The COVID-19 pandemic filled our vocabularies with more medical terms than most of us would ever hear about, but some were familiar.  It soon became clear that CT scans were a useful tool to check for COVID-19.  One 2022 study showed that COVID-19 shares some features with other viral types of pneumonia, despite some differences. They commonly present as “ground glass opacities” (GGO) along with vascular thickening, air bronchogram and consolidations. Also, they differ by age, disease severity, and outcomes among COVID-19 patients.  GGOs refer to findings CT scans of COVID-19 patients that can help diagnose and monitor the infection. A similar study published early on in the pandemic came up with similar conclusions in regard the presentation on CTs of the chest.  Another study said that while it’s important to note that GGOs aren’t specific to COVID-19, meaning they can show up in other conditions and infections, they are common among those infected with COVID-19.  The inference is that the clinical history of the patient showing GGO during or following a COVID-positive scenario must also be a factor.

What are ground glass opacities?

According to Isabel Oliva Cortopassi, MD, senior associate consultant at Mayo Clinic and former chief of thoracic imaging at Yale Medicine, ground-glass opacities (GGOs, for short) indicate abnormalities in the lungs. “Ground-glass opacities are a pattern that can be seen when the lungs are sick,” said Dr. Cortopassi. Dr. Cortopassi added that, while normal lung CT scans appear black, an abnormal chest CT with GGOs will show lighter-colored or gray patches.  Those lighter patches don’t completely obscure the other structures in the lungs, said Jennifer Possick, MD, a Yale Medicine pulmonologist—that makes them different from lesions associated with lung cancer, which can often appear as solid. With GGOs, “there is haziness seen overlying an area of the lung, but the underlying structures of the lung (airways, blood vessels, lung tissue) can still be identified,” said Dr. Possick. It resembles, well, ground glass, or glass that is still transparent but has a matte finish.

What Else can Ground-Glass Opacities Indicate?

As above, it’s important to keep in mind that GGOs aren’t specific to COVID-19 and can be seen in many different settings, emphasized Dr. Possick. GGOs in chest CT scans can also indicate congestive heart failure, inflammatory interstitial lung diseases, and diffuse alveolar hemorrhage (bleeding into the airspaces of the lungs), among other issues. But one of the most common diagnoses for GGOs is viral pneumonia, most often caused by a respiratory syncytial virus (RSV), cytomegalovirus, herpes simplex virus, and coronavirus (all types).  In terms of COVID-19, Dr. Cortopassi explained that GGOs on a CT scan indicates COVID-19-related pneumonia or lung inflammation caused by the viral infection. It’s important to note, however, that not all patients with COVID-19 will go on to develop pneumonia, stressed Dr. Cortopassi. These terms are important to know, especially if your doctor mentions ground glass opacities while treating you for COVID-19 or another illness. But Dr. Cortopassi reiterated that a COVID-19 diagnosis doesn’t automatically lead to a worsened condition in which these GGOs will show up in a CT scan, nor does an abnormal scan definitively mean a coronavirus infection. “Some people will have completely different radiologic findings, and some people will have no imaging abnormalities at all,” said Dr. Cortopassi.

Another study published in the journal, The Lancet Respiratory Medicine used people who had been hospitalized for COVID-19 and had GGOs on initial lung scans; they rescanned their lungs at three and nine months following hospital discharge. Researchers found that 78% of patients still had residual GGOs at three months post-discharge, and 24% had GGOs still showing up on scans at nine months post-discharge.

My own experience

It was a bit of a shock when my wife and I both tested positive in the middle of 2022, despite surviving unscathed through several waves since the pandemic began in early 2020.   It is an experience I would not like to repeat, and I wrote about it in this article – click here.  I was not symptomatic until 29th June and test positive on 30th June.  I was basically out of action for around 11 days and 7 days after testing negative, I’m still suffering some of the symptoms, mainly coughing and a slight shortage of breath at times.  I felt fit enough to attend a planned NET surveillance appointment on 13th July to receive the results of my surveillance tests including a CT scan on 22nd June. It is then my Oncologist informed me that ground glass opacities had been found on this scan which occurred 7 days prior to me becoming symptomatic and testing positive. He described them as “fluffy objects on my left lung.  My own analysis and opinion is that my chest infection history since childhood has perhaps influenced the severity of the covid infection I experienced.  I’m happy that I had been vaccinated before I caught it.  I will be getting a repeat CT of my chest in 3 months to check the GGO.

I wanted to publish my own experience as I frequently see ground glass opacities discussed in my private group, normally by Lung NET patients.  Clearly, a possible connection to COVID-19 must be assessed in new findings.

Disclaimer: The information in this story is accurate as of the publication date.  After almost 2.5 years of pandemic, clinicians know a lot more but the situation around COVID-19 continues to evolve.  It’s possible that some data have changed since the publication of any studies I referenced.  Please refer to the latest guidance from your own national disease control agencies and organisations.