Reticular opacities present as thin short lines that are usually peripheral and subpleural. When the reticular lesions are predominant, resembling an NSIP pattern (blue arrow), this appearance is usually seen in resolving cases (top left). Some ground glass (yellow arrow) is almost always present.
Reticular opacities can also be random (blue arrows) as seen in the top right image, accompanying areas of consolidation or ground glass. Septal thickening is also a type of reticular opacity (blue arrow) that forms part of the crazy-paving pattern, along with ground glass (yellow arrow) seen in acute cases (bottom image).