Purpose To develop a new concept for a hardware platform that

Purpose To develop a new concept for a hardware platform that enables integrated parallel reception, excitation, and shimming (iPRES). reduce the B0 root-mean-square error by 62C81% and minimize distortions in echo-planar images. The simulations show that dynamic shimming with the 48-coil iPRES array can reduce the B0 root-mean-square Flumequine manufacture error in the prefrontal and temporal regions by 66C79% as compared to static 2nd-order spherical harmonic shimming and by 12C23% as compared to dynamic shimming with a 48-coil conventional shim array. Conclusion Our results demonstrate the feasibility of the iPRES concept to perform parallel excitation/reception and B0 shimming with a unified coil system as well as its promise for applications. simulations with a 48-coil array to demonstrate the feasibility of this approach. Theory The proposed iPRES concept is to implement parallel excitation/reception and B0 shimming by employing a single set of localized coils, Flumequine manufacture with each coil simultaneously working in both an RF mode for excitation/reception and a DC mode for B0 shimming. The DC mode is integrated into each coil element of a conventional RF coil array by modifying its circuit to create a closed loop and enable a DC current to flow, thereby generating additional B0 fields that can be used for B0 shimming. This concept is based on the simple principle in electronics that currents at different frequencies can coexist independently in the same circuit with no electromagnetic interference between them (13,14). This modification does not compromise the design characteristics of the RF coil array for generating flexible B1 fields, including the coil orientation and geometry and the RF current properties (amplitude, phase, timing, and frequency) in each coil element. Furthermore, previous studies on multi-coil field modeling and shimming (10C12) have shown that the B0 field shaping capability of a shim coil array does not critically depend on the exact number, size, positioning, or geometry of the individual coils as long as a reasonably large number of coils is used (typically 24C48). In particular, flexible B0 fields can be generated even if the coils are all oriented parallel to the B0 field, as would be the case for a conventional RF coil array. This advantage is naturally preserved in a unified coil system, which makes the proposed concept generally applicable to a variety of coil geometries designed for different applications, such as cardiac (15), brain (16), or musculoskeletal (17) imaging. In its most general form, the iPRES concept can therefore perform multiple coil RF transmission (for B1 shimming), parallel reception, and B0 shimming with the same CR1 coil array, which may be desirable for specific ultra-high field applications. For other applications (e.g., at 3T and below), it may be preferable to use separate transmit and receive coil arrays, for example to minimize the local specific absorption rate and maximize the signal-to-noise ratio (SNR). In this case, the iPRES concept can still be applied by adding the B0 shimming capability to the receive array. Such an implementation may be more practical as it would require fewer modifications to the architecture of state-of-the-art MRI systems. Methods Proof-of-Concept Implementation with a Two-Coil Array To demonstrate the feasibility of the iPRES concept without loss of generality, proof-of-concept experiments were performed with a two-coil array designed for concurrent RF excitation/reception and B0 shimming. Two RF coil prototypes were designed and built based on an 1111 cm figure-8 surface coil and an 1111 cm single-loop surface coil. Fig. 1 shows a schematic circuit of the modified figure-8 coil. The addition of an inductor L1 to the original circuit forms a Flumequine manufacture closed loop and allows a DC current to circulate in the figure-8 pathway, thereby generating an additional B0 field that can be used for B0 shimming. A DC power supply is fed into the circuit across the frequency-tuning capacitor. As a result, both the RF and DC currents can circulate in.

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