Functional MRI using multiple receiver coils: BOLD signal changes and signal-to-noise ratio for three-dimensional-PRESTO vs. single shot EPI in comparison to a standard quadrature head coil.

Purpose: To compare the performance of single shot echo planar imaging (SSEPI) with three-dimensional-multishot echo-planar imaging (EPI) based on principles-of-echo-shifting-with-a-train-of-observations (PRESTO) in combination with a standard quadrature head coil and, as an alternative, a multiple receiver coil in intraoperative functional magnetic resonance imaging (fMRI).

Materials And Methods: Six healthy subjects underwent fMRI with visual stimulation using a SSEPI and a PRESTO-sequence with both coil systems. Statistical evaluation was done with a scanner-based post-processing software and SPM 99.

Optimized distortion correction of epi-based statistical parametrical maps for stereotactic neurosurgery.

A new approach is presented for unwarping geometrical distortions in echo planar imaging (EPI)-based statistical parametrical maps (SPM). With the developed method, a substantial reduction of geometrical distortions in the order of 5-15 mm down to a residue of approximately 1-2 mm was possible, thus allowing reliable activation localization and, hence, interpretation after fusion with undistorted conventional anatomic images. The unwarping procedure is an optimized combination of two distortion correction methods, the "inhomogeneity mapping" and the coregistration approach.

Intraoperative functional MRI as a new approach to monitor deep brain stimulation in Parkinson's disease.

This article deals with technical aspects of intraoperative functional magnetic resonance imaging (fMRI) for monitoring the effect of deep brain stimulation (DBS) in a patient with Parkinson's disease. Under motor activation, therapeutic high-frequency stimulation of the subthalamic nucleus was accompanied by an activation decrease in the contralateral primary sensorimotor cortex and the ipsilateral cerebellum. Furthermore, an activation increase in the contralateral basal ganglia and insula region were detected.

Proton spectroscopic metabolite signal relaxation times in preterm infants: a prerequisite for quantitative spectroscopy in infant brain.

Purpose: To determine relaxation times of metabolite signals in proton magnetic resonance (MR) spectra of immature brain, which allow a correction of relaxation that is necessary for a quantitative evaluation of spectra acquired with long TE. Proton MR spectra acquired with long TE allow a better definition of metabolites as N-acetyl aspartate (NAA) and lactate especially in children.

Materials And Methods: Relaxation times were determined in the basal ganglia of 84 prematurely born infants at a postconceptional age of 37.

Femoral pseudoaneurysms: management with percutaneous thrombin injections--success rates and effects on systemic coagulation.

Purpose: To determine the success rate of percutaneous ultrasonographically (US) guided thrombin injection in the treatment of femoral pseudoaneurysms and to evaluate the effects of thrombin injection on systemic coagulation parameters.

Materials And Methods: Fifty femoral pseudoaneurysms (37 simple pseudoaneurysms with one lobe and 13 complex pseudoaneurysms with two or three lobes) were treated with US-guided percutaneous thrombin injections. Pseudoaneurysm size, neck length and width, thrombin dose, outcome of therapy, and complications were documented prospectively.

An isolated fourth ventricle in neurosarcoidosis: MRI findings.

We report on an isolated enlargement of the fourth ventricle in a patient with neurosarcoidosis which developed 3 years after the insertion of a ventriculo-atrial shunt. Repeated MRI images were obtained in a patient with known neurosarcoidosis between 1995 and 2000. Imaging findings were correlated to the medical course of the patient, who developed a hydrocephalus and a trapped fourth ventricle consecutively.