Team creates better tool to aid COVID-19 diagnosis

Date:
August 19, 2020
Source:
Louisiana State University Health Sciences Center
Summary:
A radiologist and an evolutionary anatomist have teamed up to show
the same techniques used for research on reptile and bird lungs can
be used to help confirm the diagnosis of COVID-19 in patients. Their
paper demonstrates that 3D models are a strikingly clearer method
for visually evaluating the distribution of COVID-19-related
infection in the respiratory system.



FULL STORY ==========================================================================
An LSU Health New Orleans radiologist and evolutionary anatomist have
teamed up to show the same techniques used for research on reptile and
bird lungs can be used to help confirm the diagnosis of COVID-19 in
patients. Their paper published in BMJ Case Reports demonstrates that
3D models are a strikingly clearer method for visually evaluating the distribution of COVID-19-related infection in the respiratory system.


==========================================================================
Emma R. Schachner, PhD, Associate Professor of Cell Biology & Anatomy,
and Bradley Spieler, MD, Vice Chairman of Radiology Research and Associate Professor of Radiology, Internal Medicine, Urology, & Cell Biology and
Anatomy at LSU Health New Orleans School of Medicine, created 3D digital
models from CT scans of patients hospitalized with symptoms associated
with severe acute respiratory syndrome coronavirus (SARS-CoV-2).

Three patients who were suspected of having COVID-19 underwent contrast enhanced thoracic CT when their symptoms worsened. Two had tested positive
for SARS-CoV-2, but one was reverse transcription chain reaction (RT-PCR) negative.

But because this patient had compelling clinical and imaging, the result
was presumed to be a false negative.

"An array of RT-PCR sensitivities has been reported, ranging from
30-91%," notes Dr. Spieler. "This may be the result of relatively lower
viral loads in individuals who are asymptomatic or experience only mild symptoms when tested.

Tests performed when symptoms were resolving have also resulted in
false negatives, which seemed to be the result in this case." Given
diagnostic challenges with respect to false negative results by RT-PCR,
the gold standard for COVID-19 diagnostic screening, CT can be helpful in establishing this diagnosis. Importantly, these CT features can range in
form and structure and appear to correlate with disease progression. This allows for 3D segmentation of the data in which lung tissue can be volumetrically quantified or airflow patterns could be modeled.

The CT scans were all segmented into 3D digital surface models using
the scientific visualization program Avizo (Thermofisher Scientific) and techniques that the Schachner Lab uses for evolutionary anatomy research.

"The full effect of COVID-19 on the respiratory system remains unknown,
but the 3D digital segmented models provide clinicians a new tool to
evaluate the extent and distribution of the disease in one encapsulated
view," adds Spieler.

"This is especially useful in the case where RT-PCR for SARS-CoV-2 is
negative but there is strong clinical suspicion for COVID-19." To date,
there haven't been good models of what COVID is doing to the lungs.

So, this project focused on the visualization of the lung damage in the 3D models as compared to previous methods that have been published -- volume- rendered models and straight 2D screen shots of CT scans and radiographs.

"Previously published 3D models of lungs with COVID-19 have been created
using automated volume rendering techniques," says Dr. Schachner. "Our
method is more challenging and time consuming, but results in a highly
accurate and detailed anatomical model where the layers can be pulled
apart, volumes quantified, and it can be 3D printed." The three
models all show varying degrees of COVID-19 related infection in the respiratory tissues -- particularly along the back of the lungs, and
bottom sections. They more clearly show COVID-19-related infection
in the respiratory system compared to radiographs (X-rays), CT scans,
or RT-PCR testing alone.

Schachner and Spieler are now segmenting more models for a larger follow
up project.


========================================================================== Story Source: Materials provided by Louisiana_State_University_Health_Sciences_Center. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Emma R Schachner, Bradley Spieler. Three-dimensional (3D) lung
segmentation for diagnosis of COVID-19 and the communication of
disease impact to the public. BMJ Case Reports, 2020; 13 (8):
e236943 DOI: 10.1136/bcr-2020-236943 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200819120716.htm

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