Imaging tests for the detection of osteomyelitis: a systematic review

Approach to imaging modalities in the setting of suspected infection

Imaging plays an important role in the workup of musculoskeletal infection, in conjunction with clinical history and physical exam. There are multiple imaging modalities that can be of clinical utility in the setting of suspected infection, each with their own benefits and limitations. Radiography is a low-cost, accessible modality providing a broad osseous overview, but can be insensitive for early osteomyelitis. Ultrasound plays a more limited role in the workup of musculoskeletal infection, but can be useful in the pediatric population or for real-time guidance for joint and soft tissue aspirations. Computed tomography (CT) plays an important role in the timely and accurate diagnosis of critically ill patients in the emergency setting. Its superior soft tissue characterization allows for diagnosis of abscesses, and it can help confirm the clinical diagnosis of necrotizing fasciitis when soft tissue gas is present. Magnetic resonance imaging (MRI) is often the modality of choice in the diagnosis of infection, as its superior contrast resolution allows for clear delineation of the presence and extent of both soft tissue infection and osteomyelitis. Additionally, the use of intravenous contrast and advanced imaging sequences such as diffusion weighted imaging (DWI) further increases the diagnostic utility of MRI in the assessment for infection. Familiarity with the diagnostic utility of each imaging modality will allow the radiologist to appropriately guide imaging workup in the setting of clinically suspected infection.

Point-of-care Ultrasound in Infectious Diseases: Current Insights and Future Perspectives

Point-of-care ultrasound (POCUS) is a safe, noninvasive technique performed at the patient's bedside, providing immediate results to the operator. It complements physical examination and facilitates clinical decision-making. In infectious diseases, POCUS is particularly valuable, offering an initial assessment in cases of suspected infection. It often leads to an early tentative diagnosis enabling the prompt initiation of antimicrobial treatment without the delay associated with traditional radiology. POCUS provides direct visualization of affected organs, assists in evaluating fluid balance, and facilitates various interventions, all while reducing patient discomfort. For infectious disease specialists, becoming proficient in POCUS is a critical future challenge, requiring dedicated training for effective utilization.

Extensive Emphysematous Osteomyelitis Attributed to Escherichia coli Infection: Radiological Insights and Detailed Case Report of a Rare Entity

Emphysematous osteomyelitis (EO) is a rare and severe bone infection characterized by the presence of gas within the bone and surrounding soft tissues, commonly caused by gas-forming bacteria. We present a case of an elderly patient with extensive EO due to Escherichia coli infection. The patient exhibited systemic signs of infection and severe localized pain. Radiological assessments, including computed tomography and magnetic resonance imaging, demonstrated significant gas accumulation within the bone and adjacent tissues, confirming the diagnosis. Despite intensive antibiotic treatment and surgical intervention, the patient's condition initially worsened, highlighting the high morbidity and mortality associated with this infection. However, through prompt action and targeted intervention, a positive outcome was ultimately achieved. This case emphasizes the critical need for early diagnosis and aggressive management of EO to improve patient outcomes.

Integrative gene expression analysis and animal model reveal immune- and autophagy-related biomarkers in osteomyelitis

BACKGROUND

Osteomyelitis (OM) is recognized as a significant challenge in orthopedics due to its complex immune and inflammatory responses. The prognosis heavily depends on timely diagnosis, accurate classification, and assessment of severity. Thus, the identification of diagnostic and classification-related genes from an immunological standpoint is crucial for the early detection and tailored treatment of OM.

METHODS

Transcriptomic data for OM was sourced from the Gene Expression Omnibus (GEO) database, leading to the identification of autophagy- and immune-related differentially expressed genes (AIR-DEGs) through differential expression analysis. Diagnostic and classification models were subsequently developed. The CIBERSORT algorithm was utilized to examine immune cell infiltration in OM, and the relationship between OM clusters and various immune cells was explored. Key AIR-DEGs were further validated through the creation of OM animal models.

RESULTS

Analysis of the transcriptomic data revealed three AIR-DEGs that played a significant role in immune responses and pathways. Nomogram and receiver operating characteristic curve analyses were performed, demonstrating excellent diagnostic capability for differentiating between OM patients and healthy individuals, with an area under the curve of 0.814. An unsupervised clustering analysis discerned two unique patterns of autophagy- and immune-related genes, as well as gene patterns. Further exploration into immune infiltration exhibited notable variances across different subtypes, especially between OM cluster 1 and gene cluster A, highlighting their potential role in mitigating inflammatory responses by regulating immune activities. Moreover, the mRNA and protein expression levels of three AIR-DEGs in the animal model were aligned with those in the training and validation data sets.

CONCLUSIONS

From an immunological perspective, a diagnostic model was successfully developed, and two distinct clustering patterns were identified. These contributions offer a significant resource for the early detection and personalized immunotherapy of patients with OM.

PET/CT and SPECT/CT for Infection in Joints and Bones: An Overview and Future Directions

Infections of the bones and joints, if misdiagnosed, may result in serious morbidity and even mortality. A prompt diagnosis followed by appropriate management may reduce the socioeconomic impact of bone and joint infections. Morphologic imaging such as ultrasound and plain radiographs form the first line investigations, however, in early infections findings may be negative or nonspecific. Nuclear medicine imaging techniques play a complementary role to morphologic imaging in the diagnosis of bone and joint infections. The availability of hybrid systems (SPECT/CT, SPECT/MRI, PET/CT or PET/MRI) offers improved specificity with ability to assess the extent of infection. Bone scans are useful as a gatekeeper wherein negative scans rule out sepsis with a good accuracy, however positive scans are nondiagnostic and more specific tracers should be considered. These include the use of labeled white blood cells and antigranulocyte antibodies. Various qualitative and quantitative interpretation criteria have been suggested to improve the specificity of the scans. PET has better image resolution and 18F-FDG is the major tracer for PET imaging with applications in oncology and inflammatory/infective disorders. It has demonstrated improved sensitivity over the SPECT based tracers, however, still suffers from lack of specificity. 18F-FDG PET has been used to monitor therapy in bone and joint infections. Other less studied, noncommercialized SPECT and PET tracers such as 111In-Biotin, 99mTc-Ubiquicidin, 18F-Na-Fluoride, 18F-labeled white blood cells and 124I-Fialuridine to name a few have shown great promise, however, their role in various bone and joint infections has not been established. Hybrid imaging with PET or PET/MRI offers huge potential for improving diagnostics in infections of the joints and bones.

Recurrent skin opening induced by chronic sternal osteomyelitis caused by a bite wound in a cat: A case report

BACKGROUND

Chronic sternal osteomyelitis is a rare condition in felines, with limited reported cases to date.

OBJECTIVES

We report the case of a 2-year-old castrated male, domestic shorthair cat, weighing 4.68 kg, that presented with skin openings every 3-4 months, despite skin debridement and reconstruction.

METHODS

A subcutaneous dead space larger than the skin defect was detected. Haematological analysis revealed elevated levels of inflammatory markers. Thoracic radiography revealed sternal deformation and suspected osteomyelitis. Computed tomography revealed a fistula extending from the third to the fourth sternebrae.

RESULTS

Bone and soft tissue debridement and abscess flushing were performed along with long-term antibiotic therapy. The cat remained recurrence-free throughout an 18-month post-surgery follow-up period.

CONCLUSION

To the best of our knowledge, this is the first report of chronic osteomyelitis occurring in a cat's sternebrae and represents the first successful case of its treatment. This case showcases the potential for improved treatment outcomes in similar cases. Understanding and successful treatment of such cases can pave the way for better management of feline osteomyelitis.

The usefulness of quantitative 99mTc-HMPAO WBC SPECT/CT for predicting lower extremity amputation in diabetic foot infection

We investigated the usefulness of quantitative 99mTc-white blood cell (WBC) single photon emission computed tomography (SPECT)/computed tomography (CT) for predicting lower extremity amputation in diabetic foot infection (DFI). A total of 93 feet of 83 consecutive patients with DFI who underwent WBC SPECT/CT for treatment planning were retrospectively analysed. The clinical and SPECT/CT parameters were collected along with the measurements of the maximum standardized uptake value (SUVmax) at DFI. Statistical logistic regression analysis was performed to explore the predictors of LEA and receiver operating characteristic (ROC) curve was analysed to assess the predictive value of SPECT/CT. The independent predictors of amputation were previous amputation (OR 11.9), numbers of SPECT/CT lesions (OR 2.1), and SUVmax of DFI; either continuous SUVmax (1-increase) (OR 1.3) or categorical SUVmax > 1.1 (OR 21.6). However, the conventional SPECT/CT interpretation failed to predict amputation. In ROC analysis, the SUVmax yielded a fair predictor (area under the curve (AUC) 0.782) of amputation. The model developed from these independent predictors yielded an excellent performance for predicting amputation (AUC 0.873). Quantitative WBC SPECT/CT can provide new information useful for predicting the outcomes and guiding treatment for patients with DFI.

Current updates in MSK infection imaging: A narrative review

This article presents a comprehensive overview of the diagnostic utility of existing imaging techniques including radiography, computed tomography, ultrasonography, magnetic resonance imaging (MRI), and radionuclide imaging in the context of the most common orthopaedic or musculoskeletal infections. It also includes illustrative images showcasing significant findings in various musculoskeletal infections including osteomyelitis, cellulitis, septic arthritis, necrotising infections and peri-prosthetic joint infections and their associated complications.

A comparative 18F-FDG and an anti-PD-L1 probe PET/CT imaging of implant-associated Staphylococcus aureus osteomyelitis

Background

Early and accurate diagnosis of infection-induced osteomyelitis, which often involves increased PD-L1 expression, is crucial for better treatment outcomes. Radiolabeled anti-PD-L1 nuclear imaging allows for sensitive and non-invasive whole-body assessments of PD-L1 expression. This study aimed to compare the efficacy of 18F-FDG and an 18F-labeled PD-L1-binding peptide probe (18F-PD-L1P) in PET imaging of implant-associated Staphylococcus aureus osteomyelitis (IAOM).

Methods

In this study, we synthesized an anti-PD-L1 probe and compared its efficacy with 18F-FDG and 18F-PD-L1P in PET imaging of implant-associated Staphylococcus aureus osteomyelitis (IAOM). The %ID/g ratios (i.e., radioactivity ratios between the infected and non-infected sides) of both probes were evaluated for sensitivity and accuracy in post-infected 7-day tibias and post-infected 21 days, and the intensity of 18F-PD-L1P uptake was compared with pathological changes measured by PD-L1 immunohistochemistry (IHC).

Results

Compared with 18F-FDG, 18F-PDL1P demonstrated higher %ID/g ratios for both post-infected 7-day tibias (P=0.001) and post-infected 21 days (P=0.028). The intensity of 18F-PD-L1P uptake reflected the pathological changes of osteomyelitic bones. In comparison to 18F-FDG, 18F-PDL1P provides earlier and more sensitive detection of osteomyelitis caused by S. aureus.

Conclusion

Our findings suggest that the 18F-PDL1P probe is a promising tool for the early and accurate detection of osteomyelitis caused by S. aureus.

Diagnosing acute bone and joint infection in children

Acute bone and joint infections in children are serious, and misdiagnosis can threaten limb and life. Most young children who present acutely with pain, limping, and/or loss of function have transient synovitis, which will resolve spontaneously within a few days. A minority will have a bone or joint infection. Clinicians are faced with a diagnostic challenge: children with transient synovitis can safely be sent home, but children with bone and joint infection require urgent treatment to avoid complications. Clinicians often respond to this challenge by using a series of rudimentary decision support tools, based on clinical, haematological, and biochemical parameters, to differentiate childhood osteoarticular infection from other diagnoses. However, these tools were developed without methodological expertise in diagnostic accuracy and do not consider the importance of imaging (ultrasound scan and MRI). There is wide variation in clinical practice with regard to the indications, choice, sequence, and timing of imaging. This variation is most likely due to the lack of evidence concerning the role of imaging in acute bone and joint infection in children. We describe the first steps of a large UK multicentre study, funded by the National Institute for Health Research, which seeks to integrate definitively the role of imaging into a decision support tool, developed with the assistance of individuals with expertise in the development of clinical prediction tools.

Osteomyelitis of the Lower Limb: Diagnostic Accuracy of Dual-Energy CT versus MRI

BACKGROUND

MRI is the preferred imaging technique for the identification of osteomyelitis. The key element for diagnosis is the presence of bone marrow edema (BME). Dual-energy CT (DECT) is an alternative tool which is able to identify BME in the lower limb.

PURPOSE

To compare the diagnostic performance of DECT and MRI for osteomyelitis, using clinical, microbiological, and imaging data as reference standards.

MATERIALS AND METHODS

This prospective single-center study enrolled consecutive patients with suspected bone infections undergoing DECT and MRI imaging from December 2020 to June 2022. Four blinded radiologists with various experience levels (range of 3-21 years) evaluated the imaging findings. Osteomyelitis was diagnosed in the presence of BMEs, abscesses, sinus tracts, bone reabsorption, or gaseous elements. The sensitivity, specificity, and AUC values of each method were determined and compared using a multi-reader multi-case analysis. A p value < 0.05 was considered significant.

RESULTS

In total, 44 study participants (mean age 62.5 years ± 16.5 [SD], 32 men) were evaluated. Osteomyelitis was diagnosed in 32 participants. For the MRI, the mean sensitivity and specificity were 89.1% and 87.5%, while for the DECT they were 89.0% and 72.9%, respectively. The DECT demonstrated a good diagnostic performance (AUC = 0.88), compared with the MRI (AUC = 0.92) (p = 0.12). When considering each imaging finding alone, the best accuracy was achieved by considering BME (AUC for DECT 0.85 versus AUC of MRI of 0.93, with p = 0.07), followed by the presence of bone erosions (AUC 0.77 for DECT and 0.53 for MRI, with p = 0.02). The inter-reader agreement of the DECT (k = 88) was similar to that of the MRI (k = 90).

CONCLUSION

Dual-energy CT demonstrated a good diagnostic performance in detecting osteomyelitis.

Imaging Osteomyelitis: An Update

BACKGROUND

 Hematogenous osteomyelitis has increased over the past quarter century in frequency, virulence, and degree of soft-tissue involvement, bringing about changes in clinical manifestations and management of the disease especially in children that should be reflected in the current imaging approach. Likewise, the global disease burden of diabetes has increased greatly in the same period, compounding the problem of ascertaining osteomyelitis in diabetic foot.

METHOD

 This article provides an updated overview of imaging findings in hematogenous and contiguous osteomyelitis based on the literature and our institutional experience, along with salient features of recent recommendations from expert groups on the diagnostic algorithms and reporting terminology.

RESULTS AND CONCLUSION

 Findings on radiography and especially magnetic resonance imaging (MRI) closely reflect pathophysiology in osteomyelitis, whereby the characteristic involvement of the metaphysis or metaphyseal-equivalents, the formation and subperiosteal extension of intramedullary pus collection, and the development of cloaca, sequestrum, and involucrum are all diagnostic clues. Non-enhancing foci within the medullary bone, the penumbra sign, intra- or extramedullary fat globules, and surrounding soft tissue inflammation or abscesses are among key MRI findings. Diabetic foot is a special condition with characteristic pathophysiologic and imaging features that suggest the likelihood of osteomyelitis and the main differential diagnostic consideration of acute on chronic neuropathic osteoarthropathy with or without osteomyelitis.

KEY POINTS

  · Imaging closely reflects pathophysiology in hematogenous osteomyelitis.. · Acute hematogenous osteomyelitis predominantly involves metaphyses and metaphyseal equivalent sites.. · MRI clues for hematogenous osteomyelitis include central marrow non-enhancement, intra- or extramedullary fat globules, and the "penumbra" sign.. · An increased fluid-sensitive MRI bone signal abutting a soft tissue ulcer, abscess, or sinus tract suggests a high probability of contact osteomyelitis..

CITATION FORMAT

· Aydingoz U, Imaging Osteomyelitis: An Update. Fortschr Röntgenstr 2023; DOI: 10.1055/a-1949-7641.

Nosocomial Extracardiac Infections After Cardiac Surgery

Purpose of Review

Nosocomial extracardiac infections after cardiac surgery are a major public health issue affecting 3–8.2% of patients within 30–60 days following the intervention.

Recent Findings

Here, we have considered the most important postoperative infective complications that, in order of frequency, are pneumonia, surgical site infection, urinary tract infection, and bloodstream infection. The overall picture that emerges shows that they cause a greater perioperative morbidity and mortality with a longer hospitalization time and excess costs. Preventive interventions and corrective measures, diminishing the burden of nosocomial extracardiac infections, may reduce the global costs. A multidisciplinary team may assure a more appropriate management of nosocomial extracardiac infections leading to a reduction of hospitalization time and mortality rate.

Summary

The main and most current data on epidemiology, prevention, microbiology, diagnosis, and management for each one of the most important postoperative infective complications are reported. The establishment of an antimicrobial stewardship in each hospital seems to be, at the moment, the more valid strategy to counteract the challenging problems.

Maxillary Fungal Osteomyelitis Mimicking and Treated as Endodontic Pathosis

Fungal osteomyelitis is a lethal opportunistic infection that affects only a small percentage of patients present to endodontists. It is a highly contagious infection that requires urgent treatment. We discuss three cases in which endodontic pathology was initially recognized but subsequent follow-up revealed severe osteolytic fungal infection of the maxilla manifesting as acute apical abscesses in the maxillary canine region. CBCT demonstrated osteolytic abnormalities, and further histology confirmed the illness was caused by mucormycosis in patients with uncontrolled diabetes mellitus and exposure to COVID-19.

Systematic review: investigating the added diagnostic value of gadolinium contrast agents for osteomyelitis in the appendicular skeleton

OBJECTIVE

Osteomyelitis is an infection of the bone marrow. MRI with gadolinium-based contrast is frequently performed for cases of suspected osteomyelitis. The objective of this systematic review is to examine the diagnostic accuracy of contrast-enhanced vs non-contrast-enhanced MRI for osteomyelitis in the appendicular skeleton.

MATERIALS AND METHODS

We conducted a systematic review of MRI in the diagnosis of osteomyelitis by searching MEDLINE and EMBASE from January 2000 to March 2020. There were 21 studies that met the inclusion criteria for the systematic review for a total of 1095 patients. Analytic methods were based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Evidence was evaluated using the STARD criteria for evaluation of completeness and transparency of reporting.

RESULTS

For diagnosing osteomyelitis in the appendicular skeleton, MRI with gadolinium-based contrast has 89% sensitivity (95% CI, 86-92%), 79% specificity (95% CI, 75-83%), and 90% overall diagnostic accuracy ([SE] = 0.03). For diagnosing osteomyelitis in the appendicular skeleton, MRI without gadolinium-based contrast has a 92% sensitivity (95% CI, 87-96%), 89% specificity (95% CI, 84-93%), and 96% overall diagnostic accuracy ([SE] = 0.03). The median score of included studies was 85% utilizing the STARD criteria with excellent interobserver agreement of 83.4%. Limitations included small sample size of studies, with retrospective designs.

CONCLUSION

No evidence was found to suggest an added diagnostic value of gadolinium contrast for the diagnosis of osteomyelitis in the appendicular skeleton. For routine cases of suspected non-spinal osteomyelitis, non-contrast MRI of the area of interest is the next most appropriate study after radiographs.

Diabetic foot infections: how to investigate more efficiently? A retrospective study in a quaternary university center

Background

Diabetic foot infections are frequent and associated with substantial morbidity and substantial cost to the healthcare system. Up to 34% of diabetic patients will develop an ulcer potentially leading to osteomyelitis. Imaging plays a crucial role in the diagnostic process. Imaging modalities to investigate the diabetic foot infection are many and imaging prescription habits remain heterogeneous across physicians. We aimed to improve the appropriateness of imaging examination requested, and performed, for diabetic foot osteomyelitis and we aimed to reduce the overall imaging-related cost.

Methods

Local committee was created to develop an algorithm for suspected diabetic foot osteomyelitis. Best practices were defined by the local algorithm. The algorithm was shared with our physicians. Pre- and post-intervention analysis was conducted retrospectively. All adult diabetic patients with suspected foot osteomyelitis were included. Adherence to best practices was measured. Statistical analysis with Chi-Square and two tailed unpaired t-test was performed.

Results

Pre-intervention cohort had 223 patients (mean age: 63; 168 men). Adherence to best practice was 43%. Scintigraphy (48%) preferred over MRI (44%) and performed simultaneously in 15 patients. Post-intervention cohort had 73 patients (mean age: 66; 62 men). Adherence to best practice was 78%, improved by 35% (p < 0.001). MRI (51%) preferred over scintigraphy (23%) and performed simultaneously in three patients. Scintigraphy examinations decreased by 25% (p < 0.001). MRI examinations increased by 7% (p = 0.32). Hospital imaging related fees decreased by 22% per patient (p = 0.002).

Conclusion

Interval improvement in adequate adherence while reducing unnecessary examinations for patients and decreasing costs for the healthcare system was observed.

Use of Novel Strategies to Develop Guidelines for Management of Pyogenic Osteomyelitis in Adults: A WikiGuidelines Group Consensus Statement

IMPORTANCE

Traditional approaches to practice guidelines frequently result in dissociation between strength of recommendation and quality of evidence.

OBJECTIVE

To construct a clinical guideline for pyogenic osteomyelitis management, with a new standard of evidence to resolve the gap between strength of recommendation and quality of evidence, through the use of a novel open access approach utilizing social media tools.

EVIDENCE REVIEW

This consensus statement and systematic review study used a novel approach from the WikiGuidelines Group, an open access collaborative research project, to construct clinical guidelines for pyogenic osteomyelitis. In June 2021 and February 2022, authors recruited via social media conducted multiple PubMed literature searches, including all years and languages, regarding osteomyelitis management; criteria for article quality and inclusion were specified in the group's charter. The GRADE system for evaluating evidence was not used based on previously published concerns regarding the potential dissociation between strength of recommendation and quality of evidence. Instead, the charter required that clear recommendations be made only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were drafted to discuss pros and cons of care choices. Both clear recommendations and clinical reviews were planned with the intention to be regularly updated as new data become available.

FINDINGS

Sixty-three participants with diverse expertise from 8 countries developed the group's charter and its first guideline on pyogenic osteomyelitis. These participants included both nonacademic and academic physicians and pharmacists specializing in general internal medicine or hospital medicine, infectious diseases, orthopedic surgery, pharmacology, and medical microbiology. Of the 7 questions addressed in the guideline, 2 clear recommendations were offered for the use of oral antibiotic therapy and the duration of therapy. In addition, 5 clinical reviews were authored addressing diagnosis, approaches to osteomyelitis underlying a pressure ulcer, timing for the administration of empirical therapy, specific antimicrobial options (including empirical regimens, use of antimicrobials targeting resistant pathogens, the role of bone penetration, and the use of rifampin as adjunctive therapy), and the role of biomarkers and imaging to assess responses to therapy.

CONCLUSIONS AND RELEVANCE

The WikiGuidelines approach offers a novel methodology for clinical guideline development that precludes recommendations based on low-quality data or opinion. The primary limitation is the need for more rigorous clinical investigations, enabling additional clear recommendations for clinical questions currently unresolved by high-quality data.

The Role of a Virtual Noncalcium Dual-Energy CT Application in the Detection of Bone Marrow Edema in Peripheral Osteomyelitis

Purpose: To determine the sensitivity and specificity of dual-energy CT (DECT) virtual noncalcium images (VNCa) with bone and soft tissue reconstructions in the diagnosis of osteomyelitis. Materials & Methods: Between December 1, 2014 to December 1, 2020, 91 patients who had 99 DECT performed for a clinical indication of osteomyelitis with corresponding MRI, triphasic bone scan and/or white blood cell scintigraphy with CT/SPECT performed either 2 weeks before or 1 month after the DECT were retrospectively identified. The presence or absence of osteomyelitis was established using a second imaging test, bone biopsy or surgery. Two radiologists interpreted VNCa images alone and with bone and soft tissue reconstructions for osteomyelitis. Fleiss k statistics was used to assess inter-level agreement. Results: Osteomyelitis was present in 26 cases (26.2%), of which 4 cases (4%) had co-existing septic arthritis. DECT was performed at the following sites: ankle/foot (n = 59), calf (n = 12), knee (n = 3), thigh (n = 7), hip (n = 9), pelvis (n = 6), wrist/hand (n = 1), and shoulder (n = 2). Sensitivity with VNCa images alone was 53.8% and 73.1% and specificity was 84.9% and 71.2%. Sensitivity with VNCa images and bone and soft tissue reconstructions was 80.8% and 80.8% and specificity was 80.8% and 72.6%. Interobserver agreement was 76.7% (76 of 99 cases), for VNCa images alone (k = .487), and 66.7% (66 of 99 patients) for bone and soft tissue reconstructions with VNCa images together (k = .390). Conclusion: When VNCa images were combined with bone and soft tissue reconstructions, there is improved sensitivity in the diagnosis of osteomyelitis.

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Pathophysiology and Molecular Imaging of Diabetic Foot Infections

Diabetic foot infection is the leading cause of non-traumatic lower limb amputations worldwide. In addition, diabetes mellitus and sequela of the disease are increasing in prevalence. In 2017, 9.4% of Americans were diagnosed with diabetes mellitus (DM). The growing pervasiveness and financial implications of diabetic foot infection (DFI) indicate an acute need for improved clinical assessment and treatment. Complex pathophysiology and suboptimal specificity of current non-invasive imaging modalities have made diagnosis and treatment response challenging. Current anatomical and molecular clinical imaging strategies have mainly targeted the host's immune responses rather than the unique metabolism of the invading microorganism. Advances in imaging have the potential to reduce the impact of these problems and improve the assessment of DFI, particularly in distinguishing infection of soft tissue alone from osteomyelitis (OM). This review presents a summary of the known pathophysiology of DFI, the molecular basis of current and emerging diagnostic imaging techniques, and the mechanistic links of these imaging techniques to the pathophysiology of diabetic foot infections.

Assessing the optimal imaging modality in the diagnosis of jaw osteomyelitis. A meta-analysis

Osteomyelitis is an inflammatory infectious disease that affects bone and bone marrow. Histopathology remains the gold standard method for diagnosis, but imaging modalities also play an important role. We systematically reviewed five articles with comparative studies on plain films, computed tomography (CT) scan, magnetic resonance imaging (MRI), cone beam computed tomography (CBCT), positron emission tomography (PET), single photon-emission computed tomography (SPECT), scintigraphy, and SPECT/CT. Scintigraphy and SPECT/CT has the highest sensitivity of 100%. PET is only to be used in cases of follow up. Orthopantomography (OPG) is the most common initial diagnostic tool despite its low sensitivity. CT provides the necessary specificity needed for radionuclide imaging, which has the highest negative predictive value of 100% and a positive predictive value >95%. SPECT/CT with 100% sensitivity and 85% specificity can be considered as the imaging modality of choice for initial diagnosis and follow up.

Titanium implant coating based on dopamine-functionalized sulphated hyaluronic acid: in vivo assessment of biocompatibility and antibacterial efficacy

The number of total knee and/or hip replacements are expected to exceed 5 million a year by 2030; the incidence of biofilm-associated complications can vary from 1% in primary implants to 5.6% in case of revision. The purpose of this study was to test the ability of sHA-DA, a partially sulphated hyaluronic acid (sHA) functionalized with a dopamine (DA) moiety, to prevent acute bacterial growth in an in vivo model of an intra-operatively highly contaminated implant. Previously, in vitro studies showed that the DA moiety guarantees good performance as binding agent for titanium surface adhesion, while the negatively charged sHA has both a high efficiency in electrostatic binding of positively charged antibiotics, and bone regenerative effects. The in vitro testing also highlighted the effectiveness of the sHA-DA system in inhibiting bacterial spreading through a sustained release of the antibiotic payload from the implant coating. In this study the chemical stability of the sHA-DA to β-ray sterilization was demonstrated, based on evaluation by NMR, SEC-TDA Omnisec and HPLC-MS analysis, thus supporting the approach of terminal sterilization of the coated implant with no loss of efficacy. Furthermore, an in vivo study in rabbits was performed according to UNI EN ISO 10993-6 to assess the histocompatibility of titanium nails pre-coated with sHA-DA. The implants, placed in the femoral medullary cavity and harvested after 12 weeks, proved to be histocompatible and to allow bone growth in adhesion to the metal surface. Finally, an in vivo model of bacterial contamination was set up by injecting 1 mL of bacterial suspension containing 10⁴ or 10⁶ CFU of methicillin-resistant Staphylococcus aureus (MRSA) into the femoral medullary cavity of 30 rabbits. Titanium nails either uncoated or pre-coated with sHA-DA and loaded directly by the surgeon with 5% vancomycin were implanted in the surgical site. After 1 week, only the animals treated with pre-coated nails did not show the presence of systemic or local bacterial infection, as confirmed by microbiology and histology (Smeltzer score). Further insights into the animal model setup are crucial, however the results obtained suggest that the system can be effective in preventing the onset of the bacterial infective process.

Role of ultrasound and CT in the early diagnosis and surgical treatment of primary sternal osteomyelitis caused by Salmonella: Case reports

Primary sternal osteomyelitis (PSO) caused by Salmonella is a rare condition and most commonly associated with sickle cell disease. Only one such case has been previously reported in an infant (age, <1 year) worldwide. The present study reported on two infantile cases of PSO caused by Salmonella in the absence of any hematological diseases. A total of two male infants (age, ≤1 year) were referred to our hospital for fever and rapid breathing accompanied by a chest wall mass involving the lower end of the sternum. Imaging findings on CT and ultrasound, which included sternal segment dislocation, lytic destruction and periosteal elevation, confirmed the diagnosis of PSO. Blood and purulent material cultures confirmed that the causative pathogen was Salmonella. The infants were completely cured by sequential intravenous and oral antibiotics followed by surgical debridement. The infants remained symptom-free and local recurrence of PSO was not detected at follow-up. PSO caused by Salmonella in the absence of any hematological diseases is a rare condition. Unfamiliarity with this disease may lead to a delay in diagnosis and serious complications. The current case report presents two cases of PSO along with a brief overview of the characteristics and management modalities for this condition, and it provides a comprehensive reference for pediatricians regarding this rare disease, particularly in infants.

A Comparison of the Epidemiology, Clinical Features, and Treatment of Acute Osteomyelitis in Hospitalized Children in Latvia and Norway

Background and objectives: Paediatric acute osteomyelitis (AO) may result in major life-threatening and limb-threatening complications if not recognized and treated early. The management of AO may depend on local microbial prevalence and virulence factors. This study compares the approach to paediatric AO in hospitals in two countries—Latvia and Norway. Materials and Methods: The study includes patients with AO hospitalized in the paediatric department in the Norwegian hospital Sørlandet Sykehus Kristiansand (SSK), in the period between the 1st of January 2012 and the 31st of December 2019. The results from SSK are compared to the results of a published study of AO in patients hospitalized at the Children’s Clinical University Hospital (CCUH) in Riga, Latvia. Results: The most isolated pathogen from cultures in both hospitals was S. aureus (methicillin-sensitive). The lower extremity was the most affected body part (75% in CCUH, 95% in SSK), the main clinical symptom was pain (CCUH 92%, SSK 96.6%). Deep culture aspiration was most often taken intraoperatively in CCUH (76.6%) and percutaneously in SSK (44.8%). Oxacillin was the most applied antibiotic in CCUH (89.4%), and Cloxacillin in SSK (84.6%). Combined treatment with anti-Staphylococcal penicillins and Clindamycin was administered in 25.5% and 33.8% of CCUH and SSK patients, respectively. The median duration of the intravenous antibacterial treatment in CCUH and SSK was 15 and 10 days, respectively, and a switch to oral therapy was mainly made at discharge in both hospitals. The median total duration of antibiotic treatment was 25 days in CCUH and 35 days in SSK. 75% of CCUH and 10.3% of SSK patients were treated surgically. Complications were seen in 47% of patients in CCUH and in 38% in SSK. Conclusions: The transition to oral antibacterial treatment in both hospitals was delayed, which suggests a lack of criteria for discontinuation of intravenous therapy and could potentially contribute to longer hospitalization, higher cost of treatment and risk of complications. The use of more invasive techniques for deep culturing and significantly more common surgical interventions could possibly be linked to a higher complication rate in AO patients treated at the Latvian hospital.

Imaging for detection of osteomyelitis in people with diabetic foot ulcers: A systematic review and meta-analysis

BACKGROUND

Osteomyelitis is an infection of the bone which can occur in people with diabetic foot ulcers. It can be diagnosed using X-rays, ultrasound, scintigraphy, magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET).

OBJECTIVES

To review the evidence on the diagnostic accuracy of imaging tests to diagnose osteomyelitis in people with diabetic foot ulcers.

METHODS

We conducted a systematic review and meta-analysis. MEDLINE, EMBASE and other databases were searched to July 2018. Risk of bias was evaluated. Diagnostic accuracy was estimated using bivariate meta-analyses.

RESULTS

Thirty-six studies were included in the meta-analysis. Eight studies were at high risk of bias MRI had high diagnostic accuracy (22 studies: 96.4 % sensitivity (95 % CI 90.7-98.7); 83.8 % specificity (76.0-89.5)). PET scans also had high accuracy (6 studies: 84.3 % sensitivity (52.8-96.3); 92.8 % specificity (75.7-98.2)), and possibly also SPECT, but with few studies (3 studies: 95.6 % sensitivity (76.0-99.3); 55.1 % specificity (19.3-86.3)). Scintigraphy (17 studies: 84.2 % sensitivity (76.8-89.6); 67.7 % specificity (56.2-77.4)), and X-rays (16 studies: 61.9 % sensitivity (50.5-72.1); 78.3 % specificity (62.9-88.5)) had generally inferior diagnostic accuracy.

CONCLUSIONS

MRI and PET both reliably diagnose osteomyelitis in diabetic foot ulcer patients. SPECT may also have good diagnostic accuracy, although evidence is limited. This review confirms most current guidelines, showing that MRI may be the preferable test in most cases, given its wider availability and the lack of potentially harmful ionising radiation.

Acute osteomyelitis of the distal fibula in children: Treatment options and long-term follow-up

INTRODUCTION

Acute osteomyelitis of the distal fibula is a rare disease in children and is characterized by special features compared with other sites. The objective of this study was to report the functional outcome at long-term follow-up.

METHODS

We reviewed retrospectively, between January 2000 and December 2010, all cases of acute osteomyelitis of the distal fibula. Epidemiological and bacteriological data as well as therapy and outcome factors were analyzed. At the last follow-up, functional outcome was studied based on ankle motion, growth disturbance, and radiological sequelae.

RESULTS

Seven cases of acute osteomyelitis of the distal fibula were found. The mean age was patients was 7.71 years and the sex ratio was 2.5. The portal of entry of the pathogen was a skin injury in 57% of cases. Staphylococcusaureus was identified in 71% of cases. The mean duration of antibiotic therapy was 33.2 days. At a mean of 12.85 years of follow-up, no growth disturbance was found. The mean plantar and dorsal flexion was 41° and 27.7°, respectively. The mean postoperative American Orthopedics Foot and Ankle score (AOFAS) was 96.71 points.

CONCLUSION

Acute osteomyelitis of the distal fibula in children is scarce and rarely reported in the literature. It occurs more often in boys at an average age of 7 years. Local symptoms are usually more obvious than general symptoms. Surgical debridement of the subperiosteal abscess without bone trepanation seems to lead to a satisfactory outcome.

LEVEL OF EVIDENCE

Level IV - case series. IRB: Sahloul Hospital Human Research Ethics Committee.

A comparison of ferumoxytol with gadolinium as contrast agents for the diagnostic magnetic resonance imaging of osteomyelitis

BACKGROUND

Ferumoxytol, an FDA-approved superparamagnetic iron oxide nanoparticle (SPION) preparation used for the treatment of iron deficiency anemia, is also known to be taken up by macrophages in areas of infection or inflammation, where it produces negative contrast changes on T2-weighted MR images.

PURPOSE

We sought to compare Ferumoxytol-induced MRI contrast changes with those observed using standard-of-care Gadolinium in patients presenting with symptoms suggestive of osteomyelitis.

SUBJECTS

Out of eighteen enrolled patients, 15 had MR imaging with both ferumoxytol and gadolinium. Based on clinical and/or pathologic criteria, 7 patients were diagnosed with osteomyelitis, 5 patients had osteomyelitis ruled out, and in 3 patients a definitive diagnosis could not be made.

FIELD STRENGTH

1.5 Tesla.

SEQUENCES

Used included STIR, T1-weighted and T2-weighted spin echo.

ASSESSMENT

The mean contrast changes upon ferumoxytol and gadolinium administration were measured from lesion regions of interest and compared with control regions.

STATISTICAL TESTS

Student's t-test, propagation of errors. Data are reported as means ± S.E.

RESULTS

The mean contrast changes, ΔC, associated with a diagnosis of osteomyelitis were found to be ΔCFe = -2.7 ± 0.7 when Ferumoxytol and T2w imaging sequences were used and ΔCGd = +3.1 ± 1.1 (P < 0.001) when Gadolinium and a T1w imaging sequence was used. The MRI contrast changes for both agents correlated with systemic markers of inflammation, such as the erythrocyte sedimentation rate. In patients without osteomyelitis, no significant contrast changes were observed in T2-weighted, Ferumoxytol-contrasted MRI. The macrophages in osteomyelitic lesions were found to take up at least 16 times as much iron as benign bone marrow.

DATA CONCLUSION

We conclude that in terms of its MRI diagnostic accuracy for osteomyelitis Ferumoxytol-contrasted MRI is a promising approach for diagnosing osteomyelitis that merits further study.

Management of diabetic foot infections in the light of recent literature and new international guidelines

Introduction: In May 2019 the International Working Group on the Diabetic Foot (IWGDF) launched their quadrennially updated guidelines on the management of diabetic foot infections (DFIs). Concomitantly, the number of new publications regarding DFI increased.Areas covered: The IWGDF committee developed and addressed key questions and produced evidence-based recommendations related to diagnosing and treating DFIs. This narrative review provides an overview of this new guideline and also of other recently published literature in the field of DFIs.Expert opinion: The 2019 IWGDF guidelines provide an authoritative, international, evidence-based approach to diagnosing and treating DFIs. The 27 recommendations are supported by systematic reviews of both diagnosis and interventions. Our review of this guideline, along with other recent publications in the field, allows us to offer state-of-the-art guidance for caring for these difficult infections. As the evidence base for management of DFIs remains suboptimal, we need further research to improve the management of DFIs.