Ultra-Low-Field MRI and Its Combination with MEG

Recent progress in SQUID instrumentation has demonstrated the feasibility of using SQUID sensor arrays in MEG helmets to record also MRI data. Here we describe the basic principles of MRI as well as the special requirements and solutions needed to perform ultra-low-field MRI concurrently with MEG. We consider it is feasible to build practical MEG–MRI instruments for scientific experimentation and for clinical use. Acquiring an MRI with 2-mm spatial resolution and sufficient signal-to-noise ratio and contrast appears achievable without essentially lengthening the normal MEG measurement time.

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