAR+ group.

CONCLUSIONS

The MAR+ technique has a noise reduction effect on different tissues and artifacts are significantly reduced. Although the artifacts caused by metal screws were not completely eliminated, the MAR+ technique was able to reduce the interference of artifacts in the diagnosis of CT images, thus improving their diagnostic quality.

Medical imaging diagnosis of orthopedic prosthesis-associated infections: a narrative review

Background and Objective

Orthopedic prostheses have become increasingly prevalent in clinical practice in recent years. However, orthopedic prosthesis-associated infections (OPAI) have emerged as a serious complication associated with their use. Due to the variety of orthopedic implant types and the atypical clinical manifestations of OPAI, it is easy to cause delayed diagnosis and affect the prognosis of patients. The objective of this paper is to: (I) identify the potential imaging tools available to diagnose OPAI; (II) summarize the mechanisms and features by which each imaging modality can or cannot identify infection.

Methods

All the published papers were obtained from PubMed and Web of Science Core Collection on 1 February 2024. The study included original articles and reviews published in English between 2014 and 2024. EndNote was used to remove duplicates. Two independent authors conducted a comprehensive review of the titles and abstracts of the remaining literature to assess their eligibility for inclusion. Following this initial screening, the authors meticulously analyzed the abstracts and examined the full texts to confirm their suitability for final inclusion.

Key Content and Findings

A total of 55 articles were finally included for this narrative review. This review mainly summarized and analyzed the diagnostic value of ultrasound (US), X-ray, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine for OPAI, evaluated the advantages and disadvantages of each imaging technology, and tried to illuminate the future direction of diagnostic imaging methods development in this field.

Conclusions

Medical imaging has gained multidisciplinary recognition in the diagnosis of OPAI. Currently, there is an urgent need to establish large-scale, multicenter research projects. It is worth noting the key role of nuclear medicine diagnostic techniques and their unique metabolic information in the diagnosis of OPAI.

A systematic review: Radiological findings at a minimum of 3 years follow-up for unstable ankle fractures in adults treated with surgery

BACKGROUND

Radiological investigations are critical to diagnosis and treatment of many musculoskeletal diseases including detecting earliest degenerative changes (osteoarthritis (OA)) seen in patients with unstable ankle fractures managed surgically. Despite the high incidence of ankle OA, research into early detection using imaging remains sparse.

OBJECTIVES

To identify the incidence of OA on postoperative imaging in adults with unstable ankle fractures after a minimum follow-up of 3 years with a correlation to patient reported outcomes.

KEY FINDINGS

767 studies were identified on 5 database searches, and 492 abstract titles were screened, while 53 papers were selected for full review. From these only 8 articles met the inclusion criteria. A total of 905 participants aged 18 years and above (mean 46.4 years, 53.8 % male) presented with a range of ankle fracture classifications. This includes 423 cases of Weber classification, 225 cases of OTA/AO, 204 Lauge-Hansen classification, and 53 medial malleoli. From these, 34.7 % cases of OA were identified (minimum of the 3-year follow-up) on different imaging modalities. Our results revealed that mild to moderate OA is common, and functional outcome is mainly good to excellent.

CONCLUSION

1 in 3 patients treated for unstable ankle fracture with open reduction internal fixation will show signs of radiological OA after 3-7 years of index procedure, though with good functional outcome. We were unable to correlate the grade of radiological OA observed with clinical OA. Despite the low sensitivity of X-ray in early detection of OA, we identified a lack of studies in utilising MRI and/or CT imaging, indicating the need for further research. Clinicians should consider using MRI/CT imaging for early detection of OA for patients following unstable ankle fractures, to improve early detection and consequently improve patient reported outcomes.

LEVEL OF CLINICAL EVIDENCE

Systematic review = 1.

Failure Modes in Orthopedic Oncologic Reconstructive Surgery: A Review of Imaging Findings and Failure Rates

Limb salvage surgeries utilizing endoprostheses and allografts are performed for a variety of oncologic conditions. These reconstructions can fail and require revision for many reasons, which are outlined and classified into mechanical failures (soft tissue failures, aseptic loosening, structural failure), non-mechanical failures (infection, tumor progression), and pediatric failures (physeal arrest, growth dysplasia). Distinct radiologic and clinical findings define specific failure subtypes but are sparsely illustrated in the radiology literature. Specifically, an understanding of the organizational structure of the failure modes can direct radiologists' search for post-reconstruction complications, enhance an appreciation of their prognostic significance, and facilitate research by standardizing the language and conceptual framework around outcomes. The purpose of this review is to highlight the key radiologic findings and imaging studies of each failure mode in orthopedic oncologic reconstructive surgery in the context of risk factors, failure rates, prognosis and survival statistics, and clinical decision-making regarding chemotherapy, radiation, and revision surgery.

The role of advanced metal artifact reduction MRI in the diagnosis of periprosthetic joint infection

Identification and diagnosis of periprosthetic joint infection (PJI) are challenging, requiring a multi-disciplinary approach involving clinical evaluation, laboratory tests, and imaging studies. MRI is advantageous to alternative imaging techniques due to superior soft tissue contrast and absence of ionizing radiation. However, the presence of metallic implants can cause signal loss and artifacts. Metal artifact suppression (MARS) MRI techniques have been developed that mitigate metal artifacts and improve periprosthetic soft tissue visualization. This paper provides a review of the various MARS MRI techniques, their clinical applicability and accuracy in PJI diagnosis and evaluation, and current challenges and future perspectives.

Clinical evaluation of isotropic MAVRIC-SL for symptomatic hip arthroplasties at 3 T MRI

BACKGROUND

3D multi-spectral imaging (MSI) of metal implants necessitates relatively long scan times.

OBJECTIVE

We implemented a fast isotropic 3D MSI technique at 3 T and compared its image quality and clinical utility to non-isotropic MSI in the evaluation of hip implants.

METHODS

Two musculoskeletal radiologists scored images from coronal proton density-weighted conventional MAVRIC-SL and an isotropic MAVRIC-SL sequence accelerated with robust-component-analysis on a 3-point scale (3: diagnostic, 2: moderately diagnostic, 1: non-diagnostic) for overall image quality, metal artifact, and visualization around femoral and acetabular components. Grades were compared using a signed Wilcoxon test. Images were evaluated for effusion, synovitis, osteolysis, loosening, pseudotumor, fracture, and gluteal tendon abnormalities. Reformatted axial and sagittal images for both sequences were subsequently generated and compared for image quality with the Wilcoxon test. Whether these reformats increased diagnostic confidence or revealed additional pathology, including findings unrelated to arthroplasty that may contribute to hip pain, was also compared using the McNemar test. Inter-rater agreement was measured by Cohen's kappa.

RESULTS

39 symptomatic patients with a total of 59 hip prostheses were imaged (mean age, 70 years ±9, 14 males, 25 females). Comparison scores between coronal images showed no significant difference in image quality, metal artifact, or visualization of the femur and acetabulum. Except for loosening, reviewers identified more positive cases of pathology on the original coronally-acquired isotropic sequence. In comparison of reformatted axial and sagittal images, the isotropic sequence scored significantly (p < 0.01) higher for overall image quality (3.0 vs 2.0) and produced significantly (p < 0.01) more cases of increased diagnostic confidence (42.4% vs 7.6%) or additional diagnoses (50.8% vs 22.9%). Inter-rater agreement was substantial (k = 0.798) for image quality. Mean scan times were 4.2 mins (isotropic) and 7.1 mins (non-isotropic).

CONCLUSION

Compared to the non-isotropic sequence, isotropic 3D MSI was acquired in less time while maintaining diagnostically acceptable image quality. It identified more pathology, including postoperative complications and potential pain-generating pathology unrelated to arthroplasty. This fast isotropic 3D MSI sequence demonstrates promise for improving diagnostic evaluation of symptomatic hip prostheses at 3 T while simultaneously reducing scan time.

Bone tumors: state-of-the-art imaging

Imaging plays a central role in the management of patients with bone tumors. A number of imaging modalities are available, with different techniques having unique applications that render their use advantageous for various clinical purposes. Coupled with detailed clinical assessment, radiological imaging can assist clinicians in reaching a proper diagnosis, determining appropriate management, evaluating response to treatment, and monitoring for tumor recurrence. Although radiography is still the initial imaging test of choice for a patient presenting with a suspected bone tumor, technological innovations in the last decades have advanced the role of other imaging modalities for assessing bone tumors, including advances in computed tomography, magnetic resonance imaging, scintigraphy, and hybrid imaging techniques that combine two existing modalities, providing clinicians with diverse tools for bone tumor imaging applications. Determining the most suitable modality to use for a particular application requires familiarity with the modality in question, its advancements, and its limitations. This review highlights the various imaging techniques currently available and emphasizes the latest developments in imaging, offering a framework that can help guide the imaging of patients with bone tumors.

Dual-energy CT in musculoskeletal imaging: technical considerations and clinical applications

Dual-energy CT stands out as a robust and innovative imaging modality, which has shown impressive advancements and increasing applications in musculoskeletal imaging. It allows to obtain detailed images with novel insights that were once the exclusive prerogative of magnetic resonance imaging. Attenuation data obtained by using different energy spectra enable to provide unique information about tissue characterization in addition to the well-established strengths of CT in the evaluation of bony structures. To understand clearly the potential of this imaging modality, radiologists must be aware of the technical complexity of this imaging tool, the different ways to acquire images and the several algorithms that can be applied in daily clinical practice and for research. Concerning musculoskeletal imaging, dual-energy CT has gained more and more space for evaluating crystal arthropathy, bone marrow edema, and soft tissue structures, including tendons and ligaments. This article aims to analyze and discuss the role of dual-energy CT in musculoskeletal imaging, exploring technical aspects, applications and clinical implications and possible perspectives of this technique.

Autofusion in early-onset scoliosis growing constructs: occurrence, risk factors, and impacts

PURPOSES

Autofusion (AF) during growing rod (GR) instrumentation for early-onset scoliosis (EOS) has been reported, but AF incidence, causation, and clinical implications remain unknown. This article aims to (1) quantify frequency and severity of AF, (2) determine risk factors for AF, and (3) assess the influence of AF on final curve correction and spinal lengthening.

METHODS

EOS patients were prospectively enrolled (2016-2021). Patients underwent evaluation, GR implantation, lengthenings, and posterior spinal fusion (PSF). Cobb angle and spinal length measurements were collected. AF was assessed and graded, with grades I-II being low-grade and III-V being high-grade. Exposure analysis quantified risk factors' impact via odds ratios and Pearson regression correlates. Statistical significance was p ≤ 0.05 or ≥ 0.95.

RESULTS

28 patients, with variable EOS diagnoses, were included. On average, GR were implanted at 8.54-year-old and lengthened over 4.66 years. 53.6% of patients received magnetically controlled GR (MCGR) and 46.4% traditional GR (TGR). The average construct bridged 13.4 levels. Over the lengthening period, for all indications, patients averaged 2.9 total open procedures. Curves corrected from 68.5º preoperatively to 35.3º after index GR to 35.6º after PSF. Spinal length increased from 30.0 cm preoperatively to 33.9 cm after index GR to 39.5 cm after PSF. AF grading was: 28.6% Grade I, 25.0% Grade II, 17.9% Grade III, 25.0% Grade IV, and 3.6% Grade V. Idiopathic EOS tended to have lower AF grades (p = 0.37). AF risk factors included GR age < 8 (10.4×, p = 0.01), any interval open procedures (6.3×, p = 0.05), and residual curve > 30º after index GR (13.7×, p = 0.02). Protective factors included preoperative spinal length of > 30.0 cm (0.11×, p = 0.01) and index MCGR (0.16×, p = 0.03). Maintenance of Cobb angles from index GR through PSF was relatively better in low-grade patients (p = 0.08). Spinal length gained was no different between low- and high-grade AF (p = 0.50).

CONCLUSIONS

This largest-to-date evaluation found AF is nearly ubiquitous in GR constructs, but with variable severity. Both risk factors and protective factors coincide with AF. Ultimately, even in high-grade AF, curve correction was maintained, and spinal lengthening was achieved.

LEVEL OF EVIDENCE

Level II-prospective cohort study.

Comparison of Bone Evaluation and Metal Artifact between Photon-Counting CT and Five Energy-Integrating-Detector CT under Standardized Conditions Using Cadaveric Forearms

BACKGROUND

To compare the potential of various bone evaluations by considering photon-counting CT (PCCT) and multiple energy-integrating-detector CT (EIDCT), including three dual-energy CT (DECT) scanners with standardized various parameters in both standard resolution (STD) and ultra-high-resolution (UHR) modes.

METHODS

Four cadaveric forearms were scanned using PCCT and five EIDCTs, by applying STD and UHR modes. Visibility of bone architecture, image quality, and a non-displaced fracture were subjectively scored against a reference EIDCT image by using a five-point scale. Image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were also compared. To assess metal artifacts, a forearm with radial plate fixation was scanned by with and without Tin filter (Sn+ and Sn-), and virtual monoenergetic image (VMI) at 120 keV was created. Regarding Sn+ and VMI, images were only obtained from the technically available scanners. Subjective scores and the areas of streak artifacts were compared.

RESULTS

PCCT demonstrated significantly lower noise (p < 0.001) and higher bone SNR and CNR (p < 0.001) than all EIDCTs in both resolution modes. However, there was no significant difference between PCCT and EIDCTs in almost all subjective scores, regardless of scan modes, except for image quality where a significant difference was observed, compared to several EIDCTs. Metal artifact analysis revealed PCCT had larger artifact in Sn- and Sn+ (p < 0.001), but fewer in VMIs than three DECTs (p < 0.001 or 0.001).

CONCLUSIONS

Under standardized conditions, while PCCT had almost no subjective superiority in visualizing bone structures and fracture line when compared to EIDCTs, it outperformed in quantitative analysis related to image quality, especially in lower noise and higher tissue contrast. When using PCCT to assess cases with metal implants, it may be recommended to use VMIs to minimize the possible tendency for artifact to be pronounced.

Secondary Rotator Cuff Insufficiency After Anatomic Total Shoulder Arthroplasty

» Secondary rotator cuff insufficiency is a challenging complication after anatomic total shoulder arthroplasty.» Acute tears may be amenable to open or arthroscopic repair in some instances.» Chronic attritional tears are best managed with revision to reverse shoulder arthroplasty, especially in the elderly.» Increased glenoid inclination, larger critical shoulder angle, oversized humeral components, thicker glenoid components, and rotator cuff muscle fatty infiltration have all shown to contribute to tear risk.

A Pilot Study on the Reliability of Ultrasound-Based Assessment of Patella Diameter and Sulcus Angle

This pilot study aimed to determine the reliability of a newly developed ultrasound-based protocol for the assessment of patella diameter and sulcus angle. The diameter of the patella expressed in mm and the sulcus angle, expressed in degrees were measured in the right knee in 12 healthy participants (eight women and four men) in two separate sessions by two examiners (experienced rater and inexperienced rater) using ultrasonography according to a developed standardized protocol. The reliability was determined on the calculated intraclass correlation coefficient, ICC, expressed as a 95% confidence interval (lower bound, upper bound). For the patella diameter measurement, intra-rater and inter-rater reliability were good to excellent, with the ICC exceeding 0.836-0.998 and 0.859-0.997, respectively. The intra-rater and inter-rater reliability of the sulcus measurement was moderate to excellent, as the ICC amounted to 0.559-0.993 and 0.559-0.990, respectively. The reliability of both measures increased with the experience of the examiner. Therefore, it was determined that the newly developed protocol for an ultrasound-based assessment of patella diameter and sulcus angle is reliable. Further studies validating their clinical use should be carried out.