Cerebral cortical development involves a complex cascade of events which are difficult to visualize in intact, living subjects. In this study, we apply diffusion tensor imaging (DTI) to the evaluation of cortical development in human infants ranging from 26 to 41 weeks gestational age (GA). Apparent diffusion of water in cortex is maximally anisotropic at 26 weeks GA and anisotropy values approach zero by 36 weeks GA. During this period, the major eigenvector of the diffusion tensor in cerebral cortex is oriented radially across the cortical plate, in accord with a predominately radial deployment of its neuronal constituents. Values for the rotationally averaged water diffusion coefficient increase between 26 and 32 weeks GA, then decrease thereafter. These changes in DTI parameters are specific to cerebral cortex and reflect changes in underlying cortical architecture and formation of neuronal connections. Because of its correlation with tissue microstructure and non-invasive nature, DTI offers unique insight into cortical development in preterm human newborns and, potentially, detection of derangements of its basic cytoarchiteture.

Preoperative clinical magnetic resonance imaging (MRI) protocols for gliomas, brain tumors with dismal outcomes due to their infiltrative properties, still rely on conventional structural MRI, which does not deliver information on tumor genotype and is limited in the delineation of diffuse gliomas. The GliMR COST action wants to raise awareness about the state of the art of advanced MRI techniques in gliomas and their possible clinical translation or lack thereof. This review describes current methods, limits, and applications of advanced MRI for the preoperative assessment of glioma, summarizing the level of clinical validation of different techniques. In this first part, we discuss dynamic susceptibility contrast and dynamic contrast‐enhanced MRI, arterial spin labeling, diffusion‐weighted MRI, vessel imaging, and magnetic resonance fingerprinting. The second part of this review addresses magnetic resonance spectroscopy, chemical exchange saturation transfer, susceptibility‐weighted imaging, MRI‐PET, MR elastography, and MR‐based radiomics applications.Evidence Level: 3Technical Efficacy: Stage 2

The aim of this work is to develop a remotely controlled manipulator to perform minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic cavities, with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical MR scanners. The manipulator is composed of a three degree of freedom Cartesian motion system, which resides outside the gantry of the scanner, and serves as the holder and global positioner of a three degree of freedom arm which extends inside the gantry of the scanner. At its distal end, the arm’s end-effector can carry an interventional tool such as a biopsy needle, which can be advanced to a desired depth by means of a seventh degree of freedom. These seven degrees of freedom, provided by the entire assembly, offer extended manipulability to the device and a wide envelope of operation to the user, who can select a trajectory suitable for the procedure. The device is constructed of nonmagnetic and nonconductive fiberglass, and carbon fiber composite materials, to minimize artifacts and distortion on the MR images as well as eliminate effects on its operation from the high magnetic field and the fast switching magnetic field gradients used in MR imaging. A user interface was developed for man-in-the-loop control of the device using real-time MR images. The user interface fuses all sensor signals (MR and manipulator information) in a visualization, planning, and control command environment. Path planning is performed with graphical tools for setting the trajectory of insertion of the interventional tool using multislice and∕or three dimensional MR images which are refreshed in real time. The device control is performed with an embedded computer which runs real-time control software. The manipulator compatibility with the MR environment and image-guided operation was tested on a $1.5T$ MR scanner.

Preoperative clinical MRI protocols for gliomas, brain tumors with dismal outcomes due to their infiltrative properties, still rely on conventional structural MRI, which does not deliver information on tumor genotype and is limited in the delineation of diffuse gliomas. The GliMR COST action wants to raise awareness about the state of the art of advanced MRI techniques in gliomas and their possible clinical translation. This review describes current methods, limits, and applications of advanced MRI for the preoperative assessment of glioma, summarizing the level of clinical validation of different techniques. In this second part, we review magnetic resonance spectroscopy (MRS), chemical exchange saturation transfer (CEST), susceptibility‐weighted imaging (SWI), MRI‐PET, MR elastography (MRE), and MR‐based radiomics applications. The first part of this review addresses dynamic susceptibility contrast (DSC) and dynamic contrast‐enhanced (DCE) MRI, arterial spin labeling (ASL), diffusion‐weighted MRI, vessel imaging, and magnetic resonance fingerprinting (MRF).Evidence Level: 3.Technical Efficacy: Stage 2.

It has been demonstrated previously that water diffusion anisotropy in vivo is equivalent to that observed ex vivo after perfusion fixation in the mouse brain. This finding supports the practice of ex vivo diffusion tensor imaging (DTI) measurement on perfusion‐fixed tissues. However, the validity of extrapolating ex vivo DTI measurements from immersion‐fixed autopsy specimens to the in vivo state is questionable because of variable postmortem delays often encountered before fixation. In this study, we investigated the effect of postmortem delay on the water diffusion anisotropy of ventrolateral spinal cord white matter from mice. Mouse spinal cords, each from the same animal, were examined using DTI in vivo, in situ after death before fixation, and ex vivo immersion fixed 10 h after death. Our results suggest that diffusion anisotropy in mouse spinal cord is preserved up to 10 h after death. Regional characteristics of diffusion anisotropy in mouse spinal cord white matter are equivalent in vivo, in situ after death (up to 10 h before fixation), and ex vivo 15 weeks after immersion fixation. Copyright © 2007 John Wiley & Sons, Ltd.