The early diagnosis of COVID19 plays an important role in monitoring the disease effectively According to the initial definition provided by the World Health Organization, patients with suspected clinical symptoms . need to be evaluated for definitive COVID19, which is conducted by evaluating the presence of the virus in different ways. The results of these methods are related to different factors that the time of exposure to the virus and the onset of symptoms are effective in positive serological tests [9, 16]. The diagnosis of asymptomatic patients and patients with mild symptoms, which includes a high percentage of patients , is also an important goal of health care organizations. Taken into consideration the low sensitivity of definitive diagnostic tests [9, 18], other diagnostic methods are used to accompany them [19-21]. Typical chest CT scan findings in people with definite COVID-19 pneumonia (Table 1) is one of the most commonly used methods.
This study investigated the effectiveness of RSNA classification and its features as a diagnostic tool for COVID-19 in trauma patients. Due to the presence of similar manifestations of lung contusion in chest CT scan and also the possibility of simultaneous occurrence of these two pathologies, their interactions on CT scan findings, must be evaluated in trauma patients . Evaluation of chest CT scan findings based on RSNA classification showed the lower sensitivity and specificity among the trauma patients. This outcome can be related to the prevalence rate of the disease, low sensitivity of the rt-PCR diagnostic test, as well as the weakness of the chest CT scan findings in non-traumatic patients for traumatic individuals.
Given the high prevalence of the disease in the area where the study was conducted and the acceptable sensitivity of the diagnostic tests, the findings of the chest CT scan for COVID-19 as a diagnostic tool might differ among trauma patients.
Patients were divided into positive and negative groups based on their chest CT scan findings, regardless of rt-PCR serological test results. Evaluation of clinical symptoms related to COVID-19, Systemic Inflammatory Response Syndrome (SIRS) index and Lymphocyte to Neutrophil Ratio (NLR) as a marker of systemic inflammatory responses, factors related to patients' trauma including primary vital signs as well as Injury Severity Score (ISS) and Abbreviated Injury Score (AIS), patient’s hospital course and prognosis of patients between the two groups were performed. The evaluation showed that patients were not significantly different in terms of age, COVID-19 related symptoms (except for respiratory distress), and epidemiological and underlying disease history. The evaluation of inflammatory and immune system stimulation factors as well as criteria related to the severity of trauma did not show a significant difference between the two groups.
With the exception of race and respiratory distress, the factors related to COVID-19 and inflammatory system, and trauma severity do not affect the probability of positive chest CT scan according to the criteria provided by RSNA.
The outcomes of this research are not in line with studies investigating non-traumatic individuals. Trauma and COVID-19 both stimulate the immune system. However, the degree of stimulation of the inflammatory system dependent on the degree of trauma severity and also the inflammatory stage of COVID-19. It is hypothesized that if the criteria set by RSNA were appropriate for the evaluation of COVID-19 traumatic individuals, a significant difference should be observed between the two groups.
Therefore, to evaluate the appropriate findings of COVID-19 in chest CT scan for trauma patients, patients were divided into definite and non-infected groups based on rt-PCR test results. Incidence, sensitivity and specificity, protective value, accuracy, and P. Value of each finding were evaluated in these two groups. Evaluation of common radiological features based on RSNA classification between the two groups of definitive and non-infected patients showed that the presence of peripheral, bilateral, round, and diffuse GGO as the most specific radiological features in non-traumatic individuals [23, 24], are not similar in traumatic patients. Although multiple bilateral GGO was the most sensitive in lesions (45%) according to the location in trauma patients, the specificity of multiple unilateral lesions was higher (96%). Also, the peripheral lesions were more sensitive and the central lesions had the highest specificity (93%). In terms of lesion shape, the highest sensitivity was related to irregular lesions (40%) and the highest specificity was related to round lesions (96%). Therefore, multiple unilateral or central GGO in trauma patients was the most specific type of GGO in trauma patients who had definite COVID19. Regarding consolidation, peripheral round lesions had the most diagnostic features in non-traumatic patients, but central lesions (98%) with mixed round and irregular shapes had the highest diagnostic features in traumatic patients with COVID-19.
Despite the above data, due to the possibility of co-occurrence of COVID-19 and pulmonary contusion in both groups, the findings of this research should be treated with caution and future studies should collect information about trauma patients in the pre-pandemic period of COVID-19 to determine specific lung contusion lesions.
Therefore, it seems that for the detection of COVID-19 in trauma patients, it is necessary to provide another classification for a chest CT scan. This requires further studies with a larger population and also the use of more sensitive definitive diagnostic tests.
In the evaluation of 17 patients with rib fractures in both definite and non-infected patients, it was found that rib fracture in 100% of definite patients and 71% non-infected patients, leads to damage to the pulmonary parenchyma and pleura. Also, patients with less (ISS) in a definite group develop more symptoms of regional injury in the thoracic cavity (AIS). This indicates that the presence of underlying pathology due to COVID-19 in traumatic individuals, causes the lung parenchyma to be prone to injury and rupture. Also, it seems that the ISS / Thoracic cavity AIS ratio may contribute to the possibility of underlying pathology in traumatized individuals. However, due to the small number of participants, it was not possible to statistically evaluate this finding further.
In conclusion, the results show that RSNA criteria for COVID-19 were not efficient in trauma patients. Therefore, due to the high use of CT scans in trauma patients, it is recommended to create appropriate CT scan criteria for trauma patients. This method could diagnose the disease timely and contribute positively to the termination of the transmission chain. It would also reduce the incidence of treatment and effective resource management.