Magnetic resonance imaging (MRI) has become a key technology for the understanding of cerebrovascular diseases in humans. In small vessel-associated forms of brain damage, for example, MRI allows for the detection of subtle alterations as microinfarcts, microbleeds or white-matter lesions as surrogates of an underlying disease.
Spatial resolution is crucial to identify these subtle disease-specific alterations. In this respect, the increase in the magnetic field strength from 1.5 Tesla (T) to 3 T has offered a considerable diagnostic benefit. Several years ago, ultrahigh-field MRI (UHF MRI) at 7 T became available for human brain imaging and now provides diagnostic benefit in nonvascular pathologies, for example, in multiple sclerosis1 and brain tumors.2 For cerebrovascular diseases, recent data showed that 7T MRI is not only equivalent to 3T MRI with respect to diagnostic performance, but it also offers additional information about ischemic lesion morphology, perilesional alterations, white-matter lesions, and vessel structure.3, 4, 5
Within this emerging field, the current issue presents an important study by van Veluw et al6 that combines in vivo UHF MRI of cerebral microinfarcts (CMI) with ex vivo results. The authors showed that the radiologic definition of CMI as used in their 7T MRI protocol matched the histopathological proof of CMI (although derived from a different patient sample).
A main merit of this study is that it bridges the gap between imaging patterns and histopathology. This is a valuable approach to enhance the diagnostic accuracy of MRI and is essential when a new technology like 7T MRI is applied to in vivo imaging and when its diagnostic performance has to be established.
Another important merit of this study is the finding that UHF MRI opens a new window on cerebrovascular research: CMI are a frequent form of brain infarction and may disrupt functional networks, leading to neurologic dysfunction.7 However, as they usually escape in vivo detection by standard magnetic resonance protocols, CMI are mainly defined by pathologic studies. The authors showed that UHF MRI identifies lesions in the submillimeter range and may serve as a surrogate for histopathology. A better detection and understanding of subtle vascular changes over a lifetime will help to develop surrogates for early diagnosis, for longitudinal disease assessment and for monitoring therapy in the future. In this respect, the present study points to the outstanding value of UHF MRI in cerebrovascular research and will certainly inspire further investigations.
The author declares no conflict of interest.
References
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