New and current clinical imaging techniques to study chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by both small airway and parenchymal abnormalities. There is increasing evidence to suggest that these two morphologic phenotypes, although related, may have different clinical presentations, prognosis, and therapeutic responses to medications. With the advent of novel imaging modalities, it is now possible to evaluate these two morphologic phenotypes in large clinical studies using noninvasive or minimally invasive methods such as computed tomography (CT), magnetic resonance imaging (MRI), and optical coherence tomography (OCT). In this article, we provide an overview of these imaging modalities in the context of COPD and discuss their strengths as well as their limitations for providing quantitative COPD phenotypes.