Functional imaging for assessing regional lung ventilation in preclinical and clinical research

Abstract

Dynamic heterogeneity in lung ventilation is an important measure of pulmonary function and may be characteristic of early pulmonary disease. While standard indices like spirometry, body plethysmography, and blood gases have been utilized to assess lung function, they do not provide adequate information on regional ventilatory distribution nor function assessments of ventilation during the respiratory cycle. Emerging technologies such as xenon CT, volumetric CT, functional MRI and X-ray velocimetry can assess regional ventilation using non-invasive radiographic methods that may complement current methods of assessing lung function. As a supplement to current modalities of pulmonary function assessment, functional lung imaging has the potential to identify respiratory disease phenotypes with distinct natural histories. Moreover, these novel technologies may offer an optimal strategy to evaluate the effectiveness of novel therapies and therapies targeting localized small airways disease in preclinical and clinical research. In this review, we aim to discuss the features of functional lung imaging, as well as its potential application and limitations to adoption in research.

Regional variations in allergen‐induced airway inflammation correspond to changes in soluble guanylyl cyclase heme and expression of heme oxygenase‐1

“…This will also indicate which inflamed lung segments have the worst lung ventilation and thus can be effectively targeted for therapies. 20 These studies can be extended to human lungs using 4D medical imaging 66 where the inflamed areas can be recognized and drug formulations with sGC activators can be used as bronchodilators as these have been found to be effective in human bronchioles. 17 Our current study provides a corridor of correlating lung ventilation with molecular markers of inflammation, and these studies can now be further pursued.…”

Pilot study of paediatric regional lung function assessment via X-ray velocimetry (XV) imaging in children with normal lungs and in children with cystic fibrosis

“…However, to calculate ventilation metrics, they generally undergo three computational steps, including lung volume delineation, measurement of lung motion and algorithmic calculation of surrogate measures for regional ventilation. 18 19 The most common algorithms are evaluation of lung volume changes using CT intensity or Hounsfield unit values and deformation vectors. 18 …”

“… 18 19 The most common algorithms are evaluation of lung volume changes using CT intensity or Hounsfield unit values and deformation vectors. 18 …”

“…It has been used an inhalational contrast agent for functional lung imaging due to its X-ray absorption characteristics, being similar to iodine. 18 20 Xenon CT involves a wash-in phase, where the subject inhales a xenon and oxygen mixture, followed by a period of washout, where they inhale a high oxygen concentration while the radioisotope is exhaled or absorbed. Images captured by CT are subsequently processed into three-dimensional (3D) distribution maps, where ventilation can be qualitatively and quantitatively assessed.…”

“…Images captured by CT are subsequently processed into three-dimensional (3D) distribution maps, where ventilation can be qualitatively and quantitatively assessed. 18 21 …”