key: cord-0827292-x959eni1
authors: Fard, Hossein Abdolrahimzadeh; Mahmudi-Azer, Salahaddin; Yaqoob, Qusay Abdulzahraa; Sabetian, Golnar; Iranpour, Pooya; Shayan, Zahra; Parvaz, Shahram Boland; Abbassi, Hamid Reza; Aminnia, Shiva; Salimi, Maryam; Mahmoudi, Mohammad Mehdi; Paydar, Shahram; Borazjani, Roham; Akerdi, Ali Taheri; Zare, Masome; Shayan, Leila; Sasani, Mohammadreza
title: Comparison of chest CT scan findings between COVID-19 and pulmonary contusion in trauma patients based on RSNA criteria: Established novel criteria for trauma victims
date: 2022-01-19
journal: Chin J Traumatol
DOI: 10.1016/j.cjtee.2022.01.004
sha: 7f65230023e58c6b4617394d330646735aace50c
doc_id: 827292
cord_uid: x959eni1

PROPOSE: In this study, we re-assessed the criteria defined by the radiological society of north America (RSNA) to determine novel radiological findings helping the physicians differentiating COVID-19 and pulmonary contusion. METHODS: All trauma patients with blunt chest wall trauma and subsequent pulmonary contusion, COVID-19-related signs and symptoms before the trauma were enrolled in this retrospective study from February to May 2020. Included patients (Group P) were then classified into two groups based on polymerase chain reaction tests (Group Pa for positive patients and Pb for negative ones). Moreover, 44 patients from the pre-pandemic period (Group PP) were enrolled. They were matched to group P regarding age, sex, and trauma-related scores. Two radiologists blindly reviewed the CT images of all enrolled patients according to criteria defined by the RSNA criteria. The radiological findings were compared between group P and PP; statistically significant ones were re-evaluated between Pa and Pb thereafter. Finally, the sensitivity and specificity of each significant findings were calculated. The Chi-square test was used to compare the radiological findings between two groups. RESULTS: In the group PP, 73.7% of all ground-glass opacities (GGOs) and 80% of all multiple bilateral GGOs were detected (p < 0.001 and p = 0.25, respectively). Single bilateral GGOs were only seen among the group PP. The Chi-square tests showed that the prevalence of diffused GGOs, multiple unilateral GGOs, multiple consolidations, and multiple bilateral consolidations were significantly higher in the group P (p = 0.001, 0.01, 0.003, and 0.003, respectively). However, GGOs with irregular borders and single consolidations were more significant among the group PP (p = 0.01 and 0.003, respectively). Of note, reticular distortions and subpleural spares were exclusively detected in the group PP. CONCLUSION: We concluded that the criteria set by RSNA for the diagnosis of COVID-19 are not appropriate in trauma patients. The clinical signs and symptoms are not always useful either. The presence of multiple unilateral GGOs, diffused GGOs, and multiple bilateral consolidations favor COVID-19 with 88%, 97.62%, and 77.7% diagnostic accuracy.

The rapid spread of SARS-CoV-2 viruses and the subsequent pandemic make COVID-19 a global challenge for health care systems. 1, 2 Prompt diagnosis and strict isolation of affected patients are of significant importance in preventing the further spread of the disease. Therefore, conducting effective screening systems for early detection and isolation is the first step to achieving this goal. 3 Patients with positive reverse transcription-polymerase chain reaction (RT-PCR) tests were considered definite cases regardless of COVID-19-related signs and symptoms. Moreover, asymptomatic carriers can act as the super spreaders worsening the pandemic. 4 Inadequate sensitivity and time-consuming RT-PCR tests, and the possibility of false-negative results are the present pitfalls that healthcare workers face. Therefore, other paraclinical methods should be used to increase the overall diagnostic accuracy.

The radiological society of north America (RSNA) provided a reference to detect COVID-19-induced lung injuries based on CT images, as shown in Table 1 . 5 Although not statistically significant, the higher diagnostic sensitivity, detecting asymptomatic patients, and faster access to results are some of the advantages discussed in various studies comparing the chest CT images and RT-PCR tests. 6, 7 Despite the widespread availability of CT images, it is not recommended as J o u r n a l P r e -p r o o f an initial screening method due to its low specificity and negative predictive value. Hence, CT images are efficient in association with other diagnostic tools. 5, 8 Therefore, this single-center, retrospective study aimed to define the specific findings in CT images of trauma patients helping physicians to differentiate COVID-19 and pulmonary contusion. The CT images were interpreted based on RSNA criteria, as summarized in Table 1 .

In this retrospective, cross-sectional study, we evaluated the CT images of patients referred to Rajaee hospital as the biggest referral trauma center in southern Iran from February to May 2020. Inclusion criteria were all of the following: pulmonary contusion, blunt chest wall trauma, and COVID-19-related clinical features before the chest wall trauma. Individuals with penetrating chest wall trauma, previous history of underlying pulmonary diseases, and the absence of chest CT images or RT-PCR were excluded.

Our previous study ( Fig. 1) showed that the sensitivity and specificity of RSNA criteria were not suitable for diagnosing COVID-19 in trauma patients. 10 The recent survey was designed to find appropriate radiological diagnostic features differentiating COVID-19 and pulmonary contusion (Fig. 2) . Included individuals during the pandemic (group P) were categorized based on J o u r n a l P r e -p r o o f the RT-PCR results into two subgroups: the definite, positive RT-PCR group (group Pa) and the non-definite group (group Pb) in whom RT-PCR tests were negative. However, we could not rule out COVID-19 in the Pb group due to the false-negative results. Another group was selected during the pre-pandemic period (group PP) as definite pulmonary contusion cases without COVID-19related radiological findings. This group was matched to group P based on age, sex, and traumarelated parameters. 

The coexistence of pulmonary contusion and COVID-19 in the patients with respiratory symptoms before the occurrence of blunt chest trauma and the presence of false-negative results of RT-PCR tests make it challenging to differentiate radiological findings of COVID-19 and pulmonary contusion. Therefore, in the recent survey, we aimed to compare these findings in patients with definite lung contusion (group PP) to that of patients during pandemic (group P) to eliminate the risk of concurrent infection as a confounding factor.

Finally, based on our inclusion and exclusion criteria, 16 positive RT-PCR patients were placed in the group Pa, and 17 negative RT-PCR patients who were matched to the group Pa were selected before the COVID-19 pandemic (group PP) who were matched to the Group P in terms of age, sex, and trauma-related scores ( Fig. 2) .

At first, all RSNA criteria and the trauma-related radiological findings were compared between the two main groups (group P and PP). Then, each statistically significant findings were assessed in two subgroups (group Pa and Pb).

After obtaining written informed consent from the patients or their next of kin, as a 

Collected data were analyzed using the Statistical Package for Social Sciences, version 16.0 (SPSS Inc., Chicago, IL, USA). Quantitative variables were presented as mean ± standard deviation (SD), and categorical ones were shown as frequencies (numbers and percentages). The comparison between the two groups was performed using the Chi-square test or the Fisher exact test. Also, sensitivity and specificity have been calculated to determine the diagnostic accuracy of the different protocols. The p < 0.05 was considered statistically significant.

This retrospective study was conducted between February and May 2020 at the largest referral trauma center in southern Iran. Statistical analysis between the two main groups and the subgroups did not show significant differences in age, sex, trauma-related scores as confounding factors ( Table 2. ). Besides, all patients with underlying diseases were excluded to avoid further complexity. (Fig. 3A, B and D) . By eliminating all confounding factors, this evaluation found that RSNA criteria are not suitable for differentiation of lung contusion from COVID-19 in the trauma population. Therefore, each criterion was evaluated between group P and PP to investigate the appropriate criteria differentiating COVID-19 and pulmonary contusion. Besides, each statistically significant parameter was then assessed between the two subgroups of the pandemic period (Pa and Pb).

Evaluation of RSNA criteria revealed that GGO is the most common finding in both main groups (71.3%), of which 73.7% were in the definite lung contusion group (p < 0.001). Therefore, the existence of GGO as the most common criteria in the diagnosis of COVID-19 in non-trauma patients is more common in the definitive lung contusion group (group PP). Although the evaluation of the overall GGO distribution (single bilateral, single unilateral, etc.) showed a significant difference (p = 0.024), the single and multiple GGO (p = 0.12), as well as whether they were unilateral or bilateral (p = 0.53), were not statistically significant between the two main groups (P and PP). Multiple bilateral GGO is the most common type in both main traumatic groups (52.6%). Although 80% of them are in the definitive lung contusion group (PP), but there was no significant difference between the two main groups (p = 0.25). Single bilateral GGO accounts for 7% of all lesions and can only be seen in the definitive lung contusion group (PP) (p = 0.56).

In Table 3 , diffused GGO and multiple unilateral GGO are suggestive features for COVID-19, while irregular margins GGO is a representative feature for lung contusion. The existence of J o u r n a l P r e -p r o o f consolidation was only seen in 34.1% of the total patients in both main groups, of which 60.7%

were in the PP group (Fig. 3.C1) . However, there was no statistically significant difference in the consolidation between the two main groups (p = 0.89). However, if consolidation existed, there was a statistically significant difference in the number and side of pleural cavity involvement between the two main groups (p = 0.007). The overall prevalence of consolidation was lower than that of GGO, and our results showed that multiple unilateral consolidations were suggestive features for lung contusion. In contrast, multiple bilateral lesions were associated with COVID-19.

Other radiological findings showed that 15.9% of all trauma patients had reticular distortion, and this feature existed only in the group PP (p=0.001). Also, the subpleural spare has been seen in only 14.6% of patients, of which 91.7% are in the definitive lung contusion group (p=0.015). Evaluation of trauma-related lesions showed the prevalence of rib fracture and pneumothorax were not different between the two groups, but hemothorax was statistically more common in the group P (p=0.02).

The subgroup analysis revealed that the prevalence of GGO with irregular margins was significantly higher in PCR-positive cases during the pandemic period ( Table 4 ). Of note, few patients had subpleural spare, and none showed reticular distortion in CT images during the pandemic; therefore, their results were not shown in Table 4 . ground-glass opacity

Note: Only few patients had subpleural spare, and none of them had reticular distortion during the pandemic period. Therefore, these radiological findings were not shown in this table.

The recent survey showed that single consolidation, reticular distortion, subpleural spare, and GGOs with irregular margins were suggestive radiological findings for the lung contusion; meanwhile, diffused distributed GGOs, multiple bilateral consolidations, multiple bilateral GGOs, and multiple consolidations were suggestive findings for COVID-19.

Finally, the group Pa was considered as patients with concomitant COVID-19 and pulmonary contusion. Also, the group PP was classified as non-infected patients with an isolated lung contusion.

Then sensitivity, specificity, positive and negative predictive value, the accuracy of each identified finding in the diagnosis of lung contusion, and COVID-19 were evaluated ( Table 5) .

The results of this comparison provided diagnostic criteria for CT scans in trauma patients ( Table   6 ).

J o u r n a l P r e -p r o o f 

Pulmonary contusion is the most common sequels of blunt chest wall injuries (30%-75%) and

is the major cause of mortality among all vehicle occupants in traffic accidents. 12 Clinical presentations vary; mild pulmonary contusion may be thoroughly asymptomatic, although more severe cases may cause pain, hemoptysis, hypoxia, cyanosis, dyspnea, and bronchorrhea. [13] [14] [15] [16] Patients are usually asymptomatic early after insult, however, signs and symptoms may develop during the following hours. 17 Several methods were occupied to diagnose and assess the severity of pulmonary contusion, of which chest CT images are the most sensitive. CT images can detect pulmonary contusion immediately after the insults when the clinical manifestations do not yet develop.

However, these images lack specificity when they occurred concomitantly with viral pneumonia, especially COVID-19. 18 To the best of our knowledge, a few studies are available discussing the similarities and differences between COVID-19 and pulmonary contusion. Six of these surveys were case reports that exclusively showed some similarities, although they did not conduct proper criteria to differentiate these two entities. 19 Patients with pulmonary contusion, except the asymptomatic ones, usually complain of pain, dyspnea, hemoptysis, tachypnea with shallow breathing. These symptoms are present in patients with COVID-19 to some extent. Local tenderness, paradoxical movement of the chest wall, seat belt sign, and deformity are suggestive of pulmonary contusion 28, 29 ; however, they could not preclude the concomitant COVID-19. Associated injuries such as hemothorax, bilateral pleural effusion, and pneumothorax are characteristic of pulmonary contusions (Fig. 3. C-2) . However, Kong et al. 30 and Aydın et al. 31 reported a COVID-19 patient complicated by pneumomediastinum and spontaneous pneumothorax, respectively. Besides, our previous study showed that COVID-19 might contribute to increase pulmonary fragility and subsequent pneumothorax and hemothorax. 10 As mentioned before, during the COVID-19 pandemic, it seems impossible to differentiate COVID-19 from pulmonary contusion in patients with concomitant respiratory symptoms and blunt chest wall trauma. In addition, the history taking is disturbed in unconscious patients, and the physicians are unable to distinguish whether the victims had a history of respiratory signs and symptoms before the trauma.

Based on radiological findings, GGOs with irregular margins and single consolidation are highly suggestive of pulmonary contusion with a diagnostic accuracy of 88.08% and 77.77%, respectively. On the other hand, diffused and multiple unilateral GGO had the best diagnostic accuracies for COVID-19 diagnosis (97.62% and 88 %, respectively).

Our study had some limitations, further research with a higher sample size conducting in multiple centers is needed to eliminate confounding factors and assess our results. Moreover, it is better to use a CT scan as a part of a scoring system for trauma patients due to the previously mentioned diagnostic limitations.

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