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Magnetic resonance imaging (MRI) of the lung is an exciting field that is currently undergoing a period of rapid advancement. With its ability to measure lung function as well as structure, MRI stands to greatly improve our understanding of cystic fibrosis (CF) pathophysiology in children. However, there are still a number of significant hurdles to overcome if MRI is to become a tool for routine monitoring of paediatric CF lung disease.
Compared to other commonly used modalities such as computed tomography (CT), spirometry, and multiple breath washout (MBW), MRI is considerably more expensive and, due to high demand, generally has long wait times for access. In addition, the cost of Helium for inhalation as a contrast agent is substantial, and due to diminishing reserves, access is likely to be more problematic in the future. The use of hyperpolarised gas requires expensive equipment that is not available in all centres, such as specially tuned radiofrequency coils and a gas hyperpolariser, as well as the expertise to run them . The significant cost to set up and maintain such a system presents a huge barrier to entry for many CF centres, compared to the nearly universal presence of CT and lung function testing facilities.
Standardisation of MRI between centres is challenging. Many sequences are protected under intellectual property law resulting in vendor-specific protocols, hampering comparisons between platforms . Magnetic field inhomogeneity can lea...
Standardisation of MRI between centres is challenging. Many sequences are protected under intellectual property law resulting in vendor-specific protocols, hampering comparisons between platforms . Magnetic field inhomogeneity can lead to variability between individual scanners, even of the same model/manufacturer . In comparison, the SCI-FI project has demonstrated that image quality standardisation of CT is feasible, facilitating collaborative studies and longitudinal lung disease monitoring .
Finally, due to long imaging times, the need for the patient to remain still, and loud noises generated by the scanner, lung MRI is challenging to perform in children under six years unless sedation is used. As a result, the sensitivity of MRI to detect early CF-related lung disease in these young children has not yet been established. In contrast, with the advent of high-pitch, rapid acquisition techniques, CT can be performed in infants and young children without the need for sedation and with minimal motion artefact , with a high sensitivity [6, 7].
Radiation-free lung imaging is an attractive prospect for monitoring respiratory disease in children with CF. However, it is important to recognise that the risks from CT, if any, are extremely small [8, 9], especially in the era of ultra-low dose CT imaging . The long-term risks of, for example, sedation or Xenon inhalation, are not well characterised and have not undergone such scrutiny as medical radiation.
In summary, lung MRI is a promising research tool that has an important role to play in understanding and treating CF lung disease. However, there are still many challenges that need to be overcome before MRI becomes a routine clinical tool for monitoring lung disease in children with CF.
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