The role of 18F-fluorodeoxyglucose positron emission tomography in the assessment of disease activity of adult-onset Still's disease

[Application of 18F-FDG PET/CT in rheumatic diseases]

OBJECTIVE

To explore the application of 18F-flurodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in rheumatic diseases, to compare these different imaging features, and to describe the current PET/CT imaging status in clinical practice.

METHODS

A total of 486 cases in our department from January 2012 to December 2018 were enrolled in this study, and 18F-FDG PET/CT examination was performed in all the patients. The clinical use of 18F-FDG PET/CT was retrospectively analyzed to discuss the clinical application and its imaging characteristics of rheumatic diseases. Categorical data were used to ascertain prevalence statistics, whereas continuous data were used to delineate means and standard deviations. Independent sample t test, Chi square test and Mann-Whitney U test were used for statistical analysis. A P-value of < 0.05 was considered significant.

RESULTS

(1) From 2012 to 2018, totally 486 patients in the Department of Rheumatology and Immunology underwent 18F-FDG PET/CT examination, accounting for 5.30% of the total number of PET/CT examinations in the whole hospital. In this study, 304 of the 486 patient were female (62.55%), 182 of them were male (37.45%), the average age of the patients was (53.21±18.81) years, and the proportion of the patients aged 45-65 (227/486, 46.71%) was the highest group. (2) Three leading purposes of the PET/CT examination in our department were to exclude cancers (55.56%), assist in diagnosis (24.60%) and evaluate the disease activity (19.84%). (3) Of the 486 patients who underwent 18F-FDG PET/CT, 327 cases might indicate a differential diagnosis of rheumatic disease, of which, 292 cases were highly suggestive of diagnosis, including 61 cases of myositis, 60 cases of vasculitis, 37 cases of adult still's disease, 32 cases of IgG4 related diseases, 30 cases of rheumatoid arthritis, 22 cases of Sjögren's syndrome, 22 cases of systemic lupus erythematosus, and 9 cases of rheumatic polymyalgia; the remaining 35 cases only prompted the possibility of autoimmune disease. Of the 486 patients, 74 cases suggested the diagnosis of cancers, 25 cases indicated the diagnosis of infectious diseases, while 60 cases could not show any diagnostic values. Ten patients with rheumatic disease were followed up with a post-treatment repeat PET/CT, and the findings in remission showed reduced 18F-FDG metabolic activity as well as a reduction in the extent of metabolic hypertrophic lesions.

CONCLUSION

There are some typical sign of 18F-FDG PET/CT for diffuse connective tissue diseases, therefore 18F-FDG PET/CT has auxi-liary effect on the classification diagnosis of rheumatic diseases, especially for the exclusion of cancers.

Rheumatology experience with FDG PET / CT in inflammation of unknown origin: a single - centre report for determining factors associated with diagnostic precision

BACKGROUND / AIM: The use of PET / CT is becoming more common in the elucidation of inflammatory processes in which the underlying cause cannot be determined by conventional examinations. Although PET / CT is an effective method for detecting inflammatory foci, the precise diagnosis may not be obtained in all cases. In addition, considering factors such as radiation exposure and cost, it becomes important to identify patients who can get results with PET / CT. In this study, it was aimed to examine the factors that can predict the differential diagnostic value of PET / CT by retrospectively scanning patients who underwent PET / CT for inflammation of unknown origin (IUO) in rheumatology practice.

METHODS

Demographic, clinical and laboratory information of the patients followed up in our clinic and who underwent PET / CT for differential diagnosis were enrolled. Whether they were diagnosed after PET / CT and during the follow - up period, and their diagnoses were examined.

RESULTS

A total of 132 patients were included in the study. A previous diagnosis of rheumatic disease was present in 28.8 % of the patients, and a history of malignancy was present in 2.3 % . The patients were divided into three groups: group 1 patients with increased FDG uptake in PET / CT and diagnosis confirmed by PET / CT, group 2 patients with increased FDG uptake in PET / CT but diagnosis was not confirmed, and group 3 patients without increased FDG uptake in PET / CT. Increased FDG uptake in PET / CT was detected in 73 % of the patients. While PET / CT helped the diagnosis in 47 (35.6 %) patients (group 1), it did not help the diagnosis in 85 (64.4 %) (groups 2 and 3). Thirty - one (65.9 %) of the diagnosed patients were diagnosed with a rheumatologic disease. When the 3 groups were compared, male gender, advanced age, CRP levels, presence of constitutional symptoms, SUVmax values and number of different organs with increased FDG uptake were higher in Group 1. Sixty - six percent and 74 % of the patients in groups 2 and 3 were not diagnosed during the follow - up period. No patient in group 3 was diagnosed with malignancy during follow - up.

CONCLUSION

PET / CT has high diagnostic value when combined with clinical and laboratory data in the diagnosis of IUO. Our study revealed that various factors can affect the diagnostic value of PET / CT. Similar to the literature, the statistically significant difference in CRP levels shows that patients with high CRP levels are more likely to be diagnosed with an aetiology in PET / CT. Although detection of involvement in PET / CT is not always diagnostic, there was an important finding that no malignancy was detected in the follow - up in any patient without PET / CT involvement. Key points • PET / CT is an effective method for detecting inflammatory foci. • PET / CT has proven to be effective in the diagnosis of rheumatological diseases, the extent of disease and the evaluation of response to treatment. • Indications for the use of PET / CT in the field of rheumatology and the associated factors and clinical features supporting the diagnosis with PET / CT are still to be fully clarified. • In routine practice, with PET / CT, both delays in diagnosis and examinations performed during diagnosis and the cost can be reduced.

Differential diagnostic performance of PET/CT in adult-onset still's disease and lymphoma: a retrospective pilot study

Background

Adult-onset still's disease (AOSD) and lymphoma are the common causes of fever of unknown origin (FUO) and show some similar clinical symptoms. This study aimed to establish a reliable and easy-to-used scoring model based on clinical information, laboratory characteristics and ¹⁸F-fluorodeoxyglucose positron emission tomography/computer tomography (¹⁸F-FDG PET/CT) images for the differential diagnosis of these two diseases.

Methods

A development cohort including 70 AOSD and 37 lymphoma patients was used to establish a scoring model based on the features of PET/CT images. The scoring model was then validated in a validation cohort of 15 AOSD and 12 lymphoma patients. The features of involved bone marrow, spleen, lymph nodes, and other organs or tissues displayed on PET/CT images were compared. Multiple logistics regression and decision tree analysis were used to establish the scoring model.

Results

Four features that could significantly differentiate these two diseases were selected to establish a scoring model discriminating AOSD from lymphoma, including (I) white blood cell (WBC) count ≤10×10⁹/L (1 point); (II) ferritin ≤ upper limit of normal (ULN) (1 point); (III) no abnormal bone marrow metabolism (1 point); (IV) total lesion glycolysis_total (TLG_total) >9.0 (1 point). After decision tree analysis, it showed that a score ≤1 indicates AOSD. A score ≥3 strongly suggested lymphoma, with a sensitivity of 81.1% and specificity of 90.0% in the development cohort, and a sensitivity of 58.3% and specificity of 100% in the validation cohort.

Conclusions

Our scoring model showed good diagnosis performance in distinguishing AOSD from lymphoma.

2-deoxy-2[18F]fluoro-D-glucose positron emission tomography-computed tomography in rheumatological diseases

2-deoxy-2[18F]fluoro-D-glucose (FDG) PET-CT has revolutionized oncological imaging. The cellular processes that make cancer cells visible on FDG PET-CT also occur in a number of inflammatory cells. Exploiting this phenomenon has led to a growth of evidence supporting the use of FDG PET-CT in a wide range of infective and inflammatory diseases. Rheumatological diseases can affect multiple sites within the musculoskeletal system alongside multi-organ extra-articular disease manifestations. Inflammation is central to these diseases, making FDG PET-CT a logical choice. In this review article we describe the various applications of FDG PET-CT in rheumatological diseases using illustrative examples to highlight the beneficial role of FDG PET-CT in each case.

Characteristics and Clinical Value of 18F-FDG PET/CT in the Management of Adult-Onset Still's Disease: 35 Cases

While the diagnosis of adult-onset Still’s disease (AOSD) involves the exclusion of differential diagnoses, the characteristics and value of 18F-Fluorodeoxyglucose (18F-FDG) Positron Emission Tomography coupled with CT (PET/CT) in the management of AOSD remain poorly known. Our retrospective study included patients from four centers, fulfilling Yamaguchi or Fautrel criteria, who underwent a PET/CT during an active AOSD. Thirty-five patients were included. At the time of PET/CT, the Yamaguchi criteria were met in 23 of 29 evaluable cases. PET/CT showed bone marrow (74.3%), lymph node (74.3%), and splenic (48.6%) FDG uptake. Despite arthralgia or arthritis in most patients, joints were rarely the sites of 18F-FDG accumulation. The spatial distribution of 18F-FDG uptake was nonspecific, and its intensity could be similar to malignant disease. Lymph node or bone marrow biopsy was performed after PET/CT in 20 patients (57.1%). The intensity of bone marrow; splenic and lymph node hypermetabolism appeared to be correlated with disease activity. Abnormal PET/CT in the cervical lymph nodes and age ≥ 60 years seemed to be predictive factors for monocyclic evolution. The clinical value of PET/CT is not in direct diagnosis; but as an aid in excluding differential diagnoses by searching for their scintigraphic features and guiding biopsy.

18F-FDG PET/CT Associates With Disease Activity and Clinical Recurrence of AOSD Patients

Objective: The purpose of this study was to explore the value of ¹⁸F-FDG PET/CT in monitoring the disease activity and predicting the prognosis of the Adult-onset Still's disease (AOSD).

Methods: We retrospectively analyzed the electronic medical records of 45 AOSD patients who underwent ¹⁸F-FDG PET/CT in the Second Xiangya Hospital. PET/CT imaging and clinical information were retrospectively reviewed and analyzed. ¹⁸F-FDG uptake was assessed by measuring standard uptake value (SUV) in the spleen, liver, bone marrow, and lymph nodes. The spleen-to-liver ratio of the SUVmax (SLRmax) and SUVmean (SLRmean), the bone-to-liver ratio of the SUVmax (BLRmax), and SUVmean (BLRmean), and the lymph nodes-to-liver ratio of the SUVmax (LyLRmax) were calculated. Clinical and laboratory information were collected and evaluated for association with metabolic parameters of ¹⁸F-FDG PET/CT. The influencing factors for recurrence within 1 year were analyzed to determine whether ¹⁸F-FDG PET/CT can predict the prognosis of AOSD patients.

Results: Elevated ¹⁸F-FDG uptake could be observed in bone marrow, spleen, and lymph nodes of AOSD patients. Correlation analysis between ¹⁸F-FDG uptake of organs and laboratory examinations showed that SLRmean positively correlated with LDH, AST, ferritin, and the systemic score (r = 0.572, 0.353, 0.586, and 0.424, P < 0.05). The SLRmean had the highest correlation with ferritin (r = 0586, P < 0.001). All metabolic parameters in spleen, including SUVmax, SUVmean, SLRmax, and SLRmean, are positively correlated with LDH level (r = 0.405, 0.539, 0.481, and 0.572, P < 0.05). Bone marrow SUVmax, BLRmax, and BLRmean were correlated with C-reactive protein (CRP) level (r = 0.395, 0.437, and 0.469, P < 0.05). Analysis of the influencing factors of recurrence within 1 year showed that the spleen SUVmax, spleen SUVmean, SLRmax, SLRmean, ferritin, and the systemic score of the recurrence group was significantly higher than the non-recurrence group (P < 0.05). The SLRmean cutoff of 1.66 with a sensitivity of 72.7% and specificity of 80.0% had the highest performance in predicting recurrence.

Conclusion: The glucose metabolism of the liver, spleen, and bone marrow of AOSD patients were correlated with laboratory inflammatory indicators and system score, suggesting that ¹⁸F-FDG PET/CT could be applied to evaluate disease activity. Moreover, spleen ¹⁸F-FDG uptake may be a potential biomarker for predicting clinical prognosis of AOSD patients.

Total metabolic lesion volume of lymph nodes measured by 18F-FDG PET/CT: a new predictor of macrophage activation syndrome in adult-onset Still's disease

Background

To investigate the potential utility of quantitative parameters obtained by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in the assessment of disease severity and the occurrence of macrophage activation syndrome (MAS) in adult-onset Still’s disease (AOSD).

Methods

Fifty-seven patients with AOSD who underwent pre-treatment ¹⁸F-FDG PET/CT were recruited in this study and compared with 60 age- and sex-matched healthy controls. Clinical features and laboratory data were recorded. The systemic score was assessed to determine the disease severity. The maximal standardized uptake value (SUV_max), metabolic lesion volume (MLV), and total lesion glycolysis (TLG) were used to evaluate the involved organs and tissues that abnormally accumulated ¹⁸F-FDG. Multivariate analysis was performed to identify the PET/CT-derived risk factors contributing to the AOSD-related MAS, and their diagnostic efficiency was evaluated.

Results

High ¹⁸F-FDG accumulation was observed in the bone marrow (SUV_max median, 5.10), spleen (SUV_max median, 3.70), and lymph nodes (LNs, SUV_max median, 5.55). The SUV_max of the bone marrow (rho = 0.376, p = 0.004), SUV_max of the spleen (rho = 0.450, p < 0.001), TLG_total of LNs (rho = 0.386, p = 0.017), and MLV_total of LNs (rho = 0.391, p = 0.015) were correlated with the systemic score. The SUV_max of the spleen (p = 0.017), TLG_total of LNs (p = 0.045), and MLV_total of LNs (p = 0.012) were higher in patients with MAS than in those without MAS. A MLV_total of LNs > 62.2 (OR 27.375, p = 0.042) was an independent predictive factor for MAS with a sensitivity of 80.0% and a specificity of 93.9%.

Conclusions

The glucose metabolic level of the spleen could be an effective and easy-to-use imaging indicator of disease severity, and MLV_total of LNs > 62.2 was a strong predictor of MAS occurrence in patients with AOSD.

18F-Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography With Magnetic Resonance for Diagnosing Adult-Onset Still's Disease

Objective: The objective of the study was to assess the advantages of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography with magnetic resonance (PET/CT-MR) in diagnosing and monitoring patients with adult-onset Still's disease (AOSD).

Methods: Participants in this retrospective case-control study underwent whole-body ¹⁸F-FDG-PET/CT-MR imaging. All PET scans were qualitatively and semiquantitatively analyzed using standardized uptake values (SUVs) normalized to liver uptake, i.e., we calculated the ratio (SUVr) between the minimum, maximum, and mean SUVs for different organs and tissues and the mean SUV for the liver. Disease activity scores were assessed using Pouchot's criteria.

Results: Eighteen patients diagnosed with AOSD and 24 controls (non-AOSD patients diagnosed with solid tumors, excluding lymphomas) were considered. A total of 38 PET/MR and nine PET/CT scans were analyzed. AOSD patients had higher SUVr than controls. All SUVr differed significantly between the patient and control group for bone marrow, and for the spleen, the only difference lacking statistical significance concerned the ratio of the minimum SUV for spleen to the mean SUV for liver. Though limited in number, AOSD responders to therapy showed lower uptakes during the period monitored. No correlations were found between Pouchot's scores and SUVr.

Conclusion: Our data revealed higher spleen and bone marrow ¹⁸F-FDG uptakes on PET/CT and PET/MR images in AOSD patients than in controls. Together with clinical examinations and laboratory data, PET/CT and PET/MR seemed more reliable than Pouchot's score in assessing disease activity.

Current Applications for Nuclear Medicine Imaging in Pulmonary Disease

Purpose of Review

The main goal of the article is to familiarize the reader with commonly and uncommonly used nuclear medicine procedures that can significantly contribute to improved patient care. The article presents examples of specific modality utilization in the chest including assessment of lung ventilation and perfusion, imaging options for broad range of infectious and inflammatory processes, and selected aspects of oncologic imaging. In addition, rapidly developing new techniques utilizing molecular imaging are discussed.

Recent Findings

The article describes nuclear medicine imaging modalities including gamma camera, SPECT, PET, and hybrid imaging (SPECT/CT, PET/CT, and PET/MR) in the context of established and emerging clinical applications. Areas of potential future development in nuclear medicine are discussed with emphasis on molecular imaging and implementation of new targeted tracers used in diagnostics and therapeutics (theranostics).

Summary

Nuclear medicine and molecular imaging provide many unique and novel options for the diagnosis and treatment of pulmonary diseases. This article reviews current applications for nuclear medicine and molecular imaging and selected future applications for radiopharmaceuticals and targeted molecular imaging techniques.

FDG PET/CT used in identifying adult-onset Still's disease in connective tissue diseases

PURPOSE

To explore the ¹⁸F-fluoro-dexoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) imaging characteristics of adult-onset Still's disease (AOSD) and its significance in differential diagnosis from other connective tissue diseases (CTDs).

METHODS

FDG PET/CT images of 54 patients with AOSD and 66 with other CTD from patients suffering from fever of unknown origin (FUO) were retrospectively studied and compared with 40 healthy controls. Clinical and PET/CT characteristics of AOSD and other CTDs were compared, and SUV_max (maximum standardized uptake value) was used to analyze the differences of FDG uptake in the blood pool, liver, spleen, bone marrow, and hyperplastic lymph nodes between the AOSD and other CTDs. The SUV_max ratios of the spleen, bone marrow, and lymph nodes to the liver were used to establish the diagnostic criteria for differential diagnosis of AOSD, and its diagnostic efficiency was evaluated.

RESULTS

Positive findings are presented in 53/54 (98.1%) AOSD patients and 61/66 (92.4%) other CTD patients in PET/CT imaging. AOSD manifested as diffusely increased FDG uptake in the spleen and bone marrow, and multiple reactive hyperplasia lymph nodes are symmetrically distributed mainly in the neck and axilla, while other organs were seldom involved. Although these abnormalities could be seen in other CTDs, its incidence and uptake value were both higher in AOSD. If two or more of the following three standard were met, the sensitivity, specificity, and accuracy of diagnosing AOSD could reach 90.7%, 92.4%, and 91.7%, respectively: ① spleen SUV_max/liver SUV_max ≥ 1.2 and/or bone marrow SUV_max/liver SUV_max ≥ 1.4; ②symmetrically distributed reactive hyperplastic lymph nodes mainly in the neck and axilla with a lymph node SUV_max/liver SUV_max ≥ 1.8; and ③ no other abnormal uptake found in other organs.

CONCLUSION

Characteristic manifestations in AOSD were found on FDG PET/CT. These findings could help to identify AOSD from the other CTDs, especially in cases of fever of unknown origin, where it can assist in identifying the cause. Key Points • Image characteristics of FDG PET/CT in adult-onset Still's disease were described. • FDG PET/CT helps in identifying adult-onset Still's disease from the other connective tissue diseases. • FDG PET/CT imaging standard for diagnosing adult-onset Still's disease were established.