Comparison between linear and circular polarization for magnetic resonance imaging of objects and human subjects indicates according to Glover G.H. et al (1985) that use of circular polarization reduces excitation power up to 50%, improves signal-to-noise ratio (√2) and reduces significantly artifact intensity.

 

According to Schratter M. et al (1990) it improves signal-to-noise ratio, lowers background noise and therefore ameliorates significantly images sharpness, and moderately the recognition of anatomical details. According to the same authors, additional advantages of circular polarization are shorter measurement times (reduced number of acquisitions) and possibility to use thinner slices.

 

 

Additionally, as mentioned by the study of Mrózek M. et al entitled "Circularly polarized microwaves for magnetic resonance study in the GHz range: application to nitrogen-vacancy in diamonds": 

"In contrast to linear polarization, the circular polarization allows one to eliminate the Bloch-Siegert shift (1), increase the effective strength (2), improve the homogeneity (3) of the field-matter interaction and to address a specific spin state in the case of many-state quantum systems, which is crucial for experiments in the field of quantum information (4,5). For small frequencies this task is easily accomplished by two orthogonal coils driven by two radio-frequency (RF) signals phase shifted by 90°, produced by the, so called, quadrature coils."