Cerebellar Cortical Layers: In Vivo Visualization with Structural High-Field-Strength MR Imaging

Abstract

Purpose:To perform in vivo imaging of the cerebellum with an in-plane resolution of 120 mm to observe its cortical granular and molecular layers by taking advantage of the high signal-to-noise ratio and the increased magnetic susceptibility-related contrast available at high magnetic fi eld strength such as 7 T. Materials and Methods:The study was approved by the institutional review board, and all patients provided written consent. Three healthy persons (two men, one woman; mean age, 30 years; age range, 28-31 years) underwent MR imaging with a 7-T system. Gradient-echo images (repetition time msec/echo time msec, 1000/25) of the human cerebellum were acquired with a nominal in-plane resolution of approximately 120 m m and a section thickness of 1 mm. Results:Structures with dimensions as small as 240 m m, such as the granular and molecular layers in the cerebellar cortex, were detected in vivo. The detection of these structures was confi rmed by comparing the contrast obtained on T2*-weighted and phase images with that obtained on images of rat cerebellum acquired at 14 T with 30 m m in-plane resolution. Conclusion:In vivo cerebellar imaging at near-microscopic resolution is feasible at 7 T. Such detailed observation of an anatomic area that can be affected by a number of neurologic and psychiatric diseases, such as stroke, tumors, autism, and schizophrenia, could potentially provide newer markers for diagnosis and follow-up in patients with such pathologic conditions.q RSNA, 2010

How to choose the right MR sequence for your research question at 7 T and above?

“…T2* weighted imaging has been demonstrated to give access to exquisite contrast not only between veins and tissue (as typically explored in Susceptibility Weighted Imaging, SWI, at lower fields) but also between grey and white matter, within grey matter (Duyn et al, 2007;Fukunaga et al, 2010), within white matter (Li et al, 2009) and between cerebellar cortical layers (Marques et al, 2010b). Many of these features can be observed both in the standard magnitude and phase components of the image (after high pass filtering) (Rauscher et al, 2005) or the combination of both via SWI (Haacke et al, 2004).…”

Digit somatotopy in the human cerebellum: A 7T fMRI study

“…The use of a local surface coil gives an additional increase in SNR, which can be traded for spatial resolution in fMRI (van der Zwaag et al, 2009b). Similar coils were previously used to acquire very high resolution anatomical images of the cerebellum (Marques et al, 2010b;Marques et al, 2012). fMRI data was acquired using an EPI sequence with sinusoidal readout (Speck et al, 2008) with the following parameters: matrix size: 128 × 128 × 36, FOV 154× 154 mm 2 , leading to a spatial resolution of 1.2×1.2 ×1.2 mm 3 , TR=2500 ms, TE=28 ms, BW/px=1565 Hz/px and α nominal =80°in the centre of the cerebellum.…”

“…In addition to the high level of foliation, the cerebellar grey matter layer is 3-5 fold thinner than the cerebral grey matter sheet (Marques et al, 2010b), further complicating comparisons across individuals. The spatial resolution at which the cerebellar homunculus is studied is important because the body representation is somatotopically organised at a coarse spatial resolution (Adrian, 1943;Buckner et al, 2011), but presents a more fractured organisation at sub-millimeter scales (Shambes et al, 1978).…”

Physiological noise in human cerebellar fMRI

“…Because of its relatively small size and fine-scale anatomical structure, compared to the cerebrum, cerebellar fMRI benefits strongly from high spatial resolution, both during acquisition [1,2] and in data post-processing strategies used in fMRI [3,4]. High spatial resolution in fMRI is most easily achieved at high field strengths, where fMRI benefits from increased signal-tonoise ratio (SNR), increased blood oxygen level-dependent (BOLD) signal [5,6] and increased spatial specificity of the BOLD responses [7,8].…”