Archive for January, 2010

multidetector ct

This article addresses an attempt to differentiate with ct scan the amount of air trapping or amount of air that is not released from an asthmatic lung. The patients were stratified by severity of asthma bny duration, hx of pneumonia,high level of airway neutrophils,airflow obstruction and atopy. These were some of the objective factors that correlated with severity of air trapping. They were also correlated with hx of hopitilizations,ICU visits,and mechanical ventilations.

Chest. 2009 Jan;135(1):48-56. Epub 2008 Aug 8.
A multivariate analysis of risk factors for the air-trapping asthmatic phenotype as measured by quantitative CT analysis.

Busacker A, Newell JD Jr, Keefe T, Hoffman EA, Granroth JC, Castro M, Fain S, Wenzel S.

Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.

BACKGROUND: Patients with severe asthma have increased physiologically measured air trapping; however, a study using CT measures of air trapping has not been performed. This study was designed to address two hypotheses: (1) air trapping measured by multidetector CT (MDCT) quantitative methodology would be a predictor of a more severe asthma phenotype; and (2) historical, clinical, allergic, or inflammatory risk factors could be identified via multivariate analysis. METHODS: MDCT scanning of a subset of Severe Asthma Research Program subjects was performed at functional residual capacity. Air trapping was defined as >or= 9.66% of the lung tissue < – 850 Hounsfield units (HU). Subjects classified as having air trapping were then compared to subjects without air trapping on clinical and demographic factors using both univariate and multivariate statistical analyses. RESULTS: Subjects with air trapping were significantly more likely to have a history of asthma-related hospitalizations, ICU visits, and/or mechanical ventilation. Duration of asthma (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.08 to 1.87), history of pneumonia (OR, 8.55; 95% CI, 2.07 to 35.26), high levels of airway neutrophils (OR, 8.67; 95% CI, 2.05 to 36.57), airflow obstruction (FEV(1)/FVC) [OR, 1.61; 95% CI, 1.21 to 2.14], and atopy (OR, 11.54; 95% CI, 1.97 to 67.70) were identified as independent risk factors associated with the air-trapping phenotype. CONCLUSIONS: Quantitative CT-determined air trapping in asthmatic subjects identifies a group of individuals at high risk for severe disease. Several independent risk factors for the presence of this phenotype were identified: perhaps most interestingly, history of pneumonia, neutrophilic inflammation, and atopy.
The study concluded that the severity of asthmatic was identified by this CT scan technique. This also possibly measure one phenotype of asthma that is measurable. Larger studies are necessary to confirm this. Thanks arthur lubitz md
PMID: 18689585 [PubMed – indexed for MEDLINE]

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