Covid-19 Epidemic: IMAGING UPDATE
France is currently in stage-2 epidemic status with regard to SARS-CoV-2, and demand on radiology departments, whether hospital-based or not, is increasing.
This surge in demand requires the role of imaging in this epidemic context to be clarified
What are the indications for imaging, and what type of exam should be performed?
1. There is no place for chest X-ray; if imaging is indicated, a CT scan should be performed.
2. In patients with no clinical severity or comorbidities, for whom there is diagnostic uncertainty between bacterial pneumonia and Covid-19 involvement, clinical evidence (auscultatory findings, chest pain) and biological evidence (leukocytosis) should take precedence, and a PCR test may be indicated in the event of fever resistant to antibiotic therapy, rather than prescribing imaging.
3. There is currently no indication for performing a chest CT scan for screening purposes in patients with no signs of severity and no comorbidities.
4. Performing a chest CT scan without contrast, using thin slices, is currently indicated in patients with a suspected or confirmed diagnosis and clinical signs of severity (dyspnea, desaturation, etc.) either at presentation or subsequently, requiring hospital care. It may also be considered in suspected patients with comorbidities, while awaiting PCR results, or as a first-line option if PCR turnaround times and availability become a limiting factor, which now seems likely.
5. In COVID-19-positive patients in intensive care and critical care who are deteriorating, the CT scan should look for worsening lesions progressing towards ARDS, as well as ventilator-associated pneumothorax or a thromboembolic complication, and should therefore be performed with contrast injection.
What precautions should radiography technicians and radiologists take?
If a decision is made to perform CT imaging, the measures to take are those currently recommended for all healthcare workers caring for suspected patients:
– The patient: must wear a surgical mask and perform hand rubbing with alcohol-based hand rub.
– Physicians and radiography technicians:
– Hand rubbing with alcohol-based hand rub, surgical mask.
– If the patient needs to be positioned on the exam table and/or given an IV line:
– Long-sleeved disposable gown, cap and single-use gloves.
– Ideally, reusable protective goggles, disinfected after use.
– FFP2 filtering masks are reserved for hospital staff in close, prolonged contact with confirmed cases (intensive care or when an interventional radiology procedure is required).
– The CT scanner should then undergo bio-cleaning in line with the hygiene department’s recommendations (FB spray or any other disinfectant detergent for surfaces, Anios Oxy’floor for floors).
Patients must come accompanied (contact isolation), wearing clothing that allows them to be positioned directly on the CT table without undressing.
The radiology department must be notified in advance, to organize things in a way that avoids waiting among other patients.
Specific pathways must be set up, with, depending on patient volume and the number of available scanners, dedicated time slots on one scanner, or one scanner fully dedicated to this activity.
NB: For ultrasound scans of hospitalized patients, it is preferable to perform them bedside using a portable ultrasound machine, to limit patient movement.
What CT findings have been observed?
These are illustrated using a few annotated clinical cases. See the clinical cases
These mainly consist of non-systematized ground-glass areas, predominantly subpleural, and, at a later stage, alveolar consolidation. There is usually no cavitation, nodules or masses. Bronchiolar micronodules, mediastinal lymphadenopathy and pleural effusions are rare, although effusions are possible in the event of cardiac decompensation.
Pr REVEL, Pr LEDE
