Ultrahigh‐resolution quantitative spinal cord MRI at 9.4T

Abstract

Purpose To present the results of the first human spinal cord in vivo MRI scans at 9.4T. Methods A human brain coil was used to image the human spinal cord at 9.4T. All anatomical images were acquired with a T2*‐weighted gradient‐echo sequence. A comparison of the influence of four different B0 shimming routines on the image quality was performed. Intrinsic signal‐to‐noise‐ratio maps were determined using a pseudo‐multiple replica approach. Measurements with different echo times were compared and processed to one multiecho data image combination image. Based on the multiecho acquisitions, T2*‐relaxation time maps were calculated. Algorithmic spinal cord detection and gray matter/white matter segmentation were tested. Results An echo time between 9 and 13.8 ms compromised best between gray matter/white matter contrast and image quality. A maximum in‐plane resolution of 0.15 × 0.15 mm2 was achieved for anatomical images. These images offered excellent image quality and made small structures of the spinal cord visible. The scanner vendor implemented B0 shimming routine performed best during this work. Intrinsic signal‐to‐noise‐ratio values of between 6600 and 8060 at the upper cervical spinal cord were achieved. Detection and segmentation worked reliably. An average T2*‐time of 24.88 ms ± 6.68 ms for gray matter and 19.37 ms ± 8.66 ms for white matter was calculated. Conclusion The proposed human brain coil can be used to image the spinal cord. The maximum in‐plane resolution in this work was higher compared with the 7T results from the literature. The 9.4T acquisitions made the small structures of the spinal cord clearly visible.

Multiparametric magnetic resonance imaging for detection of pathological changes in the central nervous system of a mouse model of multiple sclerosis in vivo

“…However, they should be pursued because they will assist clinical diagnosis and efficacy of treatments. Cryoprobe technology is currently not available in human scanners, but increased MR sensitivity may be obtained using a dedicated spinal cord coil and imaging at ultrahigh field using 7‐ and 9.4‐T scanners 66,67 …”

“…Cryoprobe technology is currently not available in human scanners, but increased MR sensitivity may be obtained using a dedicated spinal cord coil and imaging at ultrahigh field using 7‐ and 9.4‐T scanners. 66 , 67 …”

Ultra-high field spinal cord MRI in multiple sclerosis: Where are we standing? A literature review

“…With 7T scanners becoming more accessible and the first scanners being FDA-approved for clinical use, this will further drive progress in UHF research. Additionally, recently, the first steps have been made in moving even beyond 7T for in vivo spinal cord MRI (Geldschlager et al, 2021) with encouraging results. Finally, besides the needed technical improvements, spinal cord UHF MRI, on top of the expensive scanner (7 to 10 million US dollars (Ineichen et al, 2021)), requires specialized coils and hardware (e.g., shim coils) in order to achieve acceptable quality.…”

Actively-shielded ultrahigh field MRI/NMR superconducting magnet design

“…Ultrahigh field strength and large bore size are two main challenging technological parameters in superconducting magnet development, and the corresponding limits of technology have been pushed again and again. After the 9.4 T whole-body MRI revealing superb imaging performance in the brain function and anatomical structure [11,32,33], a higher magnetic field target applied in the brain mechanism and complex nerve disease study fascinates scientists [34,35]. The magnetic field strength of whole-body MRI has been elevated to 10.5 T and was first applied to human body scanning in 2018 [36].…”