Open Source 3D Multipurpose Measurement System with Submillimetre Fidelity and First Application in Magnetic Resonance

Abstract

Magnetic resonance imaging (MRI) is the mainstay of diagnostic imaging, a versatile instrument for clinical science and the subject of intense research interest. Advancing clinical science, research and technology of MRI requires high fidelity measurements in quantity, location and time of the given physical property. To meet this goal a broad spectrum of commercial measurement systems has been made available. These instruments frequently share in common that they are costly and typically employ closed proprietary hardware and software. This shortcoming makes any adjustment for a specified application difficult if not prohibitive. Recognizing this limitation this work presents COSI Measure, an automated open source measurement system that provides submillimetre resolution, robust configuration and a large working volume to support a versatile range of applications. The submillimetre fidelity and reproducibility/backlash performance were evaluated experimentally. Magnetic field mapping of a single ring Halbach magnet, a 3.0 T and a 7.0 T MR scanner as well as temperature mapping of a radio frequency coil were successfully conducted. Due to its open source nature and versatile construction, the system can be easily modified for other applications. In a resource limited research setting, COSI Measure makes efficient use of laboratory space, financial resources and collaborative efforts.

A 32-channel parallel transmit system add-on for 7T MRI

“…Only one analog and three digital signals have to be taken from the original MRI system to make the add-on fully functional. In comparison to the development of complete consoles [48, 49], which might pose more powerful tools, the big advantage is the use of the standard vendor software that clinicians and researchers are accustomed to. For simple RF shimming with the add-on system, the vendor-provided sequences can remain completely unchanged.…”

Image distortion correction for MRI in low field permanent magnet systems with strong B0 inhomogeneity and gradient field nonlinearities

“…The low field system is a k = 1 Halbach magnet, constructed as described in [18], producing an 0.05 T (2.15 MHz) magnetic field at the center of the bore. The main magnetic field was measured in a 225 × 225 × 300 mm 3 field of view (FOV) at 5 × 5 × 5 mm 3 resolution using a gaussmeter (Lake Shore Cryotronics, Westerville, OH) connected to a 3D positioning robot [19]. The center frequency was subtracted from the field map, which was subsequently converted to Hz and fitted to a basis of spherical harmonics up to 15th order (…”

Parallel transmission medical implant safety testbed: Real‐time mitigation of RF induced tip heating using time‐domain E‐field sensors

“…For precise, reproducible and automated positioning of the guidewire‐sensor assembly, the open‐source hardware 3D positioning system COSI Measure was used 47 . A wireless Bluetooth connection was established between positioning system and Tx/Rx console to steer the positioning system from within the pTx implant safety testbed console and to allow automated mapping.…”