Configuration of bioelectrical impedance measurements affects results for phase angle.

OBJECTIVE: Phase angle (PhA) obtained by bioelectrical impedance analysis is a well-established predictor of malnutrition that reflects the amount and quality of soft tissue. However, PhA results may depend on configurations of the measurement that differ between devices. The aim was to analyze differences between devices for supine and standing measurements. APPROACH: In a cross-sectional study, differences in PhA were analyzed comparing supine vs. standing positions, metal vs. adhesive electrodes and the right vs. left side of the body in 302 multi-ethnic adults (18-65y) and 1298 Mexican children and adolescents (4-20y). MAIN RESULTS: PhA was higher in supine than in standing position (from 0.71°±0.22° in children to 0.97°±0.25° in adults; all p < 0.001) with approximately fifty percent of observed differences explained by electrode placement. PhA differences increased with increasing PhA (r = 0.419) and decreased with age (r = -0.346) in adults, but increased with PhA (r = 0.677), age (r = 0.752) and height (r = 0.737) in children (all p <0.001). In adults, PhA was higher on the right side of the body (standing 0.18°±0.17°; supine 0.36°±0.33°; p <0.001). SIGNIFICANCE: Phase angle results are influenced by posture and electrode placement. Measurement configuration must be considered when phase angle values are compared between different devices or with literature values.

Limitations of Fat-Free Mass for the Assessment of Muscle Mass in Obesity.

BACKGROUND: A high amount of adipose tissue limits the accuracy of methods for body composition analysis in obesity. OBJECTIVES: The aim was to quantify and explain differences in fat-free mass (FFM) (as an index of skeletal muscle mass, SMM) measured with bioelectrical impedance analysis (BIA), dual energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), and deuterium dilution in comparison to multicompartment models, and to improve the results of BIA for obese subjects. METHODS: In 175 healthy subjects (87 men and 88 women, BMI 20-43.3 kg/m2, 18-65 years), FFM measured by these methods was compared with results from a 3- (3C) and a 4-compartment (4C) model. FFM4C was compared with SMM measured by magnetic resonance imaging. RESULTS: BIA and DXA overestimated and ADP underestimated FFM in comparison to 3C and 4C models with increasing BMI (all p < 0.001). -Differences were largest for DXA. In obesity, BIA results were improved: valuecorrected = -valueuncorrected - a(BMI - 30 kg/m2), a = 0.256 for FFM and a = 0.298 for SMM. SMM accounts for 45% of FFM in women and 49% in men. CONCLUSIONS: In obesity, the use of FFM is limited by a systematic error of reference methods. In addition, SMM accounts for about 50% of FFM only. Corrected measurement of SMM by BIA can overcome these drawbacks.

Refractory central nervous system vasculitis and gastrocnemius myalgia syndrome in Crohn's disease successfully treated with anti-tumor necrosis factor-alpha antibody.

BACKGROUND: Secondary vasculitis represents a rare extraintestinal manifestation of Crohn's disease (CD). Appropriate and prompt diagnosis is often delayed by uncertainties about the relationship of the vasculitic manifestations and CD. OBJECTIVE: To describe our experience with vasculitis in CD and review the literature with respect to different manifestations and pathophysiological aspects of extraintestinal vasculitic manifestations of CD. METHODS: We report 2 new cases of CD with secondary small-vessel vasculitis. We also extensively review the literature (1960-2007) using a broad range of key words related to secondary vasculitis in CD. Relevant publications were evaluated for the number of reported patients and manifestations of vasculitis. RESULTS: Vasculitis is a rare extraintestinal manifestation of CD. Different types of vasculitis affect large-, medium-, and small-sized vessels associated with CD. Common immunologic features include intestinal inflammation as well as an infiltration of gammadelta-T-cells and/or Th1-type cells into vessel walls. The 2 new cases of secondary vasculitis in CD reported here reflect 2 major types of CD-related inflammatory vascular disorders. The first involves the central nervous system, while the second represents circumscribed Musculus gastrocnemius involvement (so-called "gastrocnemius myalgia syndrome"). Successful treatment of refractory secondary vasculitis in CD with an anti-tumor necrosis factor-alpha antibody is shown for the first time. CONCLUSION: Vasculitis secondary to CD is an uncommon finding. Therefore, it has to be carefully differentiated from other forms of primary or secondary vasculitis with intestinal involvement. Treatment with an anti- tumor necrosis factor-alpha antibody may prove a treatment option in vasculitis as an extraintestinal manifestation of CD.

Value of single-dose contrast-enhanced magnetic resonance angiography versus intraarterial digital subtraction angiography in therapy indications in abdominal and iliac arteries.

The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committe was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 degrees , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses > or = 50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.