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OBJECTIVES: Interstitial pneumonia is a severe complication induced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Several treatments have been proposed alone or, more often, in combination, depending, also, on the presence of other organ disfunction. The most frequently related, well-described, and associated phenomenon is pan-lymphopenia with circulating, high levels of cytokines. We report, here, on two patients with COVID-19 and lymphoproliferative disorders treated with Tocilizumab (a humanized monoclonal antibody against the interleukin-6 receptor) and followed by an [18F]FDG PET/CT to early evaluate the therapy's efficacy. METHODS: One patient with angioimmunoblastic T-lymphoma (A), one with Hodgkin lymphoma (A), and both with positive RT-PCR for SARS-CoV-2 and with similar clinical findings of interstitial pneumonia at the CT scan, were imaged by [18F]FDG PET/CT before and 14 days after a single dose of Tocilizumab. RESULTS: In both patients, the basal [18F]FDG PET/CT showed a diffused lung parenchyma uptake, corresponding to the hyperdense areas at the CT scan. After 2 weeks of a Tocilizumab infusion, patient B had an improvement of symptoms, with normalization of the [18F]FDG uptake. By contrast, patient A, who was still symptomatic, showed a persisting and abnormal distribution of [18F]FDG. Interestingly, both patients showed a low bone marrow uptake of [18F]FDG at the diagnosis and after 15 days, while the spleen uptake was low only in lymphopenic patient A; both are indirect signs of an immune deficiency. CONCLUSIONS: In conclusion, in these two patients, interstitial pneumonia was efficiently treated with Tocilizumab, as demonstrated by the [18F]FDG PET/CT. Our results confirm that interleukin-6 (IL6) has a role in the COVID-19 disease and that anti-cytokine treatment can also be performed in patients with lymphoproliferative disorders.
RESUMO
UNLABELLED: White blood cell (WBC) scintigraphy is considered the nuclear medicine imaging gold standard for diagnosing osteomyelitis in the diabetic foot. Recent papers have suggested that the use of (18)F-FDG PET/CT produces similar diagnostic accuracy, but clear interpretation criteria have not yet been established. Our aim was to evaluate the role of sequential (18)F-FDG PET/CT in patients with a high suspicion of osteomyelitis to define objective interpretation criteria to be compared with WBC scintigraphy. METHODS: Thirteen patients whom clinicians considered positive for osteomyelitis (7 with ulcers, 6 with exposed bone) were enrolled. The patients underwent (99m)Tc-exametazime WBC scintigraphy with acquisition times of 30 min, 3 h, and 20 h and sequential (18)F-FDG PET/CT with acquisition times of 10 min, 1 h, and 2 h. A biopsy or tissue culture was performed for final diagnosis. Several interpretation criteria (qualitative and quantitative) were tested. RESULTS: At final biopsy, 7 patients had osteomyelitis, 2 had soft-tissue infection without osteomyelitis, and 4 had no infection. The best interpretation criterion for osteomyelitis with WBC scintigraphy was a target-to-background (T/B) ratio greater than 2.0 at 20 h and increasing with time. A T/B ratio greater than 2.0 at 20 h but stable or decreasing with time was suggestive of soft-tissue infection. A T/B ratio of no more than 2.0 at 20 h excluded an infection. Thus, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 86%, 100%, 100%, 86%, and 92%, respectively. For (18)F-FDG PET/CT, the best interpretation criterion for osteomyelitis was a maximal standardized uptake value (SUVmax) greater than 2.0 at 1 and 2 h and increasing with time. A SUVmax greater than 2.0 after 1 and 2 h but stable or decreasing with time was suggestive of a soft-tissue infection. An SUVmax less than 2.0 excluded an infection. (18)F-FDG PET at 10 min was not useful. Using these criteria, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for osteomyelitis were 43%, 67%, 60%, 50%, and 54%, respectively. Combining visual assessment of PET at 1 h and CT was best for differentiating between osteomyelitis and soft-tissue infection, with a diagnostic accuracy of 62%. CONCLUSION: (18)F-FDG PET/CT, even with sequential imaging, has a low diagnostic accuracy for osteomyelitis and cannot replace WBC scintigraphy in patients with diabetic foot.
