Blogs

Additional COVID-19 Findings - Bilateral Adrenal Hemorrhage
October 21, 2020
This 70-years old man with COVID-19 has a CT scan showing typical lung findings. He also has bilateral adrenal hemorrhage in the upper abdomen, which was unsuspected clinically. There have been a few case reports of patients with adrenal hemorrhage and insufficiency in the setting of COVID-19, likely related to a coagulation disorder. This can be life-threatening causing acute adrenal insufficiency. Unfortunately, this patient did not survive. He collapsed the next day befor...
Incidental COVID-19 Pick-Up - IV - CT Abdomen
October 21, 2020
This 60-years old man came for a CT KUB, which shows a right ureteric calculus. The lower lobe lung images that are always captured on a CT scan of the abdomen show changes of COVID-19, for which the patient is and was asymptomatic. Are these new or old or resolving or active? I guess an antibody test would tell us whether the patient has been infected in the recent past and an RT-PCR test would tell us whether the patient is current infected or not. However we have no idea ...
Incidental COVID-19 Pick-Up - III - MRI
October 21, 2020
This 53-years old man came with a recent inferior wall infarct, for viability imaging. The top left image shows the inferior wall infarct with a thrombus (arrow). The HASTE and contrast VIBE MRI images showed wedge-shaped areas (arrows) of altered signal in the posterior segment of the left upper lobe and the superior segment of the left lower lobe of the lung. A CT scan done immediately thereafter shows typical COVID-19 lung changes (arrows) in the same segments and the dia...
Incidental COVID-19 Pick-Up - II - PET/CT
October 21, 2020
This 52-years old lady also came for a follow-up PET/CT for Ca breast evaluation. She had been COVID-19 positive in the first week of August and hospitalized. Unfortunately the Augst scan is not available. The lung shows typical findings of post COVID-19 sequelae with no significant uptake on the PET. In about 8 weeks, the activity has regressed. But are these regressing residual lesions with regression of active inflammation or is this already fibrosis? It is hard to tell. ...
Incidental COVID-19 Pick-Up - I - PET/CT
October 21, 2020
This 59-years old lady came for a follow-up PET/CT for Ca breast evaluation. She had no respiratory symptoms. The lung shows typical findings of COVID-19 with uptake on the PET. Almost all patients with incidental COVID-19 show some level of activity, which likely lasts for some time, even after the RT-PCR becomes negative. In these patients, we never really know at what stage of the disease they are when we pick up these findings on PET. Some are tested, some not, some are ...
Covid-19 CT Chest - Temporal Changes - IX - Fibrosis
October 21, 2020
This 47-years old had COVID-19 in mid-June. Her CT scan of 16 Jun shows typical subpleural areas of ground glass. In most patients, these resolve completely or with residual subtle ground glass or reticular opacities, as we have been seeing. This lady had particularly severe disease and the scan of 25 Jul shows traction bronchiectasis and distortion of architecture with volume loss, findings that are suggestive of fibrosis. Her repeat scan of 25 Sep shows further volume loss...
Covid-19 CT Chest - Temporal Changes - VIII - “Tinted” Sign
October 21, 2020
This 61-years old man came after 4 days of fever. The first CT scan shows a classic perivascular and subpleural lesion. 7 days later, the lesion has partly “melted” - this has been called the “tinted” sign in some recent papers. More and more, we now believe that this is fluid getting partly absorbed as part of the changes that occur due to the local angiopathy / vasculopathy and that this is not really “pneumonia”. ...
Covid-19 CT Chest - Temporal Changes - VII - Unexplained Creeping Ground Glass at 4 Months
October 21, 2020
This 57-years old man was tested positive in mid-May. He had a scan in June and now in September. While there is resorption of some of the ground glass and reticular opacities between Jun and Sept, some of the “normal” lung now shows ground glass. The patient however is stable and has not worsened. Is this just a normal evolution given that this is an angiopathy / vasculopathy, we have no experience of? What will happen another 3 months further down the line? Can doctors/rad...
Covid-19 CT Chest - Temporal Changes - VI - Melted Sugar, Cotton Candy Sign
October 21, 2020
This 74-years old individual had a CT scan 1 month after her COViD-19 diagnosis showing consolidation and thick bands in the lower lobes. 10 weeks later, the lesions have resorbed. This appearance has been labeled the “melted sugar” appearance, though I have a feeling that this translation from Mandarin, is likely more “cotton candy”, which is what the appearance looks like - wisps of residual ground glass and reticular opacities. ...
Covid-19 CT Chest - Temporal Changes - V
September 18, 2020
This middle-aged individual had bad disease and was hospitalized for over a month. The first scan shows significant lung involvement. 3 weeks later, the lesions have started regressing / melting. Another 5 weeks later, there is some further improvement. The question remains. How much of this is permanent? Which of these lesions will eventually melt away / regress. The patient is improving clinically though slowly. Only time will tell as we see more and more patients coming f...
Covid-19 CT Chest - Temporal Changes - IV
September 18, 2020
This 52 years old man presented with mild disease that progressed in 3 days. He was Covid negative but breathless and a scan done 1 month later shows dense opacities with traction bronchiectasis. Is this fibrosis? Or resolving organizing pneumonia? Many of these tend to regress further as we shall see in future cases and unless there is frank honeycombing or volume loss, it may be difficult to label this as fibrosis. We just read them and describe them and mention whether th...
Covid-19 CT Chest - Temporal Changes - III
September 18, 2020
Then we have this 42-years old man with two scans done 9 days apart, who was mildly symptomatic at the time of the first scan and is asymptomatic at the time of the 2nd scan. The upper lobe lesions seen on the first scan have improved (green arrows), but there are new lesions in both lower lobes, especially the left (red arrows). So is this progressive disease? Or is it more likely that the lesions increased immediately after the first CT and have settled and this is now the...
Covid-19 CT Chest - Temporal Changes - II
September 18, 2020
On the other hand, this 34-years old patient had minimal subtle disease at presentation and then 13 days later landed up with extensive lung involvement, most of it likely related to angiopathy with an associated acute lung injury pattern. Some patients suddenly deteriorate like this. ...
Covid-19 CT Chest - Temporal Changes - I
September 18, 2020
This 43-years old man has typical changes of ground glass and crazy-paving at presentation. One week later, the lesions have resolved significantly with residual ground glass, reticular opacities and a thin band. Most patients follow this pattern. ...
Earliest Covid Signs on CT Chest
September 18, 2020
These are two asymptomatic individuals who tested positive, but sent for CT scan. Both patients show subtle opacities, which are predominantly perivascular, with ground glass or slightly denser appearance. Both of them had 4-5 such foci in thelungs. ...
Covid-19 CT Chest Patterns - VIII - Vasculopathy - IV - Thromboembolism & Bubble Lucencies
September 18, 2020
This is a 41-years old with severe disease. The red arrows show the “target sign”, one in the right lower lobe and the other in the left lower lobe. The patient has pulmonary thromboembolism (blue arrows), which is associated with increased morbidity and mortality. “Bubble lucencies” (yellow arrow) are seen on the soft tissue window images and generally imply hemorrhagic infarction. ...
Covid-19 CT Chest Patterns - VI - Vasculopathy - III - Target Sign
September 18, 2020
The target sign has been described to be a result of perivascular inflammation and organizing pneumonia. Whether there is also an element of infarction is uncertain. As seen in the video, the sign consists of the pin-point or sometimes thickened vessel in the center (red arrow), the perivascular opacity of inflammation (blue arrow), the relative “spared” halo (yellow arrow) and the ground glass halo (green arrow). Irrespective of the exact reason for the target sign, its pre...
Covid-19 CT Chest Patterns - VI - Vasculopathy - II - Vascular “Tree-in-Bud”
September 18, 2020
The vascular “tree-in-bud” appearance has been recently described by Brijesh Patel from the Royal Brompton in London and his colleagues. This refers to the presence of branching peripheral vessels, in a way, similar to the bronchial “tree-in-bud” (top left) we see with infectious bronchiolitis / tuberculosis. This vascular “tree-in-bud” (top right) is supposedly a marker of a thrombotic vasculopathy with angiogenesis and micro-thromboses. The presence of this sign in admitte...
Covid-19 CT Chest Patterns - V - Vasculopathy - I
September 18, 2020
One major difference between Covid-19 and other inflammatory / infective diseases of the lungs is the presence of a vasculopathy / angiopathy. While there is still debate about the exact pathophysiology behind the vascular involvement, there are radiology signs that allow us to identify the presence of a vasculopathy. Many patients show prominent / dilated proximal or intra-lesional vessels. This is perhaps the simplest sign of a vasculopathy, rarely seen outside of a Covid-...
Visualizing Ground Glass - Tips & Tricks
September 18, 2020
Ground glass (GG) foci are the commonest manifestation of Covid-19 and in subtle cases, may be difficult to diagnose. This difficulty may then turn a positive into a negative scan. Here are two ways to improve conspicuity of GG areas during interpretation.   1. Minimum Intensity Projection (minIP) images while scrolling on the workstation. I use a 3 mm sliding minIP and it allows quick pick-up of subtle lesions. In this case (top row), while a static image does not capture t...