The sectorial loop‐gap resonator for ³¹P NMR of the adult human liver at 1.5 t with surface tissue suppression

Abstract

A new type of loop-gap resonator, which because of its topology is called a "sectorial resonator," is described in considerable analytical detail. It was used for 31P NMR of the livers of two human adult normal volunteers. An effective strategy for suppression of signals from surface tissue was developed. Depth selection was achieved using a separate excitation coil, permitting a reasonable degree of control of the shape of the sensitive region by adjustment of the dimensions of the excitation coil and of the type of pulse delivered. In addition a new principle for cancellation is described: the topology of the sectorial resonator leads to cancellation signals from tissue masses at the two openings of the structure. Using a phase-alternated repeated 90 degrees FID pulse sequence, good spectra were achieved in 2.5 min that are free from contamination by the phosphocreatine peak.

Use of mutually inductive coupling in probe design

“…We could simply extract i 2 from the inversion of Eq. [5] or, alternatively, note that the back EMF induced in the matching coil is [10] and use Eq. [6] for Z in .…”

“…However, mutually inductive coupling, wherein the probe coil is the primary and a separate matching loop is the secondary, although common in ESR was probably only first reported in NMR in 1983 in the articles on quadrature laboratory frame detection by Hoult et al (4,5). With an ESR background, Grist and Hyde naturally used this matching method (6) and the concept was soon expanded by Decorps and colleagues (7), who used both tuned and untuned matching loops, and by Froncisz et al (8,9) and Jesmanowicz et al (10); various applications were also described by Kuhns and coworkers (11). Meanwhile, Schnall et al (12) published a note on the advantages of the method with an implanted probe, and this use appears to be the only one where the technique has become standard (13)(14)(15)(16)(17)(18)(19)(20)(21)(22), despite Kuhn et al's opinion that inductive coupling techniques "should be part of the standard repertoire of probe designers."…”

Parallel‐plate split‐conductor surface coil: Analysis and design

“…Surface coils of various configurations have been proposed by a number of researchers for magnetic resonance imaging experiments (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Each type of coil was designed to meet specific requirements and applications.…”

A complication in prescan strategy when using surface coils

“…The free space field distribution of the receiving coil was calculated using the Biot-Savart law following the procedure of Ref. (3). Results are shown in Fig.…”