title: Differentiation between Polymyalgia Rheumatica (PMR) and Elderly-Onset Rheumatoid Arthritis Using 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: Is Enthesitis a New Pathological Lesion in PMR?
abstract: BACKGROUND
  It is difficult to differentiate polymyalgia rheumatica (PMR) from elderly-onset rheumatoid arthritis (EORA) in clinical practice. We compared FDG-PET/CT findings between patients with PMR and those with EORA and extracted factors useful for differentiating the two disorders.
  
  
  METHODS
  We compared abnormal FDG accumulation sites and maximum standardized uptake value (SUVmax) between 15 patients with PMR and 7 with EORA in whom FDG-PET/CT was performed.
  
  
  RESULTS
  The proportion of patients in the PMR group with abnormal FDG accumulation at the following 9 sites on FDG-PET/CT was significantly higher than that in the EORA group: periarticular region of the scapulohumeral joint, enthesis of the pectineus muscle, vicinity of the enthesis of the rectus femoris muscle, lateral side of the greater trochanter, ischial tuberosity, hip joint, spinous process of the lower cervical vertebra, intervertebral joint of the lumbar vertebra, and spinous process of the lumbar vertebra. The PET/CT score was evaluated at 9 sites consisting of the abovementioned sites. The median score in the PMR group was 8, which was significantly higher than that of 0 in the EORA group (P = 0.0003). ROC curve analysis was performed with the PET/CT scores, and a score of 5 was shown to maximize the area under the ROC curve (sensitivity: 86.7%, specificity: 86.7%).
  
  
  CONCLUSIONS
  FDG-PET/CT is useful for differentiating PMR from EORA. In patients with PMR, abnormal FDG accumulation was observed at the entheses, suggesting the presence of enthesitis in addition to bursitis and synovitis.
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Wakura
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Kotani
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Takeuchi
authors.affiliation: Department of Radiology, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Komori
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Shuzo
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Makino
authors.affiliation: Department of Internal Medicine (I), Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hanafusa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D013700:Giant Cell Arteritis / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D011111:Polymyalgia Rheumatica / Q000000981:diagnostic imaging*; D000072078:Positron Emission Tomography Computed Tomography; D012372:ROC Curve; D015203:Reproducibility of Results; D012219:Rheumatology
chemical_list: D019788:Fluorodeoxyglucose F18