{'fraction_non_alphanumeric': 0.03547410894418292, 'fraction_numerical': 0.026227303295225286, 'mean_word_length': 5.015166835187058, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 1, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The Chest CT Scanner in the Diagnosis of COVID 19 Infection, Experience of Radiology Department of University Hospital of Marrakech, Morocco

Original Research Article Introduction: To optimize patient management, medical care and pandemic control, it is important to determine the effectiveness of chest CT scan to distinguish COVID-19 from other types of pneumonia. The objective of our work is to present the contribution of the chest CT scan in the diagnosis of Covid-19 viral infection. Material and method: This is a prospective study carried out from 20 March 2020 to 31 May 2020, of 444 cases identified in the radiology department of university hospital of Marrakech, concerning all patients with a clinical suspicion of coronavirus infection. Results: The average age of our patients was 52 years, with extremes ranging from 15 to 93 years, a sex H/F ratio of 1.41. Hypertension, diabetes and smoking were the most common co-morbidities. The most common clinical signs were cough, dyspnea and fever. The radiological signs most frequently found were the peripheral ground glass opacification of the posterior regions, followed by consolidations, less frequently the crazy paving, halo sign and reverse halo sign, 2 cases of unilateral form versus 119 cases of bilateral form. The percentage reached was as follows: Minimal (<10%): 37 cases, Moderate (10-25%): 25 cases, Extensive (25-50%): 24 cases, Severe (50-75%): 15 cases, Critical (>75%): 5 cases. The differential diagnosis mainly found were bronchopneumonia, exacerbations of bronchiectasis, cardiac decompensations and tuberculosis. The scanner-PCR correlation was as follows: PCR / CT -: 106 cases, PCR + / CT +: 72 cases, PCR -/ CT +: 30 cases, PCR + / CT-: 16 cases, CT / PCR not done: 198 cases, CT + / PCR not done: 19 cases. Conclusion: The scanner has had a central role in the management of patients with respiratory symptoms in this pandemic. This review also assessed the severity of lung disease, monitored disease progression based on worsening lesions, and participated in the patient referral decision (COVID vs Non-COVID unit) anticipating PCR data.


INTRODUCTION
It was in China precisely in the city of Wuhan in December 2019, that cases of pneumomy of unexplained cause were reported, which led specialists to take samples from the lower respiratory tract to determine the nature of the implicated germ. the results were in favor of a new type of coronavirus. World Health Organization named it coronavirus disease 2019 (COVID-19) [1].
Cronavirus disease has a respiratory affinity, the most frequent clinical signs are cough, fever, fatigue and myalgia [2,3]. Even in the incubation phase, the patient carrying the virus is a contaminant, hence Radiological examinations are of great help in the diagnosis and follow-up of patients with COVID-19. They have the advantage of providing rapid diagnosis and ease of execution.
The chest x-ray may turn out to be normal, especially at the early stage of the disease, without being able to detect ground glass opacities (GGO), it is where the thin-section thoracic computed tomography intervenes to play a crucial role in assisting diagnosis [4].

MATERIAL AND METHOD
This is a prospective study carried out from 20 March 2020 to 31 May 2020, of 444 cases identified in the radiology department of university hospital of Marrakech; concerning all patients with a clinical suspicion of coronavirus infection.
This new disease threatens the biosecurity of the planet [10]. This requires a preparation on different levels involving the preventive, diagnostic, therapeutic and epidemiological [11].
In the literature [12] the most frequent comorbidities were similar to those in our studies with first hypertension, diabetes, followed by cardiovascular disease and respiratory disease.
Our study joined the literature with clinical signs mainly represented by fever and cough, followed by myalgia and dyspnea, the involvement in adults far exceeding the involvement in children [4,5,11].
The pulmonary involvement is bilateral more marked on the peripheral subpleural area, all the lobes are affected with a predominance of the lower lobes, the most frequent semiological sign was typically the GGO, the consoldation with the air bronchogram , the interlobular septal thickening and adjacent pleural thickening [16][17][18].
Our results were consistent with the literature, we found that the most frequent radiological sign was GGO with bilateral peripheral subpleural distribution [19]. All the lobes were affected especially the lower lobes. The other signs were represented by consolisations with the air bronchogram, septal thickening and more rarely pleural effusion, the sign of the inverted halo and lymphadenopathy.
Computed tomography has a very high sensitivity in the diagnosis of COVID-19 but a low specificity that cannot rule out other types of viral pneumonia [20].
Although the gold standard in the diagnosis of coronavirus disease is the detection of viral nucleic acid using RT-PCR, there are some studies [21,22] which have shown radio-bilogical discordance, with negative RT-PCR results and abnormal CT imaging, which supports the sensitivity of computed tomography by several studies [23,24] with a rate of 97% in a case series of 1,014 patients. The results of our study also showed that the sensitivity of the thoracic computed tomography was 82%, this shows the crucial role of the computed tomography in the detection of early lung lesions especially in epidemic areas.
In a review of 356 patients with COVID-19 [25], 11.5% had positive RT-PCR results and normal CT imaging. The low specificity of the tomodensitometry; does not exclude the diagnosis of Covid-19 on only radiological arguments.

CONCLUSION
Imaging and more specifically computed tomography play an important role in the diagnosis and follow-up of patients with COVID-19 but the diagnostic confirmation is always radio-bilogical.