Practical algorithmic cooling technique for MRI and NMR Imaging


Magnetic Resonance techniques rely on detection of the unique spectrum of different elements. All materials in the excited state have spins that resonate at a unique frequency. Normally, these spins point in random directions and cancel each other out. Magnetic Resonance imaging applications, such as Magnetic Resonance Imaging (MRI) and Nuclear Magnetic Resonance (NMR), use a large magnetic field to align the spins in the same direction and reduce the entropy. This usually requires large magnetic fields as large as a few Tesla.

Conventional techniques for improving the resolution in Magnetic Resonance imaging and spectroscopy, rely on increasing the magnetic field. This can be both very challenging and demanding.

Description of the invention

The University of Waterloo has developed a technique/algorithm that improves the image resolution using electromagnetic pulses.  The pulses are designed based on the specifics of the target material. With a specifically optimized pulse, the technique can increase the order for the specific species of spin under study or imaging.  MRI and NMR spectrometers are equipped with an antenna that can generate these electromagnetic pulses.

As most Magnetic Resonance based spectrometers are equipped with Radio Frequency(RF) antenna that are capable of generating these electromagnetic pulses, this new technique can be widely applicable to such applications as NMR, ESR, and MRS.


By introducing optimized, fixed electromagnetic pulses, the resolution of MRI or NMR images  can be significantly (in some cases, up to an order of magnitude) enhanced without the need to increase magnetic field and associated device physical footprint and cost.

Other techniques designed to achieve the maximum cooling (i.e. the maximum nuclear spin alignment) using algorithmic pulsing, require a different set of pulses in each round of aligning the spins and this set of pulses depend on the state of the spins in the sample that cannot be measured easily. By contrast, the UW algorithm does not rely on the state of the sample through the imaging process but rather is comprised of a fixed pulse that is repeated in each round of aligning the spins.

Potential advantages or uses

This technique may be implemented as a software update that increases the resolution of older or low magnetic field MR spectrometers machines.

This new technique is applicable to a variety of applications including nuclear magnetic resonance (NMR), electron spin resonance (ESR) and other similar magnetic resonance based spectroscopy techniques, medical imaging, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) and similar techniques, quantum metrology such as NV-centre based magnetometer and quantum computation for initialisation of quantum bits.

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Algorithmic cooling technique



Patent status

US Patent Pending

Stage of development

Concept fully developed and confirmed through simulation and analytical calculations

Scott Inwood
Director of Commercialization
Waterloo Commercialization Office
519-888-4567, ext. 33728