Back to the future in asthma imaging: quantitative assessment and new perspectives

Asthma is a heterogeneous disease characterized by respiratory involvement with wheezing, shortness of breath, dyspnea, and cough, along with systemic symptoms. The diagnosis of asthma predominantly relies on clinical history and bronchial hyperreactivity. However, due to its heterogeneity in manifestation, imaging can be a valuable option to support clinical examination. In fact, as stated by the latest guidelines, imaging examinations should not be routinely performed but should be tailored to the patient according to specific conditions or particular situations-such as exacerbation requiring advanced care, comorbidities, or severe asthma-that require further and more specific evaluation. The most common imaging findings in asthma are related to central and peripheral airway involvement, showing bronchial thickening and subsegmental bronchiectasis, along with additional radiographic features such as expiratory air trapping, inspiratory lung hyperinflation, and centrilobular micronodules. Despite having low specificity and sensitivity, chest X-ray is often the first examination performed due to its availability and usefulness in an emergency setting to identify complications as pneumothorax or superimposed infections. Among imaging techniques, HRCT remains the gold standard, allowing for the successful identification of both airway morphological changes (bronchial thickening) and parenchymal involvement related to asthma (centrilobular nodules and air trapping). Moreover, with the development of new techniques such as quantitative CT, more precise measurements of bronchial wall thickening can be done, establishing a potential correlation between HRCT imaging and data from pulmonary function tests. Despite being a promising and revolutionary technique, up to now MRI has played a marginal role in the evaluation of asthma, mainly restricted to assessing lung ventilation. However, recent studies are experimenting with MRI quantitative evaluation of bronchial wall dimensions with great results, which can be promising in the near future for new follow-up possibilities. The aim of this article is to analyze the state of the art of imaging techniques used in the field of asthma and to link advanced imaging findings with everyday clinical practice, offering insight into the future of precision medicine in asthma care.