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Among magnetic resonance imaging (MRI) techniques, ultra-low field (ULF) MRI has the potential to significantly lower the cost of implementation and maintenance, as well as the size of the scanning system. Due to the small amplitude of the signals produced by ULR-MRI, extremely sensitive magnetic sensors are required. Optically pumped magnetometers (OPMs) have been proposed for use in ULF-MRI as ultra-sensitive magnetic sensors capable of detecting very small signals. However, the cost of a ferromagnetic magnetic shield is often not affordable for many applications. By increasing the Larmor frequency, the influence of low-frequency magnetic noise can be mitigated, allowing OPM to be operated without the use of a magnetic shield chamber. This lowers the cost of the magnetic shield and further raises the signal strength, resulting in benefits such as non-prepolarization. We present a method for implementing the ULF-MRI using low-cost OPMs in this study. The Larmor frequency was adjusted to 300 kHz, and three-dimensional (3D) images of a phantom were acquired with a digital resolution of 3 × 3 × 3 mm |
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