Emerging Use of Ultra-High-Field 7T MRI in the Study of Intracranial Vascularity: State of the Field and Future Directions

Abstract

Cerebrovascular disease is a major source of mortality that commonly requires neurosurgical intervention. MR imaging is the preferred technique for imaging cerebrovascular structures, as well as regions of pathology that include microbleeds and ischemia. Advanced MR imaging sequences such as time-of-flight, susceptibility-weighted imaging, and 3D T2-weighted sequences have demonstrated excellent depiction of arterial and venous structures with and without contrast administration. While the advantages of 3T compared with 1.5T have been described, the role of ultra-high-field (7T) MR imaging in neurovascular imaging remains poorly understood. In the present review, we examine emerging neurosurgical applications of 7T MR imaging in vascular imaging of diverse conditions and discuss current limitations and future directions for this technique.

MRI with ultrahigh field strength and high-performance gradients: challenges and opportunities for clinical neuroimaging at 7 T and beyond

“…The exclusion of diffusion-weighted imaging (DWI) as part of the protocol precludes its use in current clinical practice for the evaluation of acute stroke patients [ 97 ]. Despite this, the high SNR, high spatial resolution, and high CNR afforded by ultrahigh field MRI can be used to evaluate small cerebrovascular lesions (such as cortical microinfarcts) and vasculature on the submillimeter scale, thereby allowing better characterization of cerebrovascular disease including stroke using 7 T compared to lower field strengths [ 52 , 97 , 98 ].…”

“…The increased SNR, higher spatial resolution, and better fluid suppression seen at 7 T have been leveraged to evaluate patients with aneurysms that are at high risk for rupture, predict potential for atherosclerotic plaque rupture, and characterize infarct morphology [ 52 ]. For example, Sato et al used gadolinium-enhanced T1-weighted magnetization prepared rapid gradient recalled echo (MPRAGE) sequences at 7 T to describe aneurysm wall microstructures responsible for gadolinium enhancement not seen at lower field strengths.…”

High-Resolution Imaging for the Analysis and Reconstruction of 3D Microenvironments for Regenerative Medicine: An Application-Focused Review

“…MRI is the imaging modality of choice for the depiction of soft tissues. The inherent superb soft tissue contrast in combination with the absent radiation burden has rendered MRI the key imaging modality for a great variety of applications, including neurological and musculoskeletal disease [ 52 , 53 ]. The magnetic field strength of most clinical-grade magnets ranges between 1.5 T and 3 T, with 7 T systems being slowly introduced in hospitals.…”

Assessing the Utility of Low Resolution Brain Imaging: Treatment of Infant Hydrocephalus

“…The quality of an MRI image ultimately depends on the signal-to-noise ratio (SNR) per voxel. Higher field strength systems (>1.5 Tesla) can produce increased signal-to-noise pushing voxel size as low as hundreds of micrometers [13]. Low-field systems (<0.1 Tesla) inherently suffer from low signal-to-noise placing limits on achievable voxel size with typically more baseline noise than most clinicians are accustomed to.…”