ABSTRACT
BACKGROUND AND PURPOSE: A cleft-like non-enhancing hypointensity was observed repeatedly in the pituitary gland at the adenohypophysis/neurohypophysis border on contrast-enhanced 3D-Fat-Saturated T1-MPRAGE (C+3D-FS-T1 MPRAGE) using clinical 7T MRI. Our primary goal is to assess the prevalence of this finding. The secondary goals are to evaluate the frequency of other incidental pituitary lesions, MRI artifacts, and their effect on pituitary imaging on the C+3D-FS-T1 MPRAGE at 7T. MATERIALS AND METHODS: 100 patients who underwent 7T neuroimaging between 10/27/2021 and 8/10/23 were included. Each case was evaluated for cleft-like pituitary hypointensity, pituitary masses, and artifacts on C+3D-FS-T1 MPRAGE. Follow-up exams were evaluated if present. The average prevalence for each finding was calculated, as were descriptive statistics for age and sex. RESULTS: A cleft-like hypointensity was present in 66% of 7T MRIs. There were no significant differences between the "cleft-like present" and "cleft-like absent" groups regarding sex (P = .39) and age (P = .32). The cleft-like hypointensity was demonstrated in follow-up MRIs in 3/3 patients with 7T, 1/12 with 3T, and 1/5 with 1.5T. A mass was found in 22%, while 75% had no mass, and 3% were indeterminate. A mass was found in 18 (27%) of the "cleft-like present" and 4 (13%) of the "cleft-like absent" groups. The most common mass types were Rathke cleft cyst (RCC) in 7 (31.8%) patients, "RCC vs. entrapped CSF" in 6 (27.3%), and microadenoma in 6 (22.2%) in the "cleft-like present" group. There were no significant differences in the mass types between the "cleft-like present" and "cleft-like absent" groups (P = .23). Susceptibility and/or motion artifacts were frequent in general using C+3D-FS-T1 MPRAGE (54%). Artifact-free scans were significantly more frequent in the "cleft-like present" group (P =.03). CONCLUSIONS: A cleft-like non-enhancing hypointensity was frequently seen on the C+3D-FS-T1 MPRAGE at 7T MRI, which most likely represents a normal embryological Rathke's cleft remnant and cannot be seen in lower field strength MRIs. Susceptibility and motion artifacts are common in the sella. They may affect image quality, and the artifacts at 7T may lead to an underestimation of the prevalence of Rathke cleft and other incidental findings. ABBREVIATIONS: C+3D-FS-T 1MPRAGE = Contrast-Enhanced 3D-Fat-Saturated T1-Magnetization Prepared Rapid Gradient Echo Imaging; RCC = Rathke's Cleft Cyst.
ABSTRACT
The visual system develops abnormally when visual input is absent or degraded during a critical period early in life. Restoration of the visual input later in life is generally thought to have limited benefit because the visual system will lack sufficient plasticity to adapt to and utilize the information from the eyes. Recent evidence, however, shows that congenitally blind adolescents can recover both low-level and higher-level visual function following surgery. In this study, we assessed behavioral performance in both a visual acuity and a face perception task alongside longitudinal structural white matter changes in terms of fractional anisotropy (FA) and mean diffusivity (MD). We studied congenitally blind patients with dense bilateral cataracts, who received cataract surgery at different stages of adolescence. Our goal was to differentiate between age- and surgery-related changes in both behavioral performance and structural measures to identify neural correlates which might contribute to recovery of visual function. We observed surgery-related long-term increases of structural integrity of late-visual pathways connecting the occipital regions with ipsilateral fronto-parieto-temporal regions or homotopic contralateral areas. Comparison to a group of age-matched healthy participants indicated that these improvements went beyond the expected changes in FA and MD based on maturation alone. Finally, we found that the extent of behavioral improvement in face perception was mediated by changes in structural integrity in late visual pathways. Our results suggest that sufficient plasticity remains in adolescence to partially overcome abnormal visual development and help localize the sites of neural change underlying sight recovery.
Subject(s)
Cataract , White Matter , Adolescent , Humans , Blindness , Vision, Ocular , EyeABSTRACT
Amblyopia is a common perceptual disorder resulting from abnormal visual input during development. The clinical presentation and visual deficits associated with amblyopia are well characterized. Less is known however, about amblyopia's impact on the central nervous system (CNS). While early insights into the neuropathophysiology of amblyopia have been based on findings from animal models and postmortem human studies, recent advances in noninvasive magnetic resonance imaging (MRI) techniques have enabled the study of amblyopia's effects in vivo. We review recent retinal and neuroimaging research documenting amblyopia's structural and functional impact on the CNS. Clinical imaging provides some evidence for retinal and optic nerve abnormalities in amblyopic eyes, although the overall picture remains inconclusive. Neuroimaging studies report clearer changes in both structure and function of the visual pathways. In the optic nerves, optic tracts, and optic radiations of individuals with amblyopia, white-matter integrity is decreased. In the lateral geniculate nuclei, gray matter volume is decreased and neural activity is reduced. Reduced responses are also seen in the amblyopic primary visual cortex and extrastriate areas. Overall, amblyopia impacts structure and function at multiple sites along the visual processing hierarchy. Moreover, there is some evidence that amblyopia's impact on the CNS depends on its etiology, with different patterns of results for strabismic and anisometropic amblyopia. To clarify the impact of amblyopia on the CNS, simultaneous collection of retinal, neural, and perceptual measures should be employed. Such an approach will help (1) distinguish cause and effect of amblyopic impairments, (2) separate the impact of amblyopia from other superimposed conditions, and (3) identify the importance of amblyopic etiology to specific neural and perceptual deficits.