News | Coronavirus (COVID-19) | April 17, 2020

A Review of Studies Cautions Against Chest CT for Coronavirus Diagnosis

Regarding sensitivity, specificity, and clinical practice, CT should be reserved for evaluation of complications of COVID-19 pneumonia or for assessment if alternative diagnoses are suspected

#COVID19 #Coronavirus #2019nCoV #Wuhanvirus #SARScov2 According to the 10 authors from multiple institutions across the US who reviewed the most frequently cited studies on the subject: 'Test performance and management issues arise when inappropriate and potentially overreaching conclusions regarding the diagnostic performance of CT for COVID-19 pneumonia are based on low-quality studies with biased cohorts, confounding variables, and faulty design characteristics.

According to the 10 authors from multiple institutions across the US who reviewed the most frequently cited studies on the subject: 'Test performance and management issues arise when inappropriate and potentially overreaching conclusions regarding the diagnostic performance of CT for COVID-19 pneumonia are based on low-quality studies with biased cohorts, confounding variables, and faulty design characteristics. Image courtesy of American Journal of Roentgenology (AJR)

April 17, 2020 — To date, the radiology literature on coronavirus disease (COVID-19) pneumonia has consisted of limited retrospective studies that do not substantiate the use of computed tomography (CT) as a diagnostic test for COVID-19, according to an open-access Clinical Perspective article in the American Journal of Roentgenology (AJR).

"This is not to say these studies are not valuable," maintained lead investigator Constantine A. Raptis, M.D., of Washington University in Saint Louis. As Raptis, Travis S. Henry, M.D., of the University of California-San Francisco, and nine co-authors from six institutions across the United States noted of the most frequently cited studies on the subject, reporting the various CT features of COVID-19 pneumonia remains "an important first step" in helping radiologists identify patients who may have COVID-19 in the appropriate clinical environment.

"However," they continue, "test performance and management issues arise when inappropriate and potentially overreaching conclusions regarding the diagnostic performance of CT for COVID-19 pneumonia are based on low-quality studies with biased cohorts, confounding variables, and faulty design characteristics."

CT Sensitivity

Because misdiagnosing even a single patient (i.e., obtaining a false-negative finding) could result in large outbreaks among future contacts, understanding the potential effects of selection bias is important in determining sensitivity. As Raptis and colleagues explained, "if a study cohort contains patients who are more likely to have a true-positive finding and less likely to have a false-negative finding, sensitivity will be overestimated."

CT Specificity

The specificity and positive predictive value of a laboratory test — in the case of COVID-19, reverse transcription-polymerase chain reaction (RT-PCR) — are based on its ability to limit false-positive findings. Acknowledging false-positive RT-PCR results are possible, Raptis, Henry, et al. maintained they are often caused by contamination and are likely insignificant in the setting of assays for COVID-19. CT, on the other hand, does not test for singular features unique to the disease, and even those features most characteristic of COVID-19 pneumonia — peripheral, bilateral ground-glass opacities typically in the lower lobes — have been reported in a number of other conditions, both infectious and noninfectious.

CT in Clinical Practice

Finally, Raptis and colleagues addressed the hazards of wide deployment of CT: overuse of hospital resources, including the use of PPE already limited in availability but required to safely perform CT studies; clustering of affected and nonaffected patients in the radiology department, increasing the risk of disease transmission among imaging staff.

"At present," the authors of this AJR article concluded, "CT should be reserved for evaluation of complications of COVID-19 pneumonia or for assessment if alternative diagnoses are suspected."

Moderated by AJR Cardiopulmonary Imaging Section Editor Patrick M. Colletti, Constantine A. Raptis and Travis S. Henry served as speakers for a recent AJR Live Webinar exploring the radiography and CT findings associated with EVALI and COVID-19 — including the limitations of imaging in their diagnosis.

For more information: www.arrs.org

Related Content

JAMA Oncol. Published online  July 30, 2020. doi:10.1001/jamaoncol.2020.2783

Table 1. JAMA Oncol. Published online  July 30, 2020. doi:10.1001/jamaoncol.2020.2783

News | Coronavirus (COVID-19) | July 31, 2020
July 31, 2020 — An article published in JAMA...
A World Health Organization (WHO) rapid advice guide on the use of chest imaging in the diagnosis and management of COVID-19 was published in the journal Radiology.

Getty Images

News | Coronavirus (COVID-19) | July 30, 2020
July 30, 2020 — A World Health Organization (WHO) rapid advice gui
It covers every major modality, including breast imaging/mammography, fixed and portable C-arms (cath, IR/angio, hybrid, OR), CT, MRI, nuclear medicine, radiographic fluoroscopy, ultrasound and X-ray
News | Radiology Imaging | July 29, 2020
July 29, 2020 — IMV Medical Information, part of Scien...
It has been estimated that the overwhelming focus on COVID-19 could cause up to 35,000 excess cancer deaths in the UK during the next 12 months, and  Zegami, the Oxford University data visualization spin-out which has worked on several projects focused on the detection, diagnosis, or management of cancer, is calling for greater use of technology to speed up the process of diagnosis and treatment.

Getty Images

News | Radiation Oncology | July 29, 2020
July 29, 2020 — It has been estimated that the overwhelming focus on...
Left, a 3-D rendering of a heart from a cardiac CT exam. Right, a lung-CT exam showing the heart and ground glass lesions in the lungs of a COVID-19 patient. CT has become a front-line imaging modality in the COVID era because it offers both cardiac and lung information to help determine a patients disposition with chest pain, COVID-19 and COVID-caused myocarditis and pulmonary embolism. #COVID19 #CCTfirst #YesCCT

Left, a 3-D rendering of a heart from a cardiac CT exam. Right, a lung-CT exam showing the heart and ground glass lesions in the lungs of a COVID-19 patient. CT has become a front-line imaging modality in the COVID era because it offers both cardiac and lung information to help determine a patients disposition with chest pain, COVID-19 and COVID-caused myocarditis and pulmonary embolism.

Feature | Computed Tomography (CT) | July 28, 2020
July 28, 2020 — The use of cardiova...
ams Commended by United Imaging for Accelerated Supply of Unprecedented Levels of Essential CT Detectors to Fight Covid-19 (SARS-CoV-2)
News | Coronavirus (COVID-19) | July 28, 2020
July 28, 2020 — ams, a leading worldwide supplier of high performance sensor solutions, has been thanked by long-term
Prostate biopsy with cancer probability (blue is low, red is high). This case was originally diagnosed as benign but changed to cancer upon further review. The AI accurately detected cancer in this tricky case. Image courtesy of Ibex Medical Analytics

Prostate biopsy with cancer probability (blue is low, red is high). This case was originally diagnosed as benign but changed to cancer upon further review. The AI accurately detected cancer in this tricky case. Image courtesy of Ibex Medical Analytics

News | Prostate Cancer | July 28, 2020
July 28, 2020 — A study published in 
A cardiac CT of a patient with pacemaker leads, which can be challenging to get good images due to metal artifact. This image was rendered from using Canon's AiCE AI-assisted interactive reconstruction with Global Illumination 3-D rendering from a scan on an Aquilion One Genesis SP system.

A cardiac CT of a patient with pacemaker leads, which can be challenging to get good images due to metal artifact. This image was rendered from using Canon's AiCE AI-assisted interactive reconstruction with Global Illumination 3-D rendering from a scan on an Aquilion One Genesis SP system.

Feature | Computed Tomography (CT) | July 27, 2020
There has been tremendous growth in the field of cardiovascular...