A 63-year-old man came to the emergency room complaining of unverified fever and myalgia.
Oropharyngeal material was collected for reverse transcription testing followed by
polymerase chain reaction (RT-PCR) for coronavirus disease 2019 (COVID-19), and a
chest radiography was performed (normal), and the patient was discharged to home isolation,
due to his mild symptoms, until the test result.
After 3 days, the patient evolved with dyspnea, a drop in oxygen saturation (95%),
and measured fever (38.6°C), and a chest computed tomography was performed (Figure
1) and he was admitted to hospital. The RT-PCR test for COVID-19 was positive.
Three days later, his respiratory pattern worsened, with a decrease in oxygen saturation
to 90%, and he was referred to a stepdown unit and a new tomography was performed
(Figure 1).
An 80-row CT scanner (Aquillion Prime, Canon Medical Systems, Tochigi, Japan) was
used, with the patient in supine position, during maximum inspiration, and without
injection of contrast medium. The following parameters were used: reconstructions
with slice-thickness of 1 mm, a tube voltage of 80 kVp to 120 kVp, and adjustable
current, varying between 10 mA and 440 mA. The images of these two exams were then
processed, using the 3DSlicer software to segment the normal parenchyma, ground-glass
opacities and consolidation areas in both lungs in the two exams performed for the
patient (Figure 1).
From this, a quantitative analysis was conducted, showing in the first study a total
lung volume of 4,289.62cm3, with the right lung measuring 2,214.91cm3 and the left
lung measuring 2,074.71cm3. The preserved parenchyma area measured 2,110.48cm3 (95.29%)
in the right lung, and 2,056.79cm3 (99.14%) in the left lung. The right lung presented
with 81.01cm3 (3.66%) of ground-glass opacities and 23.42cm3 (1.06%) of consolidations;
the left lung presented with 14.98cm3 (0.72%) of ground-glass opacities, and 2.95cm3
(0.14%) of consolidations. In total, the patient had 2.85% of parenchyma affected
by ground-glass opacities or consolidations in the first study.
In the second study, the total lung volume calculated was 3,569.85cm3, with 1,814.95cm3
in the right lung and 1,754.90cm3 in the left lung. The preserved parenchyma area
measured 915.17cm3 (50.42%) in the right lung, and 1,301.17cm3 (74.15%) in the left
lung. The ground-glass opacity areas totaled 857.49cm3 (47.25%) in the right lung,
and 447.63cm3 (25.51%) in the left lung, and the consolidation areas totaled 42.29cm3
(2.33%) in the right lung, and 6.09cm3 (0.35%) in the left lung.
In three days of progression, the patient showed an increase of 1,259.93% in ground-glass
opacity volume, with 958.47% in the right lung, and 2,888.06% in the left lung, and
an 83.44% increase in the consolidation volume, with 80.57% in the right lung, and
106.66% in the left lung. These numbers resulted in a 46.81% reduction in the preserved
parenchyma volume, with a reduction of 56.64% in the right lung, and 36.74% in the
left lung.
DISCUSSION
Several cases of pneumonia of unknown origin that occurred in Wuhan, China, in late
2019, led to the discovery of a new type of coronavirus (2019-nCoV), called novel
coronavirus-infected pneumonia (COVID-19).(1-4) The virus quickly spread and started
to affect individuals outside the initial contagion area, in other countries and,
finally, on all continents, and was declared a pandemic by the World Health Organization
(WHO).(1-4)
The 3DSlicer software is a free tool available online for download, whose use in quantitative
imaging is well-established, having even been used in the evaluation of pulmonary
nodules in chest imaging.(5-7)
Much has been studied since the beginning of the pandemic about the role of imaging
tests in the prognosis and progressive control of COVID-19 patients, but a forceful
answer has yet to be found. Our service, for instance, has been using the assessment
of the tomographic progression of the disease as an auxiliary criterion in the clinical
decision of hospitalization. The present case demonstrates the use of the 3DSlicer
tool for the quantification of pulmonary tomographic changes, applied in the clinical
monitoring of the patient, enabling an objective estimation of the involvement percentage
and the progression rate of the disease. We believe that this tool can be an important
resource for borderline cases or those that raise doubts about the significance of
the progression. In addition, its association with artificial intelligence strategies
can optimize the quantification process, rendering it possible the use of this quantification
in a greater number of cases.
Figure 1
Chest computed tomography and superimposed 3DSlicer software quantification images.
The upper series (A) show the findings when the patient returned to the emergency
room, and the lower series (B) show the findings at the time of his clinical worsening.
Axial sections of the chest tomography showing multifocal pulmonary ground-glass opacities
predominantly peripheral and basal, more extensive in the last study, and quantitative
images generated by the 3DSlicer software superimposed over the tomographic images.
The areas marked in yellow show ground-glass opacities, those marked in green are
areas of normal parenchyma, and those marked in orange are areas of consolidation.
The extensive progression of the findings illustrates the numerical data provided