Seven-Tesla MRI and neuroimaging biomarkers for Alzheimer’s disease

Abstract

<jats:p>The goal of this paper was to review the effectiveness of using 7-T MRI to study neuroimaging biomarkers for Alzheimer’s disease (AD). The authors reviewed the literature for articles published to date on the use of 7-T MRI to study AD. Thus far, there are 3 neuroimaging biomarkers for AD that have been studied using 7-T MRI in AD tissue: 1) neuroanatomical atrophy; 2) molecular characterization of hypointensities; and 3) microinfarcts.</jats:p> <jats:p>Seven-Tesla MRI has had mixed results when used to study the 3 aforementioned neuroimaging biomarkers for AD.</jats:p> <jats:p>First, in the detection of neuroanatomical atrophy, 7-T MRI has exciting potential. Historically, noninvasive imaging of neuroanatomical atrophy during AD has been limited by suboptimal resolution. However, now there is compelling evidence that the high resolution of 7-T MRI may help overcome this hurdle. Second, in detecting the characterization of hypointensities, 7-T MRI has had varied success. PET scans will most likely continue to lead in the noninvasive imaging of amyloid plaques; however, there is emerging evidence that 7-T MRI can accurately detect iron deposits within activated microglia, which may help shed light on the role of the immune system in AD pathogenesis. Finally, in the detection of microinfarcts, 7-T MRI may also play a promising role, which may help further elucidate the relationship between cerebrovascular health and AD progression.</jats:p>

Investigation of hippocampal substructures in focal temporal lobe epilepsy with and without hippocampal sclerosis at 7T

“…The higher spatial resolution provided by 7T MRI has allowed improved SNR, revealing internal substructures of the hippocampus not visible at the resolution provided by 1.5T. 20,21 This work aimed to use the increased resolution for in vivo detection of pathological TLE subtypes for better prediction of surgical outcomes. To this end, an atlas of hippocampal substructures was developed through the manual segmentation of healthy volunteer MRI scans at 7T.…”

“…This increased SNR can also be exploited through imaging with increased resolution at 7T. This field strength has been shown to consistently reveal hippocampal subfield morphometry at 300–500 μm within a clinically acceptable imaging time …”

Utility of 7 Tesla MRI for Preoperative Planning of Endoscopic Endonasal Surgery for Pituitary Adenomas

“…There is growing interest in exploiting imaging at 7 T to characterize structures and processes for various disease profiles including nonlesional epilepsy, 11 multiple sclerosis, 12 and Alzheimer's disease. 13 However, few studies have employed 7 T MRI to image skull base tumors, in part due to physical complexities of imaging in close proximity to bone and air-filled cavities in the skull base. de Rotte et al first reported the feasibility of pituitary imaging at 7 T MRI.…”

Clinical PET Imaging of Microglial Activation: Implications for Microglial Therapeutics in Alzheimer’s Disease

“…High-field MRI scanners, particularly 7 T MRI, have been increasingly used as powerful tools for AD studies in vivo . The main neuroimaging biomarkers of 7 T MRI that have been identified for AD patients are neuroanatomical atrophy, molecular characterization of hypo-intensities and micro-infarcts ( Ali et al, 2015 ). Recent studies have shown colocalization of ferritin with microglia in AD patient samples ( van Duijn et al, 2013 ; Kwiatek-Majkusiak et al, 2015 ), and high-field MRI is quite sensitive to microscopic iron.…”