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Biomedical subjects

C A Stewart

Publications and source records attributed to C A Stewart.

At least 91 records · Page 5Linked to original sources
PubMed1989

Unusual pattern of lung uptake of technetium-99m sulfur colloid seen on the liver scan of a patient with pulmonary tuberculosis.

In evaluating alcoholic liver disease in a patient with pulmonary tuberculosis, a liver-spleen scan was performed that showed an unusual uptake of sulfur colloid in the lungs. There was diffuse uptake in the left lung and portions of the right lower lung with absent uptake in the right upper lobe and portions of the right lower lung corresponding to areas of pulmonary consolidation. A perfusion lung scan confirmed absent pulmonary arterial perfusion in these areas and a gallium scan demonstrated active infection there.

Female↗
PubMed1988

Continuous distributions of NMR relaxation times applied to tumors before and after therapy with X-rays and cyclophosphamide.

In vivo measurements of T1 and T2 values in two experimental tumors growing in the legs of mice were made during tumor growth and after treatment of the tumor with either X-rays or cyclophosphamide. The T1 and T2 values were obtained by fitting the data to continuous distributions of relaxation times. This technique gives broad distributions of relaxation times which are characterized by a number of peaks with characteristic T1 and T2 values. Before treatment, the T1 and T2 values increased before a palpable tumor mass could be detected. The response to subcurative doses of either treatment method was a reduction in the T1 and T2 values and a parallel reduction in tumor weight. Although local recurrence was characterized by the same pattern of tumor growth as was observed before treatment, therapy was found to give higher relaxation time values than those measured in untreated tumors. The higher relaxation time values of tumor-bearing legs were the result of redistribution of the peaks in the distribution and not changes in the relaxation times of the individual peaks.

Animals↗
PubMed1988

The application of depth-pulse localized 31P NMR spectroscopy to monitor tumor metabolism and response to chemotherapy in the rat kidney.

To illustrate the spatial variations in metabolism within tumors, 31P spectral data are presented from a predefined, depth-pulse localized region of a rat kidney impregnated with Walker sarcoma cells. These data display the changes in energy metabolism during infiltration of the kidney by the tumor and during treatment of the tumor with cyclophosphamide.

Animals↗
PubMed1988

Gated radionuclide ventriculography in the evaluation of cardiac function in Duchenne's muscular dystrophy.

Left ventricular ejection fractions were determined in 38 patients with Duchenne's muscular dystrophy. No significant correlation between the severity of respiratory dysfunction or age and cardiac function was seen. We suggest that the cardiac status of each patient should be evaluated separately from his respiratory status, particularly when long-term assisted ventilation is being considered.

Adolescent↗
PubMed1986

Scintigraphic demonstration of splenosis.

A case of splenosis, or the autotransplantation of splenic tissue following trauma, was encountered unexpectedly on a routine liver scan performed in the workup of alcoholic liver disease. Confirmatory scintigraphic images using Tc-99m labeled, heat-damaged, autologous erythrocytes are presented with CT scans of the abdomen.

Adult↗
PubMed1986

Demonstration of hydrothorax by intraperitoneal injection of technetium-99m MAA in the evaluation of peritoneovenous shunt patency.

A case of hydrothorax in a patient with recurrent ascites following Le Veen peritoneovenous shunt placement is presented. Patency of the Le Veen shunt was studied by the intraperitoneal injection of Tc-99m MAA with subsequent activity seen in the right hemithorax only. A standard perfusion lung scan showed only the left lung to be perfused. Thus, the right hemithorax activity seen could not be due to shunt patency, but represented direct communication between the labeled ascitic fluid and the right hydrothorax seen on chest x-ray.

Female↗
PubMed1986

Evaluation of peritoneovenous shunt patency by intraperitoneal Tc-99m macroaggregated albumin: clinical experience.

The clinical utility of peritoneovenous shunt patency studies using intraperitoneal Tc-99m macroaggregated albumin was studied. The patency of a peritoneovenous shunt can be reliably determined using the intraperitoneal injection of Tc-99m macroaggregated albumin with the appearance of lung activity as an indicator of patency. In an evaluation of 66 cases of clinically suspected peritoneovenous shunt obstruction, using the appearance of lung activity as the sole criterion of patency, this technique was shown to have a sensitivity of 100%, specificity of 92.2%, and accuracy of 98.5%. Visualization of efferent shunt tubing was variable and not a reliable criterion of shunt patency. This technique should be considered when peritoneovenous shunt patency is questioned.

Adult↗
PubMed1986

Osteomyelitis associated with pressure ulcers.

Bone biopsies were performed in spinal cord injured patients with pressure ulcers in whom osteomyelitis was suspected. Roentogenograms and bone and gallium scans were also evaluated to determine their usefulness in diagnosing osteomyelitis. Infected bone underlying pressure ulcers revealed only mild focal inflammatory changes which did not correlate well with x-ray and nuclear scan abnormalities. Negative scans, however, essentially ruled out osteomyelitis. There was no clear association of delayed healing or recurrence of pressure sore with osteomyelitis. Antibiotic therapy of greater than three weeks' duration did not significantly affect the outcome of the disease.

Adult↗
PubMed1983

An index to measure the healing potential of ischaemic ulcers using Thallium 201.

Prediction of healing of ulcers in ischaemic limbs can preclude unnecessary treatment for ulcers that cannot heal. Non-invasive methods are of marked value as the ischaemic limb is susceptible to further ulceration from local skin penetration. Relative hyperemia of the ulcer was measured by scintillation count over the ulcer and at points 2.5 cm from the edge of the ulcer. Relative hyperemia was determined by dividing the count per unit area of the ulcer by the counts per unit area of the surrounding tissue. All ulcers with a relative hyperemia over 1.5 healed.

Humans↗
PubMed1982

201Tl perfusion study of "ischemic" ulcers of the leg: prognostic ability compared with Doppler ultrasound.

Thallium 201 perfusion analysis was compared with Doppler ultrasound as a means of determining the healing potential of an ischemic ulcer of the leg in 27 patients. The degree of hyperemia was determined by comparative point counting of the 201Tl distribution in and about the ulcer. Using established Doppler criteria and a hyperemia ratio greater than 1.5:1, ultrasound alone correctly predicted healing in 15 out of 23 cases and 201Tl in 20 out of 23. Ultrasound correctly predicted non-healing in 3 out of 6 cases, compared with 5 out of 6 for 201Tl. The positive predictive value of the 201Tl study was 63%, versus 27% for ultrasound, and the negative predictive value was 95% for 201Tl and 83% for ultrasound. The accuracy of 201Tl and ultrasound was 86% and 62%, respectively. This limited study suggests that 201Tl perfusion scanning is a useful noninvasive test of ulcer healing potential and may be more sensitive than Doppler ultrasound.

Adult↗
PubMed1981

Thallium-201 peripheral perfusion scans: feasibility of single-dose, single-day, rest and stress study.

The distribution and redistribution kinetics of thallium-201 in the lower extremities were investigated to determine the relationships among the rest, stress, and delayed-stress perfusion studies. The distribution of perfusion when the tracer was administered at rest was compared with that when administered during stress, and the distribution 5--6 hr after the stress injection. The distribution was evaluated qualitatively by scanning and quantitatively by point counting. In nine of 10 subjects without peripheral vascular disease, the 5--6 poststress redistribution pattern was unchanged from the stress pattern and was different from the rest pattern. However, in all patients with peripheral vascular disease, the delayed poststress perfusion distribution had greater similarity to the rest pattern and was substantially different from that noted immediately after stress. Using the time frame of this study, the stress and delayed-stress 201Tl perfusion study of the lower extremities cannot be used to represent true rest perfusion. However, because of the similarity of the delayed-stress to the true rest distribution in abnormals, it may be clinically useful in defining rest and stress alterations.

Humans↗
PubMed1981

A new objective criterion for determining, noninvasively, the healing potential of an ischemic ulcer.

Peripheral vascular perfusion studies using intravenously administered thallium-201 were performed on 13 patients suffering from ischemic ulcer of the lower extremities. Scintillation camera views and point counting over the lesion and adjacent region were utilized to define qualitatively and quantitatively the relative hyperemia of the lesion. The preliminary findings demonstrate that when the relative hyperemia was equal to or greater than 1.5, 100% (seven of seven) went on to heal their ulcer with conservative management. Of those without this degree of hyperemia, 83% (five of six) will require amputation. Based on this limited series, noninvasive assessment of the relative hyperemia of an ischemic ulcer using thallium-201 is a new, useful, and objective indicator of the healing potential of a so-called ischemic ulcer.

Amputation, Surgical↗
PubMed1980

Carcinoid tumour of the thymus with Cushing's syndrome.

A 29-yr-old male developed Cushing's syndrome with severe hypokalaemia, alkalosis and hypernatraemia. He died with Pseudomonas septicaemia and Nocardia pneumonia. At autopsy he was found to have a carcinoid tumour of the thymus which was not suspected before death, and marked bilateral hyperplasia of the adrenal cortex.

Adult↗