High Field Brain MRI by Tommaso Scarabino Saverio Pollice & Teresa Popolizio

High Field Brain MRI by Tommaso Scarabino Saverio Pollice & Teresa Popolizio

Author:Tommaso Scarabino, Saverio Pollice & Teresa Popolizio
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham


Ultrahigh-Field MRI

Ultrahigh-field MRI allows detection of a significant higher number of lesions [60], better definition of lesions located in the WM and gray matter (GM), their morphology, and their association with the vasculature [40, 43, 50, 109, 110] at a resolution closer to that of histopathological assessment than what was previously shown by using 1.5 [112] or 3.0 [97] T scanners. This suggests that abnormalities detected using quantitative MR techniques in the normal-appearing (NA) WM are, at least in part, due to the presence of focal lesions which go undetected when using low-field magnets. Whether the assessment of lesion number and distribution using ultrahigh-field MRI scanners assists in making an earlier diagnosis of MS in CIS patients has not yet been evaluated. Several studies have identified some interesting lesion characteristics, which can aid the differential diagnosis between MS and other neurological conditions. The better definition of the relationship between demyelinating lesions and the intraparenchymal venous system, obtained by using T2*-weighted magnitude and phase imaging, confirms pathological studies demonstrating that many MS plaques form around the microvasculature [40, 43, 50, 57, 109, 110, 111]. The perivenular lesion location can help to distinguish WM lesions in MS patients from incidental (ischemic) WM lesions [50, 111]. This finding has been reinforced by investigation of blood-brain barrier abnormalities in MS at 7 T, which showed that the majority of enhancing lesions are perivenular and that the smallest lesions have a concentric pattern of enhancement, suggesting that they grow outward from a central vein [1, 39] (Fig. 16.1). The presence of a central small vein and a rim of hypointensity on 7 T T2*-weighted magnitude or FLAIR* [50] could be a distinctive feature of MS WM lesions, which may assist in the differentiation from lesions of patients with neuromyelitis optica (NMO) spectrum disorders [105] or Susac syndrome [117]. In this latter condition, T1-hypointense lesions within the central part of the CC, which are not commonly seen in MS, have also been detected [117].

Fig. 16.1Seven-tesla T2*/phase features and contrast enhancement dynamics in (a, b) centripetal and (c) centrifugal enhancing lesions. The hypointense phase rim is clearly visible in (a, b), but whereas it is clearly seen on T2* in (a), it is virtually invisible on T2* in (b). In (c), a centrifugal lesion is subtly but homogeneously hypointense on phase. The area of phase hypointensity, delimited by cyan dashes, is smaller than the area of T2* hyperintensity (indicated by white dashes). (d) Stable phase and T2* features, including a thick rim, in a chronic lesion at baseline and 1.3 years later. DCE5 dynamic contrast-enhanced; MPRAGE5magnetization-prepared rapid gradient echo”



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