Potential clinical implication of18F-FDG PET/CT in diagnosis of periprosthetic infection and its comparison with18F-Fluoride PET/CT

ACR Appropriateness Criteria® Imaging After Total Hip Arthroplasty

This article reviews evidence for performing various imaging studies in patients with total hip prostheses. Routine follow-up is generally performed with radiography. Radiographs are also usually the initial imaging modality for patients with symptoms related to the prosthesis. Following acute injury with pain, noncontrast CT may add information to radiographic examination regarding the presence and location of a fracture, component stability, and bone stock. Image-guided joint aspiration, noncontrast MRI, and white blood cell scan and sulfur colloid scan of the hip, are usually appropriate studies for patients suspected of having periprosthetic infection. For evaluation of component loosening, wear, and/or osteolysis, noncontrast CT or MRI are usually appropriate studies. Noncontrast MRI is usually appropriate for identifying adverse reaction to metal debris related to metal-on-metal articulations. For assessing patients after hip arthroplasty, who have trochanteric pain and nondiagnostic radiographs, ultrasound, or MRI are usually appropriate studies. 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.

Diagnostic accuracy of positron emission tomography/computerized tomography for periprosthetic joint infection of hip: systematic review and meta-analysis

BACKGROUND

American Academy of Orthopaedic Surgeons (AAOS) has provided the guidelines for diagnosing a patient with periprosthetic joint infection including the use of positron emission tomography/computed tomography (PET/CT). Systematic evidence focussing on periprosthetic joint infection (PJI) of hip is limited, which also contains limited number of studies. Hence, the current study aims to perform a pooled analysis of all studies that have assessed the diagnostic accuracy of PET/CT for PJI of hip.

METHODS

Searches were done in PubMed Central, EMBASE, MEDLINE, SCOPUS and Cochrane library until December 2022. Meta-analysis was carried out using random-effects model. With 95% confidence intervals (CIs), pooled sensitivity and specificity were reported.

RESULTS

Twenty-six studies met the inclusion criteria. The pooled sensitivity of PET/CT was 89% (95% CI 84-93%), while the pooled specificity was 86% (95% CI 79-91%). The AUROC was 0.94 (95% CI 0.72-0.99). There was statistically significant heterogeneity (p < 0.001) with I2 value of 96%. The diagnostic odds ratio was 52 (95% CI 26-106). Likelihood ratio positive was 6.5 (95% CI 4.1-10.3) and negative was 0.13 (95% CI 0.08-0.19).

CONCLUSION

Our study found that PET/CT was found to have higher level of accuracy in terms of sensitivity and specificity. Further large-scale research can help to find answers for such questions and provide final conclusive evidence on the inclusion of the imaging modality into the routine clinical practice guidelines for suspected periprosthetic joint infection patients.

A Systematic Review and Meta-Analysis on the Accuracy of Fluorodeoxyglucose Positron Emission Tomography/ Computerized Tomography for Diagnosing Periprosthetic Joint Infections

Objective

Fluorodeoxyglucose Positron emission tomography/computerized tomography (FDG PET/CT) has become popular for diagnosing periprosthetic joint infections (PJI). However, the diagnostic accuracy for this technique has varied from report to report. This meta-analysis was performed to assess the accuracy of FDG PET/CT for PJI diagnosis.

Material and Methods

We conducted a systematic search of online academic databases for all studies reporting the diagnostic accuracy of FDG PET/CT for PJI. Meta-analysis was performed using STATA software.

Results

23 studies, containing data on 1,437 patients, met inclusion criteria. Pooled sensitivity and specificity of FDG PET/CT for diagnosing PJI were 85% (95% CI, 76%, 91%) and 86% (95% CI, 78%, 91%), respectively with an AUC of 0.92. LRP was 6.1 (95% CI, 3.8, 9.7) and LRN was 0.17 (0.11, 0.28), indicating that FDG PET/CT cannot be used for confirmation or exclusion of PJI. There was significant inter-study heterogeneity, but no significant publication bias was noted.

Conclusions

Our study found that FDG PET/CT has an important role as a diagnostic tool for PJI with high sensitivity and specificity. Further studies exploring its accuracy in different PJI locations remain necessary.

Updates in postoperative imaging modalities following musculoskeletal surgery

Postoperative imaging following orthopaedic surgeries is essential in assessing complications post-surgery and also helps plan further treatment. Combining a high degree of clinical insight with appropriate imaging can guide the treating clinician to the correct diagnosis. Imaging is quite challenging because of surgery-related soft tissue changes, especially in the early postoperative period and the presence of metal implants resulting in image scatter and metal artifacts. Newer modalities and advances in imaging have helped overcome shortcomings and assess better, especially in procedures that involve implants. Collaborative decision-making involving radiologists and clinicians has shown to be beneficial and is the way forward. This narrative review discusses the utility of imaging in evaluating postoperative complications following musculoskeletal surgeries with specific relation to trauma, arthroplasty, and tumour by discussing commonly encountered clinical scenarios.

Evaluation of the Small-animal Nano Scan PET/CT System using 89Zr

INTRODUCTION

The purpose of the present work was to evaluate the imaging characteristics of ⁸⁹Zr-PET in comparison with those obtained using fluorine-18 Fluorodeoxyglucose (18FFDG) PET (a gold standard tracer in PET imaging) using a small-animal NanoScan PET/CT scanner.

METHODS

The system's spatial resolution, sensitivity, uniformity, and image quality were measured on a Nano Scan small-animal PET/CT scanner according to the NEMA NU4-2008 protocols. For reconstruction images, we used 2D and 3D reconstruction algorithms. The reconstruction methods included filter back projection (FBP), the ordered subsets expectation maximization (OSEM) algorithm, and the 3D Tera-Tomo algorithm, which are developed for the NanoScan small-animal PET/CT scanner.

RESULTS

The results obtained showed a significant difference in the spatial resolution for ⁸⁹Zr as compared to 22Na and 18F when using a 2D reconstruction algorithm. The spatial resolution values were much enhanced by using the 3D Tera-Tomo reconstruction for each isotope, the Full width at half maximum (FWHM) values was less than 1 for all isotopes at the center of the field of view (FOV). This difference in spatial resolution is dependent on the positron range, energy, and the reconstruction method.

CONCLUSION

The long half-life of ⁸⁹Zr makes it an ideal positron emitter for performing immuno- PET, which is matched with the biological half-life of intact mAbs.⁸⁹Zr can also give several advantages over other long half-life positron emitters in relation to the overall imaging performance because of its relatively short positron range and simpler decay scheme. The values of ⁸⁹Zr sensitivity that were obtained in the present study were less than those of previous studies.

Novel Musculoskeletal and Orthopedic Applications of 18F-Sodium Fluoride PET

PET imaging with ¹⁸F-sodium fluoride (NaF), combined with computed tomography or magnetic resonance, is a sensitive method of assessing bone turnover. Although NaF-PET is gaining popularity in detecting prostate cancer metastases to bone marrow, osseous changes represent secondary effects of cancer cell growth. PET tracers more appropriate for assessing prostate cancer metastases directly portray malignant activity and include ¹⁸F-fluciclovine and prostatic specific membrane antigen ligands. Recent studies investigating NaF-PET suggest utility in the assessment of benign musculoskeletal disorders. Emerging applications in assessing traumatic injuries, joint disease, back pain, orthopedic complications, and metabolic bone disease are discussed.

Does Antibiotic Treatment Affect the Diagnostic Accuracy of 18F-FDG PET/CT Studies in Patients with Suspected Infectious Processes?

¹⁸F-FDG PET/CT plays a significant role in the assessment of various infectious processes. Patients with suspected or known sites of infection are often referred for ¹⁸F-FDG imaging while already receiving antibiotic treatment. The current study assessed whether antibiotic therapy affected the detectability rate of infectious processes by ¹⁸F-FDG PET/CT. Methods: A 5-y retrospective study of all adult patients who underwent ¹⁸F-FDG PET/CT in search of a focal source of infection was performed. The presence, duration, and appropriateness of antibiotic treatment before ¹⁸F-FDG imaging were recorded. Diagnosis of an infectious process was based on microbiologic or pathologic data as well as on clinical and radiologic follow-up. Results: Two hundred seventeen patients underwent 243 PET/CT studies in search of a focal source of infection and were included in the study. Sixty-seven studies were excluded from further analysis because of a final noninfectious etiology or lack of further follow-up or details regarding the antibiotic treatment. The final study population included 176 ¹⁸F-FDG PET/CT studies in 153 patients (107 men, 46 women; age range, 18-86 y). One hundred nineteen studies (68%) were performed in patients receiving antibiotic therapy for a range of 1-73 d. A diagnosis of infection was made in 107 true-positive cases (61%), including 63 studies (59%) in patients receiving appropriate antibiotic therapy started before the performance of the ¹⁸F-FDG PET/CT study. There were 52 true-negative (29%) and 17 false-positive (10%) ¹⁸F-FDG PET/CT studies. No false-negative results were found. Conclusion:¹⁸F-FDG PET/CT correctly identified foci of increased uptake compatible with infection in most patients, including all patients receiving appropriate antimicrobial therapy, with no false-negative cases. On the basis of the current study results, the administration of antibiotics appears to have no clinically significant impact on the diagnostic accuracy of ¹⁸F-FDG PET/CT performed for evaluation of known or suspected infectious processes.

Developments in imaging methods used in hip arthroplasty: A diagnostic algorithm

BACKGROUND

Several imaging modalities can be used to diagnose complications of hip prosthesis placement. Despite progress in these imaging techniques, there are, as yet, no guidelines as to their respective indications.

METHODS

We formed a panel of experts in fields related to prosthesis imaging (radiology, nuclear medicine, orthopedic surgery) and conducted a review of the literature to determine the value of each modality for diagnosing complications following hip replacement.

RESULTS

Few recent studies have investigated the benefits related to the use of the latest technical developments, and studies comparing different methods are extremely rare.

CONCLUSIONS

We have developed a diagnostic tree based on the characteristics of each imaging technique and recommend its use. Computed topography was found to be the most versatile and cost-effective imaging solution and therefore a key tool for diagnosing the complications of hip replacement surgery.

Bilateral periprosthetic joint infection with Ureaplasma urealyticum in an immunocompromised patient

This case study discusses how we diagnosed and treated a patient with a late haematogenous bilateral periprosthetic joint infection (PJI) after total knee arthroplasties caused by Ureaplasma urealyticum. This has never been reported before. We will discuss how we used a PET-CT, synovial fluid cell count, and synovial fluid analysis by 16S rRNA gene sequencing to diagnose this PJI. We will also discuss how we treated this patient to obtain full recovery.