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Noncontrast Chest Computed Tomographic Imaging of Obesity and the Metabolic Syndrome: Part II Noncardiovascular Findings.
Nattenmüller, J, Schlett, CL, Tsuchiya, N, Reeder, SB, Pickhardt, PJ, Kramer, H, Kauczor, HU, Wielpütz, MO, Seo, JB, Hatabu, H, et al
Journal of thoracic imaging. 2019;(2):126-135
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Abstract
The purpose of this review article is to acquaint the reader with the current state of the art for the noncardiovascular imaging biomarkers of metabolic syndrome found on noncontrast computed tomography (NCCT) of the chest and their prognostic significance. Routine chest NCCT includes quantitative information with regard to tissue density and organ volumes in the neck, chest, and upper abdomen. The specific imaging biomarkers that may be seen in association with metabolic syndrome include low thyroid iodine organification, hepatic steatosis, sarcopenia (muscle volume and density), demineralization of the thoracic and upper lumbar vertebral bodies, loss of axial skeletal muscle mass, premature lung inflammation, and an increased deposition of subcutaneous and visceral fat. These easily identified imaging biomarkers can have prognostic implications, which include nonalcoholic steatohepatitis, cirrhosis, hypothyroidism, early lung fibrosis with interstitial abnormalities, sarcopenia, and osteoporotic thoracic and lumbar spine vertebral body compression fractures. NCCT examinations of the chest have the opportunity to become an important imaging tool for outcomes research.
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Imaging appearances of toxic and acquired metabolic encephalopathic disorders.
Vamadevan, T, Howlett, D, Filyridou, M
British journal of hospital medicine (London, England : 2005). 2019;(7):372-376
Abstract
Most imaging findings relating to toxic and acquired metabolic disorders follow a certain pattern with affinity to a specific topographic area, which can help narrow the differential diagnosis. This is especially useful when the clinical presentation can be variable and there is diagnostic uncertainty. Usually, there is bilateral symmetrical abnormality within the deep grey matter structures and the cerebral cortex because of the high metabolic activity and raised oxygen requirements in these areas. Magnetic resonance imaging, particularly diffusion weighted imaging and fluid-attenuated inversion recovery sequences, is very important in differentiating between various aetiologies in this group. Magnetic resonance imaging can be useful in demonstrating both acute and chronic damage, in evaluating treatment response and in disease prognostication. This pictorial review discusses the computed tomography and magnetic resonance imaging appearances of a spectrum of toxic and metabolic disorders observed in a district general hospital with reference to clinical presentation and imaging features that may allow diagnosis. This includes carbon monoxide poisoning, hypoglycaemia, non-ketotic hyperglycaemia, osmotic demyelination syndrome, posterior reversible encephalopathy syndrome, hypoxic ischaemic encephalopathy, the syndrome of delayed post-hypoxic leukoencephalopathy, hepatic encephalopathy and cocaine toxicity.
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Psoas muscle fluorine-18-labelled fluoro-2-deoxy-d-glucose uptake associated with the incidence of existing and incipient metabolic derangement.
Kim, JY, Jun, DW, Choi, J, Nam, E, Son, D, Choi, YY
Journal of cachexia, sarcopenia and muscle. 2019;(4):894-902
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Abstract
BACKGROUND Skeletal muscle glucose utilization is an important component of whole-body glucose consumption in normal humans. Fluorine-18-labelled fluoro-2-deoxy-d-glucose (18 F-FDG) is a non-invasive molecular imaging probe for evaluating tissue glucose utilization. It remains unclear whether or not 18 F-FDG uptake by skeletal muscle has utility as a biomarker for metabolic derangement. We investigated the utility of measurement of muscle 18 F-FDG positron emission tomography/computed tomography uptake as a surrogate marker for existing and incipient metabolic abnormalities. METHODS Fluorine-18-labelled fluoro-2-deoxy-d-glucose (18 F-FDG) uptakes of insulin-sensitive organs (liver, pancreas, mesenteric visceral fat, psoas muscle, and abdominal subcutaneous fat) and their association with metabolic abnormalities were evaluated in an experimental group comprising 91 men and 66 women (mean age 49.9 ± 11.1 years). In this cross-sectional cohort, we assessed the predictive power of the optimal cut-off 18 F-FDG uptake [maximum standardized uptake value (SUVmax )]. We confirmed its feasibility and reliability for diagnosis of existing and incipient metabolic derangement in the validation group (longitudinal cohort comprising 91 men and 67 women; mean age 52.6 ± 7.9 years). RESULTS Fluorine-18-labelled fluoro-2-deoxy-d-glucose (18 F-FDG) uptake (SUVmax ) of psoas muscle was strongly correlated with clinical metabolic parameters in the experimental group. It was positively correlated with waist circumference, body mass index, fasting glucose, triglyceride, systolic and diastolic pressure, and negatively correlated with high-density lipoprotein cholesterol levels (for all, P < 0.05). SUVmax of the psoas muscle also showed the best area under the curve value (0.779) as a predictor of metabolic syndrome (MetS) in the experimental group. Using the optimal cut-off SUVmax of 1.34, the sensitivity, specificity, accuracy, positive, and negative predictive value for predicting existing MetS in the experimental group were 70.0%, 84.6%, 80.9%, 60.9%, and 89.2%, respectively. In the validation group, corresponding values were 47.6%, 92.3%, 86.1%, 50.0%, and 91.6%, respectively. Existing and incipient MetS were significantly higher in subjects with high 18 F-FDG uptake by the psoas muscle (SUVmax > 1.34). Subjects with higher psoas muscle SUVmax had a 3.3-fold increased risk of developing MetS (P = 0.017). CONCLUSIONS Fluorine-18-labelled fluoro-2-deoxy-d-glucose (18 F-FDG) uptake of psoas muscle is a promising surrogate marker for existing and incipient metabolic derangement.