MSCT Chest in Suspected COVID-19 Patients in Correlation With Symptomology and Laboratory Findings

Coronaviruses are non-segmented positive-stranded RNA viruses with a roughly 30 kb genome surrounded by a protein envelope . Two serious coronavirus disease outbreaks have happened in the past two decades: severe acute respiratory syndrome (SARS) in 2003, and Middle East respiratory syndrome (MERS) in 2012 .

Since December 2019, severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2) has been recognized as the causal factor in a series of severe cases of pneumonia originating in Wuhan, Hubei Province, China . The disease is highly infectious, spreads rapidly worldwide and has been named coronavirus disease 2019 by the World Health Organization that declared the ongoing outbreak as a global pandemic on March 11, 2020.

COVID-19 infection is usually transmitted from human-to-human by close contact. During close contact, people catch the disease by droplet transmission either directly after breathing of contaminated respiratory droplets that were exhaled by an infected person during coughing, sneezing or talking or indirectly by dealing with surfaces and objects used by the infected person. Some aerosol generating medical procedures (i.e., endotracheal intubation, bronchoscopy or disconnecting a patient from the ventilator), may result in easier transmission of such small droplets for greater distances and longer periods of time, in what is known as airborne transmission .

The virus is most contagious during the first three days after onset of symptoms, although the infection may occur up to two days before appearance of symptoms (presymptomatic transmission) and in later stages of the disease. Some people have been infected and recovered without showing symptoms, but uncertainties remain in terms of asymptomatic transmission .

The lungs are the organs most commonly affected by COVID 19 because the virus accesses host cells via the enzyme angiotensin-converting enzyme 2 (ACE2), which is most abundant in type II alveolar cells of the lungs. The density of ACE2 in each tissue correlates with the severity of the disease in that tissue and some have suggested that decreasing ACE2 activity might be protective .The virus uses a special surface glycoprotein called a "spike" (peplomer) to connect to ACE2 and enter the host cell . Though, autopsies of people who died of COVID 19 have found diffuse alveolar damage , and lymphocyte-containing inflammatory infiltrates within the lung .