Introduction
An acute coronavirus disease affecting mostly the respiratory tract,
named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or
COVID-19, has quickly become a pandemic (1-2 ). Within the state
of Louisiana, Orleans Parish is presently experiencing an exponential
acceleration of cases, with a large number of patients having severe
lung involvement.
Chest X-ray has been of little benefit during early stages of COVID-19,
but chest computed tomography (CT) has been noted to have abnormal
findings, even prior to the onset of respiratory symptoms
(3-5 ). These findings are not specific by themselves and should
not be used as criteria to diagnose COVID-19 infection. However, they
are helpful in the appropriate clinical setting. Findings by CT may be
be categorized into two main categories by time from onset of symptoms: Early (< 7 days from symptoms onset) or Advanced (8-14 days from symptoms onset). The Advanced stage
may then progress to either “healing” or that of deterioration with
cytokine storm and adult respiratory distress syndrome (ARDS)
(1 ).
CT Findings of COVID-19
CT abnormalities with COVID-19 have been reported to vary.
Lymphadenopathy, lung cavitation and pleural effusions are usually not
associated with COVID-19 (6-8 ).
Early category CT findings are generally associated with ground glass
opacities (GGOs). They are typically multifocal, peripheral, bilateral
at different levels, and mostly bibasilar (Figure 1-2 ). As this
Early category progresses to the Advanced category, GGOs will demonstate
a reticular pattern with a decreased GGO prominence (Figure
3-6 ). The GGOs will continue to progress to consolidation bilaterally
(Figure 7-9 ). As mentioned previously, although a pleural
effusion is not usually described as associated with COVID-19, one may
be noted on occasion (Figure 10 ).
Conclusion
Orleans Parish in Louisiana is in the midst of an exponentially
increasing number of patient admissions with COVID-19 and respiratory
symptoms. Patients have been described having CT findings most
consistent with an Early stage (< 7 days from symptoms onset)
or an Advanced stage (8-14 days from symptoms onset).
We describe and illustrate Early and Advanced stage CT findings from
patients with documented COVID-19 who have been admitted to University
Medical Center in New Orleans, Louisiana.
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Figure Legends
All images are contrast CT images of the chest in the standard axial
plane. For optimal imaging of the lungs, lung windowing was used. All
images are from patients admitted during the mid-weeks of March 2020 to
University Medical Center, New Orleans, Louisiana. All patients had
documented COVID-19 by PCR, and respiratory symptoms.
Figure 1 Left lung image. A typical GGO is noted (arrow) as a round
opacity at the level of the aortic arch, peripherally involving the
anterior segment of the left upper lobe. Typically, GGOs are more often
found in the basilar location. A – aortic arch
Figure 2 Left lung image. A peripheral GGO (arrow) with reticulation.
Reticulation is noted with development of thickening of interlobular
septa, appearing as linear opacities. DA – descending aorta, PA – main
pulmonary artery
Figure 3 Level of the heart. Right lung demonstrates an atypical
presentation of a peripheral GGO with reticulation, which is not rounded
but more band-like (horizontal arrows). Also, bilateral diffuse bandlike
subpleural consolidations are noted (vertical arrows). These bandlike
consolidations have been observed in several patients. LV – left
ventricle
Figure 4 Left lung image. A zone of GGO (oblique arrow) surrounding an
area of consolidation (horizontal arrow). This is termed a halo
sign , in which a circular area of GGO is noted around an opacity. An
area of normal lung (*) is also noted. As in the prior CT
image, a band-like consolidation is noted (vertical arrow). This is a
GGO coalesced into a consolidation with a thick band-like appearance. LV
– left ventricle
Figure 5 The reversed halo sign or atoll sign(horizontal arrow) is defined as a focal area of GGO surrounded by a
crescent or ring of consolidation. A typical GGO (vertical arrow) and
area of consolidation (oblique arrow) is also noted in the left lung. Ao
– ascending aorta, PA – main pulmonary artery
Figure 6 Right lung - Area of GGO noted more centrally than usually
found (horizontal arrow). A peripheral GGO with reticulation (oblique
arrow) and the vacuole sign (small vertical arrow). The vacuole
sign is a translucent, low-density shadow within an opacity.
Left lung – A parenchymal band (horizontal arrows) is noted. This is
defined as a linear opacity, usually up to 3 mm in width and up to 5 cm
in length. It may extend to the visceral pleura, which may be retracted
where the band attaches. LV – left ventricle
Figure 7 Right lung image. Basilar level image demonstrates a GGO with
reticulation (oblique arrow). Also, a peripheral area of consolidation
(vertical arrow) is noted. D – diaphragm
Figure 8 Right lung – Linear subpleural consolidations (arrows)
Left lung - Rounded consolidation (arrow). Ao – ascending aorta, PA –
main pulmonary artery
Figure 9 Multiple peripheral consolidations are noted in both lung
fields (arrows) in this Advanced category patient. Ao – transverse
aorta
Figure 10 Left lung image. Although not usually associated with
COVID-19, this patient has a tiny left pleural effusion at the posterior
base of the left lung (horizontal arrow). D – diaphragm, DA –
descending aorta