A comparison of three radiofrequency coils for NMR studies of conductive samples

Abstract

Three rf coil designs of equal volume (approximately 15 ml) were compared using conductive samples. Magnetic loss into the sample was the dominant noise source. At physiological conductivity the sensitivity of the horizontally aligned solenoid and loop-gap resonator was only 1.3 +/- 0.2 times that of the vertically aligned slotted tube resonator.

MRI Visualization of Small Structures Using Improved Surface Coils

“…9,10 The dielectric losses are caused by voltage differences among different parts of the receiver coil that produce an electrostatic fiel around the coil. 7,8,11 Dielectric losses cause detuning of the receiver circuit, and therefore the reduction of the received signal. These losses can be reduced by designing a balanced SC, which allows improvement of up to 75% compared to the equivalent, unbalanced design.…”

“…The relationship between signal and noise is described by a dimensionless variable known as the signal-to-noise ratio (SNR); the higher the SNR is, the better the image quality. 6,7 Since the objects involved in our studies are very small, quantitative analysis of their properties requires a very high SNR in order to provide sharp images and enough contrast between the region of interest under study and the surrounding structures.…”

High-resolution imaging at 3T and 7T with multiring local volume coils

“…In our design approach for a lower noise and higher signal, we considered the issues mentioned in the literature [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. To compare SNR, we assume uniform excitation in all cases of (A) volume coil; (B) volume transmit, surface coil receive; and (D) multiring surface coil.…”