Role of 18F-FDG PET/CT in assessing systemic involvement in ANCA-associated vasculitis

The utilization of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) has become a pivotal tool in diagnosing anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, especially when the disease presents with neurological symptoms as the initial indicator. This advanced imaging technique was applied in a 68-year-old female patient who presented with recurrent limb weakness and intermittent blindness, symptoms that warranted thorough investigation due to their complexity and severity. The ¹⁸F-FDG PET/CT revealed significant radiotracer uptake in the kidneys, spleen, skeletal muscles, and right axillary lymph nodes, indicative of systemic involvement-a hallmark of ANCA-associated vasculitis (AAV) that can lead to multi-organ damage if not promptly managed. Complementary electromyography (EMG) identified multiple instances of peripheral nerve damage, adding further evidence to the diagnosis. This case underscores the intricate interplay between clinical symptoms, imaging findings, and laboratory results, all crucial in accurately diagnosing AAV. The findings highlight that ¹⁸F-FDG PET/CT not only facilitates early detection of neurogenic skeletal muscle damage and occult lesions, but also aids in precise disease classification, essential for guiding treatment strategies. The ability of this imaging modality to provide early warnings of major organ involvement offers clinicians a valuable opportunity to intervene before irreversible damage occurs, ultimately improving the accuracy of diagnosis and contributing to more effective management and outcomes for patients with this complex autoimmune disorder.