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S T Treves

Publications and source records attributed to S T Treves.

103 records · Page 6Linked to original sources
PubMed1987

Estimating the plasma time-activity curve during radionuclide renography.

Quantitative analysis of the radionuclide renogram requires an estimate of the plasma time-activity curve. This estimate is usually obtained from an externally detected blood-pool curve that is calibrated with a single plasma sample. However, external probes detect activity in the extravascular as well as the intravascular space. This may lead to significant errors in estimating the plasma time-activity curve. A method for overcoming this problem by using a continuously varying calibration factor based upon multiple plasma samples was therefore evaluated. Externally detected blood-pool curves were used to estimate the plasma time-activity curves obtained from rabbits during radionuclide renography. Estimates obtained using the externally detected curves calibrated with a constant calibration factor were found to be significantly biased, while estimates obtained using the externally detected curves calibrated with the continuously varying calibration factor were not.

Animals↗
PubMed1987

An osmium-191/iridium-191m radionuclide generator using an oxalato osmate parent complex.

A new osmium-191/iridium-191m (191Os/191mIr) radionuclide generator has been developed that offers high 191mIr yield (greater than 20%/ml) and low 191Os breakthrough (less than 5 X 10(-4)%/ml) when eluted with a solution of 0.001 M oxalic acid and 0.9% (normal) saline. This is the first 191Os/191mIr generator that combines the advantages of high 191mIr yield, extremely low 191Os breakthrough, and an eluate that does not require buffering prior to injection. These improvements in performance were accomplished through use of the chelate transdioxobisoxalatoosmate(VI) as the parent complex on the generator. The clinical result of the combination of higher yield and lower breakthrough is a 100-fold decrease in the estimated patient radiation dose compared with the same study performed with technetium-99m (99mTc), and the injectable eluate makes the generator easier to use. Acute and subacute toxicity studies performed on this generator eluate have shown no adverse effects attributable to the eluate.

Iridium↗
PubMed1986

Osteoid osteoma: localization by intraoperative magnification scintigraphy.

Surgical localization of osteoid osteomas is a major problem in the diagnosis and therapy of this lesion. Visual, tactile, and radiographic localization is often equivocal and as a consequence incomplete excision of the tumor, or excessive removal of bone may result. We performed magnification intraoperative bone scintigraphy using a portable gamma camera and a radioactive pointer in six patients with osteoid osteoma. Accurate localization and complete removal of the tumor was achieved in all six with only minimal delays in the surgical procedure. The advantages of this technique and recommendations for its use are discussed.

Adolescent↗
PubMed1986

Comparison of ultrashort-lived iridium-191m with technetium-99m for first pass radionuclide angiocardiographic evaluation of right and left ventricular function in adults.

Ultrashort-lived iridium-191m (Ir-191m, physical half-life = 5.0 seconds) has been used in angiocardiography, primarily in pediatric patients. A theoretical obstacle to more widespread use of Ir-191m is the belief that its physical half-life is too short to permit evaluation of left ventricular function in adult patients. To evaluate its usefulness in adults, first pass ejection fractions of the left and right ventricles determined with use of Ir-191m and technetium-99m (Tc-99m) were compared in 33 adult patients. An osmium-191m----iridium-191m (Os-191----Ir-191m) generator was employed to deliver doses of 150 to 250 mCi (5.5 to 9.2 GBq) of Ir-191m for intravenous injection. The whole body radiation absorbed dose with Ir-191m was 15 to 25 mrad. High quality angiocardiograms were obtained with both Tc-99m and Ir-191m. Total counts per image for the right ventricle were 51,000 +/- 8,000 (mean +/- SD) for Ir-191m and 30,000 +/- 8,000 for Tc-99m. The left ventricular counts were comparable for both radiotracers (25,000 +/- 7,000 for Ir-191m and 25,000 +/- 8,000 for Tc-99m). Right ventricular ejection fractions were similar: 44 +/- 8% for Ir-191m and 47 +/- 9% for Tc-99m. The correlation coefficient was 0.93 with a standard deviation of the regression of 3.1% ejection fraction units. The left ventricular ejection fractions were also similar: 45 +/- 14% for Ir-191m and 46 +/- 13% for Tc-99m. The left ventricular ejection fraction correlation coefficient was 0.96 with a standard deviation of the regression of 3.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Radionuclide angiocardiography in children.

Clinical use of radiotracer techniques in pediatric cardiology is increasing. Three basic methods being employed are first pass radionuclide angiocardiography, gated blood pool scanning and myocardial perfusion scintigraphy. These methods are rapid, safe and accurate. They are minimally invasive and result in a low radiation dose to the patient. The development of ultrashort-lived radionuclides (such as iridium-191m with a half-life of only 5 seconds), improvements in nuclear imaging instrumentation and numerical analysis should contribute to a further utilization of these methods.

Angiocardiography↗
PubMed1985

Pectus excavatum in children: pulmonary scintigraphy before and after corrective surgery.

Regional distribution of pulmonary function was evaluated preoperatively and postoperatively with xenon-133 perfusion and ventilation scintigraphy in 17 patients with pectus excavatum. Ventilatory preoperative studies were abnormal in 12 of 17 patients, resolving in seven of 12 postoperatively. Perfusion scans were abnormal in ten of 17 patients preoperatively; six of ten showed improvement postoperatively. Ventilation-perfusion ratios were abnormal in ten of 17 patients, normalizing postoperatively in six of ten. Symmetry of ventilation-perfusion ratio images improved in six out of nine in the latter group. The distribution of regional lung function in pectus excavatum can be evaluated preoperatively to support indications for surgery. Postoperative improvement can be documented by physiological changes produced by the surgical correction.

Adolescent↗
PubMedDate not supplied

Acute pulmonary embolism in a neonate: precipitation during cardiac catheterization and successful treatment.

This report illustrates the rare occurrence of a pulmonary embolus in a neonate during cardiac catheterization. The patient was a term newborn who underwent repair of obstructed infradiaphragmatic total anomalous pulmonary venous connection. Postoperative risk factors for pulmonary embolism included severe pulmonary hypertension unresponsive to nitric oxide therapy, an indwelling venous catheter, and young age. Successful management was achieved by initial mechanical fragmentation with streptokinase infusion and monitoring by serial lung perfusion scans.

Acute Disease↗
PubMedDate not supplied

Correlation of 99mTc-HMPAO SPECT with EEG monitoring: prognostic value for outcome of epilepsy surgery in children.

Sixteen children who had focal cortical resections for medically intractable epilepsy were preoperatively evaluated with 99mtechnetium-labelled hexamethylpropyleneamineoxime single photon emission computed tomography (99mTc-HMPAO SPECT). Video-EEG monitoring was performed in all patients. Outcome was assessed according to the criteria of Engel et al. [1], at a mean follow up length of 13.4 +/- 8.7 months, in all patients. Interictal SPECT showed appropriate localization in 11/15 cases, of whom nine had a class 1 outcome and two had class 2 and 4 outcomes. Interictal SPECT did not correlate with ictal EEG in 4/15 patients, of whom two had a class 1 outcome, and two had class 3 and 4 outcomes. Two postictal studies obtained in group I showed good correlation with the area of ictal EEG onset, and both patients had a class 1 outcome. Interictal HMPAO SPECT imaging, when positively correlated with the ictal EEG focus or with the site of surgery determined by other means, may have prognostic value for outcome of cortical resections for epilepsy in children. The use of ictal and post-ictal studies shows promise for further improving prognostic information in this population.

Adolescent↗
PubMedDate not supplied

Renal and hemodynamic effects of dopamine in infants following cardiac surgery.

The renal and hemodynamic effects of dopamine were measured during the immediate postoperative period in six infants following repair of congenital cardiac defects. Dopamine was infused at rates of 5, 10, and 15 micrograms/kg/min. Cardiac index (CI) increased significantly at a dopamine infusion rate of 15 micrograms/kg/min. The glomerular filtration rate (GFR) and urine output increased at dopamine infusion rates of 5 and 10 micrograms/kg/min and returned to baseline at 15 micrograms/kg/min. No significant changes occurred in right atrial pressure (RAP), left atrial pressure (LAP), systemic artery pressure, systemic vascular resistance (SVR), or pulmonary vascular resistance (PVR). Heart rate (HR) increased slightly at a dopamine infusion rate of 15 micrograms/kg/min. Pulmonary artery pressure (PAP) increased significantly in only one patient. These data demonstrate that infants require high doses of dopamine to produce the hemodynamic effects seen in adults and that these higher doses may be used without adverse renal effects.

Blood Pressure↗
PubMedDate not supplied

Radiation exposure of anesthesiologists.

STUDY OBJECTIVE: To determine the level of radiation exposure of anesthesiologists in the operating rooms and cardiac catheterization laboratory. DESIGN: Prospective study of all anesthesia fellows. SETTING: Operating rooms (ORs) and radiology department of a tertiary care pediatric hospital. SUBJECTS: Anesthesiologists caring for patients in a pediatric hospital requiring anesthesia or monitored anesthesia care. (Patients were not directly studied.) MEASUREMENTS AND MAIN RESULTS: Anesthesiologists wore standard radiation safety film badges, which were sensitive to cumulative doses of radiation greater than 10 mrem. In the ORs, anesthesiologists were exposed to less than 10 mrem/mon. In the cardiac catheterization laboratory, they had dosimetric readings that ranged from 20 to 180 mrem/mon and frequently exceeded the guidelines for nonradiation workers. CONCLUSIONS: There is no need for routine dosimetric monitoring of anesthesiologists working in the OR setting, since this is associated with negligible radiation exposure. Monitoring of radiation film badges should be considered for anesthesiologists who frequently work in fluoroscopy areas, such as the cardiac catheterization laboratory. All personnel working near radiation sources should wear appropriate shielding and, whenever patient safety permits, distance themselves as far as possible from the source of radiation.

Anesthesiology↗
PubMedDate not supplied

Pediatric skeletal scintigraphy: applications of pinhole magnification.

Pinhole magnification scintigraphy is an effective means of evaluating the pediatric skeleton because it provides optimal high-resolution images. This technique is indicated when diagnostic uncertainty persists after high-resolution imaging with parallel hole collimation. Pinhole magnification scintigraphy requires approximately 20 minutes of acquisition time per image and meticulous attention to details such as choice of pinhole insert, collimator positioning, and patient immobilization. However, the technique is superior to planar imaging in demonstrating acute osteomyelitis in bone adjacent to growth centers and epiphyseal involvement that is either primary or the result of local spread of infection. In addition, pinhole imaging has proved highly reliable in the early diagnosis of Legg-Calvé-Perthes disease and is useful in depicting osteonecrosis related to specific causes such as corticosteroid treatment or trauma. Scintigraphic manifestations of femoral head ischemia or infarction and findings indicative of osteomyelitis associated with a hip effusion are well demonstrated with pinhole imaging. This technique also helps characterize osteoid osteomas and may be used intraoperatively to confirm the complete excision of this benign tumor. Finally, pinhole magnification scintigraphy clearly depicts fractures of the femoral neck and allows a high degree of confidence in diagnosing injuries to the small bones of the hands and feet.

Adolescent↗
PubMedDate not supplied

Quantitative evaluation of 99mTc-hexamethylpropylenamineoxime brain SPECT in childhood-onset epilepsy.

In 10 patients with childhood-onset epilepsy, quantitative evaluation (QE) of interictal regional cerebral blood flow (rCBF) using technetium-99m-hexamethylpropylenamine oxime (99mTc HMPAO) single-photon emission computed tomography (SPECT) was correlated with seizure foci localized by electroencephalography (EEG). Eighty regions of interest (5 x 5 pixels) were placed at five different neocortical areas in both cerebral hemispheres, in coronal and transaxial planes. Mean counts/pixel were calculated for each region and multiple right-left comparisons were done. Quantitative evaluation of 99mTc-HMPAO increased detection of rCBF abnormalities by 26%. Abnormal EEG patterns correlated with abnormal rCBF in 75% of cases (Phi = 0.788, p < 0.001), and with visually detected abnormalities in 50% (Phi = 0.493, p < 0.001). Discordance between EEG and SPECT was most frequent in patients with non-localizing EEG (n = 3). In childhood-onset epilepsy, quantitative evaluation of brain perfusion scans provides: (a) objective estimates of interictal rCBF; (b) more precise detection of epileptogenic foci, when used to complement EEG.

Adolescent↗