Facet arthropathy evaluation: CT or MRI?

OBJECTIVE: To assess the reliability of lumbar facet arthropathy evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) in patients with and without lumbar disc prosthesis and to estimate the reliability for individual CT and MRI findings indicating facet arthropathy. METHODS: Metal-artifact reducing CT and MRI protocols were performed at follow-up of 114 chronic back pain patients treated with (n = 66) or without (n = 48) lumbar disc prosthesis. Three experienced radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade facet arthropathy at each of the three lower lumbar levels on both CT and MRI, using Weishaupt et al's rating system. CT and MRI examinations were randomly mixed and rated independently. Findings were dichotomized before analysis. Overall kappa and (due to low prevalence) prevalence- and bias-adjusted kappa were calculated to assess interobserver agreement. RESULTS: Interobserver agreement on total grade facet arthropathy was moderate at all levels with CT (kappa 0.47-0.48) and poor to fair with MRI (kappa 0.20-0.32). Mean prevalence- and bias-adjusted kappa was lower for osteophyte/hypertrophy versus other individual findings (CT 0.58 versus 0.79-0.86, MRI 0.35 versus 0.81-0.90), higher with CT versus MRI when rating osteophyte/hypertrophy (0.58 versus 0.35) and total grade facet arthropathy (0.54 versus 0.31), and generally similar at levels with versus levels without disc prosthesis. CONCLUSION: Interobserver agreement on facet arthropathy was moderate with CT and better with CT than with MRI. Disc prosthesis did not influence agreement. A more reliable grading of facet arthropathy requires a more consistent evaluation of osteophytes/hypertrophy. KEY POINTS: • In this study, interobserver agreement on facet arthropathy (FA) severity-based on facet joint space narrowing, osteophyte/hypertrophy, erosions, and subchondral cysts-was better with CT versus MRI. • Metal-artifact reducing CT and MRI protocols helped to improve visibility and maintain agreement when evaluating severity of FA at levels with metallic disc prosthesis. • Agreement was poorer for severity of osteophytes/hypertrophy than for the other evaluated FA findings; improved agreement on total grade FA evaluated with CT or MRI thus requires more consistent grading of osteophytes/hypertrophy between different radiologists.

Major Increase in Microbiota-Dependent Proatherogenic Metabolite TMAO One Year After Bariatric Surgery.

BACKGROUND: Trimethylamine-N-oxide (TMAO) is formed in the liver from trimethylamine (TMA), a product exclusively generated by the gut microbiota from dietary phosphatidylcholine and carnitine. An alternative pathway of TMAO formation from carnitine is via the microbiota-dependent intermediate γ-butyrobetaine (γBB). Elevated TMAO levels are associated with cardiovascular disease (CVD), but little is known about TMAO in obesity. Given the proposed contribution of microbiota alterations in obesity and type 2 diabetes (T2D), we investigated the potential impact of obesity, lifestyle-induced weight loss, and bariatric surgery on plasma levels of TMAO, its microbiota-dependent intermediate γBB, and its diet-dependent precursors carnitine and choline. METHODS: TMAO, γBB, carnitine, and choline were measured by high-performance liquid chromatography in 34 obese individuals (17 with and 17 without T2D) undergoing bariatric surgery and 17 controls. RESULTS: TMAO was not elevated in obese patients or reduced by lifestyle interventions but increased approximately twofold after bariatric surgery. Similar to TMAO, plasma levels of γBB were not influenced by lifestyle interventions but increased moderately after bariatric surgery. In contrast, carnitine and choline, which are abundant in nutrients, such as in red meat and eggs, and not microbiota dependent, were reduced after lifestyle interventions and rebounded after bariatric surgery. CONCLUSIONS: The major increase in TMAO after bariatric surgery was unexpected because high TMAO levels have been linked to CVD, whereas bariatric surgery is known to reduce CVD risk. Prospective studies of gut microbiota composition and related metabolites in relation to long-term cardiovascular risk after bariatric surgery are warranted.

Soluble CD14 is associated with markers of vascular dysfunction in bariatric surgery patients.

BACKGROUND: Chronic endotoxemia has been proposed to contribute to obesity-related complications. We aimed to investigate the potential impact of lipopolysaccharide (LPS) and subsequent monocyte activation measured as soluble CD14 (sCD14) on markers of vascular dysfunction in obese subjects undergoing bariatric surgery. METHODS: This was a prospective study of 49 obese patients and 17 controls, assessed by plasma levels of LPS, sCD14, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA). RESULTS: Levels of ADMA were increased in obese subjects compared to controls, but were not significantly reduced after bariatric surgery. In obese subjects at baseline, there was a significant trend to increasing levels of ADMA and SDMA through tertiles of sCD14 and decreasing levels of both markers through tertiles of LPS. In models adjusting for age and gender, sCD14 but not LPS remained independently associated with ADMA and SDMA. For every 10% age- and gender-adjusted increase in sCD14, ADMA increased 0.031 µM (5.6%), whereas SDMA increased 0.039 µM (10.8%). CONCLUSIONS: Our results suggest that monocyte activation as measured by sCD14 is associated with obesity-related vascular dysfunction, whereas potential upstream triggers including microbial products should be investigated in future studies.

Plasma lipopolysaccharide is closely associated with glycemic control and abdominal obesity: evidence from bariatric surgery.

OBJECTIVE: It is of vital importance to elucidate the triggering factors of obesity and type 2 diabetes to improve patient care. Bariatric surgery has been shown to prevent and even cure diabetes, but the mechanism is unknown. Elevated levels of lipopolysaccharide (LPS) predict incident diabetes, but the sources of LPS are not clarified. The objective of the current study was to evaluate the potential impact of plasma LPS on abdominal obesity and glycemic control in subjects undergoing bariatric surgery. RESEARCH DESIGN AND METHODS: This was a prospective observational study involving a consecutive sample of 49 obese subjects undergoing bariatric surgery and 17 controls. Main assessments were plasma LPS, HbA1c, adipose tissue volumes (computed tomography), and quantified bacterial DNA in adipose tissue compartments. RESULTS: Plasma levels of LPS were elevated in obese individuals compared with controls (P < 0.001) and were reduced after bariatric surgery (P = 0.010). LPS levels were closely correlated with HbA1c (r = 0.56; P = 0.001) and intra-abdominal fat volumes (r = 0.61; P < 0.001), but only moderately correlated with subcutaneous fat volumes (r = 0.33; P = 0.038). Moreover, there was a decreasing gradient (twofold) in bacterial DNA levels going from mesenteric via omental to subcutaneous adipose tissue compartments (P = 0.041). Finally, reduced LPS levels after bariatric surgery were directly correlated with a reduction in HbA1c (r = 0.85; P < 0.001). CONCLUSIONS: Our findings support a hypothesis of translocated gut bacteria as a potential trigger of obesity and diabetes, and suggest that the antidiabetic effects of bariatric surgery might be mechanistically linked to, and even the result of, a reduction in plasma levels of LPS.