Biomedical subjects

R E Latchaw

Publications and source records attributed to R E Latchaw.

At least 19 recordsLinked to original sources

PubMed1992

Quantitative computer tomography in Alzheimer's disease: a re-evaluation.

This investigation addresses the question of usefulness of computer-tomographic (CT) scanning in discriminating patients with Alzheimer's disease (AD) from healthy, aged controls. Quantitative measures of brain volume loss found to be significant by other investigators as well as additional unique variables are used to discriminate 58 longitudinally studied patients meeting NINCDS-ADRDA criteria for the clinical diagnosis of probable AD from 59 controls. The sensitivity and specificity of both single CT scan parameters and multivariate models comprised of such CT parameters are explored. Reasons for diagnostic misclassification are also illuminated.

Aged↗

PubMed1992

Imaging of intracranial infection.

Modern imaging techniques define the anatomic region infected and the evolution of the disease, help to evaluate treatment efficacy, and frequently can help to determine extra-central nervous system sources of infection, such as sinusitis or mastoiditis. These techniques are discussed by anatomic region, and differential diagnosis based on image pattern is formulated. Special attention is given to the findings in the immunocompromised host and in congenital infection.

Acquired Immunodeficiency Syndrome↗

PubMed1989

MR imaging of the pars interarticularis.

MR imaging of the lumbar spine has become a useful method for the noninvasive evaluation of low back pain. However, bone abnormalities are more difficult to detect than soft-tissue lesions, such as herniated disk. We reviewed 14 MR images of the lumbar spine in adults with spondylolisthesis. These were correlated with CT scans and plain films in all cases. From the CT scans and plain films we found that seven patients had spondylolysis and that seven had other causes for their spondylolisthesis. It was our opinion that the MR images suggested an abnormality of the pars interarticularis in all seven of the cases confirmed to have spondylolysis and in six of the seven patients that did not have spondylolysis. We also studied four cadaver lumbar spine, obtained as blocks of tissue, and scanned in the coronal, sagittal, and axial planes with MR and in the sagittal and axial planes with CT. The tissue blocks were then sectioned in the sagittal plane. Spondylolysis is suggested on sagittal MR images when there is an inability to resolve the marrow signal in the pars as uninterrupted from the superior to the inferior facet. This is caused by a dark signal on all pulsing sequences in the pars resulting from marginal sclerosis at the site of the break. If there is also a gap at the site of the break then there will also be an increased signal in the gap resulting from the presence of soft tissue. We found four situations in which the pars can simulate spondylolysis on sagittal MR images: (1) sclerosis of the neck of the pars: (2) partial volume imaging of the degenerative spur of the superior facet slightly lateral to the pars; (3) partial facetectomy; and (4) osteoblastic metastatic replacement of the marrow of the pars.

Adult↗

PubMed1989

The acetazolamide challenge: imaging techniques designed to evaluate cerebral blood flow reserve.

Cerebral blood flow was analyzed by the stable xenon (Xe)/CT scanning technique in 29 patients with significant vascular lesions before and after administration of an acetazolamide (Diamox) vasodilatory challenge. Three response types were identified: I, normal flow before Diamox with flow augmentation after Diamox; II, low flow before Diamox with flow augmentation after Diamox; and III, low or normal flow before Diamox with no augmentation or decreased flow after Diamox. Twenty-four percent of the patients studied qualified for category III. We believe that patients in this category represent a group of individuals without blood flow reserve whose clinical management should include careful consideration of their hemodynamic status. The Xe/CT scanning technique with the addition of Diamox flow challenge is a clinically accessible and effective method for assessing cerebral blood flow and blood flow reserve.

Acetazolamide↗

PubMed1988

Local "inverse steal" induced by hyperventilation in head injury.

Hyperventilation is used routinely to reduce intracranial pressure in victims of severe head injury. In the clinical setting, the effects of hyperventilation on regional cerebral blood flow usually are not known. We describe a case in which hyperventilation resulted in local, paradoxic increases in cerebral blood flow (i.e., "inverse steal") associated with a reduction in intracranial pressure. Although the reduced intracranial pressure was thought to be beneficial, serial computed tomographic scans suggested that the inverse steal response could have promoted cerebral edema, resulting in secondary brain injury.

Brain Injuries↗

PubMed1988

Comparison of MR imaging, CT, and angiography in the evaluation of the enlarged cavernous sinus.

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.

Adult↗

PubMed1988

Magnetic resonance imaging of spinal dysraphism.

MR imaging has become the definitive diagnostic procedure for the evaluation of suspected spinal dysrhaphic processes. Techniques for spinal MR imaging are discussed and MR findings in patients with surgically verified dysrhaphic spinal lesions are reviewed.

Child↗

PubMed1987

Xenon-enhanced computed tomography in brain death.

The absence of cerebral blood flow is a valuable adjunct confirming clinical criteria of brain death. However, current methods to confirm absent cerebral blood flow have problems that limit their clinical use. We reviewed cerebral blood flow data obtained with xenon-enhanced computed tomography in nine patients who were being evaluated for brain death. In eight patients who met clinical criteria for brain death, mean cerebral blood flow was 1.6 +/- 2.0 mL X 100 g X min. This value was within the range of error inherent in the method, and therefore represented absent flow. In a patient with persistent respiratory efforts, flow values compatible with absent flow were obtained in the supratentorial compartment, while mean flows as high as 24 mL X 100 g X min were measured in selected regions of interest in the infratentorial compartment, correlating with the clinical evidence of residual function of the brain stem. Xenon-enhanced computed tomography may be a useful test to confirm the absence of cerebral blood flow in patients being evaluated for brain death.

Adult↗

PubMed1987

Relief of nonhemispheric symptoms in low flow states by anterior circulation revascularization: a physiologic approach.

Operative intervention remains controversial for patients with transient nonhemispheric symptoms with occlusive disease of both the anterior and posterior cerebral circulations. In addition to the standard evaluation of these patients, we have used stable xenon-enhanced computed tomographic mapping of cerebral blood flow (Xe/CT CBF). This relatively new and potentially widely available CBF methodology, by measuring approximately 30,000 CBF values within each of three CT levels, provides a readily interpretable means of evaluating extremes of hemodynamic compromise within any or all vascular territories. In the past 30 months, Xe/CT CBF studies in 300 patients with occlusive vascular disease have identified nine patients with global low flow and nonhemispheric symptoms (vertigo, lightheadedness, and/or blurred vision). Blood pressures determined by ocular pneumoplethysmography of Gee were markedly abnormal with reduced ocular/brachial ratios. Each patient had a combination of both segmental carotid and vertebrobasilar occlusive disease. Each patient had a flow-augmenting procedure performed on the anterior circulation in an attempt to improve global flow: carotid endarterectomy (two patients), subclavian-external carotid bypass (one patient), and superficial temporal artery-middle cerebral artery bypass (six patients). In each case disabling transient symptoms were relieved. There were no operative deaths, but one stroke occurred, probably as a result of a brief period of postoperative hypotension. Postoperative Xe/CT CBF studies show a long-term improved global CBF in all patients.

Brain↗

PubMed1987

Stereotactic software for the GE 8800 CT scanner.

A computer software program (Seapit) was developed for precise determination of intracranial targets identified by stereotactic computed tomography (CT). This program was added to the software of a GE 8800 CT scanner to perform the following operations: millimetre precise calculation and display of the rectilinear coordinates of a target identified on axial CT images; preplotting of phantom target trajectories on the CT images or electronic radiographs; calculation of probe angles required to achieve various trajectories; display of a coordinate scale on each CT image to allow direct target determination without mathematical calculations; calculation of the intercommissural plane for functional neurosurgery. In a series of 100 patients undergoing stereotactic surgery, the Seapit program proved to be a superior and accurate method of target coordinate calculation. Preview display on the CT images of 'phantom' probes significantly enhanced the safety of stereotactic intervention.

Biopsy↗

PubMed1987

Spinal and paraspinal neurofibromatosis: surface coil MR imaging at 1.5 T1.

Twelve patients with neurofibromatosis affecting the spine and paraspinal regions were examined with magnetic resonance (MR) imaging performed using a 1.5-T magnet, surface coils, and spin-echo pulse sequences. In all 11 patients with neurofibromas, these tumors had slightly greater signal intensity than muscle on T1-weighted images and markedly increased signal intensity on T2-weighted images. In seven patients central areas of decreased signal intensity within the neurofibromas were demonstrated on T2-weighted images. In one patient these central areas corresponded pathologically to relatively fibrous components of the tumors surrounded by myxoid matrix. Five patients had extensive plexiform neurofibromatosis, one had lateral meningoceles, one had a neurofibrosarcoma, three had extradural spinal cord compression, and two had cystic intramedullary tumors of the spinal cord. The ability to obtain high-resolution, multiplanar images in a noninvasive fashion makes surface coil MR imaging an ideal technique for evaluating neurofibromatosis involving the spinal cord, spinal canal, and paraspinal soft tissues.

Humans↗

PubMed1987

Adverse reactions to xenon-enhanced CT cerebral blood flow determination.

Fourteen institutions performed 1,830 computed tomographic (CT) cerebral blood flow (CBF) examinations with 32% inhaled stable xenon. Respiratory rate delay greater than 10 seconds occurred in 3.6% of patients, with 83% of the delays lasting 10-15 seconds. There was no incident of prolonged respiratory difficulty. Headache (0.4%), seizures (0.2%), nausea and vomiting (0.2%), and change in neurologic status (0.1%) were uncommon, and there were no transient ischemic attacks. The CT CBF method with 32% inhaled stable xenon is thus associated with an acceptably low incidence of adverse reactions.

Brain↗

PubMed1986

Operative exposure and management of the petrous and upper cervical internal carotid artery.

The exposure and operative management of the petrous and upper cervical internal carotid artery (ICA) in 29 patients is detailed. Twenty-seven of these patients had extensive cranial base neoplasms (benign or malignant), 1 had an inflammatory cholesteatoma, and 1 had an aneurysm of the upper cervical ICA immediately proximal to the carotid canal. Preoperative studies useful in the evaluation of these patients included computed tomography, magnetic resonance imaging, cerebral and cervical angiography, and a balloon occlusion test of the ICA with evaluation of neurological status and of cerebral blood flow. The exposure of the upper cervical and petrous ICA was useful to obtain proximal control of the cavernous ICA, aided in the operative approach to extensive petroclival, intracavernous, and parapharyngeal neoplasms, and enabled the total resection of 23 of 27 such tumors. A subtemporal and preauricular infratemporal fossa approach was most commonly used for the exposure of the artery. Intraoperative arterial management consisted of exposure and decompression only, dissection from encasing neoplasm, resection of the invaded arterial segment and vein graft reconstruction, or intentional arterial occlusion. Vascular complications included 1 stroke due to delayed arterial occlusion, 1 stroke and death due to infection spreading from the nasopharynx with bilateral ICA rupture, and 1 pseudoaneurysm formation secondary to wound infection necessitating postoperative balloon occlusion of the ICA. Nonvascular complications included facial nerve paralysis in 10 patients (usually temporary), glossopharyngeal and vagal paralysis in 13 patients requiring Teflon injection of the vocal cord in 9, temporary difficulties with mastication in 9 patients, and wound infection in 3. The surgical exposure and management of the upper cervical and petrous ICA may permit a total operative resection of extensive cranial base neoplasms and is also an alternative for the management of vascular lesions involving these segments of the artery. With malignant neoplasms extending from the nasopharynx, postoperative infection remains a problem and may best be resolved by the use of a vascularized rectus abdominis muscle flap to reconstruct defects of the nasopharynx. Bilateral ICA encasement by neoplasms is also a major problem to be solved. The value of such an aggressive approach to the management of malignant neoplasms remains to be proven.

Carcinoma, Squamous Cell↗

PubMed1986

Stereotaxic surgery with a magnetic resonance- and computerized tomography-compatible system.

Modern stereotaxic surgery is dependent upon compatible advanced imaging tools, including computerized tomography (CT) scanning and magnetic resonance (MR) imaging. The authors describe three cases in which the patients underwent stereotaxic surgery for mass lesions identified by both MR imaging and CT scans. Identical target coordinates were defined by both techniques, and accuracy was confirmed by intraoperative CT. In comparison to stereotaxic CT, MR provided superior contrast resolution, allowed direct multiplanar imaging and target determination, and permitted accurate correlation of the image with histological features. The operative set-up and technique are described. Stereotaxic surgery with MR imaging may permit more accurate histopathological definition of tumor margins and ultimately lead to better dosimetry for therapeutic procedures such as interstitial brachytherapy.

Adult↗

PubMed1986

Computerized tomographic and magnetic resonance imaging of intracranial lipoma. Case report.

Intracranial lipoma is an uncommon lesion that has been well described in both the neurosurgical and neuroradiological literature for many years. This lesion is usually only an incidental finding, but it may be symptomatic. The authors describe a case of symptomatic intracranial lipoma of the superior medullary velum with emphasis on the correlation between computerized tomography and magnetic resonance imaging in evaluation of the lesion.

Brain Neoplasms↗

PubMed1986

Magnetic resonance imaging does not define tumor boundaries.

To define tumor boundaries prior to radiation therapy, 13 patients with intracranial glial neoplasms had tumor biopsies using magnetic resonance imaging (MRI)--computed tomography (CT) stereotactic technique. Precise histologic sampling of the lesion volume was correlated with the MRI and CT-defined 'lesion'. Tumor boundaries extended beyond the CT or MRI margin in 4 of 4 cases of glioblastoma, 1 of 3 cases of anaplastic astrocytoma, and 1 of 6 cases of well-differentiated astrocytoma. While stereotactic MRI is superior to stereotactic CT in the visualization of glial neoplasms, accurate tumor biopsy is mandatory to define both tumor type and margins before pre-operative radiation therapy.

Adult↗

PubMed1986

Xenon/CT cerebral blood flow determination following cranial trauma.

Xenon/CT cerebral blood flow (CBF) analysis has been utilized in the evaluation of 35 patients sustaining severe cranial trauma. The patient population included closed head injury, focal hematoma, and the sequelae of trauma including coma, persistent alteration of consciousness, and brain death. Xe/CT CBF analysis has proven helpful in the determination of appropriate degrees of hyperventilation therapy for the head injured patient. The technique is helpful for determining both local and remote changes of CBF as an aid in deciding upon surgical intervention. Severely decreased flows, compatible with brain death, can be demonstrated. The technique shows promise in the evaluation of physiologic changes accompanying therapy for the injured brain.

Adult↗

PubMed1986

Cerebral blood flow measured by xenon-enhanced computed tomography as a guide to management of patients with cerebrovascular disease.

CT scanning performed before and sequentially during the inhalation of stable xenon (32%), coupled with end-tidal xenon measurements, has made possible the routine construction of regional cerebral blood flow (rCBF) maps with resolution that approximates that of the CT scanner. The capability of obtaining quantitative flow maps with direct anatomic correlation is now available with a commercial package of hardware and software adapted to the General Electric 9800 scanner. The ability to distinguish between normal and reduced rCBF in specific vascular territories has proved useful in the management of cerebrovascular disease. Specific clinical dilemmas that have been addressed with rCBF information from xenon-enhanced CT scanning include the following: In the patient with asymptomatic occlusive disease, is normal rCBF preserved? Is there adequate collateral flow? Are cerebrovascular symptoms a result of emboli or chronic regional low flow? In the patient with complex multivessel occlusive disease, which revascularization procedure is indicated first? Did operation improve rCBF? Should a further procedure be added? May a diffusely diseased but patent artery, which is the source of emboli, be sacrificed safely without compromising rCBF? On the basis of experience with 155 patients, the management and understanding of cerebrovascular disease has been aided substantially by the incorporation of rCBF mapping by xenon-enhanced CT scan in the evaluation of these patients.

Aged↗