Abstract:Aim: 2-deoxy-2-[ 18 F]fluoro-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) can portray increased glycolysis due to inflammation in rheumatoid arthritis (RA). The aim of this study was to evaluate and compare the reliability and construct validity of two methods of quantifying RA disease activity using FDG-PET/CT.
Method:Nineteen RA patients and 19 healthy controls matched to sex and age underwent prospective FDG-PET/CT imaging. Metabolic and volumetric metrics were calculated using fi… Show more
“…Data from the approach have similarly demonstrated great importance in patients with cancer, atherosclerosis, systemic inflammation, and musculoskeletal disorders. 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 Fig. 2 Maximum intensity projection (MIP) FDG PET/CT scans of a 60-year-old patient with multiple myeloma ( A ) pretreatment 1 hour and ( B ) pretreatment 3 hours after administration of FDG.…”
Total-body PET scans will initiate a new era for the PET clinic. The benefits of 40-fold effective sensitivity improvement provide new capabilities to image with lower radiation dose, perform delayed imaging, and achieve improved temporal resolution. These technical features are detailed in the first of this 2-part series. In this part, the clinical impacts of the novel features of total-body PET scans are further explored. Applications of total-body PET scans focus on the real-time interrogation of systemic disease manifestations in a variety of practical clinical contexts. Total-body PET scans make clinical systems biology imaging a reality.
“…Data from the approach have similarly demonstrated great importance in patients with cancer, atherosclerosis, systemic inflammation, and musculoskeletal disorders. 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 Fig. 2 Maximum intensity projection (MIP) FDG PET/CT scans of a 60-year-old patient with multiple myeloma ( A ) pretreatment 1 hour and ( B ) pretreatment 3 hours after administration of FDG.…”
Total-body PET scans will initiate a new era for the PET clinic. The benefits of 40-fold effective sensitivity improvement provide new capabilities to image with lower radiation dose, perform delayed imaging, and achieve improved temporal resolution. These technical features are detailed in the first of this 2-part series. In this part, the clinical impacts of the novel features of total-body PET scans are further explored. Applications of total-body PET scans focus on the real-time interrogation of systemic disease manifestations in a variety of practical clinical contexts. Total-body PET scans make clinical systems biology imaging a reality.
“…FDG is a glucose analog whose cellular uptake is proportional to the metabolic activity of the cells. The value of FDG in the diagnosis of inflammation as well as malignancy is well established, and FDG PET/CT is used in rheumatologic diseases such as rheumatoid arthritis, vasculitis, and polymyalgia rheumatica [37][38][39][40]. Recently, its use in IIMs has also been described, and researchers have demonstrated higher SUVs in patients than controls [25,29] or persons with non-inflammatory muscle disease [41], but also an overlap of FDG uptake in patients with IIM and without [31].…”
Background
Imaging of idiopathic inflammatory myopathies (IIMs) is challenging, and no pathognomonic signs exist. Different tracers have been tested for this purpose, mainly inflammation markers including technetium-99m-pyrophosphate (PYP). We aimed to examine the utility of fluorine-18-fluorodeoxyglucose (FDG) relative to PYP in idiopathic inflammatory myopathy (IIM).
Methods
Using visual grading and CT-guided muscular segmentation and standardized uptake values (SUVs), we assessed muscular tracer uptake qualitatively and quantitatively, comparing FDG uptake in eight patients with recent-onset IIM and 24 healthy control persons and FDG and PYP uptake in seven patients.
Results
Muscular FDG and PYP uptake was increased in all patients. However, uptake distribution and signal intensity differed considerably. FDG scans revealed clear involvement of certain muscle groups including core and swallowing muscles and, in addition, abnormality in diseased extra-muscular organs. PYP was mainly visible in bones, whereas muscular PYP uptake was generally discrete and primarily located in the extremities. Quantitatively, FDG uptake was significantly higher in patients than in controls; the volume-weighted SUVmean for all right-side muscles was 0.84 versus 0.60 g/ml (95% confidence interval (CI) for mean difference 0.14–0.34, p = 0.0001). FDG SUVmean values were up to four times higher than PYP mean values in upper limb muscles (95% CI for the mean ratio 2.37–3.77, p = 0.0004) and two–three times higher in lower limb muscles (95% CI for the mean ratio 2.28–2.71, p < 0.0001).
Conclusions
Muscular FDG uptake was higher in treatment-naïve IIM patients than in healthy controls and more distinct than PYP uptake in patients with a potential to reveal extra-muscular IIM involvement and malignancy. Thus, FDG appears to be superior to PYP in the diagnostic evaluation of IIM.
“…Several studies have shown the feasibility of whole-body PET to assess disease activity in patients with RA. 12,[21][22][23][24][25][26] Most studies have used FDG as tracer, which is sensitive but not specific for imaging arthritis. Some studies have looked only at visually enhanced uptake, whereas in other studies, quantitative analyses were performed.…”
Objective To investigate the potential of whole body positron emission tomography/computed tomography (PET/CT) with a macrophage tracer to image arthritis in patients with early rheumatoid arthritis (RA). Methods Thirty-five previously untreated, clinically active early RA patients underwent whole body PET/CT scanning with the macrophage tracer (R)-[11C]PK11195 in addition to clinical assessment (Disease Activity Score of 44 joints [DAS44]). Tracer uptake was assessed quantitatively as standardized uptake values (SUV). In addition, two readers blinded to clinical assessment visually scored tracer uptake in joints. Clinical and PET variables were compared using Cohen's kappa, linear regression/correlation, and Ttests where appropriate. Results All but one patient showed enhanced tracer uptake in at least 1 joint. Twelve percent of all joints (171/1470) was visually PET positive, most frequently the small joints in feet (40%) and hands (37%), followed by wrists (15%). Correlations of visual scores with clinical findings both at patient and joint levels were absent or weak. In contrast, average SUV in hands, feet and whole body showed significant correlations with DAS- 44 scores, with the best correlation seen in the feet (R2 = 0.29, p < 0.01). Conclusion Clinically active, early RA patients had increased joint uptake of a macrophage PET tracer, especially in the feet. Quantitative, but not visual PET measures of whole body and joint groups, particularly the feet, showed moderate and statistically significant correlations with clinical outcome.
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