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Biomedical subjects

M Viamonte

Publications and source records attributed to M Viamonte.

At least 19 recordsLinked to original sources
PubMed1992

Primary squamous-cell carcinoma of the small bowel. Report of a case.

This is the first case report of a primary, pure squamous-cell carcinoma of the small bowel. Small bowel cancer represents only 1 to 2 percent of all gastrointestinal malignancies. Over 35 different histologic types of small bowel tumors have been described. By far, most small bowel epithelial tumors are metastatic. A 65-year-old white female presented with abdominal pain, melena, and hematochezia and was found to have a 5.5-cm, ulcerated, well-differentiated, keratinizing, squamous-cell carcinoma of the terminal ileum.

Aged↗
PubMed1991

Comparison of serial quantitative evaluation of calcified coronary artery plaque by ultrafast computed tomography in persons with and without obstructive coronary artery disease.

Coronary artery calcium indicates atherosclerosis. Ultrafast computed tomography (CT) can noninvasively visualize and quantify coronary calcium, permitting the natural history of calcified plaque to be studied. This pilot study evaluates the ability of ultrafast CT to follow the progression of calcified plaque within the coronary arteries in patients with and without obstructive coronary artery disease (CAD). Twenty-five subjects had serial ultrafast CT scans of the coronary arteries a mean of 406 days apart. Changes in the number of calcific deposits, calcified plaque area and volume, calcium density and total calcium score were measured. In the 20 patients with calcium on the first study, there were statistically significant increases in mean peak CT number, total calcified plaque volume, total calcified plaque area and total calcium score (p less than 0.0001 for all). Subjects with proved obstructive CAD (n = 10) on angiography had a 48% increase in calcified plaque volume compared with 22% in asymptomatic subjects (n = 10). Comparison of serial studies showed that smaller calcific deposits often coalesced into single larger calcific deposits. Ninety-eight percent (235 of 241) of deposits identified on the first study were accounted for on the second study. Patients with obstructive CAD had a higher number of new calcific deposits than did those in the asymptomatic group (55 vs 18, p = 0.058). Serial ultrafast CT accurately tracks the progression of coronary artery calcium. It is a useful technique for assessing changes in calcified plaque formation in both asymptomatic subjects and in patients with obstructive CAD. It may be useful for studying the natural history of CAD and the effects of intervention on the course of CAD.

Adult↗
PubMed1991

New technique for Hartmann's reconstruction.

Since the introduction of Hartmann's operation and its broader applications, restoration of intestinal continuity has posed technical challenges and significant morbidity. We describe a technique for Hartmann's reconstruction, utilizing a circular anastomotic stapling device that is simple and fast and that minimizes the potential for contamination, in which the bowel lumen remains closed at all times.

Anastomosis, Surgical↗
PubMed1990

Quantification of coronary artery calcium using ultrafast computed tomography.

Ultrafast computed tomography was used to detect and quantify coronary artery calcium levels in 584 subjects (mean age 48 +/- 10 years) with (n = 109) and without (n = 475) clinical coronary artery disease. Fifty patients who underwent fluoroscopy and ultrafast computed tomography were also evaluated. Twenty contiguous 3 mm slices were obtained of the proximal coronary arteries. Total calcium scores were calculated based on the number, areas and peak Hounsfield computed tomographic numbers of the calcific lesions detected. In 88 subjects scored by two readers independently, interobserver agreement was excellent with identical total scores obtained in 70. Ultrafast computed tomography was more sensitive than fluoroscopy, detecting coronary calcium in 90% versus 52% of patients. There were significant differences (p less than 0.0001) in mean total calcium scores for those with versus those without clinical coronary artery disease by decade: 5 versus 132, age 30 to 39 years; 27 versus 291, age 40 to 49 years; 83 versus 462, age 50 to 59 years; and 187 versus 786, age 60 to 69 years. Sensitivity, specificity and predictive values for clinical coronary artery disease were calculated for several total calcium scores in each decade. For age groups 40 to 49 and 50 to 59 years, a total score of 50 resulted in a sensitivity of 71% and 74% and a specificity of 91% and 70%, respectively. For age group 60 to 69 years, a total score of 300 gave a sensitivity of 74% and a specificity of 81%. The negative predictive value of a 0 score was 98%, 94% and 100% for age groups 40 to 49, 50 to 59 and 60 to 69 years, respectively. Ultrafast computed tomography is an excellent tool for detecting and quantifying coronary artery calcium.

Adult↗
PubMed1990

World Health Organization--basic radiographic system (WHO-BRS) unit: experimental clinical evaluation.

The basic radiographic system (BRS) is a simplified version of a standard radiographic unit designed by the World Health Organization and the Pan American Health Organization. The design of the BRS includes the requirement that it should be able to perform routine radiographic examinations with a minimum of operator training. This report describes the performance of a BRS manufactured by Siemens. The physical parameters of this BRS were very good and operation should require a minimum of training. A small number of BRS films were compared with films obtained using the standard equipment in the department. The BRS films were generally regarded as satisfactory. Radiation exposure to patients is equal to, and in some cases less than, exposures with conventional X-ray units.

Developing Countries↗
PubMed1990

Continuous arteriovenous rewarming: experimental results and thermodynamic model simulation of treatment for hypothermia.

We evaluated a technique for treating hypothermia that uses extracorporeal circulation but does not require heparin or pump assistance. Hypothermia to 29.5 degrees C was induced in eight anesthetized dogs, and thermistors placed in the pulmonary artery, liver, bladder, esophagus, rectum, muscle, and skin. Four experimental animals were rewarmed by creating a fistula which connected arterial and venous femoral lines to an interposed counter-current heat exchanger. External rewarming was used in four controls. Bleeding time (BT), coagulation profile (PT, PTT, TT), and cardiac output (CO) were measured during rewarming. Core temperature (T) rose significantly faster with CAVR (0.00001). Average time to rewarming was 45 min, vs. 4 hrs in controls. Haptoglobin, platelet, fibrinogen, and fibrin split product levels were unaffected. Continuous arteriovenous rewarming (CAVR) improved T, CO, BT, and coagulation profile faster than any method yet reported not requiring heparin or cardiac bypass. The application of CAVR in post-traumatic hypothermia warrants further investigation.

Animals↗
PubMed1989

Corrosion cast studies of the bronchial arteries.

The bronchial a. are the nutrient vessels of the lung. Despite being high pressure (systemic) vessels they are of very small size compared to the pulmonary a. and their side branches are normally so minute that they are extremely difficult to visualize during in vivo studies--yet these branches also supply many important mediastinal structures including the esophagus, trachea, lymph nodes, pericardium, aorta, and mediastinal parietal pleura. The bronchial a. can react vigorously to pathological changes in the lung by hypertrophy and increased flow and their precise anatomy has become of increasing importance with the development of interventional techniques involving the systemic circulation of the lungs. In order to demonstrate the distribution and extent of these vessels we have adopted a casting technique using injections of various colors of latex to distinguish between pulmonary a. and veins, bronchial a. and veins and their connections with the pulmonary vascular bed in both normal and diseased lungs.

Adult↗
PubMed1986

Proton relaxation times in arterial wall and atheromatous lesions in man.

The proton relaxation times of autopsy samples of arterial intima-media were measured with an NMR spectrometer and results correlated to the microscopically estimated lipid content of the vascular wall. The normal arterial intima-media contained two T1 relaxation components. The short T1 component (T1s) was 90 +/- 13 ms and its relative weight was 11%. The long T1 component (T1l) was 523 +/- 89 ms and relative weight 88%, respectively. The average T2 was 99 +/- 18 ms. In diseased vessels, a positive correlation was found between the lipid content of the vessel wall and the relaxation rate of the fast component. T1s of the intima-media was significantly shorter (P less than .01) in severe atheromatosis compared with vessels without fat deposition. The results suggest that atheromatous lesions should be best highlighted in spin-echo images by using short TR and TE to suppress the influence of T1l and to avoid (noncontrast contributing) T2 decay of the signal intensity.

Adolescent↗
PubMed1985

Sensitivity of MRI in metastatic neoplasia: a case report.

Serial magnetic resonance imaging (MRI) and computed tomography (CT) were performed on a patient with metastatic lung cancer to brain. Magnetic resonance (MR) visualized two foci of intracerebral metastasis six weeks prior to CT.

Adenocarcinoma↗
PubMed1985

MR imaging of multiple sclerosis: comparison with clinical and CT examinations in 74 patients.

Magnetic resonance (MR) imaging, the latest test for evaluation of patients with multiple sclerosis (MS), was assessed against clinical evidence in 74 patients with definite or probable MS. MR imaging was positive in 55 (85%) of 65 patients with definite MS but in only one (11%) of nine patients with probable MS. The examination is most likely to be positive when the patient is classified clinically as having definite MS; when the disease is active and not in remission; and if the constellation of symptoms indicates a multiplicity of regions with neurologic dysfunction. The examination was most sensitive for detecting lesions in the cerebral hemispheres, the posterior fossa, and the cervical spinal cord, in that order; it did not detect any lesions in the optic nerves. The paraclinical tests and MR imaging were of equal sensitivity in detecting MS lesions, but the latter method was more specific in localization. Cerebrospinal fluid evaluation was slightly less sensitive than the other two tests. There was no correlation between MR imaging and these examinations. The authors conclude that MR imaging is more sensitive than computed tomography (CT), which was positive in 25% of 59 patients with definite MS; it is always positive when CT is positive; and it probably can replace CT in the diagnosis and follow-up of patients with MS.

Adult↗
PubMed1979

Positioning device for cardiac series.

The author describes a new positioning device for use during radiography of the chest. This device is particularly helpful when doing a cardiac series.

Heart Diseases↗
PubMed1979

Morphologic-radiographic correlations of the pancreas.

Numerous noninvasive and invasive imaging modalities are available for the study of pancreatic disease. Disappointingly, the radiographic demonstration of a pancreatic neoplasm is more successful than the treatment of the disease. The proximity of large vascular structures to the pancreas makes its study technically difficult and explains why vascular invasion is readily caused by dispersion of pancreatic secretions (as seen in pancreatitis) or by neoplastic infiltration. The latter heralds nonresectability. Needle biopsy under fluoroscopic or echographic control appears to be gaining popularity as a simple, sensitive and specific method for establishing the diagnosis of pancreatic malignancy. Angiography has its highest yield in the diagnosis of islet cell tumors because they are generally hypervascular. This technique has been complemented by selective catheterization of pancreatic veins followed by hormone bioassay determinations.

Adenoma, Islet Cell↗