Evaluation of High Resolution Computed Tomography Findings and its Relationship with the Clinical Course of Patients with Covid-19

Background: Due to the Covid 19 pandemic and the lack of useful information, in this study, we evaluated the hrct of patients with Covid 19 Method: 92 patients conrmed by RT_PCR in Razi Hospital in Rasht were included in the study. In addition to their demographic and clinical information, their hrct ndings were collected for evaluation. Among 92 patients (47 men, 45 women), the earliest symptoms included cough (81.5%), fever (67.4%), and muscle pain (58.7%) And Six patients required intubation and mechanical ventilation at some point during their hospital stay. Results: The most common hrct ndings in our study were grade 4, peripheral lesion 87%, bilateral 95.7%, mixed 76.08%, ggos 75%, left lower lobe 94.56%. Among 92 patients, we had some inconsistent ndings including two patients with cardiomegaly, three patients with pleural effusion, and bilateral pleural effusion in only one patient Conclusion: Compared to other studies, it can be concluded that peripheral, bilateral, mixed, ggos, left lower lobe involvement are important ndings in most patients with covid 19. We suspect that the disease has more severe lung involvement in men and less involvement in women, which needs further investigation.

lower lobe involvement are important ndings in most patients with covid 19. We suspect that the disease has more severe lung involvement in men and less involvement in women, which needs further investigation.

Background
In December 2019, a new pathogen COVID-19 was identi ed in Wuhan, Hubei Province, China that caused pneumonia and death [1,2]. COVID-19 is one of the positive-strand RNA viruses that genetically are similar to the acute respiratory syndrome virus (SARS-COV) and the Middle East respiratory syndrome (MERS-COV) [1,3,4]. Following the spread of the virus to other countries such as South Korea, Italy, Iran, and Japan and reporting a death in infected people there the World Health Organization (WHO) declared it as a pandemic and named it COVID-19 [3,5]. Until the date of writing this scienti c research, according to WHO, 35,027,546 cases of COVID-19 have been con rmed, including 1,034,837 death [6]. COVID-19 and SARS have many close clinical characters [3]. The spread and contagion of the virus happen through large droplets created during sneezing and coughing of asymptomatic and asymptomatic patients [7].
The virus can survive on different surfaces such as metal, glass, or plastic for up to 9 days and infect people by touching the nose, eyes, and mouth [5,7]. After contact with the virus, symptoms may appear within 2 to 14 days [8]. The transmission rate of SARS-CoV-2 is high between families and friends who had close contact with patients or asymptomatic carriers even with a low infective dose [9].
Elderly persons with comorbidities or underlying diseases such as diabetes, hypertension, or cardiovascular diseases (CVD), are at serious and greater risk because these diseases may weaken the immune system [3,9,10]. Although everyone is at risk, the average age of patients was between 47-59 years old, of which women make up 41.9-45.7% of patients [7,9], COVID-19 has various clinical features, from an asymptomatic state to acute respiratory distress syndrome until multi-organ dysfunction [7].
Common clinical symptoms of COVID-19 fever, nonproductive cough, dyspnea with or without diarrhea, myalgia, fatigue, usually normal or reduced leukocyte amounts, and radiographic data of pneumonia, which are similar to the symptoms of SARS-CoV and MERS-CoV contagions [1,4,7]. The most and main common symptom for screening is fever [3]. Pneumonia and kidney failure may happen in severe cases which lead to death [10]. In the second week, the infection progresses to hypoxemia, respiratory problems, and acute respiratory distress syndrome (ARDS), which leads to the need for mechanical ventilation in the intensive care unit (ICU) with isolated services [1]. Patients should drink plenty of uids and electrolytes and appropriate oxygen therapy or treatment should be provided through the oxygen mask, nasal cannula, or high ow nasal oxygen therapy. In this situation, checking some parameters like heart rate, blood pressure, pulse oxygen saturation, and respiratory rate is essential [10].
COVID-19 diagnostic tests are varied and include nucleic acid detection, CT scan, immune identi cation technology, Real-Time-PCR, ELISA, blood culture [4,10]. CT imaging normally appearances in ltrate ground-glass opacities (GGOs), and subsegmental consolidation [7] single or numerous agglomerated or scattered patchy GGOs segregated by grid-like condensed or honeycomb-like interlobular septa and pulmonary consolidation with air bronchogram. The results may differ according to disease phase, patient age, and immune status at the time of imaging [10]. For identi cation, High-Resolution Computed Tomography (HRCT) is more sensitive than chest x-ray [11] and this is necessary for quick diagnosis and assessment of COVID-19 patientʼs severity, discovering lung deformities, clinical classi cation, nding of pulmonary problems, and follow-up after discharge [4,12].

Study design and patients
This retrospective cross-sectional study was conducted from December 2019 to March 2020 on 92 cases of COVID-19 con rmed by RT-PCR in Razi Hospital, Rasht, Iran. The study was performed in accordance with the declaration of Helsinki and approved by the Ethics Committee of Guilan University of Medical Sciences (IR.GUMS.REC.1398.543). written informed consent to participate in the study was obtained from participants. Their demographic and clinical data including age, sex, underlying diseases, signs and symptoms, length of hospital stay, hospital outcome (mechanical oxygen demand (intubation) -blood oxygen saturation, recovery or death, and HRCT radiographic results were recorded and analyzed. The criterion for patient admission was the presence of a de nite laboratory result to con rm the occurrence of COVID-19 in the patient le. Patient les with incomplete information (main variables like lack of de nitive result of COVID-and also lack of HRCT image in the le report, were excluded from the study.

Imaging analysis and quanti cation
Each case underwent chest high-resolution CT (HRCT) examination within 24 hours after admission. All imaging was taken by a General Hi-speed Dual CT scanner. Then rewired and evaluated by an experienced radiologist. The imaging procedure was performed according to the common protocol of the chest. The HRCT in axial sections was used without the contrast material with a section thickness of 2 mm. The low-dose protocol (low-dose computed tomography) with radiation conditions of Kvp = 100-120, mAs = 50-100, and pitch = 1 mm was used. Lesion image analysis included the number of lesions, distribution of lung lobes, location of lesions in the lung, lesion size, the density of right upper lobe lesions, right middle lobe, lower right lobe, left upper lobe and lower left lobe. The location of the lesions in the lung included peripheral (if it is located in the outer third of the lung), central (inner 2/3 region of the lung), peripheral-central, and bilateral or unilateral. Lesion size was de ned as: no grade, grade 1 (1cm>), grade 2 (1 < X < 3 cm), grade 3 (3cm to < 50% of the lobe), and grade 4 (50-100% of lobes). The presence of ground-glass opacities, consolidation, mixed, brous stripes, reticulation or interstitial thickness, air bronchogram in each patient's chest CT image were assessed as lesions density. pleural effusion and cardiomegaly were also present. The patient puts his arm above his head and lies on the CT scanner. CT scanning started from the apex to the lowest part of the lungs in deep inspiration. The patient was told to hold his breath during the imaging.

Statistical analysis
In this study, the collected data is recorded in an Excel program and then coded and entered into SPSS software. Qualitative and Quantitative variables (mean and standard deviation) have been described using numbers and percentages. The Kolmogorov test was used to determine the normality of the variables. If normal, parametric tests and otherwise according to the variables, qualitative research using the chi-square test and Spearman correlation coe cient can be used to determine the frequency and correlation. Patients were divided into 4 groups for more analysis according to age as follows: group 1, < 20 years old; group 2, 21-40 years old; group 3, 41-60 years old; group 4, 61-80 years old and group 5, 81-100 years old.

Results
In the present study, 92 patients with PCR-con rmed COVID-19 were evaluated for HRCT in Guilan province, which is one of the COVID-19 referral centers in Iran. They were 47 men, 45 women with a mean age of 56.52 ± 14.05. Mean hospital stay time was 7.2 ± 9.93 days. Among these patients, 90 patients (8.97%) were referred to the hospital in person. Of all patients, 75 cases had not been in direct or indirect contact with other COVID-19 patients. The baseline data are recorded in (Table 1). At rst presentation, the most common early symptoms in the patients with COVID-19 in the present study, were cough (75 cases), fever (62 cases), muscle pain (54 cases), respiratory distress (34 cases), and other cases are shown in Table 2. These clinical manifestations in infected patients of different age groups were not statistically signi cant. After Antiviral treatment, 81 patients were discharged from the hospital but 11 patients died during hospitalizing. 30 of 92 patients had a history of at least one underlying disease (Table 4), which diabetes was the most common (10 cases). O 2 pressure in 25 cases was more than 93mm Hg and in 67 cases was less than 93mm Hg. Six patients required intubation and mechanical ventilation at some point during their hospital stay and three of them died.
Two patients were required to undergo dialysis (Table 3). We decided to study patients separately by gender and age for a more detailed analysis.  The present study showed that HRCT image lesions size in all patients, grade 4 (50-100 % of the lobe) were the most common. As shown in Table 5, The most common grade was 4 (seventeen cases) in men, 1 and 2 grades in women (twelve cases each). In the age groups of 20-40, grade 2 and 60-80, grade 3, in 80 to 100, grade 3 were detected in HRCT. We found that lesions were more localized in the peripheral zone (80 cases_87%). The involvement of peripheral lung lesions in the age of 40-60 was more than in other age groups. Also, lesions were involved in the peripheral-central zones in twelve cases (13%).
Based on the HRCT nding, 72 patients (78.3%) had lesions in all lung lobes. Our result showed that the most common site of involvement was the left lower lobe (87 cases) at different ages and the least involved lobe was the upper left (81 cases). The most common site of involvement lobes in men was almost all of them, but in women lower left was most common. We also diagnosed 88 patients (95.7%) with bilateral lung involvement, three patients (3.3%) with only the left lung, and one patient (1.1%) with only the right lung.
We also analyzed the characteristics of each patient lesion. 297 lesions in HRCT calculated for all infected individuals, in total, mixed (70 cases) and GGOs (69 cases) are a commonly observed HRCT nding in lung lesions in patients. In men, the most common lesion was mixed, but in women, GGOs. (Table 6 )  For each patient lesion, an air bronchogram was evaluated, which was a total of 16. There was no signi cant difference between the different age groups, but it was seen more in men (11 cases) than women (5 cases).
Among 92 patients, we had some inconsistent ndings including two patients with cardiomegaly, three patients with pleural effusion, and bilateral pleural effusion in only one patient

Discussion
The SARS-COV-2 disease is considered a global threat with a high infectious rate and CT imaging has an important role in its rapid diagnosis and evaluation [13,14]. To our knowledge, this is the rst study about hospitalized patients from Guilan province by HRCT for diagnosis and evaluation. The present study was performed HRCT on 92 patients and recorded signs of involvement in the CT images. In the present study, the cough was found to be the most common clinical manifestation (81.52 %). This rate in another study with 120 patients was 90% [8] (5) which is close to our rate. However, in other studies fever was the most common symptom [10,14,15]. In another similar study in Iran, dyspnea was the most common symptom in patients [16], Our results showed that 32.60 % of patients had a history of an underlying disease which this rate was 18.48 % [16] and 34.9% [10] in other studies. In contrast, /diabetic disease was the most contributor to disease in the present study, but study [16] declared cardiovascular disease was the most. Six out of 92 patients (6.52%) required mechanical ventilation, in contrast, whit other study results which this rate was 13(10.83%) [8].
The most common presented ndings in patients, peripheral distribution, and lower left lobe involvement, grad 4 of lesion sizes were mixed. The prevalence of mixed in the studied population was 76.08%, which is systematic and meta-analysis study was 43.0 % [17]. Also in this study, the prevalence of ground-glass opacity was 75%, which varied from 64.6-100% in other studies [8,17] In a similar study in Iran [13], GGOs were the most symptom in CT images (87.3%). The peripheral zone was the second most common nding in this study, observed in 87 % of the study population. this rate was reported in other studies 57.1% [17](6) and 82.4% [13]. Our results showed the most site of the involved lobe was the left lower lobe in 94.56% of the population. In similar systematic and meta-analyses [17], LLL was the most common (71.2%). In another study, the lesions of patients were mainly located in the lower lobe of the right lung [15].

Conclusion
Compared to other studies, it can be concluded that peripheral, bilateral, mixed, ggos, left lower lobe involvement are important ndings in most patients with covid 19. We suspect that the disease has more severe lung involvement in men and less involvement in women, which needs further investigation.