Dynamic susceptibility MR perfusion imaging of the brain offers clinically relevant physiological data not obtainable by conventional MR imaging. As new treatments continue to be developed for stroke, neoplasm, dementia, psychiatric illness, headache, and trauma, the potential clinical applications of perfusion MR imaging in the diagnosis, triage, and therapeutic monitoring of these diseases will increase.
To develop an objective method for detecting multiple sclerosis (MS) brainstem lesions, magnetic resonance (MR) images (multiple planar, spin-echo, acquired in three planes of section) of sixteen MS patients and fourteen normal subjects were analyzed with an algorithm that detected regions with a relatively increased intensity on both a spin-echo image and a T2 image. To be considered a lesion, such regions had to overlap in at least two orthogonal planes. Using a digitized atlas of the human brainstem, the lesion locations were mapped with respect to the brainstem anatomy.
Adult supratentorial gliomas continue to be one of the most challenging diagnostic and therapeutic problems for the neuro-oncologist. Despite a variety of therapeutic approaches, local control and survival rates remain disappointingly low, largely due to a relative inability to localize diffusely infiltrating glial tumor cells. FDG PET provides a relatively noninvasive method for studying glucose metabolism in normal and pathologic brain tissues.
We investigated the regional and temporal changes in cerebral blood volume (CBV), cerebral blood flow (CBF), and vascular transit time in seven mongrel cats during 30 min transient focal ischemia, caused by occlusion of the middle cerebral artery. Dynamic susceptibility contrast magnetic resonance imaging was done at 4.7 T, using fast gradient echo T2* weighted imaging and intravenous injection of gadolinium-BOPTA/Dimeglumine.
BACKGROUND AND PURPOSE: The MR imaging characteristics of oligodendrogliomas and astrocytomas on spin-echo (SE), echo-planar relative cerebral blood volume (rCBV) maps, to our knowledge, have not previously been emphasized. We compared the specificity of SE rCBV mapping with that of conventional, contrast material-enhanced MR imaging in differentiating high- from low-grade glial tumors and in predicting survival of patients with these lesions.
BACKGROUND AND PURPOSE: The integrity of white matter tracts connecting different parts of the brain is important for rapid compensation for the lost function from ischemic stroke. Impaired white matter reserve capacity secondary to leukoaraiosis may facilitate detection of new symptomatic ischemic events that would otherwise remain inconspicuous after an initial ischemic stroke. We sought to identify whether the extent of leukoaraiosis was a predictor of risk of early stroke recurrence.
OBJECTIVE: To evaluate stereotactic transcranial magnetic stimulation (TMS) as a tool for presurgical functional mapping of human motor cortex.
METHODS: Transcranial magnetic stimulation using a frameless stereotactic system was performed in two patients with tumors near the central sulcus. TMS motor function maps were plotted on the patients' three-dimensional volumetric magnetic resonance imaging data and compared with direct electrical cortical stimulation at surgery with the patient under local anesthesia.
"Single shot" magnetic resonance (MR) diffusion imaging was used to study the details of signal decay curves in experimental perturbations of cerebral perfusion induced by hypercapnia or death. Despite large perfusion increases observed with dynamic susceptibility-contrast MR imaging, no correlation with these changes was seen in either the diffusion coefficient or any other intravoxel incoherent motion (IVIM) model parameters in dog gray matter as arterial carbon dioxide pressure increased. Non-monoexponential signal decay in cat gray matter was seen both before and after death.
Dual energy CT and quantitative magnetic resonance (MR) imaging were used to evaluate marrow changes due to radiation. The bright signal intensity seen on MR was shown by the two quantitative techniques to be due to a threefold increase in the marrow fat content compared with nonradiated levels and to a normal control. Fat estimates by MR and dual energy CT were in excellent agreement. Single energy CT overestimates the amount of bone loss in the radiation field. Dual energy CT and quantitative MR can be used to correct this error.
Stroke is the third leading cause of mortality and a frequent cause of long-term adult impairment. Improved strategies to enhance motor function in individuals with chronic disability from stroke are thus required. Post‑stroke therapy may improve rehabilitation and reduce long-term disability; however, objective methods for evaluating the specific impact of rehabilitation are rare. Brain imaging studies on patients with chronic stroke have shown evidence for reorganization of areas showing functional plasticity after a stroke.
