The ability to view airways response directly during an asthmatic attack would clearly be of great advantage in our understanding and treatment of airway hyperresponsiveness. Unfortunately, traditional assessments of airway hyperresponsiveness do not permit this. Conventional clinical and research parameters, such as spirometric variables (forced expiratory volume in 1 second [FEV₁], forced expiratory flow, and so forth) and bronchoalveolar lavage, provide only gross averages of airways function. Similarly, FEV₁ assesses global changes in the normal and diseased lung, and also lacks the ability to assess regional variations that may be important in understanding and treating the disease process.<sup>50 King G.G., Eberl S., Salome C.M. , e al. Airway closure measured by technegas bolus and SPECT Am J Respir Crit Care Med 1997 ;  155 : 682-688

Cliccare qui per andare alla sezione Riferimenti</sup> Measurements of inflammatory mediators and bronchoalveolar lavage cell counts suffer from limited sampling locations. Furthermore, introduction of a fiberoptic bronchoscope into the airways of an asthmatic patient during a severe or even moderate asthmatic attack is believed to be too dangerous. Recently, noninvasive imaging methods for assessing regional and individual airway responsiveness have been developed in animal models and applied to humans with obstructive lung disease.