Retrospective analysis of thoracic CT findings in cases diagnosed with covid 19, their relationship with the treatment process and prognosis

ABSTRACT RETROSPECTIVE ANALYSIS OF THORACIC CT FINDINGS IN CASES DIAGNOSED WITH COVID 19, THEIR RELATIONSHIP WITH THE TREATMENT PROCESS AND PROGNOSIS SARS-CoV-2 is a member of the coronavirus family that causes respiratory or systemic infection and, rarely, severe respiratory failure or multiple organ failure. On January 30, 2020, the World Health Organization (WHO) recognized COVID-19 as an international emergency that threatens public health, and on March 11, 2020, it was declared a worldwide pandemic. The clinical spectrum of the disease is broad and includes asymptomatic infection, mild upper respiratory tract infection, and severe interstitial pneumonia requiring oxygen support or intubation and causing respiratory failure. The gold standard method for diagnosis is the RT-PCR (reverse transcriptase polymerase chain reaction) test. Although the specificity of the test is high, its sensitivity varies depending on the sensitivity of the test kit, the sampling method and the person collecting the sample. Moreover, although the RT-PCR test requires 5-6 hours, It has been shown that it can give false negative results in the early stages of the disease. Computed tomography (CT) provides rapid results and can be valuable for diagnosis in the early stages when the RT-PCR test is negative. In the hyperacute phase of the disease, even in the absence of clinical symptoms, it is possible to determine the typical infiltration pattern, so thorax CT is widely used for diagnostic purposes. Our aim in this study is to describe thorax CT findings in patients diagnosed with COVID 19, to determine typical-atypical involvement patterns, and to examine its value in predicting the treatment process and prognosis of the disease based on the infiltration patterns of the disease. Our study was conducted by retrospectively evaluating the thorax CT scans of patients who applied to the Fırat University Faculty of Medicine Hospital emergency department between 01.05.2020 and 31.12.2020 with suspicion of Covid 19 and whose RT-PCR test was positive. Thorax CT images were evaluated in Fırat University's radiology image archive system, Picture Archiving and Communication System (PACS). Laboratory results, follow-up and treatment processes of the patients were accessed through Fırat University Hospital Information Management System. Patients were grouped as typical, indeterminate, atypical and negative according to their lung involvement patterns. Lung findings that can be seen in Covid 19, the number of lobes involved and the dominant lobe were recorded. Patients were classified according to where their clinical follow-up and treatment was performed: at home, in the clinic, and in intensive care. Laboratory values, presence of additional diseases were investigated, and complications and mortality were examined in terms of Covid 19 prognosis. Of the 200 patients included in the study, 103 (51,5%) were women and 97 (48,5%) were men. The average age was determined as 59,4±17,4 (min=13-max=89) years. 50% of the patients followed were receiving treatment at home, 30,5% in the clinic and 19,5% in intensive care. It was observed that 74,5% of Covid 19 lung involvement patterns were typical, 9% were indeterminate, 3,5% were atypical and 13% were negative. In thorax CT, 5 lobes were involved in 59,5% of the patients, and involvement was most frequently observed in the lower lobes. Ground glass density was noted as the most common finding. Crazy paving, consolidation and the presence of pleural effusion were found to be significantly associated with intensive care treatment and poor prognosis. The nodule and halo findings were seen with home treatment and a good prognosis. 23.5% of those with a typical pattern, 16,7% of those with an indeterminate pattern, and 14,3% of those with an atypical pattern were in intensive care. All patients with negative thorax CT were followed up at home, and no complications were observed in these patients. Additionally, no mortality was observed in patients with atypical and negative patterns. In terms of Covid 19, complications, intensive care unit admission and mortality rates were significantly higher in patients with lung involvement findings on thorax CT. The gold standard method for the diagnosis of Covid 19 is considered to be RT-PCR. Computed tomography (CT), on the other hand, provides rapid results and guides the diagnosis, follow-up and treatment processes even in the early stages when clinical symptoms are not observed. In our study, the findings show that during the Covid 19 infection process, thorax CT has an important place in determining the activity of the disease, guiding the follow-up-treatment process, and predicting the prognosis. Key words: Covid 19, Thorax CT, Retrospective analysis, treatment process prognosis