Demographic characteristics and general information
218 patients [107 patients from the university hospital and 111 patients from the private hospital) were enrolled in this study (114 male, 104 female, mean age 56 ± 15.6 years (range, 24-91 years)). Mean DLP value for university hospital was 200.14 mGy × cm and for private hospital was 214.07 mGy × cm.
Of the whole study group, 197 patients (90.4%) had no CT findings suggesting pneumonia. One patient (0.5%) showed typical CT features for COVID-19 pneumonia; 12 patients (5.5%) were reported as indeterminate, and eight (3.7%) were reported as atypical for COVID-19 pneumonia. None of the patients had incidentally discovered thoracic malignancies or newly discovered metastasis.
Of 218 patients, three (1.4%) had positive and 215 (98.6%) had negative RT-PCR test result. Only one of the three patients with positive RT-PCR had findings on chest CT that may be attributed to pneumonia. Of 215 patients with negative RT-PCR result, 20 (9.3%) had CT abnormalities attributable to pneumonia. 12 of this 20 patients had indeterminate CT findings and eight had atypical CT findings for COVID-19.
Performance of chest CT-screening in diagnosing COVID-19 in asymptomatic patients
In 21 patients COVID-19 pneumonia could not be ruled out based on chest CT findings. Only one of these had typical CT findings for COVID 19 pneumonia whereas the rest had indeterminate or atypical CT findings. When RT-PCR tests were taken as reference, the sensitivity, specificity, and accuracy of chest CT in showing COVID-19 disease were 33.3%, 90.7%, and 90.0%, respectively. The positive and negative predictive values were 4.8% and 99.0%, respectively.
Two patients with positive RT-PCR results had no lesions suggesting COVID-19 pneumonia on chest CT. All 12 patients with indeterminate CT findings and all eight patients with atypical CT findings for COVID-19 were RT-PCR negative. Of the 20 patients with indeterminate or atypical findings, 16 (80%) had unilateral lung lesions, 12 (60%) had unilateral ground-glass opacities, two (10%) had segmental/subsegmental consolidation, 4 (20%) had unilateral discrete small nodules, and two (10%) had smooth interlobular septal thickening.
72 (33.0%) patients needed emergent and 146 (67.0%) patients needed elective surgery. All but three patients who needed emergent surgery had negative chest CT and RT-PCR results. Three patients had indeterminate CT findings and were operated without delay with relevant precautions for airborne infection. RT-PCR tests repeated after surgery in these three patients were also normal.
Out of the 146 patients who needed elective surgery, 126 had negative CT and PCR results and underwent surgery timely. Nine patients with indeterminate CT and eight patients with atypical CT findings had negative PCR results. 15 of these patients were operated without a delay. In the remaining two patients, both of whom had atypical CT findings, surgery was delayed for two and three days, after a repeat RT-PCR was negative.
One patient who had typical CT findings and a positive RT-PCR test was operated after 24 days of treatment with Plaquenil (Fig. 2).
None of the 21 patients with positive chest CT findings suffered from postoperative complications and were discharged with a mean hospital stay of 5.1 days. Age, gender, planned surgery, CT features and surgical outcome of CT and/or RT-PCR positive patients were summarized in table 2.
Two patients had negative CT findings but positive PCR results. One of the patients had elective endoscopy and the other lumbar discectomy. Both of the interventions were canceled till a negative PCR result is obtained. Both patients were under surveillance without medication administration.