CT-images for Covid19 screening is more sensitive than PCR.

CT-images for Covid19 screening is more sensitive than PCR.

The sensitivity and specificity of a diagnostic test depend on several factors. Not just the kit. I do not have any data on the accuracy of the kit.

However the viral load varies with site of sampling. Please see:

Wenling Wang; Yanli Xu; Ruqin Gao; et al Detection of SARS-CoV-2 in Different Types of Clinical Specimens. Jama 2020 (in press).

Although bronchoscopic samples have the highest yield these are invasive and expose healthcare professionals to highest viral load. I would not do a bronchoscopy just to get a sample for SARS-Cov-2. However if I was doing a bronchoscopy on a patient for another reason I would send the sample.

The practicalities of imaging patients with suspected and confirmed Covid-19 should be considered. When there are 1 or 2 patients this is not too much of an issue.

However, when there is a large influx of patients it will be difficult to send these patients to the radiology department then clean the room and x-ray or CT machine before imaging the next patient.

Portable x-rays will also be challenging. Tech will don PPE, Image, clean machine, doff PPE.

Lung ultrasound is emerging as the test of choice in the diagnosis of Covid-19.

During the pandemic the pre-test probability of disease in any patient will increase with the prevalence of the disease in the community.

If the pre-test probability is high enough then abnormal imaging suggestive of pneumonitis may be sufficient to 'confirm' the diagnosis of Covid-19. Whilst in reality any other respiratory virus could cause the same symptoms and imaging findings, the risk of Covid-19 becomes so high that even if a PCR test were negative we would not be able to exclude Covid-19.

A protocol using lung US for screening and triage has been suggested (not yet validated) but is being used in areas where healthcare systems have been overwhelmed (e.g. Italy).

It is available at:

https://www.butterflynetwork.com/au/covid-19#publications

This site also contains links to publications from China and Italy on the use of POCUS lung US for the management of Covid-19.

Small hand held US machines are portable, easy to clean and provide substantially more information than a portable chest x-ray. Whilst they can not replace CT, if a suspected or positive Covid-19 patient has a CT it can take up to 90 minutes to clean the CT suite. That is a significant down time.

Article Ultrasound in critical care

The understanding of the role of point of care ultrasound in healthcare is exploding. As healthcare systems are overwhelmed it is difficult to perform X-ray, CT, MRI and nuclear medicine. Small handheld portable Ultrasound devices have transformed the bedside assessment and diagnosis of patients with Covid-19. There is a great interest in research in this topic during the Covid-19 pandemic.

Anyone interested in an overview of POCUS may find the brief review above helpful.

The role of ultrasound is particularly relevant for the imaging the lungs of women with suspected or confirmed Covid-19. Especially if pregnant.

Extensive and Augmented COVID-19 X-Ray and CT Chest Images Dataset

https://data.mendeley.com/datasets/8h65ywd2jr/2

This COVID-19 dataset consists of Non-COVID and COVID cases of both X-ray and CT images. The associated dataset is augmented with different augmentation techniques to generate about 17100 X-ray and CT images. The dataset contains two main folders, one for the X-ray images, which includes two separate sub-folders of 5500 Non-COVID images and 4044 COVID images. The other folder contains the CT images. It includes two separate sub-folders of 2628 Non-COVID images and 5427 COVID images.

Cite it in your research work:

El-Shafai, Walid; E. Abd El-Samie, Fathi (2020), “Extensive and Augmented COVID-19 X-Ray and CT Chest Images Dataset”, Mendeley Data, v2

For any questions, do not hesitate to contact me.

Regards

Walid El-Shafai

[email protected]

QRT PCR