FDG PET-CT Demonstration of Sjogren??s Sialoadenitis

The role of PET/CT in connective tissue disorders: systemic sclerosis, Sjögren's syndrome and systemic lupus erythematosus

Advanced imaging techniques are needed to help clinicians in the diagnosis, in the choice of the right time for therapeutic interventions or for modifications and monitoring of treatment response in patients with autoimmune connective tissue diseases. Nuclear medicine imaging, especially PET/CT and PET/MRI, may play an important role in detecting disease activity, assessing early treatment response as well as in clarifying the complex mechanisms underlying systemic sclerosis, Sjögren's syndrome or systemic lupus erythematosus. In addition, [¹⁸F]FDG PET/CT may help in excluding or detecting coexisting malignancies. Other more specific radiopharmaceuticals are being developed and investigated, targeting specific cells and molecules involved in connective tissue diseases. Further larger studies with standardized imaging protocol and image interpretation are strongly required before including PET/CT in the diagnostic work-up of subsets of patients with autoimmune connective tissue diseases.

Imaging in Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease characterized by dysfunction and lymphocytic infiltration of the salivary and lacrimal glands. Besides the characteristic sicca complaints, pSS patients can present a spectrum of signs and symptoms, which challenges the diagnostic process. Various imaging techniques can be used to assist in the diagnostic work-up and follow-up of pSS patients. Developments in imaging techniques provide new opportunities and perspectives. In this descriptive review, we discuss imaging techniques that are used in pSS with a focus on the salivary glands. The emphasis is on the contribution of these techniques to the diagnosis of pSS, their potential in assessing disease activity and disease progression in pSS, and their contribution to diagnosing and staging of pSS-associated lymphomas. Imaging findings of the salivary glands will be linked to histopathological changes in the salivary glands of pSS patients.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

18F-FDG PET/CT in multisystem Sjögren syndrome

Sjögren syndrome (SS) is an autoimmune disease affecting exocrine glands, mostly lacrimal and salivary glands. Rarely, extraglandular sites such as skin, lung, kidneys, and nervous system may be involved. F-FDG PET/CT can be employed in SS for assessment of disease activity and for exclusion of lymphoma. We here present the case of a 61-year-old woman with SS where multisystem involvement was demonstrated on F-FDG PET/CT.

The Clinical Usefulness of (18)F-FDG PET/CT in Patients with Systemic Autoimmune Disease

PURPOSE

Individuals with systemic autoimmune disease have an increased susceptibility to both inflammation and malignancy. The aim of this study was to evaluate the clinical usefulness of (18)F-FDG PET/CT in patients with systemic autoimmune disease.

METHODS

Forty patients diagnosed with systemic autoimmune disease were enrolled. Diagnostic accuracy of FDG PET/CT for detecting malignancy was assessed. FDG PET/CT findings, including maximum standardized uptake (SUVmax) of lymphadenopathy (LAP), liver, bone marrow, spleen, joint and muscles, were considered for the characterization of LAPs.

RESULTS

FDG PET/CT could detect metabolically activated lesions in 36 out of 40 patients (90%) including inflammatory lesions in 28 out of 32 patients (88%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of FDG PET/CT for the detection of malignancy were 100, 67, 70, 25, and 100%, respectively. Multiple LAPs were found in 25 of 40 patients (63%), and comprised three malignancies, four cases of tuberculosis, and 18 reactive changes. A SUVmax ratio of bone marrow to liver below 0.78 could distinguish malignancy from tuberculosis + reactive change (AUC = 1.000, sensitivity: 100%, specificity: 100%). The SUVmax ratio of spleen to liver in the reactive group was also significantly higher than that in the malignancy group (P = 0.014). SUVmax of LAP in the TB group was significantly higher than that in the reactive group (P = 0.040).

CONCLUSIONS

PET/CT is useful in detecting and differentiating inflammation and malignancy in patients with systemic autoimmune disease. Frequent false-positive interpretations can be minimized by consideration of FDG uptake in bone marrow and spleen.

Normal and Abnormal Patterns of 18F-Fluorodeoxyglucose PET/CT in Lymphoma

In spite of the high performance of 18F-fluorodeoxyglucose (FDG) PET for the evaluation of lymphoma, inherent limitations of this modality underscore the additional value of PET/CT as an important tool in the assessment of this disease. Accumulating data on the use of PET/CT in lymphoma indicate the contribution of hybrid imaging to improved interpretation accuracy of PET using FDG and CT. Knowledge of the normal and abnormal patterns of FDG-PET/CT imaging and their variability in patients with lymphoma is important to provide a comprehensive clinically significant interpretation that has an impact on patient management and potentially on outcome.

La tomographie d'émission de positons en médecine interne : applications actuelles et perspectives d'avenir

PURPOSE

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a promising imaging technique that has already proven effective in modifying patient care in oncology. Fluorodeoxyglucose still remains the main radiopharmaceutical agent routinely used for PET imaging. A growing interest has recently lead to broaden PET research on benign disorders. The field of inflammatory or immune diseases and globally the field of internal medicine could also be impacted by FDG-PET.

MAIN POINTS

Great vessels vasculitides and fever of unknown origin have both been studied by several teams and could become indications for PET. In addition, current indications now extend to paraneoplastic syndromes. It is thus possible to foresee that the clinical applications for PET will continue to expand in these patients.

PERSPECTIVES AND PROJECTS

In the future, inflammatory arthritis, chronic inflammatory bowel diseases, systemic erythematous lupus, histiocytosis, or pulmonary and retroperitoneal fibrosis might benefit from PET even if, available data remains scarce to this day. Although PET will probably alter the landscape of patient management in internal medicine in the near future, additional clinical research is still needed to ascertain the exact role of PET.