Semi-quantitative analysis of 18F fluorodeoxyglucose uptake in the assessment of disease activity and therapeutic response in rheumatoid arthritis: An institutional experience

Abstract

18 F fluorodeoxyglucose ( 18 F-FDG) positron emission tomography (PET) can be used to image synovial inflammation in patients with rheumatoid arthritis (RA). Recently, clinical application of novel therapies for RA, such as tumor necrosis factor-α (TNF-α) inhibitor and anti-interleukin-6 receptor antibody, has been introduced. The radiological assessment of disease activity changes of patients who underwent these therapies will help the clinicians to obtain more information about the patients and to decide drug withdrawal or change of medication. It is considered that 18 F-FDG PET scan is generally very expensive; however, the information from 18 F-FDG PET about patients during biological treatments helps discontinuation of these treatments with incomplete response despite its high costs and with possible side effects such as malignant lymphoma. In this study, we evaluated if the 18F-FDG uptake of the affected joints represented by standardized uptake value (SUV) correlated with the clinical assessment of patients with RA. In addition, we would like to evaluate if there was a correlation between the difference of SUV and improvement of clinical findings in RA patients undergoing anti TNF therapies. RA patients who underwent anti-TNFα therapies in a tertiary care hospital were assessed using whole-body 18 F-FDG PET/computed tomography (CT). PET assessments were performed on hip joints, knees, shoulders, wrists, ankles, MCP, and PIP for a total of 28 joints in each patient. The 18 F–FDG uptake was then quantified using the maximum SUV (SUVmax) prior to, and 6 months after the initiation of treatment with anti-TNF-α drugs. Disease activity score (DAS28 and DAS28-C-reactive protein [CRP]) were recorded and white blood cell, matrix metalloproteinases (MMP-3) and rheumatoid factor (RF) were examined in all patients. The average of SUV max among measured joints, or the sum of these joints (total SUV max ), correlated with DAS28 ( r = 0.671, P < 0.001), DAS28-CRP ( r = 0.623, P < 0.001), ESR ( r = 0.542, P < 0.001), CRP ( r = 0.411, P = 0.002), MMP-3 ( r = 0.399, P = 0.006), and RF ( r = 0.447, P = 0.002). There were correlations between ΔSUV and ΔDAS28 ( r = 0.651, P < 0.001), ΔSUV and ΔDAS28-CRP ( r = 0.682, P < 0.001), ΔSUV and ΔESR ( r = 0.449, P = 0.023), and ΔSUV and ΔMMP-3 ( r = 0.457, P = 0.027), respectively. The number of PET-positive joints and the cumulative SUV significantly corre...

18F-FDG and 18F-NaF PET/CT Global Assessment of Large Joint Inflammation and Bone Turnover in Rheumatoid Arthritis

“…Some other studies, however, used ROIs manually drawn by nuclear physicians and radiologists [ 8 , 11 , 37 , 38 ] or created through the use of different types of software and dedicated workstations [ 9 , 22 , 39 , 40 ]. Many studies also used SUVmax [ 12 , 40 , 41 ] instead of SUVmean, which could have varied results.…”

“…Both of these studies used a larger sample size and had similar results to ours, supporting the hypothesis that increased BMI is correlated to increased reactive bone formation and inflammation. Some other studies, however, used ROIs manually drawn by nuclear physicians and radiologists [8,11,37,38] or created through the use of different types of software and dedicated workstations [9,22,39,40]. Many studies also used SUVmax [12,40,41] instead of SUVmean, which could have varied results.…”

“…While an abundance of previous research has focused on imaging with MRI, considering it the “gold standard”, recent studies have been analyzing the usefulness of PET in combination with CT. In fact, when compared to MRI, FDG PET showed promising results in many of the RA studies in both the more commonly studied small joints and the less often studied large joints [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. The aim of this study is to explore the feasibility of calculating the FDG and NaF mean SUV (SUVmean) in the knee joint, hip joint, and sacroiliac (SI) joint of RA patients and to determine the association of these values with clinical characteristics of patients with the disease.…”

The role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in rheumatoid arthritis patients tapering tumour necrosis factor inhibitor

“…Some studies report that FDG-PET/CT is useful to detect disease activity in RA patients and to predict progression of disease [5][6][7][8][9][10]. Table 1 shows an overview of recent studies reporting the use of FDG-PET/CT in RA patients.…”