This atlas provides a contemporary depiction of the pathology of polymyalgia rheumatica (PMR) and outlines how this knowledge translates into a pattern of findings on whole-body 18F-FDG PET/CT that can reliably confirm its diagnosis. PMR is a common, chronic rheumatic disease that causes inflammation of musculotendinous structures. A pattern of findings throughout the whole body is characteristic of PMR on 18F-FDG PET/CT. Whole-body 18F-FDG PET/CT should be considered the new gold standard investigation for PMR diagnosis. PMR is the most common inflammatory rheumatic disease of older people. It typically causes disabling pain and stiffness in affected individuals at the shoulders and hips. Until recently, the precise cause for these symptoms was poorly understood. Modern scans using whole-body PET/CT and MRI have now identified characteristic muscle and tendon inflammation around the shoulder and hip joints, in addition to other features within the spine and at the knees and wrists/hands. This unique appearance has resulted in increasing use of PET/CT to aid PMR diagnosis in everyday clinical practice and research settings. The impact of modern imaging in uncovering the underlying pathology of PMR cannot be understated. Long-dismissed as an inflammatory syndrome with links to the large vessel vasculitis giant cell arteritis (GCA), a pathognomonic pattern of musculotendinous inflammation is now attributed to PMR and may be used to confirm its diagnosis. Among the available modalities, 18F-fluorodeoxyglucose (18F-FDG) PET/CT is increasingly recognized for its high sensitivity and specificity, as well as added ability to detect concomitant large vessel GCA and exclude other relevant differentials like infection and malignancy. The atlas provides a modern interpretation of PMR's underlying pathology based on imaging insights, together with examples of hallmark findings that may be detected by whole-body 18F-FDG PET/CT. The atlas highlights the importance of 18F-FDG PET/CT in diagnosing PMR, as it can reliably confirm the diagnosis by showing characteristic findings in the musculotendinous structures, interspinous regions, and around the ischial tuberosities. The atlas also discusses the role of 18F-FDG PET/CT in detecting concomitant large vessel GCA and other relevant differentials. The atlas also discusses the challenges in diagnosing PMR, including the need for a standardized protocol and the impact of glucocorticoid use on the accuracy of 18F-FDG PET/CT findings. The atlas concludes that 18F-FDG PET/CT is the new gold standard for PMR diagnosis, although further research is needed to develop a lower-cost imaging test with greater availability. The atlas provides a comprehensive overview of the pathology of PMR and its detection on 18F-FDG PET/This atlas provides a contemporary depiction of the pathology of polymyalgia rheumatica (PMR) and outlines how this knowledge translates into a pattern of findings on whole-body 18F-FDG PET/CT that can reliably confirm its diagnosis. PMR is a common, chronic rheumatic disease that causes inflammation of musculotendinous structures. A pattern of findings throughout the whole body is characteristic of PMR on 18F-FDG PET/CT. Whole-body 18F-FDG PET/CT should be considered the new gold standard investigation for PMR diagnosis. PMR is the most common inflammatory rheumatic disease of older people. It typically causes disabling pain and stiffness in affected individuals at the shoulders and hips. Until recently, the precise cause for these symptoms was poorly understood. Modern scans using whole-body PET/CT and MRI have now identified characteristic muscle and tendon inflammation around the shoulder and hip joints, in addition to other features within the spine and at the knees and wrists/hands. This unique appearance has resulted in increasing use of PET/CT to aid PMR diagnosis in everyday clinical practice and research settings. The impact of modern imaging in uncovering the underlying pathology of PMR cannot be understated. Long-dismissed as an inflammatory syndrome with links to the large vessel vasculitis giant cell arteritis (GCA), a pathognomonic pattern of musculotendinous inflammation is now attributed to PMR and may be used to confirm its diagnosis. Among the available modalities, 18F-fluorodeoxyglucose (18F-FDG) PET/CT is increasingly recognized for its high sensitivity and specificity, as well as added ability to detect concomitant large vessel GCA and exclude other relevant differentials like infection and malignancy. The atlas provides a modern interpretation of PMR's underlying pathology based on imaging insights, together with examples of hallmark findings that may be detected by whole-body 18F-FDG PET/CT. The atlas highlights the importance of 18F-FDG PET/CT in diagnosing PMR, as it can reliably confirm the diagnosis by showing characteristic findings in the musculotendinous structures, interspinous regions, and around the ischial tuberosities. The atlas also discusses the role of 18F-FDG PET/CT in detecting concomitant large vessel GCA and other relevant differentials. The atlas also discusses the challenges in diagnosing PMR, including the need for a standardized protocol and the impact of glucocorticoid use on the accuracy of 18F-FDG PET/CT findings. The atlas concludes that 18F-FDG PET/CT is the new gold standard for PMR diagnosis, although further research is needed to develop a lower-cost imaging test with greater availability. The atlas provides a comprehensive overview of the pathology of PMR and its detection on 18F-FDG PET/