Coronary Artery Inflammation in Rheumatoid Arthritis Using Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography
We report a case of coronary artery inflammation in a patient with active rheumatoid arthritis (RA). Cardiac fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) scans were done at baseline and 6 months follow-up as part of a study assessing cardiovascular disease (CVD) in RA patients. At baseline, there was significant 18F-FDG uptake in the left main (LM) coronary artery indicative of active inflammation. At posttreatment with step-up RA therapy 6 months later, inflammatory biomarkers of RA decreased in the patient, and no 18F-FDG uptake was observed on PET imaging (Fig.).
As part of a research study assessing CVD in RA patients, a 62-year-old man underwent serial PET imaging to assess cardiac function and inflammation. The patient was a nonsmoker, with a history of well-controlled hyperlipidemia and a new diagnosis of seronegative RA made 7 months prior to study entry. Despite treatment with methotrexate 25 mg weekly and prednisone 4 mg daily, his Disease Activity Score in 28 Joints remained elevated at 5.52 units with a C-reactive protein of 6.79 mg/L. Sulfasalazine and hydroxychloroquine were added to background methotrexate. After 6 months of triple therapy, his Disease Activity Score in 28 Joints decreased to 2.39 units, corresponding to low disease activity, and his C-reactive protein normalized to 0.46 mg/L. The patient underwent cardiac ammonia (NH3) and 18F-FDG PET imaging at baseline and after 6 months of triple therapy to assess myocardial rest/stress perfusion and vascular inflammation, respectively. The PET 18F-FDG study was conducted after a 24-hour no-carbohydrate diet, and the patient was imaged 90 minutes after radiotracer injection. Corridor4DM software (INVIA, Ann Arbor, MI) was used to quantify mean standard uptake value (SUVmean) by drawing regions of interest around the area of inflammation on the 6 consecutive slices with inflammation, and then averaging regions of interest to generate an SUVmean.
On the first scan, visually assessed 18F-FDG uptake was present in the LM coronary artery with an SUVmean of 2.03. NH3 stress/rest PET imaging showed no ischemia/infarct, a coronary artery calcium score of 0, and a normal coronary flow reserve (>2.0) of 2.73. A follow-up scan 6 months later showed no qualitative and no quantitatively measurable radiotracer uptake.