Magnetic Resonance Imaging Techniques and Safety

Magnetic resonance imaging (MRI) has evolved into a versatile modality that combines non-invasive anatomical visualisation with functional and spectroscopic capabilities. Advances in radiofrequency (RF) coil design, including flexible and self-decoupled arrays, have significantly boosted signal-to-noise ratio (SNR) and spatial coverage, enabling higher field strengths up to 10.5 T for human brain studies. Parallel transmission and reception techniques now permit tailored RF pulses and accelerated imaging protocols, reducing scan time and mitigating field inhomogeneity. Concurrently, safety considerations have prompted detailed investigation of specific absorption rate (SAR) distribution, RF-induced heating of implants, and potential biological effects of non-ionising fields. Modern numerical simulations and subject-specific monitoring schemes facilitate individual risk assessment, aiding the development of safety guidelines and device labelling standards. Together, these technical and safety innovations underscore the global relevance of MRI in clinical diagnosis, neurosurgical planning and biomedical research while ensuring patient welfare remains paramount.

Research from Nature Portfolio

Recent studies have introduced a novel self-decoupled RF coil design that achieves high inter-element isolation without complex matching networks, improving array flexibility and enabling adjustable geometries for diverse anatomical regions. Investigations into printed flexible receive coils have demonstrated that lightweight, conforming devices can match or exceed the performance of conventional rigid arrays at both 1.5 T and 3 T, with prototypes embedded in infant blankets exemplifying clinical applicability. Further work on magnetic metamaterials has realised engineered structures that locally amplify RF fields, yielding up to a fourfold increase in SNR; these developments promise enhanced image resolution or reduced acquisition times and herald rapid clinical translation.

Magnetic Resonance Imaging Techniques and Safety publication trend

The graph below shows the total number of articles in magnetic resonance imaging techniques and safety across all publications each year (not limited to Nature Index journals).

Technical terms

Signal-to-Noise Ratio (SNR): The ratio of true signal intensity to background noise, reflecting image quality and resolution potential.

Specific Absorption Rate (SAR): A measure of RF energy deposited per unit mass of tissue, used to assess heating risk during MRI scans.

Radiofrequency (RF) Coil: A device that transmits and/or receives electromagnetic waves in the MHz range to excite and detect nuclear spin signals.

Parallel Imaging: A technique employing multiple coil elements to accelerate data acquisition and improve spatial encoding.

Metamaterial: An engineered structure with tailored electromagnetic properties that can enhance RF field distribution and increase local SNR.

References

1. A 32-Channel Sleeve Antenna Receiver Array for Human Head MRI Applications at 10.5 T. IEEE Transactions on Medical Imaging (2023).
2. Image reconstruction in SNR units: A general method for SNR measurement†. Magnetic Resonance in Medicine (2005).
3. Screen-printed flexible MRI receive coils. Nature Communications (2016).
4. Parallel transmission for ultrahigh‐field imaging. NMR in Biomedicine (2015).
5. Self-decoupled radiofrequency coils for magnetic resonance imaging. Nature Communications (2018).
6. Boosting magnetic resonance imaging signal-to-noise ratio using magnetic metamaterials. Communications Physics (2019).
7. Biological Effects and Safety in Magnetic Resonance Imaging: A Review. International Journal of Environmental Research and Public Health (2009).
8. MRI‐Related Heating of Implants and Devices: A Review. Journal of Magnetic Resonance Imaging (2020).