skope™-fx - Skope

skope-fx

skope-fx is the software at the heart of field monitoring. It enables the collection and analysis of dynamic field data for field monitored image reconstruction and MR methods development.

Introduction

Skope’s field explorer (skope-fx), is the software architecture that drives field-monitoring workflows. With the latest release, skope-fx enters its second generation delivering a completely redesigned and simplified user experience, and enhanced system performance. At the heart of this release is a seamless synergy with NYOX, Skope’s new hardware platform for field monitoring. Whether you're planning, executing, or analyzing field acquisitions, skope-fx provides a streamlined interface, modern graphics, and powerful new features including accelerated and responsive user workflows, built-in data compression for efficient handling as well as intuitive and simplified navigation. Importantly, skope-fx maintains backward compatibility with data from earlier generations, allowing smooth integration into existing workflows.

Acquisition Setup

skope-fx provides users with flexible control over field monitoring acquisition parameters, allowing adjustments to meet various measurement requirements. Parameters can be set manually or automatically via the MR scanner, helping to streamline setup and reduce the chance of configuration errors.

Calibration of Field Probes

Prior to acquisition, the probe locations and resonance frequencies are determined through a guided calibration menu. During this process, signal quality indicators such as lifetime and SNR are displayed, providing an initial check of system performance. The interface supports straightforward exploration and adjustment of settings, contributing to a reliable and efficient setup.

Dynamic field camera calibration: single probe signal readouts (magnitude, top; phase, bottom).

Dynamic field camera calibration: spatial locations of the field probes.

Dynamic Field Monitoring

Field probe data acquired in skope-fx is processed using spherical harmonic fitting, enabling detailed analysis and visualization of field dynamics. By tracking linear field variations, users can examine the actual shapes of readout gradients. Nonlinear higher-order field components can also be visualized, providing a broader overview of field behavior. This information can be used to reduce image distortions and support sequence optimization.

Fig. 1: Signal evolutions recorded by Skope’s dynamic field cameras reporting for a Fast-Field-Echo readout: k-space trajectories (top) and gradients (bottom) measured for a single readout.

Fig. 2: Signal evolutions recorded by Skope’s dynamic field cameras reporting for a Fast-Field-Echo readout: k-space trajectories (top) and gradients (bottom) measured for a range of readout acquisitions showing increments of phase encoding gradients.

Fig. 3: Signal evolutions recorded by Skope’s dynamic field cameras reporting for a Fast-Field-Echo readout: linear field dynamics for a single k-space readout.

Fig. 4: Signal evolutions recorded by Skope’s dynamic field cameras reporting for a Fast-Field-Echo readout: nonlinear field dynamics up to the 3rd order for a single k-space readout.

Inspection of k-space Trajectories

In skope-fx, visualizing the measured gradient waveforms and corresponding k-space trajectories offers a straightforward and efficient framework for pulse sequence design and debugging, allowing users to easily verify expected behavior. The parametric display of linear dynamic field evolutions provides a fast and direct method for inspecting k-space trajectories.

Fig. 1: EPI readout: k-space time course recorded by a Skope dynamic field camera.

Fig. 2: EPI readout: k-space trajectory recorded by a Skope dynamic field camera.

Fig. 3: Spiral readout: k-space time course recorded by a Skope dynamic field camera.

Fig. 4: Spiral readout: k-space trajectory recorded by a Skope dynamic field camera.

System Characterization

Inspecting the actual behavior of pulse sequences is a valuable approach for characterizing both MR systems and sequence performance. Interactions between hardware components can introduce a variety of image artifacts, which may become more pronounced over repeated acquisitions. Identifying the sources of these errors provides critical insights for optimizing protocol design and improving overall image quality.

Fig. 1: Examples of B₀ dynamic nonlinear field temporal drifts recorded by a Skope Field Camera for an EPI based diffusion-weighted imaging protocol. The colorcode scheme display a range of acquired temporal field dynamics, as reported by the Acquisition legend. Progressive acquisitions explore stronger diffusion encoding gradients as well as different diffusion encoding directions. The B₀ terms exhibit direction-dependent dynamics due to the influence of the preceding diffusion gradients, highlighting the impact of gradient history on field evolution.

Fig. 2: Examples of high order terms (3rd) dynamic nonlinear field temporal drifts recorded by a Skope Field Camera for an EPI based diffusion-weighted imaging protocol. The colorcode scheme display a range of acquired temporal field dynamics, as reported by the Acquisition legend. Progressive acquisitions explore stronger diffusion encoding gradients as well as different diffusion encoding directions. The high order terms display stronger offsets when higher diffusion encoding gradient are prescribed, highlighting the impact of diffusion encoding on field evolution.

Fig. 3: Examples of B₀ dynamic nonlinear field temporal drifts recorded by a Skope Field Camera for a Fast-Field-Echo protocol.

Compact Data Format

The new hierarchical data format, introduced with the NYOX platform and based on HDF5, enables the storage of an entire measurement session in a single file. This format ensures that all necessary information for viewing and reprocessing the acquired data is readily accessible to the user. By storing only the low-pass filtered raw field probe signal, the raw data size is reduced by a factor of 5 to 10 compared to the legacy file format. The latest version of skope-fx is back compatible with any data collected with skope-fx (up to release 2018).

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