Gradient-Free MR Spatial Selectivity With Multi-Coil RF Fields

The system divides the MR testing space into multiple distinct excitation areas by using multiple coil groups (first coil group and second coil group) that generate different RF fields. Each coil group is responsible for a specific spatial region, enabling spatial selectivity without requiring a complex gradient system. The segmentation of coil groups creates naturally distinct excitation zones based on their different RF field characteristics.

Different coil groups are designed with different RF field characteristics to provide locally optimized excitation for different spatial areas. The first coil group generates an RF field with specific properties for its target area, while the second coil group generates a different RF field for its target area. This local quality differentiation enables spatial selectivity through inherent field differences rather than complex gradient encoding.

Each coil group serves multiple functions: it acts as both a transmission coil for generating RF fields and as a reception coil for detecting MR signals from its corresponding excitation area. This multi-functionality reduces the need for separate transmit and receive coil systems, thereby limiting the increase in device complexity while maintaining spatial encoding capability.

Instead of using a single coil system with complex gradient fields to achieve spatial encoding, the invention inverts the approach by using multiple coil groups with inherently different RF field characteristics. The spatial encoding is achieved through the natural field differences of the coil groups rather than through active gradient manipulation, simplifying the overall system architecture.

The system uses the TR switch to control the sequential operation of different coil groups, with the data processing module coordinating the transmission and reception timing. This feedback control ensures that signals are acquired in the correct sequence and that the different signal intensities from different coil groups are properly managed, maintaining reliability despite spatial selectivity requirements.

The system employs periodic alternating operation between the first coil group and second coil group, with each coil group transmitting RF fields and receiving signals in alternating time periods. This periodic action allows the system to manage the different signal intensities from different excitation areas systematically, maintaining signal reliability while achieving spatial selectivity through time-multiplexed operation.