Vibration Response Imaging (VRI) is a novel non-invasive technology that creates images of the lungs by recording vibrations from the chest wall during the respiratory cycle. It was hypothesized that some features of VRI images at baseline might predict results of a subsequently performed methacholine inhalation challenge (MIC) test.
14 patients underwent baseline VRI imaging immediately prior to a MIC test performed for evaluation of respiratory symptoms. Two readers that were blind to the MIC results independently scored these baseline VRI images, on a scale of 0-3, at different points of the respiratory cycle for shape and intensity, right-left symmetry, and maximum vibration energy detected. Regression analysis was used to test the association between the 16 subcomponent scores describing the VRI image and MIC test results.
VRI images were satisfactory for analysis in 13 patients and MIC test results were positive in 6. There was a correlation between the total VRI scores by the two readers (r=0.62, p=0.03). Average of the total scores by the two readers had a poor association with MIC results (odds ratio=0.90, p=0.21). However, 3 subcomponent scores for specific image features (early inspiratory expansion, the direction of expansion during inspiration, and maximum vibration energy) showed, in aggregate, a predictive trend (odds ratio=3.0, p=0.07). The 3 patients with the lowest subcomponent scores had a positive MIC and the 2 patients with the highest scores had a negative MIC.
Features of VRI images can be scored with interobserver correlation. Early inspiratory expansion, direction of image expansion during inspiration, and maximum vibration energy showed a trend for predicting MIC test results. A larger, prospective clinical evaluation of a scoring system based on these image features needs to be performed.
A semi-quantitative scoring system based on specific features of the baseline VRI image may be useful for the diagnosis of asthma. If such a scoring system can be validated prospectively, VRI would be a new and potentially sensitive method for evaluating asthma.
Payam Aghassi, Grant monies (from industry related sources) Supported by Deep Breeze, Ltd.; Product/procedure/technique that is considered research and is NOT yet approved for any purpose.