Nuclear medicine imaging of bone infections

Machine learning diagnosis of active Juvenile Idiopathic Arthritis on blood pool [ 99M Tc] Tc-MDP scintigraphy images

PURPOSE

Neural network has widely been applied for medical classifications and disease diagnosis. This study employs deep learning to best discriminate Juvenile Idiopathic Arthritis (JIA), a pediatric chronic joint inflammatory disease, from healthy joints by exploring blood pool images of 2phase [ 99m Tc] Tc-MDP bone scintigraphy.

METHODS

Self-deigned multi-input Convolutional Neural Network (CNN) in addition to three available pre-trained models including VGG16, ResNet50 and Xception are applied on 1304 blood pool images of 326 healthy and known JIA children and adolescents (aged 1-16).

RESULTS

The self-designed model ROC analysis shows diagnostic efficiency with Area Under the Curve (AUC) 0.82 and 0.86 for knee and ankle joints, respectively. Among the three pertained models, VGG16 ROC analysis reveals AUC 0.76 and 0.81 for knee and ankle images, respectively.

CONCLUSION

The self-designed model shows best performance on blood pool scintigraph diagnosis of patients with JIA. VGG16 was the most efficient model rather to other pre-trained networks. This study can pave the way of artificial intelligence (AI) application in nuclear medicine for the diagnosis of pediatric inflammatory disease.

ACR Appropriateness Criteria® Imaging After Total Knee Arthroplasty: 2023 Update

Total knee arthroplasty is the most commonly performed joint replacement procedure in the United States. This manuscript will discuss the recommended imaging modalities for six clinical variants; 1. follow-up of symptomatic or asymptomatic patients with a total knee arthroplasty. Initial imaging, 2. Suspected infection after total knee arthroplasty. Additional imaging following radiographs, 3. Pain after total knee arthroplasty. Infection excluded. Suspect aseptic loosening or osteolysis or instability. Additional imaging following radiographs, 4. Pain after total knee arthroplasty. Suspect periprosthetic or hardware fracture. Additional imaging following radiographs, 5. Pain after total knee arthroplasty. Measuring component rotation. Additional imaging following radiographs, and 6. Pain after total knee arthroplasty. Suspect periprosthetic soft-tissue abnormality unrelated to infection, including quadriceps or patellar tendinopathy. Additional imaging following radiographs. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Value of [18F]FDG PET/CT in Diagnosis and Management of Spondylodiscitis

Vertebral osteomyelitis is the third most common form of osteomyelitis in patients over 50 years of age.Whereas prompt (pathogen-directed) therapy is crucially associated with better outcomes, the heterogeneous clinical presentation of disease with unspecific symptoms often delays adequate treatment initiation. Diagnosis requires a careful investigation of medical history, clinical findings and diagnostic imaging, including magnetic resonance imaging and nuclear medicine techniques.Due to its high sensitivity, [18F]FDG PET/CT is becoming increasingly important in diagnosis and management of spondylodiscitis, especially in the postoperative setting with presence of spinal hardware or other implantable devices in which MRI is limited.

Value of [18F]FDG PET/CT in diagnosis and management of spondylodiscitis

Vertebral osteomyelitis is the third most common form of osteomyelitis in patients over 50 years of age.Whereas prompt (pathogen-directed) therapy is crucially associated with better outcomes, the heterogeneous clinical presentation of disease with unspecific symptoms often delays adequate treatment initiation. Diagnosis requires a careful investigation of medical history, clinical findings and diagnostic imaging, including magnetic resonance imaging and nuclear medicine techniques.Due to its high sensitivity, [¹⁸F]FDG PET/CT is becoming increasingly important in diagnosis and management of spondylodiscitis, especially in the postoperative setting with presence of spinal hardware or other implantable devices in which MRI is limited.

2022 SPILF - Clinical Practice guidelines for the diagnosis and treatment of disco-vertebral infection in adults

These guidelines are an update of those made in 2007 at the request of the French Society of Infectious Diseases (SPILF, Société de Pathologie Infectieuse de Langue Française). They are intended for use by all healthcare professionals caring for patients with disco-vertebral infection (DVI) on spine, whether native or instrumented. They include evidence and opinion-based recommendations for the diagnosis and management of patients with DVI. ESR, PCT and scintigraphy, antibiotic therapy without microorganism identification (except for emergency situations), therapy longer than 6 weeks if the DVI is not complicated, contraindication for spinal osteosynthesis in a septic context, and prolonged dorsal decubitus are no longer to be done in DVI management. MRI study must include exploration of the entire spine with at least 2 orthogonal planes for the affected level(s). Several disco-vertebral samples must be performed if blood cultures are negative. Short, adapted treatment and directly oral antibiotherapy or early switch from intravenous to oral antibiotherapy are recommended. Consultation of a spine specialist should be requested to evaluate spinal stability. Early lifting of patients is recommended.

Application of Artificial Intelligence Nuclear Medicine Automated Images Based on Deep Learning in Tumor Diagnosis

In order to correctly obtain normal tissues and organs and tumor lesions, the research on multimodal medical image segmentation based on deep learning fully automatic segmentation algorithm is more meaningful. This article aims to study the application of deep learning-based artificial intelligence nuclear medicine automated images in tumor diagnosis. This paper studies the methods to improve the accuracy of the segmentation algorithm from the perspective of boundary recognition and shape changeable adaptive capabilities, studies the active contour model based on boundary constraints, and proposes a superpixel boundary-aware convolution network to realize the automatic CT cutting algorithm. In this way, the tumor image can be cut more accurately. The experimental results in this paper show that the improved algorithm in this paper is more robust than the traditional CT algorithm in terms of accuracy and sensitivity, an increase of about 12%, and a slight increase in the negative prediction rate of 3%. In the comparison of cutting images of malignant tumors, the cutting effect of the algorithm in this paper is about 34% higher than that of the traditional algorithm.

Hybrid imaging of complicating osteomyelitis in the peripheral skeleton

Diagnosing complicating osteomyelitis (COM) is clinically challenging. Laboratory tests are of limited utility, and other than isolation of the offending organism, diagnostic imaging tests are of paramount importance. Nuclear Medicine techniques play an important role in noninvasive evaluation of osteomyelitis, using both single-photon emission tomography (SPECT) and positron emission tomography (PET) radiopharmaceuticals. It is well-known that those conventional imaging modalities are not performing well in the distinction between soft-tissue and deep bone infection due to the lack of anatomical information. These difficulties have been overcome, to a great extent, with the introduction of in-line SPECT-CT and PET-CT systems which have revolutionized the field of diagnostic medical imaging. Hybrid imaging is especially useful in sites of suspected COM with underlying structural bone alterations. The first clinical studies with these integrated hybrid machines in the field of COM, including metallic implants imaging, are highly promising. In summary, WBC/AGA SPECT-CT and FDG-PET-CT seem to be the most accurate hybrid imaging modality for COM of the peripheral bone. However, there are still false positives, especially in aseptic tibial nonunions and/or metallic implants, as well as in the immediate postoperative setting. Furthermore, there is a lack of well-designed large multicentre prospective studies. Hopefully, in the future, the complementary use of morphological and functional hybrid imaging modalities may overcome some of the challenges faced in the assessment of COM.

Molecular imaging in MSK radiology: Where are we going?

Musculoskeletal (MSK) pathologies are one of the leading causes of disability worldwide. However, treatment options and understanding of pathogenetic processes are still partially unclear, mainly due to a limited ability in early disease detection and response to therapy assessment. In this scenario, thanks to a strong technological advancement, structural imaging is currently established as the gold-standard of diagnosis in many MSK disorders but each single diagnostic modality (plain films, high-resolution ultrasound, computed tomography and magnetic resonance) still suffer by a low specificity regarding the characterization of inflammatory processes, the quantification of inflammatory activity levels, and the degree of response to therapy. To overcome these limitations, molecular imaging techniques may play a promising role. Starting from the strengths and weaknesses of structural anatomical imaging, the present narrative review aims to highlight the promising role of molecular imaging in the assessment of non-neoplastic MSK diseases with a special focus on its role to monitor treatment response.

Nuclear Medicine Scans in Total Joint Replacement

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A 3-phase bone scan is a potential first-line nuclear medicine study for pain after total joint arthroplasty (TJA) when there is concern for periprosthetic joint infection or aseptic loosening.

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In patients who have a positive bone scintigraphy result and suspected infection of the joint, but where aspiration or other studies are inconclusive, labeled leukocyte scintigraphy with bone marrow imaging may be of benefit.

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Magnetic resonance imaging (MRI), while not a nuclear medicine study, also shows promise and has the advantage of providing information about the soft tissues around a total joint replacement.

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Radiotracer uptake patterns in scintigraphy are affected by the prosthesis (total knee arthroplasty [TKA] versus total hip arthroplasty [THA]) and the use of cement.

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Nuclear medicine scans may be ordered 1 year postoperatively but may have positive findings that are due to normal physiologic bone remodeling. Nuclear studies may be falsely positive for up to 2 years after TJA.

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Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) (SPECT/CT), fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT, and MRI show promise; however, more studies are needed to better define their role in the diagnostic workup of pain after TJA.

Research Progress of [68Ga]Citrate PET's Utility in Infection and Inflammation Imaging: a Review

Imaging diagnosis of infection and inflammation has been challenging for many years. Infection imaging agents commonly used in nuclear medicine, such as [⁶⁷Ga]citrate, 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG), and radionuclide-labeled leukocytes, have their own shortcomings. Identification of a tracer with considerable economic benefit, high specificity, and low radiation dose has become clinically urgent. In the twenty-first century, with the increasing availability of positron emission tomography (PET) devices and the commercialization of Ge-68/Ga-68 generators, the study of [⁶⁸Ga]citrate applications for infection and inflammation has increased and shown good potential. In this report, the research progress that supports [⁶⁸Ga]citrate PET's applications various infectious diseases and inflammation is reviewed.

Comparison between gallium-68 citrate positron emission tomography-computed tomography and gallium-67 citrate scintigraphy for infection imaging

BACKGROUND

Preliminary studies have reported promising results for the utility of gallium-68 (Ga-68) citrate positron emission tomography-computed tomography (PET-CT) for infection imaging. This technique offers reduced radiation dose to patients, shorter time between injection and imaging and reduced time for image acquisition compared to the 'gold standard' nuclear imaging technique: gallium-67 (Ga-67) citrate scintigraphy.

AIMS

To compare the two imaging modalities to ascertain whether Ga-68 citrate PET-CT is of equivalent diagnostic efficacy for bone and joint infection or pyrexia of unknown origin (PUO) and to assess image quality and reporter confidence.

METHODS

Patients with PUO and suspected bone or joint infection underwent Ga-67 citrate scintigraphy and Ga-68 citrate PET-CT. Participants were followed up for 3 months to record subsequent treatment, investigations and outcome.

RESULTS

60 patients were recruited to this multicentre prospective study: 32 for bone and joint infection, 28 for PUO. The results show a sensitivity of 81% for Ga-67 citrate scintigraphy and 69% for Ga-68 citrate PET-CT, a specificity of 79% for Ga-67 citrate and 67% for Ga-68 citrate and were concordant for 76% of the participants. The reporting physician confidence was significantly lower for Ga-68 citrate (P < 0.05), frequently due to prominent physiologic blood pool activity adjacent to the site of infection.

CONCLUSION

The sensitivity and specificity of Ga-68 citrate PET-CT were found to be consistently lower than Ga-67 citrate scintigraphy. Additionally, due to the insufficient level of confidence of the reporting physicians for the Ga-68 citrate PET-CT, this modality could not currently be recommended to replace Ga-67 citrate scintigraphy for routine clinical use.

Joint EANM/ESNR and ESCMID-endorsed consensus document for the diagnosis of spine infection (spondylodiscitis) in adults

PURPOSE

Diagnosis of spondylodiscitis (SD) may be challenging due to the nonspecific clinical and laboratory findings and the need to perform various diagnostic tests including serologic, imaging, and microbiological examinations. Homogeneous management of SD diagnosis through international, multidisciplinary guidance would improve the sensitivity of diagnosis and lead to better patient outcome.

METHODS

An expert specialist team, comprising nuclear medicine physicians appointed by the European Association of Nuclear Medicine (EANM), neuroradiologists appointed by the European Society of Neuroradiology (ESNR), and infectious diseases specialists appointed by the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), reviewed the literature from January 2006 to December 2015 and proposed 20 consensus statements in answer to clinical questions regarding SD diagnosis. The statements were graded by level of evidence level according to the 2011 Oxford Centre for Evidence-based Medicine criteria and included in this consensus document for the diagnosis of SD in adults. The consensus statements are the result of literature review according to PICO (P:population/patients, I:intervention/indicator, C:comparator/control, O:outcome) criteria. Evidence-based recommendations on the management of adult patients with SD, with particular attention to radiologic and nuclear medicine diagnosis, were proposed after a systematic review of the literature in the areas of nuclear medicine, radiology, infectious diseases, and microbiology.

RESULTS

A diagnostic flow chart was developed based on the 20 consensus statements, scored by level of evidence according to the Oxford Centre for Evidence-based Medicine criteria.

CONCLUSIONS

This consensus document was developed with a final diagnostic flow chart for SD diagnosis as an aid for professionals in many fields, especially nuclear medicine physicians, radiologists, and orthopaedic and infectious diseases specialists.

Diagnosis of peripheral bone and prosthetic joint infections: overview on the consensus documents by the EANM, EBJIS, and ESR (with ESCMID endorsement)

OBJECTIVES

Peripheral bone infection (PBI) and prosthetic joint infection (PJI) are two different infectious conditions of the musculoskeletal system. They have in common to be quite challenging to be diagnosed and no clear diagnostic flowchart has been established. Thus, a conjoined initiative on these two topics has been initiated by the European Society of Radiology (ESR), the European Association of Nuclear Medicine (EANM), the European Bone and Joint Infection Society (EBJIS), and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID). The purpose of this work is to provide an overview on the two consensus documents on PBI and PJI that originated by the conjoined work of the ESR, EANM, and EBJIS (with ESCMID endorsement).

METHODS AND RESULTS

After literature search, a list of 18 statements for PBI and 25 statements for PJI were drafted in consensus on the most debated diagnostic challenges on these two topics, with emphasis on imaging.

CONCLUSIONS

Overall, white blood cell scintigraphy and magnetic resonance imaging have individually demonstrated the highest diagnostic performance over other imaging modalities for the diagnosis of PBI and PJI. However, the choice of which advanced diagnostic modality to use first depends on several factors, such as the benefit for the patient, local experience of imaging specialists, costs, and availability. Since robust, comparative studies among most tests do not exist, the proposed flowcharts are based not only on existing literature but also on the opinion of multiple experts involved on these topics.

KEY POINTS

• For peripheral bone infection and prosthetic joint infection, white blood cell and magnetic resonance imaging have individually demonstrated the highest diagnostic performance over other imaging modalities. • Two evidence- and expert-based diagnostic flowcharts involving variable combination of laboratory tests, biopsy methods, and radiological and nuclear medicine imaging modalities are proposed by a multi-society expert panel. • Clinical application of these flowcharts depends on several factors, such as the benefit for the patient, local experience, costs, and availability.

Immuno-Imaging to Predict Treatment Response in Infection, Inflammation and Oncology

Background: Molecular nuclear medicine plays a pivotal role for diagnosis in a preclinical phase, in genetically susceptible patients, for radio-guided surgery, for disease relapse evaluation, and for therapy decision-making and follow-up. This is possible thanks to the development of new radiopharmaceuticals to target specific biomarkers of infection, inflammation and tumour immunology. Methods: In this review, we describe the use of specific radiopharmaceuticals for infectious and inflammatory diseases with the aim of fast and accurate diagnosis and treatment follow-up. Furthermore, we focus on specific oncological indications with an emphasis on tumour immunology and visualizing the tumour environment. Results: Molecular nuclear medicine imaging techniques get a foothold in the diagnosis of a variety of infectious and inflammatory diseases, such as bacterial and fungal infections, rheumatoid arthritis, and large vessel vasculitis, but also for treatment response in cancer immunotherapy. Conclusion: Several specific radiopharmaceuticals can be used to improve diagnosis and staging, but also for therapy decision-making and follow-up in infectious, inflammatory and oncological diseases where immune cells are involved. The identification of these cell subpopulations by nuclear medicine techniques would provide personalized medicine for these patients, avoiding side effects and improving therapeutic approaches.

Consensus document for the diagnosis of peripheral bone infection in adults: a joint paper by the EANM, EBJIS, and ESR (with ESCMID endorsement)

INTRODUCTION

In adults with a suspicion of peripheral bone infection, evidence-based guidelines in choosing the most accurate diagnostic strategy are lacking.

AIM AND METHODS

To provide an evidence-based, multidisciplinary consensus document on the diagnostic management of adult patients with PBIs, we performed a systematic review of relevant infectious, microbiological, orthopedic, radiological, and nuclear medicine literature. Delegates from four European societies (European Bone and Joint Infection Society, European Society of Microbiology and Infectious Diseases, European Society or Radiology, and European Association of Nuclear Medicine) defined clinical questions to be addressed, thoroughly reviewed the literature pertinent to each of the questions, and thereby evaluated the diagnostic accuracy of each diagnostic technique. Inclusion of the papers per statement was based on a PICO (Population/problem - Intervention/indicator - Comparator - Outcome) question following the strategy reported by the Oxford Centre for Evidence-based Medicine. For each statement, the level of evidence was graded according to the 2011 review of the Oxford Centre for Evidence-based Medicine. All approved statements were addressed taking into consideration the available diagnostic procedures, patient acceptance, tolerability, complications, and costs in Europe. Finally, a commonly agreed-upon diagnostic flowchart was developed.

Bone Scintigraphy: A Review of Technical Aspects and Applications in Orthopedic Surgery

Due to its high sensitivity, low cost, accessibility, and ease of use, bone scintigraphy is used in orthopedic surgery for the diagnosis and management of varied pathology. It is commonly used for insufficiency fractures, metastatic neoplasia, staging and surveillance of sarcoma, and nonaccidental trauma. It augments diagnoses, including stress or occult fractures, musculoskeletal neoplasia or infection, and chronic regional pain syndrome, in patients presenting with normal results on radiographs. Bone scan images are resistant to metal-based implant artifact, allowing effective evaluation of failed total joint prostheses. Bone scintigraphy remains an underused tool in the evaluation and management of orthopedic patients. [Orthopedics. 2019; 42(1):e14-e24.].

Clinical indications, image acquisition and data interpretation for white blood cells and anti-granulocyte monoclonal antibody scintigraphy: an EANM procedural guideline

INTRODUCTION

Radiolabelled autologous white blood cells (WBC) scintigraphy is being standardized all over the world to ensure high quality, specificity and reproducibility. Similarly, in many European countries radiolabelled anti-granulocyte antibodies (anti-G-mAb) are used instead of WBC with high diagnostic accuracy. The EANM Inflammation & Infection Committee is deeply involved in this process of standardization as a primary goal of the group.

AIM

The main aim of this guideline is to support and promote good clinical practice despite the complex environment of a national health care system with its ethical, economic and legal aspects that must also be taken into consideration.

METHOD

After the standardization of the WBC labelling procedure (already published), a group of experts from the EANM Infection & Inflammation Committee developed and validated these guidelines based on published evidences.

RESULTS

Here we describe image acquisition protocols, image display procedures and image analyses as well as image interpretation criteria for the use of radiolabelled WBC and monoclonal antigranulocyte antibodies. Clinical application for WBC and anti-G-mAb scintigraphy is also described.

CONCLUSIONS

These guidelines should be applied by all nuclear medicine centers in favor of a highly reproducible standardized practice.

Osteomyelitis of the Thumb in a 21-Year-Old Chiropractic Patient: A Case Report

OBJECTIVE

The purpose of this case report is to describe the presentation of a patient with osteomyelitis of the thumb.

CLINICAL FEATURES

A 21-year-old man presented with painful, red, and edematous thumb pain over the anterior and posterior surface for a duration of 4 days. The patient reported no trauma or recent operation. The patient was treated conservatively for capsulitis. The patient's symptoms worsened within 2 days, and he was referred for additional imaging consisting of a bone scan. The bone scan showed increased uptake, resulting in a change of diagnosis to suspected osteomyelitis. The patient was referred to a medical doctor for care that consisted of antibiotics and physiotherapy.

INTERVENTION AND OUTCOME

Despite treatment, the patient had some mild permanent damage to the range of motion of the joint and soft tissue volume loss.

CONCLUSION

This case demonstrates the importance of considering osteomyelitis as a differential diagnosis. Amputation was avoided for this patient because of the early recognition and referral.

ACR Appropriateness Criteria® Imaging After Total Knee Arthroplasty

Total knee arthroplasty (TKA) is the most commonly performed joint replacement procedure in the United States and annual demand for primary TKA is expected to grow by 673% by 2030. The first part provides an overview of imaging modalities (radiographs, CT, MRI, ultrasound, and various nuclear medicine studies) and discusses their usefulness in the imaging evaluation of TKA. The second part focuses on evidence-based imaging and imaging-guided intervention algorithms for the workup of TKA and its complications, including routine follow-up, component wear, periprosthetic infection, aseptic loosening, granulomas/osteolysis, conventional and rotational instability, periprosthetic fracture, patellar complications, and a variety of periprosthetic soft tissue abnormalities. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

A Comparative 68Ga-Citrate and 68Ga-Chloride PET/CT Imaging of Staphylococcus aureus Osteomyelitis in the Rat Tibia

There may be some differences in the in vivo behavior of ⁶⁸Ga-chloride and ⁶⁸Ga-citrate leading to different accumulation profiles. This study compared ⁶⁸Ga-citrate and ⁶⁸Ga-chloride PET/CT imaging under standardized experimental models. Methods. Diffuse Staphylococcus aureus tibial osteomyelitis and uncomplicated bone healing rat models were used (n = 32). Two weeks after surgery, PET/CT imaging was performed on consecutive days using ⁶⁸Ga-citrate or ⁶⁸Ga-chloride, and tissue accumulation was confirmed by ex vivo analysis. In addition, peripheral quantitative computed tomography and conventional radiography were performed. Osteomyelitis was verified by microbiological analysis and specimens were also processed for histomorphometry. Results. In PET/CT imaging, the SUV_max of ⁶⁸Ga-chloride and ⁶⁸Ga-citrate in the osteomyelitic tibias (3.6 ± 1.4 and 4.7 ± 1.5, resp.) were significantly higher (P = 0.0019 and P = 0.0020, resp.) than in the uncomplicated bone healing (2.7 ± 0.44 and 2.5 ± 0.49, resp.). In osteomyelitic tibias, the SUV_max of ⁶⁸Ga-citrate was significantly higher than the uptake of ⁶⁸Ga-chloride (P = 0.0017). In animals with uncomplicated bone healing, no difference in the SUV_max of ⁶⁸Ga-chloride or ⁶⁸Ga-citrate was seen in the operated tibias. Conclusions. This study further corroborates the use of ⁶⁸Ga-citrate for PET imaging of osteomyelitis.

Intensity of 18F-FDG PET Uptake in Culture-Negative and Culture-Positive Cases of Chronic Osteomyelitis

Microbiologic cultures are not infrequently negative in patients with a histopathologic diagnosis of chronic osteomyelitis. Culture-negative cases may represent low-grade infections with a lower metabolic activity than culture-positive cases. ¹⁸F-FDG PET could potentially detect such a difference. We determined whether the level of ¹⁸F-FDG PET uptake differs in patients with culture-negative and culture-positive osteomyelitis. We reviewed the clinical charts of 40 consecutive patients, who had diagnostic ¹⁸F-FDG PET for a suspected bone infection. Twenty-six patients were eligible with a confirmed diagnosis based on microbiologic cultures and/or histopathologic examination. Sixteen of 26 patients had chronic osteomyelitis. Eight of them had positive cultures, seven had negative cultures, and one patient had no cultures of the biopsy specimen. The patients with histologically and/or microbiologically proven osteomyelitis were correctly interpreted as true positive in the routine clinical reading of ¹⁸F-FDG PET images. There was no relationship between the level of ¹⁸F-FDG PET uptake and the presence of positive or negative bacterial cultures. The result favors the concept that that culture-negative cases of osteomyelitis are false-negative infections due to nonculturable microbes. ¹⁸F-FDG PET may help to confirm the presence of metabolically active infection in these patients and guide their appropriate treatment.

Comparison of 99mTc-UBI 29-41, 99mTc-ciprofloxacin, 99mTc-ciprofloxacin dithiocarbamate and 111In-biotin for targeting experimental Staphylococcus aureus and Escherichia coli foreign-body infections: an ex-vivo study

BACKGROUND

Diagnosis of implant-associated infection is challenging. Several radiopharmaceuticals have been described but direct comparisons are limited. Here we compared in vitro and in an animal model 99mTc-UBI, 99mTc-ciprofloxacin, 99mTcN-CiproCS2 and 111In-DTPA-biotin for targeting E. coli (ATCC 25922) and S. aureus (ATCC 43335).

METHODS

Stability controls were performed with the labelled radiopharmaceuticals during 6 hours in saline and serum. The in vitro binding to viable or killed bacteria was evaluated at 37 °C and 4 °C. For in vivo studies, Teflon cages were subcutaneously implanted in mice, followed by percutaneous infection. Biodistribution of i.v. injected radiolabelled radiopharmaceuticals were evaluated during 24 h in cages and dissected tissues.

RESULTS

Labelling efficiency of all radiopharmaceuticals ranged between 94% and 98%, with high stability both in saline and in human serum. In vitro binding assays displayed a rapid but poor bacterial binding for all tested agents. Similar binding kinetic occurred also with heat-killed and ethanol-killed bacteria. In the tissue cage model, infection was detected at different time points: 99mTc-UBI and 99mTcN-CiproCS2 showed higher infected cage/sterile cage ratio at 24 hours for both E. coli and S. aureus; 99mTc-Ciprofloxacin at 24 hours for both E. coli and at 4 hours for S. aureus; 111In-DTPA-biotin accumulates faster in both E. coli and S. aureus infected cages.

CONCLUSIONS

99mTc-UBI, 99mTcN-CiproCS2 showed poor in vitro binding but good in vivo binding to E. coli only. 111In-DTPA-biotin showed poor in vitro binding but good in vivo binding to S. aureus and poor to E. coli. 99mTc-Ciprofloxacin showed poor in vitro binding but good in vivo binding to all tested bacteria. The mechanism of accumulation in infected sites remains to be elucidated.

Multimodal optical measurement for study of lower limb tissue viability in patients with diabetes mellitus

According to the International Diabetes Federation, the challenge of early stage diagnosis and treatment effectiveness monitoring in diabetes is currently one of the highest priorities in modern healthcare. The potential of combined measurements of skin fluorescence and blood perfusion by the laser Doppler flowmetry method in diagnostics of low limb diabetes complications was evaluated. Using Monte Carlo probabilistic modeling, the diagnostic volume and depth of the diagnosis were evaluated. The experimental study involved 76 patients with type 2 diabetes mellitus. These patients were divided into two groups depending on the degree of complications. The control group consisted of 48 healthy volunteers. The local thermal stimulation was selected as a stimulus on the blood microcirculation system. The experimental studies have shown that diabetic patients have elevated values of normalized fluorescence amplitudes, as well as a lower perfusion response to local heating. In the group of people with diabetes with trophic ulcers, these parameters also significantly differ from the control and diabetes only groups. Thus, the intensity of skin fluorescence and level of tissue blood perfusion can act as markers for various degrees of complications from the beginning of diabetes to the formation of trophic ulcers.

Accuracy of diagnostic imaging modalities for peripheral post-traumatic osteomyelitis - a systematic review of the recent literature

AIMS

Post-traumatic osteomyelitis (PTO) is difficult to diagnose and there is no consensus on the best imaging strategy. The aim of this study is to present a systematic review of the recent literature on diagnostic imaging of PTO.

METHODS

A literature search of the EMBASE and PubMed databases of the last 16 years (2000-2016) was performed. Studies that evaluated the accuracy of magnetic resonance imaging (MRI), three-phase bone scintigraphy (TPBS), white blood cell (WBC) or antigranulocyte antibody (AGA) scintigraphy, fluorodeoxyglucose positron emission tomography (FDG-PET) and plain computed tomography (CT) in diagnosing PTO were considered for inclusion. The review was conducted using the PRISMA statement and QUADAS-2 criteria.

RESULTS

The literature search identified 3358 original records, of which 10 articles could be included in this review. Four of these studies had a comparative design which made it possible to report the results of, in total, 17 patient series. WBC (or AGA) scintigraphy and FDG-PET exhibit good accuracy for diagnosing PTO (sensitivity ranged from 50-100%, specificity ranged from 40-97% versus 83-100% and 51%-100%, respectively). The accuracy of both modalities improved when a hybrid imaging technique (SPECT/CT & FDG-PET/CT) was performed. For FDG-PET/CT, sensitivity ranged between 86 and 94% and specificity between 76 and 100%. For WBC scintigraphy + SPECT/CT, this is 100% and 89-97%, respectively.

CONCLUSIONS

Based on the best available evidence of the last 16 years, both WBC (or AGA) scintigraphy combined with SPECT/CT or FDG-PET combined with CT have the best diagnostic accuracy for diagnosing peripheral PTO.

Evaluation of a Novel Tc-99m Labelled Vitamin B12 Derivative for Targeting Escherichia coli and Staphylococcus aureus In Vitro and in an Experimental Foreign-Body Infection Model

Purpose

Vitamin B₁₂ (cyanocobalamin, Cbl) is accumulated by rapidly replicating prokaryotic and eukaryotic cells. We investigated the potential of a Tc-99m labelled Cbl derivative ([^99mTc]PAMA(4)-Cbl) for targeting infections caused by Escherichia coli and Staphylococcus aureus. In vitro binding assays were followed by biodistribution studies in a mouse model of foreign body infection.

Procedures

E. coli (ATCC 25922) and S. aureus (ATCC 43335) were used as test strains. [⁵⁷Co]Cbl, [⁶⁷Ga]citrate and [^99mTc]DTPA served as reference compounds. The in vitro competitive binding of [⁵⁷Co]Cbl or [^99mTc]PAMA(4)-Cbl, and unlabeled Cbl, to viable or killed bacteria, was evaluated at 37 and 4 °C. A cage mouse model of infection was used for biodistribution of intravenous [⁵⁷Co]Cbl and [^99mTc]PAMA(4)-Cbl in cage and dissected tissues of infected and non-infected mice.

Results

Maximum binding (mean ± SD) of [⁵⁷Co]Cbl to viable E. coli was 81.7 ± 2.6 % and to S. aureus 34.0 ± 6.7 %, at 37 °C; no binding occurred to heat-killed bacteria. Binding to both test strains was displaced by 100- to 1000-fold excess of unlabeled Cbl. The in vitro binding of [^99mTc]PAMA(4)-Cbl was 100-fold and 3-fold lower than the one of [⁵⁷Co]Cbl for E. coli and S. aureus, respectively. In vivo, [^99mTc]PAMA(4)-Cbl showed peak percentage of injected dose (% ID) values between 1.33 and 2.3, at 30 min post-injection (p.i.). Significantly higher retention occurred in cage fluids infected with S. aureus at 4 h and with E. coli at 8 h p.i. than in non-infected animals. Accumulation into infected cages was also higher than the one of [^99mTc]DTPA, which showed similar biodistribution in infected and sterile mice. [⁵⁷Co]Cbl gradually accumulated in cages with peaks % ID between 3.58 and 4.83 % achieved from 24 to 48 h. Discrimination for infection occurred only in E. coli-infected mice, at 72 h p.i. [⁶⁷Ga]citrate, which showed a gradual accumulation into cage fluids during 12 h, was discriminative for infection from 48 to 72 h p.i. (P < 0.05).

Conclusion

Cbl displayed rapid and specific in vitro binding to test strains. [^99mTc]PAMA(4)-Cbl was rapidly cleared from most tissues and discriminated between sterile and infected cages, being a promising candidate for imaging infections in humans.

Nuclear medicine imaging of posttraumatic osteomyelitis

Introduction

Early recognition of a possible infection and therefore a prompt and accurate diagnostic strategy is essential for a successful treatment of posttraumatic osteomyelitis (PTO). However, at this moment there is no single routine test available that can detect osteomyelitis beyond doubt and the performed diagnostic tests mostly depend on personal experience, available techniques and financial aspects. Nuclear medicine techniques focus on imaging pathophysiological changes which usually precede anatomical changes. Together with recent development in hybrid camera systems, leading to better spatial resolution and quantification possibilities, this provides new opportunities and possibilities for nuclear medicine modalities to play an important role in diagnosing PTO.

Aim

In this overview paper the techniques and available literature results for PTO are discussed for the three most commonly used nuclear medicine techniques: the three phase bone scan (with SPECT-CT), white blood cell scintigraphy (also called leukocyte scan) with SPECT-CT and ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT. Emphasis is on how these techniques are able to answer the diagnostic questions from the clinicians (trauma and orthopaedic surgeons) and which technique should be used to answer a specific question. Furthermore, three illustrative cases from clinical practice are described.

Three-phase bone scintigraphy for imaging osteoradionecrosis of the jaw

This study evaluates the diagnostic utility of 3-phase bone scintigraphy for diagnosing osteoradionecrosis of the jaw (ORNJ).

METHODS

Thirty-two consecutive patients with a history of radiation to the head and neck region (range, 62-70 Gy; mean, 68 Gy; median, 69 Gy) due to squamous cell cancer and suspected ORNJ underwent 3-phase bone scans after injection of 520 to 750 MBq of Tc-MPD. In addition to planar scans, tomographic images (SPECT) were acquired in the second phase and SPECT/CT images during the third phase. Histopathologic findings (n = 18) and clinical follow-up (n = 14) served as reference standard for osteoradionecrosis.

RESULTS

The first, second, and third phases of planar images were rated positive in 18/32 patients (56.3%), 25/32 (78.1%), and 27/32 patients (84.4%), respectively. The late SPECT was positive in all patients (32/32, 100%), respectively. Histopathologic findings available in 18/32 patients (56.3%) confirmed ORNJ in all subjects. Acute inflammation was histologically proven in 18/18 specimens (100%) and additional chronic inflammation in 12/18 (66.7%). In 13/18 (72.2%) specimens, superinfection was evident histopathologically. A photopenic defect with surrounding hypermetabolism, a reported hallmark of ORJN, was found in less than 5%.

CONCLUSIONS

The predominant scintigraphic pattern of osteoradionecrosis includes increased bone mineralization phase in all patients. Central photopenia, reportedly a typical bone scan finding in bisphosphonate-induced osteonecrosis, was not characteristic for ORNJ. A differentiation of acute from chronic inflammatory processes was not possible.

Clinical impact of 18F-FDG-PET/CT in the extra cardiac work-up of patients with infective endocarditis

OBJECTIVE

The purpose of this study was to assess the clinical importance of 18F-FDG-PET/CT used in the extra cardiac work-up of patients with infective endocarditis (IE).

BACKGROUND

IE is a serious condition with a significant mortality. Besides the degree of valvular involvement, the prognosis relies crucially on the presence of systemic infectious embolism.

METHODS

Seventy-two patients (71% males and mean age 63 ± 17 years) with IE were evaluated with 18F-FDG-PET/CT in addition to standard work-up including patient history, physical examination, conventional imaging modalities, and weekly interdisciplinary conferences. When previous unknown lesions detected by 18F-FDG-PET/CT were confirmed by succeeding examinations, they were considered true positive new findings and were further assessed for their clinical importance. Number needed to investigate was calculated as the number of patients who needed to undergo 18F-FDG-PET/CT to find at least one clinical important true positive new finding, not identified by standard work-up prior to 18F-FDG-PET/CT.

RESULTS

18F-FDG-PET/CT detected 114 lesions and 64 were true positive, of which 25 were new findings and detected in 17 patients. In 11 patients, the lesions were considered to have a clinical importance; osteomyelitis (n = 7), iliopsoas abscess (n = 1), gastrointestinal lesions (n = 2), and vascular prosthetic graft (n = 1). Number needed to investigate was 7 (11 of 72 patients).

CONCLUSIONS

18F-FDG-PET/CT detected lesions of clinical importance in one of seven IE patients and may be a substantial imaging technique for tracing peripheral infectious embolism due to IE. Thus, 18F-FDG-PET/CT may help to guide adequate therapy and thereby improve the prognosis of patients with IE.

[SPECT/CT diagnostics for skeletal infections]

CLINICAL/METHODICAL ISSUE

Skeletal infections are often a diagnostic and clinical challenge.

STANDARD RADIOLOGICAL METHODS

Nuclear imaging modalities used in the diagnostic workup of acute and chronic skeletal infections include three-phase bone scintigraphy and scintigraphy with labelled leucocytes.

METHODICAL INNOVATIONS

The introduction of hybrid technologies, such as single photon emission computed tomography/computed tomography (SPECT/CT) has dramatically changed nuclear medical imaging of infections.

PERFORMANCE

In general SPECT/CT leads to a considerably more accurate diagnosis than planar or SPECT imaging.

ACHIEVEMENTS

Given the integrated acquisition of metabolic, functional and morphological information, SPECT/CT has increased in particular the specificity of three-phase skeletal scanning and scintigraphy with labeled leucocytes.

Chronic osteomyelitis of ilium presenting as an expansile mutiloculated lytic lesion - A case report

Chronic iliac osteomyelitis classically presents radiologically as an ill defined radiolucent lesion with moth eaten appearance along with periosteal reaction and sequestrum formation. Our case report presents a rare radiological picture of iliac bone osteomyelitis in the form of an expansile mutiloculated lytic lesion.

Radionuclide imaging in the diagnosis and management of orthopaedic disease

Nuclear medicine imaging is often used in the diagnosis and management of several orthopaedic conditions. Bone scintigraphy measures gamma ray emission to detect the distribution of an injected radiolabeled tracer on multiple image projections. In general, this imaging modality has relatively high sensitivity but low specificity in the diagnosis of occult fractures, bone tumors, metabolic bone disease, and infection. Positron emission tomography measures tissue metabolism and perfusion by detecting short half-life positron ray emission of an injected radiopharmaceutical tracer. Historically, positron emission tomography has been used only to monitor bone metastasis and aid in the diagnosis of osteomyelitis; however, this technology has recently been applied to other orthopaedic conditions for which current imaging modalities are insufficient.

Follow-up of acute osteomyelitis in children: the possible role of PET/CT in selected cases

BACKGROUND

Magnetic resonance imaging (MRI) and/or scintigraphy are commonly used for follow-up in children after treatment of acute osteomyelitis. Regularly, post-treatment imaging reveals pathological findings even if serum inflammatory parameters and clinical presentation are normal. We analyzed combined positron emission tomography and multislice computed tomography (PET/CT) for this condition.

METHODS

Six children received PET/CT after treatment of acute osteomyelitis. Post-treatment MRI had revealed suspicious residual and/or additional findings. All patients had physiological serum infection parameters and no clinical symptoms.

RESULTS

Median patient age was 59.5 months (range, 48-156). No increased 18-Fluor-2-deoxy-D-glucose uptake was observed in 3 patients. In 3 patients, there was minimal activity at the site of infection, which, however, did not reach the presumed range of osteomyelitis. All children were taken off antibiotic medication. No clinical symptoms reoccurred in any of them, and repeatedly controlled serum infection parameters were all normal. Median follow-up was 33 months (range, 4-65).

CONCLUSIONS

The PET/CT was superior to MRI in distinguishing between infection and reparative activity within the musculoskeletal system in selected children after acute osteomyelitis. The termination of antibiotic treatment for children after acute osteomyelitis seems justified when laboratory parameters as well as clinical presentation are normal, and PET/CT scan is unsuspicious.

Consensus document on controversial issues in the diagnosis and treatment of prosthetic joint infections

BACKGROUND

Joint replacement surgery has been on the increase in recent decades and prosthesis infection remains the most critical complication. Many aspects of the primary prevention and clinical management of such prosthesis infections still need to be clarified.

CONTROVERSIAL ISSUES

The aim of this GISIG (Gruppo Italiano di Studio sulle Infezioni Gravi) working group - a panel of multidisciplinary experts - was to define recommendations for the following controversial issues: (1) Is a conservative surgical approach for the management of prosthetic joint infections effective? (2) Is the one-stage or the two-stage revision for the management of prosthetic joint infections more effective? (3) What is the most effective treatment for the management of prosthetic joint infections due to methicillin-resistant staphylococci? Results are presented and discussed in detail.

METHODS

A systematic literature search using the MEDLINE database for the period 1988 to 2008 of randomized controlled trials and/or non-randomized studies was performed. A matrix was created to extract evidence from original studies using the CONSORT method to evaluate randomized clinical trials and the Newcastle-Ottawa Quality Assessment Scale for case-control studies, longitudinal cohorts, and retrospective studies. The GRADE method for grading quality of evidence and strength of recommendation was applied.

Guidelines for the labelling of leucocytes with (99m)Tc-HMPAO. Inflammation/Infection Taskgroup of the European Association of Nuclear Medicine

We describe here a protocol for labelling autologous white blood cells with (99m)Tc-HMPAO based on previously published consensus papers and guidelines. This protocol includes quality control and safety procedures and is in accordance with current European Union regulations and International Atomic Energy Agency recommendations.

A review on the clinical uses of SPECT/CT

In the era when positron emission tomography (PET) seems to constitute the most advanced application of nuclear medicine imaging, still the conventional procedure of single photon emission computed tomography (SPECT) is far from being obsolete, especially if combined with computed tomography (CT). In fact, this dual modality imaging technique (SPECT/CT) lends itself to a wide variety of useful diagnostic applications whose clinical impact is in most instances already well established, while the evidence is growing for newer applications. The increasing availability of new hybrid SPECT/CT devices with advanced technology offers the opportunity to shorten acquisition time and to provide accurate attenuation correction and fusion imaging. In this review we analyse and discuss the capabilities of SPECT/CT for improving sensitivity and specificity in the imaging of both oncological and non-oncological diseases. The main advantages of SPECT/CT are represented by better attenuation correction, increased specificity, and accurate depiction of the localization of disease and of possible involvement of adjacent tissues. Endocrine and neuroendocrine tumours are accurately localized and characterized by SPECT/CT, as also are solitary pulmonary nodules and lung cancers, brain tumours, lymphoma, prostate cancer, malignant and benign bone lesions, and infection. Furthermore, hybrid SPECT/CT imaging is especially suited to support the increasing applications of minimally invasive surgery, as well as to precisely define the diagnostic and prognostic profile of cardiovascular patients. Finally, the applications of SPECT/CT to other clinical disorders or malignant tumours is currently under extensive investigation, with encouraging results in terms of diagnostic accuracy.