NeuroCam™ 7T

• Field fluctuations from system and physiological sources noticeably degrade image quality at ultra-high field strength
• High-performance scanners operating at the technical limit of the hardware inevitably exhibit some system non-linearities that influence image quality
• Non-Cartesian encoding schemes are attractive for advanced neuroimaging but require very accurate knowledge of the encoding fields
• Both, high SNR and spatial resolution are required to answer some of the most fundamental questions about the human brain

MRI has revolutionized our understanding of the human brain by providing non-invasive and detailed insights into its structure and function. The advent of ultra-high field (UHF) MRI scanners, operating at field strengths of 7 Tesla and beyond, has opened up new possibilities for exploring the complexities of the brain. However, along with the numerous advantages offered by UHF imaging, several challenges and considerations must be addressed to ensure optimal image quality and reliable data acquisition. The pursuit of answering fundamental questions about the human brain necessitates both high SNR and spatial resolution in UHF MRI. Achieving these requirements simultaneously presents a technical challenge due to various trade-offs and limitations inherent to UHF systems. Innovations in coil design, parallel imaging techniques, and image reconstruction methods are continuously evolving to strike a balance between SNR and resolution, enabling researchers to obtain the highest quality data for insightful brain investigations. Efforts to mitigate field fluctuations, correct system non-linearities, and optimize non-Cartesian encoding schemes are essential for improving image quality and ensuring reliable data acquisition.

Head Coil with Integrated Field Monitoring for Accurate Neuroimaging at 7 Tesla

NeuroCam^TM 7T with its 64 highly sensitive receive elements provides new opportunities for neuroimaging at 7 Tesla. The tight-fitting geometry ensures optimal coil-head coupling, maximizing sensitivity and minimizing signal loss. Additionally, it features an 8 or 16 channel transmit coil, enabling parallel transmission to achieve a homogeneous spin excitation. By elevating SNR and enabling finer spatial resolution, NeuroCam^TM 7T captures subtle anatomical details and facilitates the detection of intricate brain activity.

Susceptibility-Weighted Imaging

Minimum intensity projection

Acquisition parameters Field-of-view: 220 x 179 mm Slices: 72 In-plane resolution: 0.1 x 0.1 mm Slice thickness: 1.5 mm Acceleration factor PE: 3 Acquisition time: 7:29 CP mode

T2-Weighted Imaging of the Hippocampus

Acquisition parameters Field-of-view: 80 x 162 mm Slices: 42 In-plane resolution: 0.2 x 0.2  mm Slice thickness: 1.5 mm Acceleration factor PE: 2 Acquisition time: 6:12 CP mode

T2 Turbo Spin Echo Imaging

Acquisition parameters Field-of-view: 230 x 173 mm Slices: 39 In-plane resolution: 0.2 x 0.2 mm Slice thickness: 3 mm Acceleration factor PE: 2 Acquisition time: 3:38 CP mode

T2 FLAIR FS Turbo Spin Echo Imaging

Acquisition parameters Field-of-view: 220 x 220mm In-plane resolution: 0.55 x 0.66 mm Slice thickness: 2 mm Acceleration factor PE: 3 Acquisition time: 4:00 pTX mode

DICOM Viewer

Further Information & Images

NeuroCam^TM 7T is available with a fully integrated array of 16 fluorine field probes for concurrent measurement of the encoding fields. The probes are located in the enclosure of the receiver array and distributed around the imaging volume to provide optimal conditioning for the spatial expansion of the spherical harmonics basis fields. The housing of the frontend electronics for the field probe array is attached to the back of the coil, where it does not obstruct the visual field of the rear-view mirror.

Physiological fluctuations

By monitoring the field, adjustments can be made in real time to compensate for fluctuations caused by breathing or other factors, ensuring a more stable and uniform field throughout the imaging procedure. Alternatively, the corrections can be made during image reconstruction by incorporating the measured fields in the process. The figure below shows frequency fluctuations caused by a breathing subject in a 7 T MR scanner as measured by four field probes at different locations in the scanner bore (Courtesy of DZNE Bonn, Germany).

Higher-order field terms

The example below demonstrates the influence of a diffusion preparation on a spiral readout (Courtesy of Sajjad Feizollah and Christine Tardif, McGill University, Montreal, Canada). The data was acquired with a Clip-on Camera on a 7T scanner. The animation on the left-hand side illustrates a field-monitored spiral trajectory that was not preceded by a diffusion gradient. Upon closer examination, distinct characteristics differentiate it from its counterpart on the right-hand side that is influenced by a preceding diffusion gradient. Particularly noteworthy is the considerable disparity observed in the zeroth order term (k0), which represents the fluctuation of the global magnetic field. Upon magnification, discernible amplification of higher order fields is observed beyond the zeroth term. These amplified higher-order fields can be attributed to eddy currents induced by the diffusion gradients. Higher-order terms can have a direct impact on image quality and geometric consistency, which makes their characterization very important.

The ability to simultaneously measure the actual encoding fields provides the opportunity to select more demanding yet efficient readout schemes. To illustrate this, intra-cellular volume fraction (ICVF) maps derived from diffusion-weighted data acquired using two different readout techniques are shown below: echo planar imaging (EPI) on the left and spiral imaging on the right. The usage of a spiral readout, which achieves higher SNR, directly translates into ICVF maps of superior quality.

Versions

NeuroCam^TM 7T exists in three versions, each tailored to meet specific imaging needs. Choose from our Standard, Advanced, and Excellence versions, each offering unique features and capabilities for exceptional neuroimaging performance.