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Biomedical subjects

R E Latchaw

Publications and source records attributed to R E Latchaw.

At least 19 recordsLinked to original sources
PubMed1998

The American Society of Neuroradiology. Neuroradiology research: the opportunities and the challenges.

The next decade will witness an explosion of research and development in the neurosciences. The imaging of physiologic and functional processes--the frontier today--will become the norm. There are huge populations of patients with neurodegenerative and cerebrovascular diseases that require nonanatomic diagnostic evaluation. Radiologists must cease being just readers of morphologic images. They must broaden their scope and their areas of expertise. Imaging-guided therapy of all forms will alter the types of interventions we perform on patients. These new techniques will increase the efficacy of neuro-interventions while decreasing their morbidity and mortality. Resources, both human and financial, will be conserved. Radiologists can participate in this wonderful future if they broaden their training. Information management and the use of imaging for procedural guidance are the bases of our profession, but we are weak in the clinical applications of the technology. We must realize that our clinical colleagues are poised to assume the leadership in imaging research and development and in its performance. The challenge to the leaders of radiology is quite apparent: the recognition of the need to train for the future with the most open of minds and the least rigidity. This requires that we all understand the depth of the merger between the imaging and the clinical sciences that is occurring and that will increase substantially in the future. We must be the leaders in such a merger; otherwise, we will not be participants.

Humans↗
PubMed1997

Three-dimensional vascular reconstruction with a clinical x-ray angiography system.

RATIONALE AND OBJECTIVES: The authors developed a technique to produce high-resolution, three-dimensional images of vasculature from a set of x-ray projections in an attempt to provide detailed anatomic representations of complex vasculature. MATERIALS AND METHODS: Projection images were acquired with a clinical angiographic system by using biplanar rotational digital subtraction angiography. The images were reconstructed with an additive algebraic reconstruction technique. RESULTS: The feasibility of the technique was tested by reconstructing three-dimensional images of several phantoms, including a wire phantom and an anatomic flow phantom. The anatomic phantom allowed replication of contrast material flow and image noise that are characteristic of patient examinations. The reconstruction procedure was then used to examine a carotid artery and a cerebral aneurysm in two patients. CONCLUSION: A method of reconstructing vasculature from x-ray angiograms has been developed and validated with geometric and anatomic phantoms. Preliminary patient applications indicate that this technique enables enhanced visualization of complex vascular relationships and structures.

Angiography, Digital Subtraction↗
PubMed1997

Brain attack. Introduction.

In today's medical community, the term "brain attack" is used in two ways. It is used as a synonym for stroke, and also as a reference to an educational and logistic campaign aimed at earlier recognition and treatment of stroke. This article presents an introduction to both uses of the phrase "brain attack," and focuses on the need for a brain attack campaign.

Brain Ischemia↗
PubMed1997

The role of CT following aneurysmal rupture.

Computed tomography is a highly effective method of detecting subarachnoid blood if performed early after aneurysmal rupture, being 95% to 98% positive when lumbar puncture is positive. The localization of the blood defines the location of the aneurysm in approximately 80% of cases. Contrast enhanced computed tomography demonstrates the aneurysm in 75% of cases with the aneurysm is greater than 5 millimeters in size. Computed tomography angiography defines the aneurysm in up to 96% of cases. The amount of subarachnoid blood correlates with the development of vasospasm; cerebral perfusion can be further evaluated with xenon-enhanced computed tomography.

Aneurysm, Ruptured↗
PubMed1995

Imaging of perinatal hypoxic-ischemic brain injury.

This article reviews some physiological parameters that influence the location and degree of injury from hypoxia-ischemia. The ability of various imaging tests, particularly magnetic resonance imaging, to detect tissue changes after hypoxia-ischemia is discussed. Most importantly, we evaluate the extent of our knowledge regarding the correlations between imaging, pathophysiological processes, and clinical medicine.

Asphyxia Neonatorum↗
PubMed1995

Intra-aortic balloon counterpulsation augments cerebral blood flow in a canine model of subarachnoid hemorrhage-induced cerebral vasospasm.

We tested the effect of intra-aortic balloon counterpulsation (IABC) on cerebral blood flow (CBF) in a canine model of cerebral vasospasm. Cerebral vasospasm was induced in ten adult mongrel dogs using a "two-hemorrhage" model. CBF was then measured using radiolabeled microspheres, before and after activation of an intra-aortic balloon pump. Physiologic parameters including pCO2 and cardiac filling pressures were maintained constant during the experiment. Cardiac output was monitored in each animal. CBF increased with IABC in all ten animals. The mean CBF was 78.5 milliliters per 100 grams per minute (ml/100g/min) before versus 93.3ml/100g/min after IABC (P = 0.0001). Increases in CBF were associated in most, but not all, cases with increases in cardiac output. This study supports the ability of IABC to raise CBF in the setting of cerebral vasospasm. IABC may represent an important clinical option in cases of refractory vasospasm following aneurysmal subarachnoid hemorrhage.

Animals↗
PubMed1995

Functional magnetic resonance imaging as a management tool for cerebral arteriovenous malformations.

The location of eloquent cortex, such as the motor strip, the visual cortex, or Broca's area, may be difficult to predict even with multiprojectional magnetic resonance imaging (MRI). Distortion and displacement of this cortex may occur with a congenital lesion, such as an arteriovenous malformation, or by an acquired disease, such as a neoplasm. A desire to avoid damaging these eloquent areas by conventional surgery, radiosurgery, or endovascular surgery makes their accurate identification an important part of the pretherapeutic planning process. Blood oxygen level dependent functional MRI is a technique that uses the local increase of oxyhemoglobin concentration in the patient that occurs as a result of the increase in flow rate and blood volume in eloquent cortex undergoing stimulation from, for example, flashing lights, hand movements, or speech. We have used the blood oxygen level dependent technique to localize eloquent cortex relative to arteriovenous malformations and tumors. Using a 4.0-T magnetic resonance (MR) system, there is a sufficiently high degree of spatial resolution of the MR signal intensity changes during stimulation to allow the identification of eloquent cortex. Alternative, non-MR, invasive techniques for functional localization include electrocorticography and stimulation from subdural grids and strips. Noninvasive, non-MR technologies, such as positron emission tomography and magnetoencephalography, can also provide functional localization of eloquent cortex. However, the perfection of functional MRI at the 1.5-T field strength and the large number of such MR systems in operation mean that a highly accurate cerebral cortical localization technique can be available to most neuroscientists without the need to purchase alternative expensive technology.

Adult↗
PubMed1995

Cyclosporine A toxicity presenting with acute cerebellar edema and brainstem compression. Case report.

A 38-year-old man receiving cyclosporine A after bilateral lung transplantation for cystic fibrosis presented with cortical blindness, generalized seizures, and cerebellar edema. Progressive brainstem compression necessitated emergency posterior fossa decompression. Replacement of cyclosporine A with an alternative immunosuppressive agent, FK506, was followed by rapid neurological recovery and dramatic resolution of radiographic abnormalities. The etiology, clinical features, and radiographic findings of cyclosporine A neurotoxicity are discussed. The pertinent literature is reviewed.

Acute Disease↗
PubMed1995

Functional MR imaging of perceptual and cognitive functions.

Functional MR imaging using the blood oxygen level dependent technique as an endogenous contrast agent localizes eloquent cortex when stimulated by a variety of motor or sensory tasks. To date, visual, motor, speech, and cerebellar studies have been conducted, revealing significant information regarding cortical localization and control of various functions. The technique is also an important management tool for localizing eloquent cortex contiguous to a tumor or arteriovenous malformation, so that injury can be avoided if ablation of the lesion is contemplated.

Cerebellum↗
PubMed1995

Functional MR imaging in the evaluation of the patient with epilepsy. Functional localization.

Functional magnetic resonance imaging is able to define noninvasively the location of eloquent cortex responsible for speech, motor, and visual function, and it holds promise for localizing other important functional tissues in the future. Such localization is extremely important to the epileptologist and surgeon planning surgical resection of an epileptic focus. Early work identifies the actual seizure focus using similar techniques. Magnetic resonance, with functional magnetic resonance added to high-resolution magnetic resonance imaging and magnetic resonance spectroscopy, has the potential of providing, in a cost-effective manner with one noninvasive modality, the functional, anatomic, and chemical parameters pertinent to the management of the seizure patient.

Brain↗
PubMed1994

Transcranial magnetic evoked potentials used to monitor the spinal cord during neuroradiologic angiography of the spine.

A current topic in intraoperative monitoring of the spinal cord is the inability of the somatosensory evoked potentials (SSEP) to adequately document anterior spinal cord function. Transcranial magnetic stimulation (TMS) of the cortex for assessing corticospinal (efferent) pathways is a developing modality. The authors demonstrate a potential application of TMS as a monitoring medium for use in the neuroradiology suite. Limitations of intraoperative applications of cortical magnetic stimulation associated with cortical suppression are caused by anesthetics and neuromuscular blockers. These limitations generally are not an issue in the neuroradiology suite. In this report, motor improvement was correctly predicted by magnetic evoked potential amplitudes, whereas an SSEP remained unchanged during neuroradiologic angiography.

Arteriovenous Malformations↗
PubMed1994

"Brain attack": the rationale for treating stroke as a medical emergency.

Stroke is the third leading cause of death in the United States, behind only heart disease and cancer. With an estimated three million survivors of stroke in the United States, the cost to society, both directly in health care and indirectly in lost income, is staggering. Despite recent advances in basic and clinical neurosciences, which have the potential to improve the treatment of acute stroke, the general approach to the acute stroke patient remains one of therapeutic nihilism. Most basic science studies show that to be effective, acute intervention to reperfuse ischemic tissue must take place within the first several hours, as is the case with ischemic myocardium. In addition, most neuroprotective agents must also be administered within a short time frame to be effective at salvaging at-risk tissue. Recent studies have suggested that the outcome after intracerebral and subarachnoid hemorrhage is improved with early intervention. However, most stroke patients fail to present to medical attention within this short "window of opportunity." The public's knowledge about stroke is woefully inadequate. However, clinicians who deal with stroke can use the dramatic changes in the treatment of acute myocardial infarction over the last 2 decades as a guide for shaping changes in the management of acute stroke. Comprehensive educational efforts aimed at clinicians and the public at large have dramatically reduced the time from symptom onset to presentation and treatment for acute myocardial infarction, enabling treatment methods such as thrombolysis to be effective. The Decade of the Brain offers a unique opportunity to all concerned with the treatment of the patient with acute stroke to engage in a concerted effort to bring patients with a "brain attack" to specialized neurological attention within the same timeframe that the "heart attack" patient is handled. Such an effort is justified because, although at the present time there are few therapeutic interventions of "proven" value in the treatment of acute stroke, there is more than sufficient suggestive evidence that a number of approaches may be beneficial within the first few hours after the onset of the stroke.

Brain↗
PubMed1994

Adrenoleukodystrophy: a scoring method for brain MR observations.

PURPOSE: To develop a scoring method for brain observations in patients with X-linked adrenoleukodystrophy. METHODS: One hundred seventy-five brain MR scans in 83 male subjects less than 20 years of age with proved biochemical defects were reviewed. A severity score (0 to 34), based on a point system derived from location and extent of disease and the presence of focal and/or global atrophy, was calculated for each exam. RESULTS: Fifty-five of the 83 patients showed MR findings consistent with adrenoleukodystrophy. Two major patterns were observed. A posterior pattern (mean score, 9; range, 0.5 to 25) was present in 80% of patients, and an anterior pattern (mean score, 10; range, 2 to 18) was present in 15% of patients. Serial MR imaging, positive for adrenoleukodystrophy in 34 patients (mean follow-up, 23 months; range, 2 months to 6 years 11 months), showed progressive disease in 52%, progressive disease with subsequent stabilization in 18%, stable disease in 24%, and minimal improvement in 6%. CONCLUSION: The adrenoleukodystrophy MR severity scoring method is a measure that can be used with standard MR images. When used in conjunction with clinical parameters, this scoring method may help define better the natural history of adrenoleukodystrophy and monitor response to developing therapies.

Adolescent↗