Pulmonary Acinus: Understanding the Computed Tomography Findings from an Acinar Perspective

Lung. 2019 Jun;197(3):259-265. doi: 10.1007/s00408-019-00214-7. Epub 2019 Mar 21.


The lung acinus is the most distal portion of the airway responsible for the gas exchange. The normal acini are not visible on conventional computed tomography (CT), but the advent of micro-CT improved the understanding of the microarchitecture of healthy acini. The comprehension of the acinar architecture is pivotal for the understanding of CT findings of diseases that involve the acini. Centriacinar emphysema, for example, presents as round areas of low attenuation due to the destruction of the most central acini with compensatory enlargement of proximal acini due to alveolar wall destruction. In pulmonary fibrosis, intralobular septal fibrosis manifests as acinar wall thickening with an overlap of acinar collapse and compensatory dilation of surrounding acini constituting the cystic disease typical of the usual interstitial pneumonia pattern. This is a state-of-the-art review to describe the acinar structure from the micro-CT perspective and display how the comprehension of the acinar structure can aid in the interpretation of its microarchitecture disruption on conventional CT.

Keywords: Computerized tomography; Micro-computed tomography; Pulmonary acinus; Secondary pulmonary lobule.

Publication types

  • Review

MeSH terms

  • Humans
  • Lung / diagnostic imaging*
  • Pulmonary Alveoli / diagnostic imaging*
  • Pulmonary Emphysema / diagnostic imaging*
  • Pulmonary Fibrosis / diagnostic imaging*
  • Tomography, X-Ray Computed
  • Tuberculosis, Pulmonary / diagnostic imaging*
  • X-Ray Microtomography