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Biomedical subjects

D Spigos

Publications and source records attributed to D Spigos.

At least 19 recordsLinked to original sources
PubMed1998

Human magnetic resonance imaging at 8 T.

In this work, we present the first human magnetic resonance image (MRI) obtained at ultrahigh field strengths (8 T). We demonstrate that clinical imaging will be possible at 8 T and that reasonable quality head images can be obtained at this field strength. Most importantly, we emphasize that the power required to excite the spins at 8 T is much lower than had previously been predicted by the nuclear magnetic resonance theory. A 90 degree pulse in the head at 8 T requires only approximately 0.085 J of energy (90 W for a 2-lobe 4 ms sinc pulse). Based on measurements at 4 T, 1-2 J of energy should have been utilized to achieve a 90 degree excitation at 8 T. The fact that the energy required for spin excitation at 8 T is much lower than predicted by the NMR theory, will be extremely important to the viability of ultrahigh field imaging, since concerns related to power absorption and specific absorption rate (SAR) violations at ultrahigh field are alleviated. As such, it will be possible to utilize RF intensive pulse sequences and adiabatic spin excitation at 8 T without significant risk to the subject.

Brain↗
PubMed1995

Use of polyetherurethane to improve the biocompatibility of vascular stents.

PURPOSE: To investigate potential differential growth on neointima following overdilating arterial trauma with polyetherurethane-coated versus bare metallic stents in swine. METHODS: Twelve specially constructed tantalum stents, 6 coated with polyetherurethane block copolymer and 6 uncoated, were overdilated by 25% in 12 normal renal arteries of six swine. The stents were harvested 8 weeks after implantation and prepared for histologic examination. Neointimal thickness was quantified and analyzed for significant differences between coated and uncoated prostheses. RESULTS: All specimens demonstrated fractures of the internal elastic lamina consistent with vascular injury. There was significantly less neointimal formation (0.0001 < p < 0.05) in coated specimens as compared to uncoated controls in each test animal. CONCLUSIONS: The vascular response to overdilating stent trauma appears to be moderated with the use of polyetherurethane block copolymer as compared to control.

Animals↗
PubMed1994

Arteriography in the evaluation of penetrating pediatric extremity injuries.

The routine use of arteriography for evaluating penetrating extremity injuries is undergoing reevaluation in the adult literature. Its role in children is less clear. Eighty-seven children treated for penetrating extremity trauma over a 5-year period were studied retrospectively to define the usefulness of arteriography. The ages ranged from 2 to 16 years. Twenty-four arteriograms were performed. Twelve were for patients who exhibited physical signs of vascular injury (diminished pulse, distal ischemia, expanding hematoma, or bruits/thrills over the wound). The other 12 were performed on asymptomatic children with wounds in proximity to major vessels. Two other patients with ongoing hemorrhage were taken directly to the operating room. Of the 12 arteriograms performed for abnormal physical signs, eight (67%) showed vascular injuries. None of the studies performed for proximity alone had abnormal results (P < .01). Ten of 10 patients with vascular injuries had abnormal physical findings, whereas only four of 77 patients without vascular injuries had abnormal findings (sensitivity 100%, specificity 95%). Eighty-five percent of patients have had follow-up in the pediatric surgery clinic, and no missed injuries or complications have been discovered. Timely diagnosis and repair is the cornerstone for successful management of vascular injuries. While the arteriogram is an important adjunct in patients who have abnormal physical findings, proximity to major vessels alone fails to identify patients at risk for significant injuries. Angiography may not be warranted in patients whose physical examination results are normal. Noninvasive modalities such as B-mode ultrasound and Doppler may have future application in the evaluation of these cases.

Adolescent↗
PubMed1989

The anorectal sphincter after rectal pull-through surgery for anorectal anomalies: MRI evaluation.

The puborectalis muscle sling was evaluated with MRI in 10 pediatric patients who had rectal pull-through surgery for anorectal anomalies. MRI (1.5T) demonstrated the puborectalis muscle equally or better than CT in 5 patients who had both CT and MRI. The amount of puborectalis muscle mass and the location of the pulled-through intestine in relation to the puborectalis sling was well shown with MRI. Our study suggests that MRI can be reliably substituted for CT in the majority of these patients, to assist in planning further surgery for relief of persistent postoperative fecal incontinence.

Anal Canal↗
PubMed1988

Assessment of splenic and RES function of patients with thalassemia major long after partial splenic embolization: in vivo clearance study.

The activity of the remaining reticuloendothelial system (RES) and the function of the splenic remnants was estimated in 5 thalassemic patients who had undergone successful partial splenic embolization (PSE) 6 yr previously. The kinetics of 125I-heat-denatured human albumin as well as that of 51Cr-heat-damaged homologous red blood cells were applied for this purpose and the parameters derived were compared to those of nonsplenectomized as well as splenectomized thalassemics with the following results: (a) The parameters of splenic function in embolized thalassemics were found to be within the limits observed in nonsplenectomized patients. (b) Their maximum phagocytic capacity was significantly lower, not only than that found in nonsplenectomized, but also than in thalassemic patients splenectomized at about the same time. It is concluded that, 6 yr after PSE has been performed, a reorientation of the altered circulatory dynamics has taken place in the splenic remnants allowing previously blockaded areas to gain normal function. It therefore seems that, despite the continuing hemolytic stimulus, RES hyperplasia is prevented, resulting in the stable, low-level transfusion requirements that have been observed in embolized thalassemics.

Adolescent↗
PubMed1987

Management of major or massive hemoptysis in active pulmonary tuberculosis by bronchial arterial embolization.

Management of massive hemoptysis in patients with active pulmonary tuberculosis is complicated. Transcatheter hemostatic embolization of bleeding vessels with absorbable material has been reported to be useful in controlling this problem. Twelve patients with active pulmonary tuberculosis who had major or massive hemoptysis were managed at Cook County Hospital, Chicago, from 1982 to 1986. Various methods of treatment have been evaluated. The technique of angiographic embolization and the criteria for selection of patients for its use constitute the basis of this report.

Adult↗
PubMed1984

Computed tomography of the heart and great vessels: present and future.

Computed tomography (CT) has emerged as a new imaging method for the diagnosis and evaluation of cardiovascular disease. With CT body scanners and contrast enhancement, evaluation of aortic dissections and aneurysms, coronary bypass graft patency, cardiovascular thrombus, cardiac tumors, and pericardial disease is possible. On occasion, this technique provides clinically useful information that is not available with other imaging methods. Electrocardiographic gating retrospectively or prospectively improves the image resolution of CT scans, but a new ultrafast CT scanner with a scan time of 30 to 50 milliseconds offers the greatest promise for expanding the application of the technology for cardiovascular diagnosis. Accurate measurement of cardiac chamber volume, mass, wall motion, and wall thickening will be feasible. Ultrafast CT scanning also shows great promise for the measurement of myocardial infarct size and regional myocardial blood flow.

Aortic Dissection↗
PubMed1981

Malposition of venous end of Le Veen shunt: a preventable complication.

The Le Veen peritoneovenous shunt for the treatment of refractory ascites is a useful adjunct in the management of these cases. For proper shunt function the venous end of the shunt must lie within the superior vena cava. This case report illustrates how an unsuspected malposition of the venous end of the shunt was discovered and documented. An alternate means of inserting the venous end of the Le Veen shunt that will guarantee that it lies in the superior vena cava is suggested.

Ascites↗
PubMed1977

Percutaneous biopsy of renal transplants using ultrasonographic guidance.

The transplanted kidney is an ideal organ for study by ultrasonic methods because it is located superficially in the iliac fossa and it is free of superimposed echoes from the intestines. Therefore, it is possible to localize the transplant accurately, measure the distance from the skin to the surface of the kidney and determine with precision the angle of the intended pathway of the needle.

Biopsy, Needle↗
PubMed1976

Ultrasonically guided percutaneous aspiration of lymphoceles following renal transplantation: a diagnostic and therapeutic method.

Percutaneous aspirations of perirenal collections under ultrasonographic control is a safe and simple therapeutic and diagnostic procedure in patients who have developed lymphoceles after renal transplantation. The diagnostic and therapeutic yield is far superior to any other method, short of surgical exploration. We encountered no complications in our cases. The technique is described in detail.

Cysts↗