Abstract
Autoimmune diseases are on the rise, likely due to many factors such as pollution, infections, dietary changes, climate modifications, and exposure to xenobiotics. These diseases impact individuals, society, and healthcare systems. Some diseases are well-known, such as type 1 diabetes, while others are orphan or rare diseases.
According to the WHO, rare diseases affect fewer than five people, 10,000 inhabitants, and over 7,000 diseases. These conditions generally have low prevalence, are mostly chronically debilitating, and typically lack treatment.
In 2013, the European Society of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging published guidelines for using [18F]FDG (the main radiotracer) in PET/CT studies of inflammation and infection. The use of this radiotracer has expanded in recent decades.
Our objective was to describe the use of PET/CT and its various radiotracers in rare or orphan autoimmune diseases classified in ICD-11. To achieve this, we followed the methodology outlined by the Joanna Briggs Institute for scoping reviews.
Seventy-seven articles were included in the thematic analysis; 71 were case reports, while the rest were case series and cross-sectional studies. The predominant finding in the PET/CT scans of the different pathologies was an increase in the uptake of various radiotracers, with [18F]FDG being the most commonly used. This diagnostic tool provided a comprehensive view of the systemic involvement of multiple conditions, such as Castleman disease and Cogan syndrome. It helped to identify the primary tumor and guide therapies for diseases like acromegaly.