This atlas reviews the use of whole-body 18F-FDG PET/CT in characterizing polymyalgia rheumatica (PMR) and its diagnostic value. PMR, a common inflammatory rheumatic disease affecting older adults, is characterized by disabling pain and stiffness in the shoulders and hips. Modern imaging techniques, particularly 18F-FDG PET/CT, have revealed characteristic musculotendinous inflammation, which is now considered pathognomonic for PMR. The atlas highlights the distinctive patterns of inflammation observed on whole-body 18F-FDG PET/CT, including peri-articular uptake at the shoulders and hips, interspinous involvement, and adjacent ischial tuberosities. These findings are highly specific for PMR and can be used to confirm its diagnosis. The atlas also discusses the role of 18F-FDG PET/CT in detecting concomitant large vessel giant cell arteritis (LV-GCA) and excluding other differential diagnoses such as infection and malignancy. The article emphasizes the importance of standardized imaging protocols and scoring systems, such as the Leuven score and Heidelberg algorithm, to ensure consistent interpretation and improve diagnostic accuracy. The authors conclude that whole-body 18F-FDG PET/CT is the gold standard for diagnosing PMR and highlights the need for further research to translate these findings into improved patient care.This atlas reviews the use of whole-body 18F-FDG PET/CT in characterizing polymyalgia rheumatica (PMR) and its diagnostic value. PMR, a common inflammatory rheumatic disease affecting older adults, is characterized by disabling pain and stiffness in the shoulders and hips. Modern imaging techniques, particularly 18F-FDG PET/CT, have revealed characteristic musculotendinous inflammation, which is now considered pathognomonic for PMR. The atlas highlights the distinctive patterns of inflammation observed on whole-body 18F-FDG PET/CT, including peri-articular uptake at the shoulders and hips, interspinous involvement, and adjacent ischial tuberosities. These findings are highly specific for PMR and can be used to confirm its diagnosis. The atlas also discusses the role of 18F-FDG PET/CT in detecting concomitant large vessel giant cell arteritis (LV-GCA) and excluding other differential diagnoses such as infection and malignancy. The article emphasizes the importance of standardized imaging protocols and scoring systems, such as the Leuven score and Heidelberg algorithm, to ensure consistent interpretation and improve diagnostic accuracy. The authors conclude that whole-body 18F-FDG PET/CT is the gold standard for diagnosing PMR and highlights the need for further research to translate these findings into improved patient care.