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Biomedical subjects

D B Hackney

Publications and source records attributed to D B Hackney.

At least 19 recordsLinked to original sources
PubMed2000

Characterization of experimental spinal cord injury with magnetization transfer ratio histograms.

This study was designed to characterize the severity of tissue damage in experimental spinal cord injury using magnetization transfer (MT) histogram analysis. Seven Sprague-Dawley rats were subjected to laminectomy and standard weight-drop injury to the spinal cord (four rats at 15 cm drop-height and three rats at 2.5 cm). Three control animals underwent laminectomy without weight-drop. After sacrifice, the animals were scanned at 1.9 T with a pulsed off-resonance MT technique. Following magnetic resonance (MR) imaging, the cords were embedded in paraffin and sectioned into 5-microm sections for semiquantitative histopathological analysis. Composite histograms were generated using data spanning an axial distance of 3 cm centered on the injury site. MT histogram parameters, such as the amount of tissue with statistical correspondence to normal white matter, were highly predictive of histopathological results, including myelination state and neurofilament damage. Less correlation with edema was observed, suggesting that the technique was most sensitive to true tissue alteration.

Animals↗
PubMed2000

Diffusional anisotropy in cranial nerves with maturation: quantitative evaluation with diffusion MR imaging in rats.

PURPOSE: To investigate the correlation between diffusional anisotropy and developmental changes in anatomy, which include myelination, in central and peripheral nerves in an animal model by using quantitative diffusion magnetic resonance (MR) imaging and electron microscopy. MATERIALS AND METHODS: In vivo transverse and longitudinal apparent diffusion coefficients (ADCs) of the optic and trigeminal nerves in 2-10-week-old rats were measured with MR imaging. Then the animals were sacrificed at each time point, and transverse and longitudinal sections of optic and trigeminal nerves were studied with electron microscopy. RESULTS: In the optic nerve, the ADC parallel to the neurofibers increased with development and increased contemporaneously with myelination, while the ADC perpendicular to the nerve did not change. This resulted in a significant increase in diffusional anisotropy. There were no significant changes in ADCs in either direction in the trigeminal nerve. Longitudinal sections of optic nerve showed a marked change in the orientation of each fiber. As development proceeded, the axons, which initially followed tortuous courses, assumed straighter and more parallel orientations. Trigeminal nerves displayed straight parallel courses at 2 weeks that did not change over the study period. CONCLUSION: Changes in fiber anatomy in maturation from tortuous to straighter and more parallel orientation can account for changes in longitudinal ADC and in diffusional anisotropy.

Animals↗
PubMed1999

Transient MRI enhancement in a patient with seizures and previously resected glioma: use of MRS.

A 35-year-old man presented with partial seizures 10 years after resection of a left-sided glioblastoma multiforme. At the old operative site MRI demonstrated extensive cortical and white matter gadolinium enhancement, and PET showed hypermetabolism. Biopsy of the area was postponed when MRS showed a normal biochemical spectrum. MRI and PET abnormalities resolved after control of the seizures. MRS is noninvasive and can provide essential information in the management of patients with seizures and previously treated cerebral neoplasms.

Adult↗
PubMed1998

Catamenial mononeuropathy and radiculopathy: a treatable neuropathic disorder.

OBJECT: The aim of this study was to investigate the indications and treatment options in patients with lower-extremity neuropathies and radiculopathies caused by endometriosis. METHODS: The authors identified five patients whose symptoms included catamenial pain, weakness, and sensory loss involving the sciatic and femoral nerves and multiple lumbosacral nerve roots. Radiographic studies supported the diagnosis of catamenial neuropathy or radiculopathy, but definitive diagnosis depended on surgical and pathological examination. Treatment of symptoms, including physical therapy and a course of antiinflammatory or analgesic medication, was not helpful. Patients responded favorably to hormonal therapy. Laparoscopy or open exploration for extrapelvic lesions was performed for diagnosis or for treatment when hormone therapy failed. Pain and sensory symptoms responded well to therapy. Weakness improved, but never recovered completely. CONCLUSIONS: Catamenial neuropathy or radiculopathy should be considered when evaluating reproductive-age women with recurring focal neuropathic leg pain, weakness, and sensory loss.

Adult↗
PubMed1997

Numerical model for calculation of apparent diffusion coefficients (ADC) in permeable cylinders--comparison with measured ADC in spinal cord white matter.

We have implemented a numerical method for calculation of the apparent diffusion coefficient (ADC) in spinal cord injury, which takes into account the distribution of axon diameters and permeability found in spinal cord white matter, as well as relative axonal volume. We propose a procedure for determining the status of axonal integrity from measured ADC values. These methods have been applied to a well characterized rat spinal cord injury model, affording a prediction of the increase in axonal permeability which is presumed to be closely related to functional deficit. ADC values are compared to those calculated from analytical formulas in the literature, and possible factors underlying the ADC behavior are explored. Calculated results indicate both axonal swelling and cell membrane permeability to be important factors contributing to ADC in traumatic spinal cord injury.

Animals↗