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Biomedical subjects

James L Fleckenstein

Publications and source records attributed to James L Fleckenstein.

7 recordsLinked to original sources
PubMed2004

Cerebral infarction in eclampsia.

OBJECTIVE: This study was undertaken to characterize the neuroimaging findings of cerebral edema associated with eclamptic seizures by use of diffusion-weighted magnetic resonance imaging (MRI). STUDY DESIGN: During the 3-year period ending March 2002, 27 nulliparous women with eclampsia were evaluated with diffusion-weighted MRI and apparent diffusion coefficient mapping. Those with findings of restricted diffusion suggestive of cytotoxic edema underwent neuroimaging again 6 weeks post partum. RESULTS: All but 2 of these 27 women (93%) had reversible vasogenic edema. Six were also found to have areas of cytotoxic edema consistent with cerebral infarction. Five of these 6 women had persistent imaging findings of infarction when studied post partum, however, without clinical neurologic deficits. CONCLUSION: The spectrum of cerebral lesions in eclampsia as seen with MRI varies from initially reversible areas of vasogenic edema that may progress to cytotoxic edema and infarction in up to a fourth of women.

Adult↗
PubMed2003

T2 mapping of muscle.

Muscle activation produces increases in magnetic resonance ( T(2)) signal intensity leading to recruitment images that demonstrate spatial patterns and intensity of muscle activation. These T(2) activation maps are useful for visualizing and quantifying various aspects of muscle function. Activity-dependent changes in T(2) result from an increase in the T(2) relaxation time of muscle water. The current state of investigation indicates that the mechanism of increased T(2) results from osmotically driven shifts of muscle water that increase the volume of the intracellular space and from intracellular acidification resulting from the end products of metabolism. Although the spatial resolution of magnetic resonance imaging is still insufficient to map territories of individual motor units, it is possible to demonstrate nonuniform activation between subregions or compartments of muscle. Taken together, the attributes of the T(2) mapping technique hold great potential for demonstrating aberrant muscle activation patterns in pathology and positive adaptation to exercise or rehabilitative intervention.

Biomechanical Phenomena↗
PubMed2003

Second-opinion magnetic resonance imaging for suspected fetal central nervous system abnormalities.

OBJECTIVE: The purpose of this study was to evaluate the relationship of magnetic resonance imaging and gestational age in the setting of fetuses with suspected abnormalities of the central nervous system that were detected by ultrasound scanning. STUDY DESIGN: Multiplanar magnetic resonance studies were performed in fetuses with suspected central nervous system abnormalities on ultrasound scanning. Magnetic resonance imaging was evaluated for its ability to provide additional information, change the diagnosis, or impact obstetric treatment. Patients were grouped by gestational age at the time of magnetic resonance imaging. RESULTS: Magnetic resonance imaging provided additional information in 46 of 72 pregnancies (64%), changed the diagnosis in 20 of 72 pregnancies (28%), and potentially altered the timing or mode of delivery in 8 of 72 pregnancies (11%). Additional information increased with increasing gestational age groups (P =.03). CONCLUSION: Magnetic resonance imaging provided additional information in two thirds of the fetuses with central nervous system abnormalities, which was significantly increased with increasing gestation. Antenatal treatment was influenced by magnetic resonance imaging in 11% of the cases.

Central Nervous System↗
PubMed2003

MR-guided catheter navigation of the intracranial subarachnoid space.

Percutaneous intraspinal navigation (PIN) is a new minimally invasive approach to the CNS. The authors studied the utility of MR-guided intracranial navigation following access to the subarachnoid compartment via PIN. The passive tracking technique was employed to visualize devices during intracranial navigation. Under steady-state free precession (SSFP) MR-guidance a microcatheter-microguidewire was successfully navigated to multiple brain foci in two cadavers. SSFP MR fluoroscopy possesses adequate contrast and temporal resolution to allow MR-guided intracranial navigation.

Brain↗