Respirators and Surgical Masks Artefacts on Phantom using Magnetic Resonance Imaging during COVID-19: A Cross-sectional Study

Abstract

Introduction: It is suitable for a patient to wear a respirator or face mask during any radiological investigation during Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) pandemic. Some face masks may have nanoparticles, or antimicrobial coating, which may comprise metal to help shape the mask according to user face shape. This kind of ferromagnetic substances can cause artefacts in the image. Aim: To detect and compare the artefacts while using different types of respirators and surgical masks in the Magnetic Resonance Imaging (MRI) phantom images. Materials and Methods: This was a prospective cross-sectional study which was conducted from July 2021-September 2021. Two Not resistant to oil-based aerosols with 95% efficiency to airborne particles (N95) respirators and two types of three-ply surgical disposable masks with a metal and plastic nose holder were used. The N95 respirators were of Halo N95 Filtering Facepiece 2 Particulate Matter (FFP2) PM 2.5 and Suchi N95 S-7400, while the surgical masks were from Venus 3 ply V-1010 with a metal nose holder and the Thea Tex Filtra 3 ply with plastic nose holder. A polymethyl methacrylate plastic phantom was used with 1.5 Tesla (Siemens Magnetom Avanto) MRI scanner for imaging. Results: When exposed to the metal detector both N95 respirators and one of the surgical masks with a metal nose clip showed strong ferromagnetic attraction. Both respirators and a surgical mask with a metal nasal holder showed magnetic susceptibility artefacts. The signal loss is caused by dephasing of spins from metal strip on the image. Conclusion: All the patients must have a recognised MR safe masks prior to an MRI investigation. When this is not possible to follow, metallic components from the face mask should be removed before the patient's arrival at the MR room. After removing the metal strip from the mask, the paper tape may be applied across the nasal bridge region for adequate transmission control and to maintain the intended function of the mask. The mask with a plastic nasal holder was ideal to use in an MR environment since it doesn’t have any distortion in the image.