Table 3 Imaging modalities supporting the diagnosis of polymyalgia rheumatica
Ultrasonography | |
US is included as an option in the 2012 classification criteria for PMR (Table 4) and increases the specificity from 81.5–91.3% [11, 57]. • Bilateral subacromial/subdeltoid bursitis • Tenosynovitis of the long head of the biceps Less commonly detected [58, 59]: • Glenohumeral- and/or hip joint arthritis • Trochanter bursitis US also serves as a valuable tool for excluding alternative differential diagnoses such as RA, CPPD disease and late-onset spondyloarthropathy [60]. Vascular US of cranial- and large vessels can help to detect patients with coexisting subclinical or clinical GCA [10, 61]. | |
Advantages | Non-invasive. Accessibility. Rapid and dynamic evaluation. |
Disadvantages | Operator dependent. Limited view of deep structures. Low sensitivity. |
FDG-PET/CT | |
Increased FDG uptake (higher than liver) in the following regions [62, 63]: • Glenohumeral, sternoclavicular and hip joints. • Greater trochanter, ischial tuberosities (most sensitive) and interspinous bursae (most specific). • Large vessel vasculitis. Increased FDG uptake in the shoulder and hip joints can occur both in PMR and primary arthritides, such as RA. However, PMR often has more periarticular involvement than RA [64]. Inflammatory low back pain, pelvic girdle- and diffuse lower limb pain have in one study been found to be predictors of positive FDG-PET/CT scan for LVV in PMR [65]. | |
Advantages | High sensitivity (85%) and specificity (81%) [62]. Full body examination. Visualization of deep structures (bursae, entheses, arteries). |
Disadvantages | Expensive. Low accessibility. Risk of tracer-related adverse events. Concomitant GC use may affect the sensitivity and should be tapered/discontinued in advance. |
MRI | |
Typical findings are symmetrical peri-articular inflammation and synovitis of the shoulders and hips ([66,67,68,69,70]): • Shoulder bursitis, biceps tenosynovitis and glenohumeral synovitis. • Greater trochanter, ischial tuberosity, pubic symphysis and hip synovitis. Cervical interspinous bursitis [71]. | |
Advantages | High sensitivity and specificity. Visualization of deep structures (bursae, entheses). MRI is more sensitive for pelvic girdle and hip findings than US [72]. |
Disadvantages | Expensive. Low accessibility. Risk of adverse events related to contrast. |