SQUID-detected magnetic resonance imaging in microtesla fields.

Area of Science:

• Biophysics
• Medical Imaging
• Quantum Sensing

Background:

• Superconducting Quantum Interference Devices (SQUIDs) offer ultra-low noise magnetometry.
• Microtesla magnetic fields are suitable for Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI).

Purpose of the Study:

• To demonstrate the capabilities of SQUID-based magnetometers for microtesla NMR and MRI.
• To evaluate the potential of microtesla MRI for enhanced contrast imaging, particularly for tumors.

Main Methods:

• Utilized an untuned superconducting flux transformer coupled to a SQUID for magnetic field noise reduction.
• Developed an MRI system operating at 132 microtesla (5.6 kHz proton frequency).
• Measured longitudinal relaxation time (T1) in agarose gel across a wide frequency range.

Main Results:

• Achieved a magnetic field noise of 10(-15) T Hz(-1/2) with the SQUID magnetometer.
• Demonstrated an in-plane MRI resolution of 0.7 x 0.7 mm2 in phantoms.
• Observed significantly greater T1-differentiation at fields below a few millitesla.

Conclusions:

• SQUID-based microtesla MRI provides high-resolution imaging.
• Microtesla MRI exhibits superior T1-weighted contrast for tumor imaging compared to high-field MRI without contrast agents.
• This technology holds promise for improved non-invasive tumor detection and characterization.