Abstract
BackgroundMuscle enzymes are the major noninvasive diagnostic parameters useful in polymyositis/dermatomyositis (PM/DM). Few studies have yet correlated findings on 18F-FDG PET with disease activity in patients with PM/DM.PurposeWe evaluated 18F-FDG muscle uptake in patients with PM/DM compared with non-muscular diseases and correlated the results with serum muscle enzymes.MethodsA total of 28 patients with untreated PM/DM and 28 control patients with non-muscular diseases were examined with 18F-FDG PET/CT. 18F-FDG uptake was evaluated in 9 proximal skeletal muscle regions bilaterally. The uptake was scored as follows: 0 = less than that of the mediastinal blood vessels, 1 = greater than or equal to that of the mediastinal blood vessels, and 2 = greater than or equal to that of the liver. A score 1 or 2 was considered positive. The mean and maximum standardized uptake values (SUV) were calculated in each muscle and were averaged for all muscle regions. PET findings were correlated with serum muscle enzymes.Results18F-FDG uptake was observed in 82% of patients with PM/DM and 7% of control patients. The number of positive regions, total score, mean SUVmean, and mean SUVmax in patients with PM/DM were significantly higher than those in the control patients (all P < 0.001). The total score of 2 was the best cut-off value that could discriminate patients with PM/DM from control patients. The total score, mean SUVmean, and mean SUVmax showed significant correlations with creatine kinase (P = 0.047, 0.002, 0.010, respectively) and aldolase (P = 0.036, 0.005, 0.038, respectively).Conclusion18F-FDG PET/CT using visual and SUV methods demonstrated its usefulness by discriminating PM/DM from non-muscular diseases and correlating with serum muscle enzymes in patients with PM/DM.
Highlights
Polymyositis (PM) and dermatomyositis (DM) are chronic inflammatory diseases that affect systemic skeletal muscles, lungs, and other extramuscular organs (Dalakas and Hohlfeld, 2003)
Tanaka et al showed that mean proximal muscle standardized uptake value (SUV) in patients with PM/DM correlated with serum creatine kinase (CK) and aldolase (Tanaka et al, 2013), whereas some other investigators found no correlation between 18F-FDG uptake in proximal muscles and serum CK levels (Pipitone et al, 2012; Tateyama et al, 2015)
The present findings demonstrated that in patients with PM/DM 18F-FDG positron emission tomography (PET)/CT visual and SUV parameters were useful in discriminating PM/DM from non-muscular diseases as well as showing correlations with serum muscle enzymes
Summary
Polymyositis (PM) and dermatomyositis (DM) are chronic inflammatory diseases that affect systemic skeletal muscles, lungs, and other extramuscular organs (Dalakas and Hohlfeld, 2003). Muscle enzymes such as creatine kinase (CK) and aldolase provide information about myogenic pathologies and are the major noninvasive diagnostic parameters useful in PM/DM. Few studies have yet correlated findings on 18F-FDG positron emission tomography (PET) with disease activity in patients with PM/DM. This prompted us to evaluate 18F-FDG uptake in proximal skeletal muscles using visual and SUV methods in PM/DM compared with non-muscular diseases and correlate the results with serum muscle enzymes. Purpose: We evaluated 18F-FDG muscle uptake in patients with PM/DM compared with non-muscular diseases and correlated the results with serum muscle enzymes
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