Ground-glass opacity: Meaning in a Radiology Report

Ground-glass opacity

Also written as: GGO, ground-glass attenuation, ground-glass nodule, GGN

Ground-glass opacity is a hazy gray area on a lung CT. The lung looks cloudy there, but the blood vessels inside it can still be seen.

Seen on: CT

How it reads in a report

Patchy ground-glass opacities in both lower lobes, likely infectious or inflammatory; follow-up CT in 3 months is suggested to confirm resolution.

What it means

Normal lung is mostly air, so it looks black on CT. In ground-glass opacity, part of the lung looks hazy gray, like frosted glass, yet the vessels and airways can still be seen through it. It happens when the tiny air sacs are partly filled, or the thin walls between them thicken. Fluid, inflammation, infection or bleeding can all do this.

When it matters

Patchy ground-glass in both lungs often comes with an infection, such as COVID-19 or another pneumonia. It usually clears over weeks to months. Fluid or inflammation can also cause it. If it lingers, or appears with scarring, doctors may look for a longer-term lung condition. A single round ground-glass spot that persists is often checked with CT over several years. That is because some turn out to be early, slow-growing cancers.

Questions to ask your doctor

Is the ground-glass patchy and widespread, or a single spot?
Could a recent infection explain it, and should it clear on a later scan?
If it is a lasting spot, how long will it need to be followed?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.