Epilepsy
Identifying very small brain lesions on MRI is very important in epilepsy. Conventional MRI field strengths (1.5T and 3T) can only reveal 60%-85% of these lesions. The 7T Epilepsy Task Force recommended the use of 7T MRI in clinical practice (Ref). Here is an example of how 7T can detect subtle abnormalities in the brain. The red crosshairs/arrows pinpoint the location of an area of focal cortical dysplasia (FCD), which was detected by visual analysis of 7T images. The vascular changes associated with the FCD can be well appreciated on the T2*-weighted GRE images in panel C (arrows).
Ref: 7T Epilepsy Task Force Consensus Recommendations on the Use of 7T MRI in Clinical Practice, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055334/
Multiple Sclerosis (MS)
7T MRI offers increased signal-to-noise ratio (SNR) and enhanced susceptibility effects, improves conspicuity of MS pathological hallmarks including cortical demyelination and the central vein sign (Ref). Observations from postmortem studies suggest that UHF imaging enhances sensitivity for cortical lesion detection up to approximately 30% to 40% (see sample images)
Ref: New Prospects for Ultra-High-Field Magnetic Resonance Imaging in Multiple Sclerosis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8505164/
7T MRI offers superior conspicuity of veins due to enhanced contrast-to-noise ratio for detecting central vein sign (see sample images)
7T T2*w
Ref: New Prospects for Ultra-High-Field Magnetic Resonance Imaging in Multiple Sclerosis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8505164/
DBS planning
Deep brain stimulation (DBS) is essential in treating advanced Parkinson disease (PD). 7T MRI enables better visualization of targets for DBS in PD. 7T MRI provides higher image contrast and resolution for brain tissues especially subcortical nuclei due to strong susceptibility contrast (see sample images of subthalamic nucleus (STN) and globus pallidus internus (Gpi)). Other conditions that may benefit from 7T MRI for DBS planning include tremor, dystonia, chronic pain, obsessive-compulsive disorder, and depression.
Ref:Direct visualization of deep brain stimulation targets in Parkinson disease with the use of 7-tesla magnetic resonance imaging, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160785/
Cerebral small vessel disease (cSVD)
Ultra-high resolution MRA imaging using 7T MRI can be employed to noninvasively visualize the lenticulostriate arteries (LSA) that supply the basal ganglia and internal capsule. One study reported the LSA branch number and radii are reduced in persons with subcortical vascular dementia (SVaD) (see sample images)(Ref)
Ref:D Measurements of lenticulostriate arteries using 7T MRI: new imaging markers for subcortical vascular dementia https://www.sciencedirect.com/science/article/pii/S0022510X12002602
7T MRA study detected a decrease in the number of LSA branches, and an increase in the proportion of discontinuous LSAs in patients with genetic cSVD (CADASIL) compared with healthy controls. (see sample images). 7T MRI is also able to visualize lacuna infarcts (C), white matter hyperintensity (D) and cerebral microbleeds (E) in CADASIL patients with great detail and conspicuity (Ref).
Ref:Lenticulostriate Arteries and Basal Ganglia Changes in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy, a High-Field MRI Study https://www.frontiersin.org/articles/10.3389/fneur.2019.00870/full
Musculoskeletal MRI
7T MRI provides higher spatiotemporal and spectral resolution compared to 1.5 or 3T MRI (see sample images showing improved spatial and contrast resolution for cartilage visualization at 7T). Better morphologic, biochemical, and functional details of musculoskeletal tissues can be observed using 7T MRI which improves the diagnostic accuracy, in particular articular cartilage.
Ref: Musculoskeletal MRI at 7 T: do we need more or is it more than enough? https://eurradiolexp.springeropen.com/articles/10.1186/s41747-020-00174-1 Figure Ref: The new frontier of imaging: the micron https://www.clinexprheumatol.org/pubmed/find-pii.asp?pii=29352839&pii=29352839
Image Gallery
T2-TSE of Hippocampus
3T: T2 TSE, 0.4x0.4x2.0mm3, 8:00 for 30 slices
7T: T2 TSE, 0.1x0.1x2.0mm3, 4x4:58 for 30 slices
T2-TSE of Hippocampus
3T: T2 TSE, 0.4x0.4x2.0mm3, 8:00 for 30 slices
7T: T2 TSE, 0.1x0.1x2.0mm3, 4x4:58 for 30 slices
7T T2 SPACE - Perivascular Space (PVS)
Sepehrband et al. ISMRM 2020
Multi-Shell HARDI Diffusion MRI
3T: Diffusion b=0, 1500, 3000, 1.5mm isotropic whole brain in 6:00
7T: Diffusion b=0, 1000, 2000, 1.25mm isotropic whole brain in 9:00
Multi-Shell HARDI Diffusion MRI
3T: Diffusion b=0, 1500, 3000, 1.5mm isotropic whole brain in 6:00
7T: Diffusion b=0, 1000, 2000, 1.25mm isotropic whole brain in 9:00
Tractography and Cortical Diffusion MRI
7T enables cortical fibers orientation mapping
Susceptibility weighted imaging (SWI)
3T: SWI minIP, 0.9x0.9x1.2mm3, 5:00
7T: SWI minIP, 0.2x0.2x1.5mm3, 5:15
T2-TSE of Hippocampus
7T 3D pCASL CBF 2x2x4 mm3
3T 3D pCASL CBF 2x2x4 mm3
Arterial spin labeling (ASL) perfusion MRI
Left: 7T 3D pCASL CBF 2x2x4mm3, Right: 3T 3D pCASL CBF 2x2x4mm3
Internal auditory canal imaging
Left internal auditory canal at 7T: T2space acquisition at 0.63 mm3
Proton MR Spectroscopy (MRS)
Fast spectroscopic imaging (TE40ms, TA 4.5min)