Background
To evaluate the clinical value of the chest CT scan compared to the reference standard real-time polymerase chain reaction (RT-PCR) in COVID-19 patients.
Methods
From March 29th to April 15th of 2020, a total of 240 patients with respiratory distress underwent both a low-dose chest CT scan and RT-PCR tests. The performance of chest CT in diagnosing COVID-19 was assessed with reference to the RT-PCR result. Two board-certified radiologists (mean 24 years of experience chest CT), blinded for the RT-PCR result, reviewed all scans and decided positive or negative chest CT findings by consensus.
Results
Out of 240 patients, 60% (144/240) had positive RT-PCR results and 89% (213/240) had a positive chest CT scans. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of chest CT in suggesting COVID-19 were 100% (95% CI: 97–100%, 144/240), 28% (95% CI: 19–38%, 27/240), 68% (95% CI: 65–70%) and 100%, respectively. The diagnostic accuracy of the chest CT suggesting COVID-19 was 71% (95% CI: 65–77%). Thirty-three patients with positive chest CT scan and negative RT-PCR test at baseline underwent repeat RT-PCR assay. In this subgroup, 21.2% (7/33) cases became RT-PCR positive.
Conclusion
Chest CT imaging has high sensitivity and high NPV for diagnosing COVID-19 and can be considered as an alternative primary screening tool for COVID-19 in epidemic areas. In addition, a negative RT-PCR test, but positive CT findings can still be suggestive of COVID-19 infection.
In asymptomatic patients, there is no significant asymmetry of the SCJ. The joint spaces did not significantly decrease with age, although such a trend could be observed. Pronounced joint space narrowing with large geodes and osteophytes was not seen. Clefts of the first costochondral junction are common and not significant.
16 tumours grew subcutaneously. In ultrasound imaging, the capsule was always intact, and subcapsular vessels were detected in every tumour. Central necrosis was seen in 10/16 tumours by sonography, but in 15/16 tumours on histological examination. The failure of sonography in detecting necrosis did not correlate with the size of the tumour. Centrally located vessels were found in 12/16 tumours using colour-coded sonography. Histology, however, showed their presence in all 16 tumours. Interestingly, the failure of sonography in detecting vessels did not correlate with tumour size. It seemed that the detection of such vessels was particularly difficult in those tumours which grew very fast. This finding explains why we often find such vessels in small tumours but not in large specimens, where they would normally be expected.
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