Fever of Unknown Origin: the Value of FDG-PET/CT

Detection of Synchronous Foci of Infection Using Positron Emission Tomography in Septic Patients Who Have a Periprosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection (PJI) with sepsis is a life-threatening condition and identification of synchronous foci of infection is challenging. Positron emission tomography using 18F-fluorodeoxyglucose combined with computed tomography (18F-FDG-PET/CT) is useful to detect PJI in elective, nonseptic patients. We hypothesized that in patients who have PJI and concomitant sepsis requiring intensive care, 18F-FDG-PET/CT could accurately identify synchronous foci of infection. We addressed the following questions: (1) How often were synchronous foci of infection detected?; (2) What were the confirmation rates of these infection foci by other complementary state-of-the-art methods?; (3) Did 18F-FDG-PET/CT findings result in surgical treatment?; and (4) What is the risk of synchronous PJI in patients who have PJI and concomitant sepsis who have another indwelling arthroplasty?

METHODS

We retrospectively analyzed mechanically ventilated septic PJI patients who underwent 18F-FDG-PET/CT between January 1, 2017 and December 21, 2022. The identified synchronous foci of infection were categorized into musculoskeletal, cardiovascular, pulmonary, or other infections and compared to results from tissue culture, histopathology, magnetic resonance imaging, or transesophageal echocardiography.

RESULTS

We identified 17 eligible patients. The 18F-FDG-PET/CT revealed at least one additional infection focus in 15 patients with the following distribution: musculoskeletal (n = 12), cardiovascular (n = 3), pulmonary (n = 13), and other infections (n = 6). Synchronous foci of infection identified with 18F-FDG-PET/CT were confirmed by another state-of-the-art method in 1 all 15 patients. Diagnoses with 18F-FDG-PET/CT led to additional surgery in 11 patients. Of the patients, 10 of 17 had another arthroplasty with a risk in three of synchronous PJI.

CONCLUSIONS

We highlight the value of 18F-FDG-PET/CT in patients who have PJI and sepsis, emphasizing its role in the comprehensive evaluation of these patients for subsequent therapeutic decision-making.

[18F]FDG PET-CT in Weber-Christian Disease

A 46-year-old woman with relapsing fever and painful pelvic subcutaneous nodules was referred to our center for a second opinion. Despite antibiotic and corticoid treatment, inflammation markers remained high. FDG-PET/CT was performed to evaluate the possible cause of her clinical condition, exclude systemic disease and evaluate the extension and inflammation of the nodules. FDG-PET/CT showed multiple abdominopelvic subcutaneous soft tissue foci without visceral involvement. The review of a previous nodule biopsy revealed Weber-Christian Disease (WCD), a rare disorder characterized by idiopathic nodular panniculitis, fever, and systemic inflammation. WCD is a diagnosis of exclusion when no other cause of panniculitis can be identified.

Subcutaneous Infection With Snow Leopard Sign on 18 F-FDG PET/CT Mimicking Subcutaneous Panniculitis-Like T-Cell Lymphoma

ABSTRACT

A 37-year-old man presented with a 2-month history of fever of unknown origin and erythema rashes on the trunk and limbs. 18 F-FDG PET/CT revealed increased 18 F-FDG uptake in subcutaneous panniculitis, forming a snow leopard sign, along with enlarged lymph nodes, which suggested subcutaneous panniculitis-like T-cell lymphoma. However, skin biopsy indicated subcutaneous infection, and bone marrow biopsy revealed no abnormal lymphocytes. After anti-infection treatment, symptoms improved, leading to a final diagnosis of systemic infection. This case demonstrates how extensive subcutaneous infections on PET/CT could be misinterpreted as subcutaneous panniculitis-like T-cell lymphoma.

The role of 18 F-FDG PET/CT in detecting recurrence and metastasis in posttreatment nasopharyngeal carcinoma patients with elevated Epstein-Barr virus DNA

OBJECTIVE

The objective of this study is to evaluate and compare the clinical utility of 18 F-fluoro-2-deoxy-d-glucose PET and computed tomography ( 18 F-FDG PET/CT) in detecting recurrence and metastasis in patients with nasopharyngeal carcinoma (NPC) who exhibit elevated levels of Epstein-Barr virus (EBV) DNA following treatment.

METHODS

A total of 103 patients with NPC were studied retrospectively. All patients were in remission following initial treatment. Elevated EBV DNA was found for the first time at review and 18 F-FDG PET/CT imaging was completed. The number of tracer lesions and the maximum standardized uptake value in the body region were recorded to evaluate the diagnostic ability of 18 F-FDG PET/CT. The final diagnosis was confirmed either through pathology or clinical follow-up lasting 6 months or longer.

RESULTS

Out of the 103 patients, 97 patients had a total of 434 lesions that were ultimately diagnosed as recurrent or metastatic. In patient-based analyses, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 18 F-FDG PET/CT imaging were 100%, 50%, 97%, and 100%, respectively. In lesion-based analyses, the sensitivity, specificity, PPV, and NPV of 18 F-FDG PET/CT imaging were 99.3%, 30.3%, 94.9%, and 83.3%, respectively.

CONCLUSION

18 F-FDG PET/CT demonstrates potential value in detecting recurrence and metastasis of NPC.

Diagnostic efficacy and necessity of 18F-FDG PET/CT in fever of unknown origin: insights from a retrospective cohort study

Background

Despite advancements in medical examination equipment and techniques, fever of unknown origin (FUO) remains challenging in internal medicine.

Purpose

This study evaluates the diagnostic efficacy and necessity of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with FUO.

Methods

We retrospectively analyzed the results of 18F-FDG PET/CT in a cohort of 284 patients with FUO admitted to the Department of Infection at the First Hospital of Jilin University between January 2018 and March 2024. All patients received a final clinical diagnosis after various treatments, which helped determine the diagnostic relevance of identified lesions using 18F-FDG PET/CT. Additionally, univariate and multivariate logistic regression analyses were performed to evaluate the predictive value of relevant laboratory indices on the true-positive results of 18F-FDG PET/CT. The diagnostic performance for different etiologies of FUO was assessed by calculating the area under the receiver operating characteristic curve.

Results

Of the 284 enrolled patients, infectious diseases were diagnosed in 53 (18.7%), non-infectious inflammatory diseases in 76 (26.8%), malignant tumors in 66 (23.2%), and 89 (31.3%) remained undiagnosed. The final diagnoses of 136 patients (47.9%) correlated with their 18F-FDG PET/CT results, yielding a sensitivity of 79.5%, specificity of 61.1%, positive predictive value of 75.6%, and negative predictive value of 66.3%. Furthermore, a correlation was found between localized pain, prolonged activated partial thromboplastin time, and true-positive 18F-FDG PET/CT results.

Conclusion

The high diagnostic efficacy of 18F-FDG PET/CT in FUO suggests its potential as a routine imaging modality, which could enhance patient management and reduce the need for costly and unnecessary invasive procedures. The identification of clinical factors that are predictive of true-positive diagnosis could facilitate more effective allocation of PET/CT imaging.

Role of Positron Emission Tomography-Computed Tomography Scan in Reaching Definite Diagnosis in Patients With Fever of Unknown Origin and Inflammation of Unknown Origin in Rheumatology Outpatient Clinic

Introduction

Patients with fever of unknown origin (FUO) and/or inflammation of unknown origin (IUO) challenge clinicians in daily rheumatology practice. Positron emission tomography-computed tomography (PET/CT) is being used in the diagnostic workup of patients with FUO and/or IUO. This study aims to evaluate the clinical utility and diagnostic performance of PET/CT in the rheumatology outpatient clinic among FUO and IUO patients.

Methods

Patients admitted to Prof. Dr. Cemil Taşcıoğlu City Hospital Internal Medicine Rheumatology Outpatient Clinic between February 2022 and September 2023 with FUO and/or IUO and for whom PET/CT scan was performed were included. Initial acute phase reactants, PET/CT results, definite diagnosis and follow-up of patients without a definite diagnosis were retrospectively evaluated.

Results

Thirty patients were included. Fifteen patients received a final diagnosis. Diagnoses were ankylosing spondylitis (n=4), rheumatoid arthritis (n=1), systemic lupus erythematosus (n=3), giant cell arteritis (n=1), adult onset Still disease (n=1), undifferentiated connective tissue disease (n=1), undifferentiated vasculitis (n=1) and crystal arthropathy (n=1), Hodgkin lymphoma (n=1) and cryptococcosis (n=1). PET/CT's diagnostic accuracy was 66.7%, sensitivity was 100% but specificity was 33%. In 15 patients a definite diagnosis was not reached but in most of these patients, fever did not recur and acute phase reactants regressed either spontaneously or with empiric treatment.

Discussion

PET/CT reliably helps 50% FUO/IUO patients in receiving definite diagnosis. PET/CT's high sensitivity implies that negative results can reliably exclude malignancies in most cases. However, due to its low specificity, positive test may not always imply a serious underlying condition. Majority of the definite diagnoses were rheumatic diseases with a very low proportion of infections and malignancies. This is mainly due to the detailed initial evaluations that are performed in internal medicine clinics. Future studies with more patients will better define the role of PET/CT in FUO/IUO patients in rheumatology clinics.

Bartonellosis in a Renal Transplant Recipient: Scratching More Than the Surface

Fever of unknown origin (FUO) presents a significant diagnostic challenge in renal transplant recipients due to their immunosuppressed state, which predisposes them to a broad spectrum of potential non-infectious and infectious causes, including atypical pathogens. Among these, Bartonella henselae, the agent of bartonellosis or cat scratch disease (CSD), is a rare but significant pathogen in this population, capable of causing several systemic manifestations, including hepatosplenic involvement. We describe the case of a 60-year-old male renal transplant recipient who presented with FUO, diarrhea, and hepatosplenomegaly six months post transplantation. The absence of classical features of CSD such as regional lymphadenopathy, along with the initial omission of relevant exposure history, delayed diagnosis. A comprehensive diagnostic workup, guided by a thorough review of history that revealed a cat scratch three weeks prior to presentation, positive polymerase chain reaction (PCR) testing for B. henselae, and positron emission tomography-computed tomography (PET-CT) findings of increased splenic uptake with a nodular lesion, corroborated the diagnosis of bartonellosis with splenic involvement. Treatment with azithromycin led to complete resolution of fever and inflammatory markers, and follow-up imaging demonstrated normalization of splenic abnormalities. This case highlights the importance of maintaining a high index of suspicion for zoonotic infections in renal transplant recipients, leveraging advanced diagnostic tools, and tailoring antimicrobial therapy to accommodate immunosuppressive regimens.

Performance and value of 18F‑FDG PET/CT in patients with fever of unknown origin

Fever of unknown origin (FUO) is a common clinical and diagnostic challenge. The main aim of the present study was to evaluate the diagnostic accuracy of 18F-fluorodeoxyglucose (18FDG) positron emission tomography (PET)/CT in patients who present with FUO. Overall, 105 consecutive patients (61 men and 44 women) with a mean age of 51±35 years with FUO underwent 18FDG PET/CT scans. The performance of 18FDG PET/CT in determining the etiology of FUO was assessed. According to the PET/CT results, patients were classified into four groups: Group 1, patients with true-positive results (n=51; 49%), in whom abnormal 18FDG uptake identified the final diagnosis; group 2, patients with false-positive results (n=24; 23%), in whom 18FDG uptake was not consistent with the final diagnosis; group 3, patients with true-negative results (n=10; 9.5%), in whom the 18FDG uptake was normal and no final disease was established; and group 4, patients with false-negative results (n=20; 19%), in whom 18FDG uptake was normal and disease was finally established. Of the 51 patients with true-positive PET/CT results, 51% had infections, 35% had malignancies and 14% had inflammatory processes. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 72, 29, 68, 33 and 58%, respectively. In conclusion, the present results demonstrated that 18FDG PET/CT established the final diagnosis of FUO in the majority of patients (72%). These results support the use of 18FDG PET/CT in the initial evaluation and management of patients with FUO.

Metagenomic next-generation sequencing in patients with fever of unknown origin: A comprehensive systematic literature review and meta-analysis

Metagenomic Next-Generation Sequencing (mNGS) holds promise in diagnosing fever of unknown origin (FUO) by detecting diverse pathogens. We systematically reviewed the literature to evaluate mNGS's accuracy, clinical efficacy, and limitations in FUO diagnosis. Nine studies revealed mNGS's positivity rate ranging from 66.7% to 93.5% for bacterial bloodstream infections and systemic infections. Meta-analysis of three studies involving 857 patients, including 354 with FUO, showed a sensitivity of 0.91 (95% CI: 0.87-0.93) and specificity of 0.64 (95% CI: 0.58-0.70). Despite lower specificity, mNGS demonstrated a higher Diagnostic Odds Ratio (DOR) of 17.0 (95% CI: 4.5-63.4) compared to conventional microbiological tests (CMTs) at 4.7 (95% CI: 2.9-7.6). While mNGS offers high sensitivity but low specificity in identifying causative pathogens for FUO, its superior DOR suggests potential for more accurate diagnoses and targeted interventions. Further research is warranted to optimize its clinical application in FUO management.

The Diagnostic Yield of [18F]FDG-PET/CT in a Heterogeneous In-Patient Population with Suspected Infection or Inflammation Is Comparable to Findings in Patients with Classic Fever of Unknown Origin

INTRODUCTION

Suspected infection or inflammation of unknown origin in in-patients remains challenging. Literature on [18F]FDG-PET/CT is abundant in classic fever of unknown origin (FUO), but evidence is complex and may not always reflect clinical reality. This study explores the application of [18F]FDG-PET/CT in a diverse clinical population of in-patients with suspected infection not defined by stringent FUO-criteria.

METHODS

Retrospective chart review of consecutive in-patients who underwent [18F]FDG-PET/CT in the workup of suspected infection or inflammation from 1 July 2022 to 31 December 2022 was conducted. We evaluated indications, diagnostic yield, and clinical impact of [18F]FDG-PET/CT, and compared the findings of [18F]FDG-PET/CT and stand-alone CT. Univariate logistic regression assessed associations between [18F]FDG-PET/CT outcome and clinical parameters. Receiver operating characteristic curve (ROC) analysis evaluated diagnostic performance.

RESULTS

77 patients met the inclusion criteria. [18F]FDG-PET/CT established a diagnosis in 35% of cases, ruled out focal infection in 26%, and thus was helpful in 61% of patients. It prompted 72 additional examinations resulting in seven incidental diagnoses, including two cancers. Antibiotic treatment was changed in 26% of cases. Regression analysis found white blood cell counts (WBC) associated with true positive outcomes. [18F]FDG-PET/CT was compared to stand-alone CT findings, and was concordant in 69% of cases.

CONCLUSIONS

Results were comparable to findings in more classic FUO. [18F]FDG-PET/CT was clinically helpful in 61% of cases but also prompted many additional examinations with relatively few clinically important findings. WBC count was a predictor of true positive outcome. CT and [18F]FDG-PET/CT were discordant in 31%, of cases, especially in cases of endocarditis and spondylodiscitis.

EANM consensus document on the use of [18F]FDG PET/CT in fever and inflammation of unknown origin

PURPOSE

Patients with fever and inflammation of unknown origin (FUO/IUO) are clinically challenging due to variable clinical presentations with nonspecific symptoms and many differential diagnoses. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is increasingly used in FUO and IUO, but the optimal diagnostic strategy remains controversial. This consensus document aims to assist clinicians and nuclear medicine specialists in the appropriate use of [18F]FDG-PET/CT in FUO and IUO based on current evidence.

METHODS

A working group created by the EANM infection and inflammation committee performed a systematic literature search based on PICOs with "patients with FUO/IUO" as population, "[18F]FDG-PET/CT" as intervention, and several outcomes including pre-scan characteristics, scan protocol, diagnostic yield, impact on management, prognosis, and cost-effectiveness.

RESULTS

We included 68 articles published from 2001 to 2023: 9 systematic reviews, 49 original papers on general adult populations, and 10 original papers on specific populations. All papers were analysed and included in the evidence-based recommendations.

CONCLUSION

FUO and IUO remains a clinical challenge and [18F]FDG PET/CT has a definite role in the diagnostic pathway with an overall diagnostic yield or helpfulness in 50-60% of patients. A positive scan is often contributory by directly guiding treatment or subsequent diagnostic procedure. However, a negative scan may be equally important by excluding focal disease and predicting a favorable prognosis. Similar results are obtained in specific populations such as ICU-patients, children and HIV-patients.

Imaging the Granzyme Mediated Host Immune Response to Viral and Bacterial Pathogens In Vivo Using Positron Emission Tomography

Understanding how the host immune system engages complex pathogens is essential to developing therapeutic strategies to overcome their virulence. While granzymes are well understood to trigger apoptosis in infected host cells or bacteria, less is known about how the immune system mobilizes individual granzyme species in vivo to combat diverse pathogens. Toward the goal of studying individual granzyme function directly in vivo, we previously developed a new class of radiopharmaceuticals termed "restricted interaction peptides (RIPs)" that detect biochemically active endoproteases using positron emission tomography (PET). In this study, we showed that secreted granzyme B proteolysis in response to diverse viral and bacterial pathogens could be imaged with [64Cu]Cu-GRIP B, a RIP that specifically targets granzyme B. Wild-type or germline granzyme B knockout mice were instilled intranasally with the A/PR/8/34 H1N1 influenza A strain to generate pneumonia, and granzyme B production within the lungs was measured using [64Cu]Cu-GRIP B PET/CT. Murine myositis models of acute bacterial (E. coli, P. aeruginosa, K. pneumoniae, and L. monocytogenes) infection were also developed and imaged using [64Cu]Cu-GRIP B. In all cases, the mice were studied in vivo using mPET/CT and ex vivo via tissue-harvesting, gamma counting, and immunohistochemistry. [64Cu]Cu-GRIP B uptake was significantly higher in the lungs of wild-type mice that received A/PR/8/34 H1N1 influenza A strain compared to mice that received sham or granzyme B knockout mice that received either treatment. In wild-type mice, [64Cu]Cu-GRIP B uptake was significantly higher in the infected triceps muscle versus normal muscle and the contralateral triceps inoculated with heat killed bacteria. In granzyme B knockout mice, [64Cu]Cu-GRIP B uptake above the background was not observed in the infected triceps muscle. Interestingly, live L. monocytogenes did not induce detectable granzyme B on PET, despite prior in vitro data, suggesting a role for granzyme B in suppressing their pathogenicity. In summary, these data show that the granzyme response elicited by diverse human pathogens can be imaged using PET. These results and data generated via additional RIPs specific for other granzyme proteases will allow for a deeper mechanistic study analysis of their complex in vivo biology.

Nuclear Medicine Imaging Tools in Fever of Unknown Origin: Time for a Revisit and Appropriate Use Criteria

Fever of unknown origin (FUO) is a clinical conundrum for patients and clinicians alike, and imaging studies are often performed as part of the diagnostic workup of these patients. Recently, the Society of Nuclear Medicine and Molecular Imaging convened and approved a guideline on the use of nuclear medicine tools for FUO. The guidelines support the use of 2-18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in adults and children with FUO. 18F-FDG PET/CT allows detection and localization of foci of hypermetabolic lesions with high sensitivity because of the 18F-FDG uptake in glycolytically active cells that may represent inflammation, infection, or neoplasia. Clinicians should consider and insurers should cover 18F-FDG PET/CT when evaluating patients with FUO, particularly when other clinical clues and preliminary studies are unrevealing.

Histopathological Confirmed Polycythemia Vera with Transformation to Myelofibrosis Depicted on [18F]FDG PET/CT

We present a case of a 59-year-old male diagnosed with polycythemia vera (PV) for many years, who presented with a relatively abrupt onset of heavy constitutional symptoms, including fatigue, night sweats, and a 10% weight loss over 6 weeks. Despite the known initial diagnosis of PV, the presence of profound B-symptoms prompted further investigation. A positron emission tomography/computed tomography (PET/CT) scan with 18F-Fluorodeoxyglucose ([18F]FDG) was performed to exclude malignant diseases. The [18F]FDG PET/CT revealed intense metabolic activity in the bone marrow of the proximal extremities and trunk skeleton, as well as a massively enlarged spleen with increased metabolic activity. Histopathologically, a transformation to myelofibrosis was revealed on a bone marrow biopsy. The case intends to serve as an exemplification for [18F]FDG PET/CT in PV with transformation to myelofibrosis (post-PV myelofibrosis).

Sarcoidosis detected after COVID‑19 with T‑SPOT.TB positive: A case report

Sarcoidosis is an idiopathic multisystem disorder with unknown etiology. Due to clinical similarities among sarcoidosis, tuberculosis (TB) infection and malignant diseases (such as lymphoma, lung carcinoma and pituitary tumor), the diagnosis of sarcoidosis is challenging. The present report describes a case of sarcoidosis in a 48-year-old male with complaint of chest pain 1 month after Coronavirus disease 2019. The patient underwent whole-body 18F-fluorodeoxyglucose (18F-FDG) PET-CT imaging, which revealed multiple lymphadenopathies throughout the body without lung parenchyma involvement. Biochemical examinations such as T-SPOT.TB test and pathological examination of right supraclavicular lymph node revealed positive T-SPOT.TB but negative Ziehl-Neelsen staining. However, non-caseating epithelioid granulomas were observed in the mediastinal biopsy, indicating the diagnosis of sarcoidosis. The patient was clinically stable, and the symptom of chest pain was gradually relieved without any specific treatment. Outpatient follow-up continued every 3 months. The present case suggested a possible link between coronavirus infection and sarcoidosis, which suggests the advantages of 18F-FDG PET-CT for the detection of sarcoidosis. However, T-SPOT.TB is insufficient for differentiating between sarcoidosis and TB.

Significance of F-18 FDG PET/MRI in the search for the etiology of inflammation of unclear origin and fever of unknown origin

PURPOSE

To evaluate the contribution of F-18 FDG-PET/MRI in the search for the etiology of the inflammation of unknown origin (IUO) and fever of unknown origin (FUO).

MATERIAL AND METHODS

The study included 104 patients who underwent F-18 FDG-PET/MRI for IUO or FUO. The sensitivity, specificity, predictive values of the PET/MRI findings in relation to the final diagnosis of IUO/FUO were evaluated. A five-point Likert scale was used to semiquantitatively assess the probability of the cause of IUO/FUO based on PET/MRI finding. Furthermore, clinical (fever, arthralgia, weight loss, night sweats, age) and laboratory (C-reactive protein, leukocytes) parameters were monitored and compared with the true positivity rate of PET/MRI.

RESULTS

In patients with definitively identified etiology of FUO and IUO, FDG-PET/MRI achieved a sensitivity of 96 %, specificity of 82 %, and positive and negative predictive values of 92 and 90 %. The cause of the IUO was determined in 71 patients (68.3 %). In 33 (31.7 %) patients, the etiology of IUO/FUO remained unknown, while in 25 (75.8 %) of them the symptoms resolved spontaneously and in 8 (24.2 %) patients they persisted without explanation even after 12 months of the follow-up. The most significant parameter in relation to subsequent PET/MRI finding was increased level of CRP, which was present in 96 % of true positive PET/MRI and normal CRP level was present in 56 % of true negative PET/MRI.

CONCLUSION

Based on this study, FDG-PET/MRI is a suitable alternative for the investigation of IUO/FUO, this imaging technique has a very high sensitivity and negative predictive value.

Interdisciplinary perspectives on computed tomography in sepsis: survey among medical doctors at a large university medical center

OBJECTIVES

This study aims to describe physicians' perspectives on the use of computed tomography (CT) in patients with sepsis.

METHODS

In January 2022, physicians of a large European university medical center were surveyed using a web-based questionnaire asking about their views on the role of CT in sepsis. A total of 371 questionnaires met the inclusion criteria and were analyzed using work experience, workplace, and medical specialty of physicians as variables. Chi-square tests were performed.

RESULTS

Physicians considered the ability to detect an unknown focus as the greatest benefit of CT scans in sepsis (70.9%, n = 263/371). Two clinical criteria - "signs of decreased vigilance" (89.2%, n = 331/371) and "increased catecholamine demand" (84.7%, n = 314/371) - were considered highly relevant for a CT request. Elevated procalcitonin (82.7%, n = 307/371) and lactate levels (83.6%, n = 310/371) were consistently found to be critical laboratory values to request a CT. As long as there is evidence of infection in one organ region, most physicians (42.6%, n = 158/371) would order a CT scan based on clinical assessment. Combined examination of the chest, abdomen, and pelvis was favored (34.8%, n = 129/371) in cases without clinical clues of an infection source. A time window of ≥ 1-6 h was preferred for both CT examinations (53.9%, n = 200/371) and CT-guided interventions (59.3%, n = 220/371) in patients with sepsis.

CONCLUSION

Despite much consensus, there are significant differences in attitudes towards the use of CT in septic patients among physicians from different workplaces and medical specialties. Knowledge of these perspectives may improve patient management and interprofessional communication.

KEY POINTS

Despite interdisciplinary consensus on the use of CT in sepsis, statistically significant differences in the responses are apparent among physicians from different workplaces and medical specialties. The detection of a previously unknown source of infection and the ability to plan interventions and/or surgery based on CT findings are considered key advantages of CT in septic patients. Timing of CT reflects the requirements of specific disciplines.

Diagnostic value of serum CA125 combined with PET/CT in ovarian cancer and tuberculous peritonitis in female patients

PURPOSE

To evaluate the diagnostic value of serum CA125 combined with 18F-FDG PET/CT in ovarian cancer (OC) and tuberculous peritonitis (TBP) in female patients and to establish a diagnostic scoring system.

METHOD

A total of 86 female patients (64 OC and 22 TBP) were included in this study. Serum CA125, PET/CT maximal intensity projection (MIP), maximal standardized uptake value, ovarian mass, ascites volume, and other indicators were analyzed and a diagnostic scoring system was established according to the weights of statistically significant indicators.

RESULTS

Univariate analysis showed that serum CA125 in OC and TBP patients were 2079.9 ± 1651.3 U/mL and 448.3 ± 349.5 U/mL (P < 0.001). In MIP images, abdominal lesions were focal distribution in 92.2% (59/64) of OC patients and diffuse distribution in 95.5% (21/22) of TBP patients (P < 0.001). Ovarian masses could be observed in 82.8% (53/64) OC patients and 31.8% (7/22) TBP patients (P <0.001). The other indicators were not statistically significant. Logistic regression analysis showed that serum CA125 and MIP were independent risk factors for diagnosis. A diagnostic scoring system could be established based on serum CA125, MIP and ovarian mass, and the diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 98.4% (63/64), 95.5% (21/22), 97.7% (84/86), 98.4% (63/64), and 95.5% (21/22), respectively.

CONCLUSION

Serum CA125 combined with PET/CT is of great value in the diagnosis of OC and TBP. A simple and efficient diagnostic scoring system can be established using serum CA125, MIP image feature, and ovarian mass.

PET vascular activity score for predicting new angiographic lesions in patients with Takayasu arteritis: a Chinese cohort study

OBJECTIVE

To investigate the ability of 18F-fluorodeoxyglucose PET/CT to predict new lesions in Takayasu arteritis.

METHODS

Eighty-two Chinese patients with newly diagnosed Takayasu arteritis were recruited. Their clinical characteristics, serum biomarkers and imaging results were recorded at baseline and every visit. They were followed up for at least 2 years. New angiographic lesions were evaluated by magnetic resonance angiography. Baseline PET vascular activity scores (PETVAS) for predicting new lesions were evaluated.

RESULTS

At baseline, a moderate correlation was observed between PETVAS and ESR (r = 0.74, P < 0.01) and CRP level (r = 0.69, P < 0.01). Overall, 18 (22%) patients showed new lesions on imaging during a median follow-up time of 36 months. The median time to the first occurrence of new lesions was 18 months. Compared with patients without new lesions, the patients with new lesions included more female patients (67.2% vs 94.4%, P = 0.03), patients with higher ESR values (20 vs 49, P = 0.02) and patients with active disease (62.5% vs 94.4%, P < 0.01). Multivariate Cox regression analysis revealed PETVAS was an independent risk factor for new angiographic lesions (PETVAS ≥8, hazard ratio = 7.56; 95% CI 2.20, 26.01, P < 0.01) with adjustment of age, sex, chest pain, ESR and Physician Global Assessment. Furthermore, patients with PETVAS ≥8 at baseline were more likely to experience adverse events including arterial ischaemic events during the follow-up.

CONCLUSION

PETVAS showed good performance in predicting new lesions in Takayasu arteritis.

Evaluation of Colonoscopic Results of Patients with Incidental Colonic FDG Uptake in PET/CT Imaging

BACKGROUND

Colorectal cancer is a significant global health concern, ranking as the second most deadly and third most common cancer worldwide. Early detection and removal of precancerous lesions play a crucial role in preventing cancer development and reducing mortality. Since FDG uptake is not specific for malignancy, incidental increased FDG uptake in the gastrointestinal tract may be challenging to interpret and may require further colonoscopic examination. This study aimed to investigate the features associated with malignant and premalignant pathology in patients with incidental colonic FDG uptake and determine the necessity of colonoscopy for each FDG uptake.

METHODS

Retrospective analysis was performed on data from patients who underwent colonoscopies between January 2016 and December 2021. Patients with FDG uptake in known colorectal malignancy regions were excluded. The study included 56 patients with incidental colonic FDG uptake. PET/CT images were visually and quantitatively analyzed, and the corresponding colonoscopy and histopathological results were recorded. Statistical analyses were conducted to evaluate the relationship between FDG uptake patterns, SUVmax values, and histopathological diagnoses. Colonoscopic findings were categorized as malignancy, polyps, and non-neoplastic lesions.

RESULTS

Among the 56 patients with incidental colonic FDG uptake, 36 lesions were identified, and histopathology revealed malignancy in 10 (17.9%) patients and premalignant polyps in the 26 (46.4%) cases. Focal FDG uptake with corresponding wall thickening or soft tissue density on CT was associated with a higher likelihood of premalignant or malignant lesions. The SUVmax values demonstrated a significant difference between negative findings and polyps/malignancies. However, no significant difference was observed between malignant and premalignant lesions. A ROC curve analysis was made and assesed a cut-off value of 11.1 SUVmax (sensitivity: 83.3% and specificity: 90%) to distinguish premalignant or malignant lesions from non-malignant lesions.

CONCLUSION

Incidental colonic FDG uptake with a focal pattern and corresponding CT findings were more likely to indicate premalignant or malignant lesions. SUVmax values were helpful in predicting the presence of pathological findings, but histopathological verification remains necessary for a definitive diagnosis. These findings contribute to our understanding of the clinical implications of incidental colonic FDG uptake and highlight the importance of follow-up colonoscopy for further evaluation.

Differential diagnosis of lymphoma with 18F-FDG PET/CT in patients with fever of unknown origin accompanied by lymphadenopathy

PURPOSE

To investigate the value of 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the differential diagnosis of lymphoma in patients with fever of unknown origin (FUO) accompanied by lymphadenopathy and to develop a simple scoring system to distinguish lymphoma from other etiologies.

METHODS

A prospective study was conducted on patients with classic FUO accompanied by lymphadenopathy. After standard diagnostic procedures, including PET/CT scan and lymph-node biopsy, 163 patients were enrolled and divided into lymphoma and benign groups according to the etiology. The diagnostic utility of PET/CT imaging was evaluated, and beneficial parameters that could improve diagnostic effectiveness were identified.

RESULTS

The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET/CT in diagnosing lymphoma in patients with FUO accompanied by lymphadenopathy were 81.0, 47.6, 59.3, and 72.7%, respectively. The lymphoma prediction model combining high SUVmax of the "hottest" lesion, high SUVmax of the retroperitoneal lymph nodes, old age, low platelet count, and low ESR had an area under the curve of 0.93 (0.89-0.97), a sensitivity of 84.8%, a specificity of 92.9%, a PPV of 91.8%, and an NPV of 86.7%. There was a lower probability of lymphoma for patients with a score < 4 points.

CONCLUSIONS

PET/CT scans show moderate sensitivity and low specificity in diagnosing lymphoma in patients with FUO accompanied by lymphadenopathy. The scoring system based on PET/CT and clinical parameters performs well in differentiating lymphoma and benign causes and can be used as a reliable noninvasive tool.

REGISTRATION NUMBER

This study on FUO was registered on http://www.

CLINICALTRIALS

gov on January 14, 2014, with registration number NCT02035670.

Value of Positron Emission Tomography Coupled With Computed Tomography for the Diagnosis of Inflammatory Syndrome of Unknown Origin in an Internal Medicine Department

Objective

To evaluate the usefulness of positron emission tomography (PET) coupled with computed tomography (CT) in the diagnostic workup for inflammatory syndrome of undetermined origin (IUO) and to determine the diagnostic delay in an internal medicine department.

Patients and methods

We retrospectively studied a cohort of patients for whom a PET/CT scan had been prescribed in an indication of IUO in an internal medicine department (Amiens University Medical Center, Amiens, France) between October 2004 and April 2017. The patients were grouped according to the PET/CT findings: very useful (enabling an immediate diagnosis), useful, not useful, and misleading.

Results

We analyzed 144 patients. The median (interquartile range) age was 67.7 years (55.8-75.8 years). The final diagnosis was an infectious disease in 19 patients (13.2%), cancer in 23 (16%), inflammatory disease in 48 (33%), and miscellaneous diseases in 12 (8.3%). No diagnosis was made in 29.2% of the cases; half of the remaining had a spontaneously favorable outcome. Fever was observed in 63 patients (43%). Positron emission tomography coupled with CT was determined to be very useful in 19 patients (13.2%), useful in 37 (25.7%), not useful in 63 (43.7%), and misleading in 25 (17.4%). The median diagnostic delay (ie, the time interval between the first admission and a confirmed diagnosis) was significantly shorter in the useful (71 days [38-170 days]) and very useful (55 days [13-79 days]) groups than that in the not useful group (175 days [51-390 days]; P<.001). The median time interval between the PET/CT scan and the diagnosis was twice as long in the not useful group than that in the pooled misleading, useful, or very useful groups (P=.03). In a univariate analysis, the poor overall condition (P=.007) and the absence of fever (P=.005) were predictive of usefulness of PET/CT.

Conclusion

Positron emission tomography coupled with CT seems to be useful in the diagnosis of IUO and might shorten the diagnostic delay.

Mycoplasma infection mimicking a malignancy in a waldenstrom macroglobulinemia patient

BACKGROUND

Mycoplasma hominis infection is common in urinary tract. ¹⁸F-FDG-PET/CT is a valuable tool for tumor and infection diagnosis. Few studies have shown the ¹⁸F-FDG-PET/CT images after mycoplasma infection.

CASE PRESENTATION

Here we described a case of Waldenstrom macroglobulinemia with thickened bladder wall. The ¹⁸F-FDG-PET/CT showed the SUVmax up to 36.1 mimicking bladder cancer. The results of histopathological examination and metagenomic sequencing of the blood and urinary revealed the Mycoplasma hominis infection.

CONCLUSION

The full consideration should be given to the possibility of infection besides tumor in lesions with high SUV value in ¹⁸F-FDG-PET/CT, especially in immunodeficiency patients.

Роль позитронно-емісійної томографії при інфекційних та запальних захворюваннях (огляд літератури)

Мета. Дослідити клінічну роль методів гібридної променевої візуалізації, зокрема позитронно-емісійної томографії (ПЕТ) у діагностиці та лікуванні пацієнтів із запальними та інфекційними захворюваннями. Матеріали та методи. Матеріалом для дослідження були наукові результати публікацій фахових наукових видань провідних країн світу  наукової та клінічної діяльності за останні 10 років щодо клінічного значення методів гібридної променевої візуалізації у діагностиці та лікуванні пацієнтів із запальними та інфекційними захворюваннями. Методи дослідження передбачали застосування методів променевої візуалізації ПЕТ при інфекційних та запальних захворюваннях. Результати. Показана ефективність ПЕТ у випадках, коли інші звичайні дослідження є неможливими через високий ризик ускладнень. В роботі розглянуто  корисність методу при діагностиці станів, які виникають як ускладнення після протезування: при ендокардитах протезованого клапану; інфекції  імплантованих електронних пристроїв; протезованих суглобів та імплантантів для фіксації переломів.  ПЕТ в таких випадках дозволяє провести диференційну діагностику між асептичним та інфекційним запаленням, особливо за наявності спричинених  металевими елементами артефактів, які можуть  обмежують дослідження за допомогою комп’ютерної томографії  або магнітно-резонансної томографії. Висновки. Позитронно-емісійна томографія у пацієнтів із запальними або інфекційними захворюваннями є ефективним допоміжним додатковим методом променевої візуалізації. ПЕТ знаходить своє ефективне застосування на різних етапах лікування, а також є корисним методом променевої візуалізації для моніторингу терапевтичної відповіді на лікування.

Is Imaging Bacteria with PET a Realistic Option or an Illusion?

The application of [¹⁸F]-fluorodeoxyglucose ([¹⁸F]FDG) as a radiotracer to detect sites of inflammation (either due to bacterial infection or primary inflammation) has led to exploring the role of PET in visualizing bacteria directly at sites of infection. However, the results from such efforts are controversial and inconclusive so far. We aimed to assess the limitations of PET as an effective modality in the diagnosis of bacterial infections. Inflammation due to bacterial infections can be visualized by using [¹⁸F]FDG-PET. However, the non-specificity of [¹⁸F]FDG makes it undesirable to visualize bacteria as the underlying cause of inflammation. Hence, more specific radiotracers that possibly bind to or accumulate in bacteria-specific receptors or enzymes are being explored. Several radiotracers, including 2-deoxy-2-[¹⁸F]fluorosorbitol ([¹⁸F]FDS), 6-[¹⁸F]-fluoromaltose, [¹¹C]para-aminobenzoic acid ([¹¹C]PABA), radiolabeled trimethoprim (¹¹C-TMP) and its analog fluoropropyl-trimethoprim (¹⁸F-FPTMP), other radiolabeled sugars, and antimicrobial drugs have been used to image microorganisms. Unfortunately, no progress has been made in translating the results to routine human use; feasibility and other factors have constrained their success in clinical settings. In the current article, we discuss the limitations of direct bacterial visualization with PET tracers, but emphasize the important role of [¹⁸F]FDG-PET as the only option for detecting evidence of infection.

Diagnostic value of FDG-PET/CT in the diagnostic work-up of inflammation of unknown origin

Introduction The present study aims to evaluate the clinical diagnostic value of FDG-PET/CT in patients with inflammation of unknown origin. Material and methods We retrospectively analyzed data of 130 patients who presented general inflammatory symptoms and/or elevated level of CRP and underwent FDG-PET/CT for the purpose of identifying unknown foci of inflammation. The accuracy of PET/CT findings was assessed against the standard of eventual clinical diagnosis e.g. results of pathology, microbiology or other imaging methods. Results In 99/130 patients (76 %) a final diagnosis was established, FDG-PET/CT showed a sensitivity and specificity of each 93 %. A decreased pseudocholinesterase is associated with a higher SUVmax value and with a higher CRP value whereas no significant relationship was found between elevated CRP values and the SUVmax, although higher CRP values are associated significantly with a true positive PET/CT result. Conclusion FDG-PET/CT is a highly sensitive, specific and accurate method for the detection of foci of inflammation of unknown origin. The combination of decreased pseudocholinesterase and increased CRP levels may be a useful tool to select patients for FDG PET/CT.

Radiometal chelators for infection diagnostics

Infection of native tissues or implanted devices is common, but clinical diagnosis is frequently difficult and currently available noninvasive tests perform poorly. Immunocompromised individuals (for example transplant recipients, or those with cancer) are at increased risk. No imaging test in clinical use can specifically identify infection, or accurately differentiate bacterial from fungal infections. Commonly used [18F]fluorodeoxyglucose (18FDG) positron emission computed tomography (PET/CT) is sensitive for infection, but limited by poor specificity because increased glucose uptake may also indicate inflammation or malignancy. Furthermore, this tracer provides no indication of the type of infective agent (bacterial, fungal, or parasitic). Imaging tools that directly and specifically target microbial pathogens are highly desirable to improve noninvasive infection diagnosis and localization. A growing field of research is exploring the utility of radiometals and their chelators (siderophores), which are small molecules that bind radiometals and form a stable complex allowing sequestration by microbes. This radiometal-chelator complex can be directed to a specific microbial target in vivo, facilitating anatomical localization by PET or single photon emission computed tomography. Additionally, bifunctional chelators can further conjugate therapeutic molecules (e.g., peptides, antibiotics, antibodies) while still bound to desired radiometals, combining specific imaging with highly targeted antimicrobial therapy. These novel therapeutics may prove a useful complement to the armamentarium in the global fight against antimicrobial resistance. This review will highlight current state of infection imaging diagnostics and their limitations, strategies to develop infection-specific diagnostics, recent advances in radiometal-based chelators for microbial infection imaging, challenges, and future directions to improve targeted diagnostics and/or therapeutics.

Molecular Imaging of Tuberculosis

Despite the introduction of many novel diagnostic techniques and newer treatment agents, tuberculosis (TB) remains a major cause of death from an infectious disease worldwide. With about a quarter of humanity harboring Mycobacterium tuberculosis, the causative agent of TB, the current efforts geared towards reducing the scourge due to TB must be sustained. At the same time, newer alternative modalities for diagnosis and treatment response assessment are considered. Molecular imaging entails the use of radioactive probes that exploit molecular targets expressed by microbes or human cells for imaging using hybrid scanners that provide both anatomic and functional features of the disease being imaged. Fluorine-18 fluorodeoxyglucose (FDG) is the most investigated radioactive probe for TB imaging in research and clinical practice. When imaged with positron emission tomography interphase with computed tomography (PET/CT), FDG PET/CT performs better than sputum conversion for predicting treatment outcome. At the end of treatment, FDG PET/CT has demonstrated the unique ability to identify a subset of patients declared cured based on the current standard of care but who still harbor live bacilli capable of causing disease relapse after therapy discontinuation. Our understanding of the pathogenesis and evolution of TB has improved significantly in the last decade, owing to the introduction of FDG PET/CT in TB research. FDG is a non-specific probe as it targets the host inflammatory response to Mycobacterium tuberculosis, which is not specifically different in TB compared with other infectious conditions. Ongoing efforts are geared towards evaluating the utility of newer probes targeting different components of the TB granuloma, the hallmark of TB lesions, including hypoxia, neovascularization, and fibrosis, in TB management. The most exciting category of non-FDG PET probes developed for molecular imaging of TB appears to be radiolabeled anti-tuberculous drugs for use in studying the pharmacokinetic characteristics of the drugs. This allows for the non-invasive study of drug kinetics in different body compartments concurrently, providing an insight into the spatial heterogeneity of drug exposure in different TB lesions. The ability to repeat molecular imaging using radiolabeled anti-tuberculous agents also offers an opportunity to study the temporal changes in drug kinetics within the different lesions during treatment.

Chronic Splenic Melioidosis in a Patient with Fever of Unknown Origin Diagnosed by Metagenomics Next-Generation Sequencing: An Emerging Cause and Literature Review

Introduction

Human melioidosis is an emerging infectious disease in tropical areas of China, and chronic melioidosis can be a rare cause of fever of unknown origin (FUO). Timely diagnosis may improve the prognosis of melioidosis.

Case Presentation

We report a case of melioidosis with splenic abscesses caused by Burkholderia pseudomallei in a 57-year-old man, who presented with FUO. Positron emission tomography/computed tomography (PET/CT) revealed multiple hypermetabolic lesions in the spleen. The spleen biopsy was conducted and metagenomics next-generation sequencing (mNGS) of the spleen specimen identified the presence of B. pseudomallei, confirming the diagnosis of melioidosis. Antimicrobial treatment was initiated with intravenous meropenem, followed by oral faropenem. During the follow-up, the patient was in good condition except having a low-grade fever occasionally. A splenectomy was performed, and subsequent culture and mNGS of the spleen pus were both positive for B. pseudomallei. Histopathological characteristics of chronic splenic melioidosis were noted.

Conclusion

Melioidosis is a serious endemic disease, and it is critical to raise awareness about this disease.

When to investigate for secondary hyperhidrosis: data from a retrospective cohort of all causes of recurrent sweating

Background: Identification of underlying diseases is crucial for secondary hyperhidrosis management, but data are lacking to guide appropriate investigation.Objective: To describe aetiologies of recurrent sweating in a hospital setting and the diagnostic performance parameters of their respective clinical/biological features.Patients and Methods: We performed a monocentric evaluative study in a tertiary care centre. Patients with recurrent generalised sweating were selected via the Clinical Data Warehouse (CDW) by screening all electronic hospital documents from the year 2018 using a keyword-based algorithm. All in and out-patients aged ≥ 18 years having reported recurrent sweating for at least 2 weeks in 2018 were included, with a minimum one-year follow-up after symptoms' onset.Results: A total of 420 patients were included. Over 130 different aetiologies were identified; 70 patients (16.7%) remained without diagnosis. Solid organ cancers (14.3% with 13 lung cancers), haematologic malignancies (14.0% with 35 non-Hodgkin's lymphomas) and Infectious Diseases (10.5% including 13 tuberculosis) were the most frequent diagnoses. Other aetiologies were gathered into inflammatory (16.9%) and non-inflammatory (27.6%) conditions. To distinguish non-inflammatory and undiagnosed hyperhidrosis from other causes, fever had a specificity of 94%, impaired general condition a sensitivity of 78%, and C-reactive protein (CRP) > 5.6 mg/l a positive predictive value of 0.86. Symptoms' duration over 1 year was in favour of non-infectious and non-malignant causes (94% specificity).Conclusions: We identified fever, impaired general condition, duration, and CRP as helpful orientation parameters to assess the need for complementary explorations for hyperhidrosis. The study provides a diagnostic algorithm for the investigation of recurrent sweating.KEY MESSAGESIn a hospital setting, malignancies and infections are the most frequently associated diseases, but 1/5 remain without diagnosis.Fever is a specific but not sensitive sign to distinguish inflammatory conditions.Over 1 year duration of symptoms significantly reduce the probability of malignancy or infection as the underlying diagnosis.

Clinical utility of whole body diffusion-weighted imaging in an immunocompetent adult with atypical cat scratch disease

BACKGROUND

Cat scratch disease (CSD) is an infectious disease caused by Bartonella henselae. CSD follows a typical course, characterized by regional lymphadenopathy. In atypical CSD, the lesions spread to systemic organs and can cause fever of unknown origin (FUO). A previous study showed the usefulness of whole-body magnetic resonance imaging (WB-MRI) with diffusion-weighted imaging (DWI) for limited areas in the diagnosis of FUO, but there are no studies on the clinical utility of whole-body DWI (WB-DWI). We herein report the case of an immunocompetent young man in whom contrast-enhanced CT-unidentifiable multiple liver abscess and osteomyelitis were successfully detected by WB-DWI. Follow-up with a liver biopsy helped confirm an atypical CSD diagnosis.

CASE PRESENTATION

A 23-year-old previously healthy man was admitted for a 19-day history of high fever despite 3-day treatment by azithromycin. His physical examination was unremarkable and contrast-enhanced CT showed only a low attenuated area in the right lobe of the liver, indicating a cyst. WB-DWI revealed multiple nodular lesions of hypo-diffusion in the liver, spine, and pelvic region. The biopsy specimens of the liver abscess showed no evidence of tuberculosis/malignancy and the polymerase chain reaction (PCR) test of liver abscess aspirate showed positive findings for Bartonellahenselae, confirming the diagnosis of CSD. He completed minocycline monotherapy for a total of 60 days without any deterioration.

CONCLUSIONS

WB-DWI can be useful for the diagnosis of atypical CSD with hepatic and bone involvement, which can cause FUO in young immunocompetent adults.

Diagnostic models for fever of unknown origin based on 18F-FDG PET/CT: a prospective study in China

Background

This study aims to analyze the 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) characteristics of different causes of fever of unknown origin (FUO) and identify independent predictors to develop a suitable diagnostic model for distinguishing between these causes. A total of 524 patients with classical FUO who underwent standard diagnostic procedures and PET/CT were prospectively studied. The diagnostic performance of PET/CT imaging was analyzed, and relevant clinical parameters that could improve diagnostic efficacy were identified. The model was established using the data of 369 patients and the other 155 patients comprised the validation cohort for verifying the diagnostic performance of the model.

Results

The metabolic characteristics of the “hottest” lesion, the spleen, bone marrow, and lymph nodes varied for various causes. PET/CT combined with clinical parameters achieved better discrimination in the differential diagnosis of FUO. The etiological diagnostic models included the following factors: multisite metabolic characteristics, blood cell counts, inflammatory indicators (erythrocyte sedimentation rate, C-reactive protein, serum ferritin, and lactate dehydrogenase), immunological indicators (interferon gamma release assay, antinuclear antibody, and anti-neutrophil cytoplasm antibody), specific signs (weight loss, rash, and splenomegaly), and age. In the testing cohort, the AUCs of the infection prediction model, the malignancy diagnostic model, and the noninfectious inflammatory disease prediction model were 0.89 (95% CI 0.86–0.92), 0.94 (95% CI 0.92–0.97), and 0.95 (95% CI 0.93–0.97), respectively. The corresponding AUCs for the validation cohort were 0.88 (95% CI 0.82–0.93), 0.93 (95% CI 0.89–0.98), and 0.95 (95% CI 0.92–0.99), respectively.

Conclusions

18F-FDG PET/CT has a certain level of sensitivity and accuracy in diagnosing FUO, which can be further improved by combining it with clinical parameters. Diagnostic models based on PET/CT show excellent performance and can be used as reliable tools to discriminate the cause of FUO.

Trial registration This study (a two-step method apparently improved the physicians’ level of diagnosis decision-making for adult patients with FUO) was registered on the website http://www.clinical-trials.gov on January 14, 2014, with registration number NCT02035670.

Clinical Value of PET.CT Based on Big Data in Colorectal and Peritoneal Metastatic Cancer

This study focuses on the evaluation of the clinical utility of PET-CT imaging in peritoneal metastases and colorectal cancer. One hundred patients with colorectal peritoneal metastases, who underwent whole-body PET-CT imaging from January 2015 to December 2019, were selected as the experimental group, and 20 healthy individuals were selected as the control group. The SUVmax of the two groups of patients was 5.73 ± 3.84 and 2.70 ± 2.32, respectively, and the difference was statistically significant. The SUVmax AUC was 0.720, and the AUC of serum AFP, CEA, CA125, and CA199 were 0.596, 0.677, 0.642, and 0.696, respectively. Conclusion. 100 patients with colorectal and peritoneal metastatic cancer underwent PET/CT examination. The follow-up or other imaging examinations confirmed the diagnosis. Analysis of the ROC curve in this study found that with a peritoneal SUVmax> 3.2 as the diagnostic index for colorectal peritoneal metastatic cancer, the sum of sensitivity and specificity reached the maximum.

Cat Scratch Disease with Generalized Bone Lesions in an Immunocompetent Child

A 9-year-old immunocompetent girl with prolonged fever for 1 month was suspected of having a malignancy because of generalized bone abnormalities identified by MRI. Histopathology of liver tissues indicated the diagnosis of cat-scratch disease (CSD). Results of NGS, immunofluorescence and immunochemical assay confirmed the causative agent was Bartonella henselae. Paediatricians should increase their awareness of CSD as a cause for bone lesions, except for malignancy.

Disease severity and status in Stevens–Johnson syndrome and toxic epidermal necrolysis: Key knowledge gaps and research needs

Stevens–Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are on a spectrum of cutaneous drug reactions characterized by pan-epidermal necrosis with SJS affecting < 10% of body surface area (BSA), TEN > 30%, and SJS/TEN overlap between 10 and 30%. Severity-of-illness score for toxic epidermal necrolysis (SCORTEN) is a validated tool to predict mortality rates based on age, heart rate, BSA, malignancy and serum urea, bicarbonate, and glucose. Despite improved understanding, SJS/TEN mortality remains constant and therapeutic interventions are not universally accepted for a number of reasons, including rarity of SJS/TEN; inconsistent definition of cases, disease severity, and endpoints in studies; low efficacy of interventions; and variations in treatment protocols. Apart from mortality, none of the other endpoints used to evaluate interventions, including duration of hospitalization, is sufficiently standardized to be reproducible across cases and treatment centers. Some of the gaps in SJS/TEN research can be narrowed through international collaboration to harmonize research endpoints. A case is made for an urgent international collaborative effort to develop consensus on definitions of endpoints such as disease status, progression, cessation, and complete re-epithelialization in interventional studies. The deficiencies of using BSA as the sole determinant of SJS/TEN severity, excluding internal organ involvement and extension of skin necrosis beyond the epidermis, are discussed and the role these factors play on time to healing and mortality beyond the acute stage is highlighted. The potential role of artificial intelligence, biomarkers, and PET/CT scan with radiolabeled glucose as markers of disease status, activity, and therapeutic response is also discussed.

Optimal use of the FDG-PET/CT in the diagnostic process of fever of unknown origin (FUO): a comprehensive review

Numerous studies have clarified the usefulness of ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT (positron emission tomography) for diagnosing the cause of fever of unknown origin (FUO). Various types of disease can cause FUO, but the cause remains unknown in a certain proportion of FUO, even when the advanced diagnostic methodologies are used. FDG-PET/CT is regarded as a second-line modality in the diagnostic process of FUO, and its potential to identify the cause of FUO will be maximized when the appropriate clinical considerations are understood. Accordingly, this review presents basic knowledge regarding FUO, and reports the current status of FDG-PET/CT applied to diagnosing the cause of FUO, including diagnostic performance, test protocols, possible factors influencing the diagnostic result, outcomes, and cost-effectiveness. This knowledge will enable effective future use of FDG-PET/CT to improve outcomes in patients with FUO.

Systemic Juvenile Idiopathic Arthritis in two children; case report on clinical course, challenges in diagnosis and the role of FDG-PET/CT-scan

Systemic juvenile idiopathic arthritis (sJIA, also called Still's disease) is a rare childhood auto-inflammatory disease with significant morbidity. This case report illustrates the clinical course and highlights diagnostic challenges. FDG-PET/CT imaging may be beneficial in the diagnostic process for some cases, in order to achieve rapid diagnosis and early treatment.

The Value of Diffuse Splenic and Hepatic 18F-FDG Uptake on PET/CT in Diagnosing Patients with Anemia

Objective

Anemia is a disease with a negative impact on the progression and prognosis of tumor diseases and usually diagnosed by blood tests. Imaging examination has been used as an alternative method to diagnose anemia in addition to blood tests for patients who cannot tolerate blood draw (such as those with severe coagulopathy). The purpose of this study was to investigate the role of diffuse splenic and hepatic ¹⁸F-FDG uptake on PET/CT in anemia, by analyzing the correlation between the hemoglobin level and diffuse splenic and hepatic as well as marrow ¹⁸F-FDG uptakes in patients who underwent PET/CT.

Materials and Methods

Forty four patients who underwent a peripheral blood examination within 2 days of a ¹⁸F-FDG-PET/CT in our hospital from March 2020 to March 2021 were included. The standardized uptake value (SUV) of the spleen, liver, and marrow were measured, including the maximum value (SUVmax) and the mean value (SUVmean), and the CT value (CTV) of the left ventricular (LV) cavity was measured, including the maximum value (CTVmax) and the mean value (CTVmean). The relation between these measurements and the blood hemoglobin level were analyzed.

Results

Our analysis revealed that the hemoglobin level was negatively correlated with the SUVmax of the spleen (P ≤ 0.01, R = −0.385), SUVmean of the spleen (P ≤ 0.01, R = −0.395), SUVmax of the liver (P ≤ 0.05, R = −0.365), and SUVmean of the liver (P ≤ 0.05, R = −0.315). The hemoglobin level was positively correlated with CTVmax of the LV cavity (P ≤ 0.05, R = 0.33) and CTVmean of the LV cavity (P ≤ 0.05, R = 0.382), while no statistically significant correlation between the hemoglobin level and the SUV of marrow was observed (P > 0.05).

Conclusion

Our study revealed a negative correlation between the hemoglobin level and spleen SUV as well as liver SUV, and a positive correlation between the hemoglobin level and CTV of the LV cavity. These findings may provide potential indictors for the imaging diagnosis of anemia, which has important clinical significance in certain clinical scenarios including the evaluation of anemia status in patients who cannot tolerate blood draws and retrospective clinical studies based on patient imaging data.

The Diagnostic Value of Fluoro-18 Fluorodeoxyglucose (F-18 FDG) PET/CT in Fever or Inflammation of Unknown Origin: A Retrospective Study at a Rheumatology Clinic

Introduction Further diagnostic procedures are necessary for patients with fever of unknown origin (FUO) and unknown cause of inflammation (inflammation of unknown origin - IUO) for the identification of the definitive diagnosis. The aim of this study was to evaluate the contribution and roles of F-18 FDG PET/CT (fluoro-18 fluorodeoxyglucose-positron emission tomography/computed tomography) in the diagnostic process of patients with FUO/IUO. Methods The data of 58 patients who had F-18 FDG PET/CT scans for FUO/IUO were re-evaluated retrospectively. The relationships between definitive diagnosis and fluorodeoxyglucose uptake and SUVmax (maximum standardized uptake value) were examined. Results  Rheumatic disease was diagnosed in 26 patients (44.5%), malignancy in 20 patients (34.5%), and infectious diseases in six patients (10.3%). The most prevalent rheumatic disease in patients with FUO/IUO was systemic vasculitis (n:10, 17.2%), especially large vessel vasculitis. There were 37 patients (63.7%) with clinically significant true positive fluorodeoxyglucose uptake. True positive fluorodeoxyglucose uptake was significantly higher in patients diagnosed with malignancy (85%, 17/20 patients) compared to other diagnoses. Fluorodeoxyglucose uptake above physiological levels was determined in 15 of the 26 patients (57.6%) diagnosed with rheumatic diseases. Conclusion The results of this study showed that F-18 FDG PET/CT is a useful imaging modality in FUO/IUO patients, who present a challenging diagnostic process for clinicians. In addition to malignancies, the presence of chronic inflammatory diseases, especially early period systemic vasculitis, were diagnosed in these patients.

Fever of unknown origin (FUO) in children: a single-centre experience from Beijing, China

OBJECTIVE

To date, there is no standard diagnostic practice to identify the underlying disease-causing mechanism for paediatric patients suffering from chronic fever without any specific diagnosis, which is one of the leading causes of death in paediatric patients. Therefore, we aimed this retrospective study to analyse medical records of paediatric patients with fever of unknown origin (FUO) to provide a preliminary basis for improving the diagnostic categories and facilitate the treatment outcomes.

DESIGN

A retrospective study.

SETTING

Beijing Children's Hospital.

PARTICIPANTS

Clinical data were collected from 1288 children between 1 month and 18 years of age diagnosed with FUO at Beijing Children's Hospital between January 2010 and December 2017.

INTERVENTIONS

According to the aetiological composition, age, duration of fever and laboratory examination results, the diagnostic strategies were analysed and formulated.

PRIMARY AND SECONDARY OUTCOME MEASURES

The statistical analyses were carried out using SPSS V.24.0 platform along with the χ² test and analysis of variance (p<0.05).

RESULTS

The duration of fever ranged from 2 weeks to 2 years, with an average of 6 weeks. There were 656 cases (50.9%) of infectious diseases, 63 cases (4.9%) of non-infectious inflammatory diseases (NIIDs), 86 cases (6.7%) of neoplastic diseases, 343 cases (26.6%) caused by miscellaneous diseases and 140 cases (10.9%) were undiagnosed. With increasing age, the proportion of FUO from infectious diseases gradually decreased from 73.53% to 44.21%. NIID was more common in children over 3 years old, and neoplastic diseases mainly occurred from 1 to 6 years of age. Among miscellaneous diseases, the age distribution was mainly in school-aged children over 6 years. Respiratory tract infection was the most common cause of FUO in children, followed by bloodstream infections. Bacterial infection was the most common cause in children with less than 1 year old, while the virus was the main pathogen in children over 1 year old.

CONCLUSIONS

The diagnosis of neoplastic diseases and miscellaneous diseases-related diseases still depends mainly on invasive examination. According to our clinical experience, the diagnostic process was formulated based on fever duration and the type of disease. This process can provide a guide for the diagnosis and treatment of paediatric FUO in the future.

Diagnostic value of F-18 FDG PET/CT in fever or inflammation of unknown origin in a large single-center retrospective study

Cause determination is challenging in fever or inflammation of unknown origin (FUO/IUO) despite today’s diagnostic modalities. We evaluated the value of F-18 FDG PET/CT in an unselected patient collective. This retrospective nonrandomized single-center study enrolled 300 male and female patients with FUO/IUO. PET/CT findings were compared with final clinical outcomes to determine the sensitivity, specificity, clinical significance, etiological distribution of final diagnoses, impact on treatment, role of white-blood cell count (WBC), and C-reactive protein (CRP). In 54.0% (162/300) PET/CT was the decisive exanimation for establishing the final diagnosis, in 13.3% (40/300) the findings were equivocal and indecisive, in 3.3% (10/300) PET/CT findings were false positive, while in 29.3% (88/300) a normal F-18 FDG pattern was present. Statistical analysis showed a sensitivity of 80.2% and a specificity of 89.8% for the contribution of PET/CT to the final diagnosis. CRP levels and WBC were not associated with PET/CT outcome. PET/CT let to new treatment in 24.0% (72/300), treatment change in 18.0% (54/300), no treatment change in 49.6% (149/300), and in 8.3% (25/300) no data was available. Our study demonstrates the utility of F-18 FDG PET/CT for source finding in FUO/IUO if other diagnostic tools fail.

Differential Diagnosis of Hemophagocytic Syndrome by 18F-FDG PET/CT: A Meta-Analysis

Hemophagocytic syndrome (HPS) is a rare disease in clinical practice, and there are often cases of delayed diagnosis. At present, researchers have applied 18F-FDG PET/CT in the differential diagnosis of HPS, but no consensus has been formed. Therefore, this study aims to systematically evaluate the application value of 18F-FDG PET/CT in the diagnosis of HPS patients. PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Wangfang database (Wangfang), and Chinese Biomedical Network (CBM) were searched to collect the relevant studies of 18F-FDG PET/CT in the diagnosis of HPS. Data from the articles were screened and extracted for meta-analysis using Stata16.0 software. A total of 10 retrospective studies, including 300 patients, were included in this meta-analysis. The meta-analysis results showed that the pooled sensitivity was 0.82 (95% CI: 0.67-0.95), specificity was 0.72 (95% CI: 0.51-0.86), positive likelihood ratio was 2.89 (95% CI: 1.46-5.75), positive likelihood ratio was 0.25 (95% CI: 0.12-0.54), diagnostic odds ratio was 2.89 (95% CI: 1.46-5.75), and AUC was 0.84 (95% CI: 0.81-0.87). The SUVmax in the liver, spleen, lymph nodes, and bone marrow of HPS patients was greater than 2.5, and the SUVmax in the spleen, lymph nodes, and bone marrow of malignant HPS patients was higher than that of benign HPS patients. The difference was statistically significant (P < 0.05). According to the existing literature evidence, 18F-FDG PET/CT is an effective method for diagnosing HPS.

Application of Machine Learning for the Prediction of Etiological Types of Classic Fever of Unknown Origin

Background: The etiology of fever of unknown origin (FUO) is complex and remains a major challenge for clinicians. This study aims to investigate the distribution of the etiology of classic FUO and the differences in clinical indicators in patients with different etiologies of classic FUO and to establish a machine learning (ML) model based on clinical data. Methods: The clinical data and final diagnosis results of 527 patients with classic FUO admitted to 7 medical institutions in Chongqing from January 2012 to August 2021 and who met the classic FUO diagnostic criteria were collected. Three hundred seventy-three patients with final diagnosis were divided into 4 groups according to 4 different etiological types of classical FUO, and statistical analysis was carried out to screen out the indicators with statistical differences under different etiological types. On the basis of these indicators, five kinds of ML models, i.e., random forest (RF), support vector machine (SVM), Light Gradient Boosting Machine (LightGBM), artificial neural network (ANN), and naive Bayes (NB) models, were used to evaluate all datasets using 5-fold cross-validation, and the performance of the models were evaluated using micro-F1 scores. Results: The 373 patients were divided into the infectious disease group (n = 277), non-infectious inflammatory disease group (n = 51), neoplastic disease group (n = 31), and other diseases group (n = 14) according to 4 different etiological types. Another 154 patients were classified as undetermined group because the cause of fever was still unclear at discharge. There were significant differences in gender, age, and 18 other indicators among the four groups of patients with classic FUO with different etiological types (P < 0.05). The micro-F1 score for LightGBM was 75.8%, which was higher than that for the other four ML models, and the LightGBM prediction model had the best performance. Conclusions: Infectious diseases are still the main etiological type of classic FUO. Based on 18 statistically significant clinical indicators such as gender and age, we constructed and evaluated five ML models. LightGBM model has a good effect on predicting the etiological type of classic FUO, which will play a good auxiliary decision-making function.

Fluorodeoxyglucose Positron Emission Tomography Imaging in Pneumocystis jiroveci Pneumonia

Fever or pyrexia of unknown origin (PUO) is commonly defined as body temperature higher than 38.3°C on several occasions for a period of at least 3 weeks with uncertain diagnosis after initial routine obligatory investigations. In most cases of PUO, there is an uncommon presentation of a common disease which includes infection, noninfectious inflammatory diseases, malignancy, and miscellaneous causes. We present an interesting case of a 48-year-old man with PUO, who is a known case of multiple myeloma on immunosuppressive therapy, where 18F-fluorodeoxyglucose positron emission tomography-computed tomography was able to detect occult cause of infective etiology.

Economic assessment of molecular imaging in the oncology treatment process

The development towards targeted treatments in oncology has been accompanied by significant improvements in molecular imaging. Yet, broad application of novel imaging techniques has partly been slowed down due to economical considerations. Building on the broad positive evidence of its diagnostic accuracy, modelling of effects on long-term costs and effectiveness may help to foster a broader application and acceptance of comprehensive molecular imaging techniques, such as PET/MRI. In this article, common economic evaluation techniques and cost-effectiveness analysis (CEA) evaluation methods will be introduced including Markov models and incremental cost-effectiveness ratios (ICER). This is complemented with a review of literature on recently published cost-effectiveness of molecular imaging. Additionally, the strategic relevance of CEAs for the molecular imaging community is discussed and combined with a global outlook.

Usefulness of 18FDG-PET/CT and MRI in an immunocompetent patient with fever of unknown origin and following diagnosis of skeletal tuberculosis

INTRODUCTION

Fever of unknown origin (FUO) is one of the most difficult diagnostic dilemmas in current medicine. The main causes of FUO in developed countries are non-infectious inflammatory diseases, while infections are predominant in developing countries. Among infections, Mycobacterium Tuberculosis (TB) is the most frequent cause and it can involve multiple tissues and organs.

CASE AND OUTCOMES

We report a case of FUO in an immunocompetent patient with fever of unknown origin, finally diagnosed with skeletal TB thanks to a multidisciplinary approach, using FDG-PET/CT, MRI, and biopsy. PET/CT findings were non-specific (infection or inflammation versus malignancy); therefore, hip Magnetic Resonance Imaging (MRI) was performed and infection was suspected on basis of MRI findings, so a bone biopsy was then performed and skeletal TB was diagnosed.

DISCUSSION

A successful diagnostic workup of FUO has to take into account detailed medical history, physical examination, laboratory tests, blood and urine cultures, and standard imaging (Ultrasonography, CT, or MRI). However, this combination of clinical evaluation, standardized laboratory tests and simple imaging procedures often do not lead to a definite diagnosis; ⁸F-FDG-PET-CT could be performed to help in diagnosis and also to guide additional diagnostic tests such as MRI and biopsy.

CONCLUSION

This case demonstrates the importance of the integration of different imaging modalities, in particular, MRI and FDG-PET/CT in patients with FUO. Skeletal TB should always be included in the diagnostic hypothesis of FUO, even in immunocompetent patients of non-endemic countries.