Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

Meta-analysis of the association of beta2-adrenergic receptor polymorphisms with asthma phenotypes

BACKGROUND: Two common polymorphisms of the beta2-adrenergic receptor gene (Arg16Gly and Gln27Glu ) have been extensively studied for their possible association with asthma-related phenotypes, but the results of individual studies have been inconclusive. OBJECTIVE: We aimed to integrate quantitatively the available evidence on the association of the Arg16Gly and the Gln27Glu polymorphisms with asthma, nocturnal asthma, asthma severity, and bronchial hyperresponsiveness. METHODS: Meta-analysis of case-control and cohort studies using random effects models. RESULTS: A total of 28 studies were included in the meta-analysis. The summary estimates suggested that neither the Gly16 nor the Glu27 allele contributes to asthma susceptibility overall (odds ratio [OR], 1.01; 95% CI, 0.90-1.13; and OR, 0.95; 95% CI, 0.83-1.09, respectively) or to bronchial hyperresponsiveness (OR, 0.90; 95% CI, 0.77-1.05; and OR, 1.07; 95% CI, 0.94-1.22, respectively). There was a strong association of Gly16 with nocturnal asthma (OR, 2.20; 95% CI, 1.56-3.11) and a less strong association with severe or moderate rather than milder asthma (OR, 1.42; 95% CI, 1.04-1.94). No such effects were seen for the Glu27 allele (OR, 1.02; 95% CI, 0.74-1.40; and OR, 0.82; 95% CI, 0.59-1.14, respectively). Moreover, there was evidence that Gly16 homozygotes had a much higher risk for nocturnal asthma (OR, 5.15; 95% CI, 2.44-10.84) and asthma severity (OR, 2.84; 95% CI, 1.62-4.96) than the Arg16 homozygotes. CONCLUSION: The Gly16 allele of the beta2-adrenergic receptor gene predisposes to nocturnal asthma, and this may also explain the association with asthma severity. Neither polymorphism modulates the risk for bronchial hyperresponsiveness or mild asthma.     

Reporting of conflicts of interest in guidelines of preventive and therapeutic interventions

Background

Guidelines published in major medical journals are very influential in determining clinical practice. It would be essential to evaluate whether conflicts of interests are disclosed in these publications. We evaluated the reporting of conflicts of interest and the factors that may affect such disclosure in a sample of 191 guidelines on therapeutic and/or preventive measures published in 6 major clinical journals (Annals of Internal Medicine, BMJ, JAMA, Lancet, New England Journal of Medicine, Pediatrics) in 1979, 1984, 1989, 1994 and 1999.

Results

Only 7 guidelines (3.7%) mentioned conflicts of interest and all were published in 1999 (17.5% (7/40) of guidelines published in 1999 alone). Reporting of conflicts of interest differed significantly by journal (p=0.026), availability of disclosure policy by the journal (p=0.043), source of funding (p < 0.001) and number of authors (p=0.004). In the entire database of 191 guidelines, a mere 18 authors disclosed a total of 24 potential conflicts of interest and most pertained to minor issues.

Conclusions

Despite some recent improvement, reporting of conflicts of interest in clinical guidelines published in influential journals is largely neglected.

     

Osteopetrosis: MR characteristics at 1.5 T

Four patients with proved osteopetrosis (three with the infantile malignant form and one with the benign form) were examined with magnetic resonance imaging at 1.5 T. All patients were studied in the coronal and sagittal planes using both short and long repetition time/echo time sequences. The infantile malignant form was characterized by a complete lack of signal from the marrow alternating with a signal intensity equivalent to that of the intervertebral disks, resulting in a "stepladder" appearance. In the benign form or after successful marrow transplantation in the infantile malignant form, intermediate or high signal intensity in the vertebrae was noted, suggesting the presence of some marrow elements.