This study is about using contrast-enhanced ultrasound (CEUS) to assess the degree of synovitis (joint inflammation) in patients with inflammatory arthritis, such as rheumatoid arthritis, and whether it can be used for assessing a treatment response. The investigators hope to learn whether contrast enhanced ultrasounds are better than regular imaging techniques, such as MRI, when used to evaluate the response to disease modifying anti-rheumatic drug (DMARD) therapy in inflammatory arthritis.

Inflammatory arthritis affects approximately 1% of the world population and can lead to significant pain and disability. Although radiographs can identify characteristic patterns of joint space narrowing and erosive changes, these findings are typically late findings and represent irreversible damage. With the development of disease modifying anti-rheumatic drugs (DMARDs), the goal is now to identify the pre-erosive inflammatory features and identify the patients that progress further into severe functional debility if not treated immediately.

MRI with gadolinium enhancement is proven to be very effective in early detection of soft tissue, bone erosions, synovitis, the integrity of ligaments, cartilage and bone marrow edema. However, MRI is expensive, may be impractical for assessing multiple joints and has relatively long examination time. Some patients may have claustrophobia and some may have contraindications to gadolinium administration. The investigators overarching goal is to determine whether the perfusion information provided by novel ultrasound based techniques such as, contrast enhanced ultrasound and superb microvascular imaging, can be used for assessment of treatment response to DMARD therapy for inflammatory arthritis. The recent advances in evaluation of vascularity of the tumors using contrast ultrasound technique can also be applied to rheumatological diseases. It is ideal to develop a sensitive imaging technique that can be routinely available and is relatively cheap. Ultrasound is available and has low cost and can be used for assessment of treatment response to DMARD therapy

Inclusion Criteria:

• Patients (≥ 18 years of age) that meet diagnostic criteria for an inflammatory arthritis.
• Clinical suspicion of active synovitis involving at least one target joint.
• Patients competent to sign study specific Informed Consent.
• Patients willing to comply with protocol requirements.
• Intent to treat with disease-modifying anti-rheumatic drugs (DMARDs).

Exclusion Criteria:

• Patients who are pregnant or less than 18 years of age.
• Patients who have a known cardiac shunt or pulmonary hypertension.
• Patients with any known hypersensitivity to perflutren or gadolinium contrast agents or renal insufficiency (GFR < 30 mL/min).
• Patients who cannot consent for themselves.