Unilateral Hyperlucency of the Lung: A Systematic Approach to Accurate Radiographic Interpretation

ABSTRACT

The radiographic appearance of a unilateral hyperlucent lung is related to various conditions, the accurate radiographic interpretation of which requires a structured approach as well as an awareness of the spectrum of these entities. Firstly, it is important to determine whether a hyperlucent hemithorax is associated with artifacts resulting from rotation of the patient, grid cutoff, or the heel effect. The second step is to determine whether or not a hyperlucent lung is abnormal. Lung that is in fact normal may appear hyperlucent because of diffusely increased opacity of the opposite hemithorax. Thirdly, thoracic wall and soft tissue abnormalities such as mastectomy or Poland syndrome may cause hyperlucency. Lastly, abnormalities of lung parenchyma may result in hyperlucency. Lung abnormalities can be divided into two groups: a) obstructive or compensatory hyperinflation; and b) reduced vascular perfusion of the lung due to congenital or acquired vascular abnormalities. In this article, we describe and illustrate the imaging spectrum of these causes and outline a structured approach to accurate radiographic interpretation.