Advanced pulmonary MRI to quantify alveolar and acinar duct abnormalities: Current status and future clinical applications

Abstract

There are serious clinical gaps in our understanding of chronic lung disease that require novel, sensitive, and noninvasive in vivo measurements of the lung parenchyma to measure disease pathogenesis and progressive changes over time as well as response to treatment. Until recently, our knowledge and appreciation of the tissue changes that accompany lung disease has depended on ex vivo biopsy and concomitant histological and stereological measurements. These measurements have revealed the underlying pathologies that drive lung disease and have provided important observations about airway occlusion, obliteration of the terminal bronchioles and airspace enlargement, or fibrosis and their roles in disease initiation and progression. ex vivo tissue stereology and histology are the established gold standards and, more recently, micro‐computed tomography (CT) measurements of ex vivo tissue samples has also been employed to reveal new mechanistic findings about the progression of obstructive lung disease in patients. While these approaches have provided important understandings using ex vivo analysis of excised samples, recently developed hyperpolarized noble gas MRI methods provide an opportunity to noninvasively measure acinar duct and terminal airway dimensions and geometry in vivo, and, without radiation burden. Therefore, in this review we summarize emerging pulmonary MRI morphometry methods that provide noninvasive in vivo measurements of the lung in patients with bronchopulmonary dysplasia and chronic obstructive pulmonary disease, among others. We discuss new findings, future research directions, as well as clinical opportunities to address current gaps in patient care and for testing of new therapies. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:28–40.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

“…One exception is the description of a method for the evaluation of the pulmonary vasculature using microCT (464). Recent attention to the use of advanced pulmonary MRI to quantify alveolar and acinar duct abnormalities in BPD patients (623) raises the possibility of extending these approaches to preclinical models.…”

Analytic determination of lung microgeometry with gas diffusion magnetic resonance

“…Ever since the microgeometry dependence of gas diffusion magnetic resonance (MR) measurements on the lung was first demonstrated experimentally [1][2][3], there has been great interest in utilizing this dependence in clinical and research applications, such as detection and investigation of emphysema (see, e.g., Refs. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]). However, due to the lack of a general analytic relation relating the microgeometry and the measured quantity, it has so far not been clear what specific information the dependence allows one to extract.…”