Related Experiment Videos
Regional measurements of pulmonary edema by using magnetic resonance imaging
S D Caruthers1, C B Paschal, N A Pou
1Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
Abstract:
A three-dimensional magnetic resonance imaging (MRI) method to measure pulmonary edema and lung microvascular barrier permeability was developed and compared with conventional methods in nine mongrel dogs. MRIs were obtained covering the entire lungs. Injury was induced by injection of oleic acid (0.021-0.048 ml/kg) into a jugular catheter. Imaging followed for 0.75-2 h. Extravascular lung water and permeability-related parameters were measured from multiple-indicator dilution curves. Edema was measured as magnetic resonance signal-to-noise ratio (SNR). Postinjury wet-to-dry lung weight ratio was 5.30 +/- 0.38 (n = 9). Extravascular lung water increased from 2.03 +/- 1.11 to 3.00 +/- 1.45 ml/g (n = 9, P < 0.01). Indicator dilution studies yielded parameters characterizing capillary exchange of urea and butanediol: the product of the square root of equivalent diffusivity of escape from the capillary and capillary surface area (D1/2S) and the capillary permeability-surface area product (PS). The ratio of D1/2S for urea to D1/2S for butanediol increased from 0.583 +/- 0.027 to 0.852 +/- 0.154 (n = 9, P < 0.05). Whole lung SNR at baseline, before injury, correlated with D1/2S and PS ratios (both P < 0.02). By using rate of SNR change, the mismatch of transcapillary filtration flow and lymph clearance was estimated to be 0.2-1.8 ml/min. The filtration coefficient was estimated from these values. Results indicate that pulmonary edema formation during oleic acid injury can be imaged regionally and quantified globally, and the results suggest possible regional quantification by using three-dimensional MRI.
Insights
A new 3D MRI method quantifies pulmonary edema and lung microvascular barrier permeability. This technique shows promise for regional imaging and global quantification of lung injury.
Area of Science:
- Medical Imaging
- Pulmonary Medicine
- Physiology
Background:
- Pulmonary edema and microvascular barrier dysfunction are critical in lung injury.
- Accurate measurement of these parameters is essential for diagnosis and treatment.
- Current methods may lack regional specificity or quantitative precision.
Purpose of the Study:
- To develop and validate a novel three-dimensional magnetic resonance imaging (MRI) method for measuring pulmonary edema and lung microvascular barrier permeability.
- To compare the efficacy of this MRI technique against conventional methods in an animal model of lung injury.
Main Methods:
- A three-dimensional MRI technique was developed to assess pulmonary edema and lung microvascular barrier permeability.
- The method was applied to nine mongrel dogs following oleic acid-induced lung injury.
- Measurements included magnetic resonance signal-to-noise ratio (SNR) for edema, extravascular lung water, and indicator dilution curves for permeability parameters (D1/2S and PS).
Main Results:
- The 3D MRI method successfully imaged and quantified pulmonary edema.
- Increased extravascular lung water (P < 0.01) and altered permeability parameters (D1/2S, PS) were observed post-injury.
- Whole lung SNR correlated with permeability indices (P < 0.02), suggesting a link between edema and barrier function.
Conclusions:
- Three-dimensional MRI can regionally image and globally quantify pulmonary edema formation.
- The study suggests potential for regional quantification of lung injury using this advanced MRI technique.
- This method offers a promising non-invasive approach for assessing lung microvascular integrity.