Whole body MRI with Diffusion Weighted Imaging versus 18F-fluorodeoxyglucose-PET/CT in the staging of lymphomas.

PURPOSE: To assess the diagnostic performance of Whole Body (WB)-MRI in comparison with 18F-Fluorodeoxyglucose-PET/CT (18F-FDG-PET/CT) in lymphoma staging and to assess whether quantitative metabolic parameters from 18F-FDG-PET/CT and Apparent Diffusion Coefficient (ADC) values are related. MATERIALS AND METHODS: We prospectively enrolled patients with a histologically proven primary nodal lymphoma to  undergo 18F-FDG-PET/CT and WB-MRI, both performed within 15 days one from the other, either before starting treatment (baseline) or during treatment (interim). Positive and negative predictive values of WB-MRI for the identification of nodal and extra-nodal disease were measured. The agreement between WB-MRI and 18F-FDG-PET/CT for the identification of lesions and staging was assessed through Cohen's coefficient k and observed agreement. Quantitative parameters of nodal lesions derived from 18F-FDG-PET/CT and WB-MRI (ADC) were measured and the Pearson or Spearman correlation coefficient was used to assess the correlation between them. The specified level of significance was p ≤ 0.05. RESULTS: Among the 91 identified patients, 8 refused to participate and 22 met exclusion criteria, thus images from 61 patients (37 men, mean age 30.7 years) were evaluated. The agreement between 18F-FDG-PET/CT and WB-MRI for the identification of nodal and extra-nodal lesions was 0.95 (95% CI 0.92 to 0.98) and 1.00 (95% CI NA), respectively; for staging it was 1.00 (95% CI NA). A strong negative correlation was found between ADCmean and SUVmean of nodal lesions in patients evaluated at baseline (Spearman coefficient rs = - 0.61, p = 0.001). CONCLUSION: WB-MRI has a good diagnostic performance for staging of patients with lymphoma in comparison with 18F-FDG-PET/CT and is a promising technique for the quantitative assessment of disease burden in these patients.

Imaging Activated-T-Lymphocytes in the Salivary Glands of Patients with Sjögren's Syndrome by 99mTc-Interleukin-2: Diagnostic and Therapeutic Implications.

Background: Sjögren's syndrome (SS) is a progressive autoimmune disease characterized by local mononuclear cell infiltration of the salivary and lachrymal glands. Labial biopsy demonstrates local infiltration by Th1 cells that produce pro-inflammatory cytokines, such as interleukin-2 (IL2). The aim of this study was to assess the utility of 99mTc-labelled-IL2 (99mTc-IL2) in evaluating in vivo the extent and severity of lympho-mononuclear cell infiltration in the salivary glands of patients with SS. Methods: We investigated 48 patients with primary SS and 27 control subjects using 99mTc-IL2 scintigraphy. Furthermore, in a subgroup of 30 patients, we also performed 99mTc-pertechnetate scintigraphy (99mTcO4−) for evaluation of the salivary gland function. Results: 99mTc-IL2 uptake in the salivary glands of SS patients was higher than in the control subjects (1.30 ± 0.16 vs. 0.83 ± 0.08 for parotids and 1.36 ± 0.15 vs. 1.16 ± 0.07 for submandibular glands; p < 0.0001). The salivary gland uptake of 99mTc-IL2 in patients with a longer history of disease was lower compared with the recently diagnosed patients. A significant direct correlation was found between the uptake of 99mTc-IL2 and histology. Conclusions: 99mTc-IL2 scintigraphy showed that the degree of lymphocytic infiltration of major salivary glands is variable in patients with different disease durations. Patients with a high 99mTc-IL2 uptake could be efficiently treated with immuno-modulatory drugs and the efficacy of treatment could be followed-up by 99mTc-IL2 scintigraphy.

Nuclear Medicine and Radiological Imaging of Pancreatic Neuroendocrine Neoplasms: A Multidisciplinary Update.

Pancreatic neuroendocrine neoplasms (panNENs) are part of a large family of tumors arising from the neuroendocrine system. PanNENs show low-intermediate tumor grade and generally high somatostatin receptor (SSTR) expression. Therefore, panNENs benefit from functional imaging with 68Ga-somatostatin analogues (SSA) for diagnosis, staging, and treatment choice in parallel with morphological imaging. This narrative review aims to present conventional imaging techniques and new perspectives in the management of panNENs, providing the clinicians with useful insight for clinical practice. The 68Ga-SSA PET/CT is the most widely used in panNENs, not only fr diagnosis and staging purpose but also to characterize the biology of the tumor and its responsiveness to SSAs. On the contrary, the 18F-Fluordeoxiglucose (FDG) PET/CT is not employed systematically in all panNEN patients, being generally preferred in G2-G3, to predict aggressiveness and progression rate. The combination of 68Ga-SSA PET/CT and 18F-FDG PET/CT can finally suggest the best therapeutic strategy. Other radiopharmaceuticals are 68Ga-exendin-4 in case of insulinomas and 18F-dopamine (DOPA), which can be helpful in SSTR-negative tumors. New promising but still-under-investigation radiopharmaceuticals include radiolabeled SSTR antagonists and 18F-SSAs. Conventional imaging includes contrast enhanced CT and multiparametric MRI. There are now enriched by radiomics, a new non-invasive imaging approach, very promising to early predict tumor response or progression.