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Biomedical subjects

L A Saint-Louis

Publications and source records attributed to L A Saint-Louis.

12 recordsLinked to original sources
PubMed2001

Lumbar spinal stenosis assessment with computed tomography, magnetic resonance imaging, and myelography.

Degenerative spinal stenosis of the lumbar spine is caused by many factors, some of which include: disc herniation, ligamentum flavum and facet hypertrophy, spondylolisthesis, and compression fracture. Most often the stenosis is caused by a combination of these factors. The imaging modalities in routine use to evaluate these conditions are computed tomography, magnetic resonance imaging and computed tomography-myelogram. They each have their advantages and disadvantages although any one of these modalities can adequately diagnose lumbar stenosis. The overall accuracy rate of computed tomography, magnetic resonance imaging, and computed tomography-myelogram has been reported to be similar and even complimentary. It is recommended that the least invasive modality be performed first. Magnetic resonance imaging should be the first choice because it does not require ionizing radiation or contrast injection. The aim of the current study is to present the common causes of lumbar stenosis. Where appropriate, each case is shown with images from each modality so that their similarities and differences can be highlighted.

Fractures, Spontaneous↗
PubMed1990

Optimizing radiologic costs in the DRG environment.

Previously developed consensus algorithms expressing a suggested radiologic workup for the diagnostic related groups (DRGs) specified by the prospective reimbursement policy have proven to be useful tools for investigating radiologic decision making and the resulting economic implications. The mathematical equations for determining diagnostic and therapeutic costs for two alternative algorithms for suspected acute cholecystitis are formulated. Illustrative examples and graphic displays are given regarding how such algorithms and equations are useful in finding answers to questions about the appropriate diagnostic workup, time, and cost. Exploration of the effect of different parameter values on the choice of the appropriate algorithm is illustrated.

Algorithms↗
PubMed1989

Bilateral cholesterol granulomas of the petrous apices: case report and review.

This paper describes the diagnostic investigations and surgical treatment of a patient with bilateral lesions of the petrous apices. Many surgical methods were considered before choosing one that would allow simultaneous drainage and hearing preservation. A transsphenoidal, transclival route was used and the surgical goals achieved. A review of the pertinent otologic, neurosurgical and radiologic literature is presented. To our knowledge, this is the first case report in the English language of the transclival approach to both petrous apices.

Adult↗
PubMed1989

Mascara and eyelining tattoos: MRI artifacts.

Magnetic resonance imaging (MRI) is very useful in the evaluation of ocular and orbital disease. Heavy metal particles, used in the pigment base of mascara and eyelining tattoos, have a paramagnetic effect that causes alteration of the local magnetic field in adjacent tissues. These changes in normal signal result in distortion of the globes. In some cases, the distortion may mimic actual ocular disease such as a ciliary body melanoma or cyst.

Cosmetics↗
PubMed1987

Advanced diagnostic imaging techniques in ophthalmology.

Diagnostic imaging techniques continue to gain tremendous importance in the evaluation of ocular and orbital disease as technical developments and refinements are made. This article presents key diagnostic imaging methods, with special focus directed toward the advanced modalities important in evaluation of the traumatized eye and orbit. The text has been prepared specifically for the clinical ophthalmologist. Each of the diagnostic modalities discussed is presented in terms of its basic biophysical mechanism, indications, and advantages and disadvantages. The techniques described include simple plain film roentgenography (and its contrast-related applications: dacryocystography, orbital venography, and angiography), axial hypocycloidal tomography, computed tomography, ultrasonography, and magnetic resonance imaging.

Diagnostic Imaging↗
PubMed1986

Periventricular hyperintensity as seen by magnetic resonance: prevalence and significance.

Periventricular hyperintensity was identified using long repetition and echo times in spin-echo magnetic resonance imaging of patients with white-matter disease (e.g., multiple sclerosis) caused by local demyelination and in hydrocephalic patients caused by transependymal migration of spinal fluid. A review of 365 consecutives studies revealed that some degree of periventricular hyperintensity is present in most patients (93.5%) regardless of diagnosis. Mild periventricular hyperintensity was seen in patients with no other evidence of intracranial pathology. Periventricular hyperintensity is a normal finding that should not be considered indicative of either demyelinating disease or hydrocephalus. More extensive and severe periventricular hyperintensity is associated with intracerebral pathology, but the finding often is nonspecific. For example, mild periventricular edema from hydrocephalus is impossible to differentiate from the increased periventricular hyperintensity seen in patients with multiple white-matter lesions. Thus, the pattern of periventricular hyperintensity has proven to be of limited value in the clinical assessment of hydrocephalic patients.

Adolescent↗
PubMedDate not supplied

Magnetic resonance imaging of meningiomas.

Twenty-eight patients with 32 meningiomas were studied on a 0.5-T superconductive magnetic resonance (MR) imager. This common, benign treatable tumor was more clearly seen on computed tomography (CT) than MRI in 53% of cases. This is a result of poor contrast between the tumor and the adjacent brain on all spin-echo and inversion-recovery pulse sequences. Those sequences that provide the greatest anatomic detail were best for identifying this low-contrast lesion. Inversion-recovery scans in particular demonstrated the tumor as a discrete hypointense mass (relative to nearby white matter) with excellent visualization of the dural base and white matter buckling indicative of extracerebral mass effect. Other characteristic features include: a hypointense rim because of the venous capsule (66%); mottling due to hypervascularity; a well defined edema collar that demarcates the tumor from adjacent brain; and hyperostosis with thickening of the calvaria and obliteration of its normal landmarks. MRI did not demonstrate tumor calcification but did demonstrate vascular encasement, displacement, and occlusion better than CT and as well as digital venous angiography.

Adult↗