Abstract
1122
Objectives: Highlight the indications of PET imaging in psoriasis. Present two novel methods for assessing uptake in joints a) quantifying the global metabolic activity in psoriatic arthritis in large joints using CT segmentation and b) visually assessing the small joints in the hands.
Methods: Psoriasis is a chronic inflammatory autoimmune disease of the skin characterized by presence of scales. The skin lesions are center to disease manifestation, but psoriasis can have systemic manifestations too. These include psoriatic arthritis, which occurs in up to 10 to 30% of patients with psoriasis. Sacroiliac (SI) joint involvement is seen in 34- 78% of patients with psoriatic arthritis. Involvement of the hip joint in patients with psoriasis is an important marker for disease severity. It has been noted that patients with psoriatic spondylitis have higher rates of total hip arthroplasty. In the knee joint, subclinical synovitis and enthesitis are commonly found in early stages of psoriatic arthritis. Up to 50% patients with psoriatic arthritis have involvement of the spine and complain of back pain, stiffness and show spondylitis and syndesmophyte formation on imaging. In this review, we will be discussing the use of NaF-PET and FDG-PET in psoriatic arthritis. FDG and NaF are important tracers as they are sensitive in detecting joint inflammation and bone remodeling and destruction, respectively, in its earliest stages in joint disease. We will also highlight novel methods to quantify global uptake and visually assess in various joints affected by this disease.
Results: X-Ray, CT and MR are the conventional imaging modalities used in the diagnoses and treatment follow-up of patients with psoriatic arthritis. PET has been traditionally utilized in oncology, but recently there has been an increased interest to use this modality in the evaluation of joints diseases such as osteoarthritis, rheumatoid arthritis and psoriatic arthritis.
Conclusions: PET has the advantage of being able to detect degenerative joint changes at a molecular level even before the structural changes have taken place. Hence, it has superiority over other conventional imaging modalities to detect arthritis in the early stages as well as investigate multiple joints in a single scan. As the resolution of PET is relatively low, combining PET with CT provides structural information to better assess the joint. Quantifying disease activity has the benefit of surveilling disease activity over the course of time and monitoring treatment response, remission and relapse of the disease.