Clinical Applications of fMRI

The clinical scenario in which fMRI is requested by a referring physician is usually after detection of a lesion in the brain of a patient for whom surgical intervention is being contemplated. This unit discusses the suitable parameters of a functional MRI system and also presents the for imaging language function.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145198/1/cpmia0601.pd

Paradigms for Clinical fMRI

This unit presents description of four basic clinical paradigms for clinical fMRI of language cmprehension, eye movement (visually guidede saccades), motor cortex (finger‐thumb apposition), and visual cortex. Given the neurosurgical concern with preservation of eloquent cortex, brain functions of particular interest are primary sensory (e.g., visual, auditory) and motor functions, and high level processing of language comprehension and expression. Compromise of these functions is usually readily apparent clinically and the quality of life of the patient is severely diminished. Functional MRI offers a means to locate these functions, thereby allowing the surgeon to plan on preserving these functions, or prepare the patient appropriately.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145259/1/cpmia0603.pd

Metastatic Extra‐Axial Neoplasia

There are a multitude of tumors that may spread to the extra‐axial compartment (i.e., meninges, skull base, and calvarium). The role of imaging in the search for metastases is to detect the full extent of and to correctly localize the disease. This unit presents basic protocols for imaging extra‐axial metastatic tumors. Specific modifications are discussed where necessary. The sequences described in this unit are based on a 1.5 T scanner (Echospeed GE Medical Systems, Milwaukee, Wisconsin), but can be expected to be equally applicable to other field strengths and scanners from other manufacturers.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145221/1/cpmia0302.pd

Clinical fMRI

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145338/1/cpmia0600.pd

Quality Assurance for Clinical fMRI

The functional MRI (fMRI) procedure has several sources of variance that determine the success of the examination. These include the scanner, patient, and paradigm. As blood oxygenation level dependent (BOLD) contrast is a small effect, high signal‐to‐noise performance is mandatory. Because the preparation of a functional activation map requires averaging multiple images over time, the scanner must produce high temporal stability of the signal intensity. This unit presents the for achieving scanner stability. There are many determinants of such performance but not all possibilities need to be checked separately. An adequate approach has been to verify total system performance under the conditions of a functional MRI study on a phantom. This testing is done daily prior to patient studies.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145361/1/cpmia0602.pd

Transverse NMR relaxation as a probe of mesoscopic structure

Transverse NMR relaxation in a macroscopic sample is shown to be extremely sensitive to the structure of mesoscopic magnetic susceptibility variations. Such a sensitivity is proposed as a novel kind of contrast in the NMR measurements. For suspensions of arbitrary shaped paramagnetic objects, the transverse relaxation is found in the case of a small dephasing effect of an individual object. Strong relaxation rate dependence on the objects' shape agrees with experiments on whole blood. Demonstrated structure sensitivity is a generic effect that arises in NMR relaxation in porous media, biological systems, as well as in kinetics of diffusion limited reactions.Comment: 4 pages, 3 figure

Impact of Sauropod Dinosaurs on Lagoonal Substrates in the Broome Sandstone (Lower Cretaceous), Western Australia

Existing knowledge of the tracks left by sauropod dinosaurs (loosely ‘brontosaurs’) is essentially two-dimensional, derived mainly from footprints exposed on bedding planes, but examples in the Broome Sandstone (Early Cretaceous) of Western Australia provide a complementary three-dimensional picture showing the extent to which walking sauropods could deform the ground beneath their feet. The patterns of deformation created by sauropods traversing thinly-stratified lagoonal deposits of the Broome Sandstone are unprecedented in their extent and structural complexity. The stacks of transmitted reliefs (underprints or ghost prints) beneath individual footfalls are nested into a hierarchy of deeper and more inclusive basins and troughs which eventually attain the size of minor tectonic features. Ultimately the sauropod track-makers deformed the substrate to such an extent that they remodelled the topography of the landscape they inhabited. Such patterns of substrate deformation are revealed by investigating fragmentary and eroded footprints, not by the conventional search for pristine footprints on intact bedding planes. For that reason it is not known whether similar patterns of substrate deformation might occur at sauropod track-sites elsewhere in the world