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Biomedical subjects

M A Quaife

Publications and source records attributed to M A Quaife.

At least 19 recordsLinked to original sources
PubMed1993

Current procedural terminology coding of nuclear medicine procedures.

The future of nuclear medicine is dependent on payment for new procedures. Today, the basis of payment by the federal government is a relative value unit (RVU) system; the RVUS employed in this system are for medical services and procedures listed and described in Physicians' Current Procedural Terminology, fourth edition. Current procedural terminology (CPT) is maintained by the AMA; annual revisions include adding new codes or revised or deleted old codes. This process involves all national medical specialty societies. Starting in 1992 a new process, the Relative Updating Committee, which was initiated by the AMA, organized medicine to formalize a method for recommending relative values for physician procedures and services. In this rapidly changing scenario, all nuclear medicine procedure codes are under review by the coding and nomenclature committees of the medical societies interested in imaging. Significant CPT changes and additions were made in the cardiovascular nuclear medicine codes in 1992, reflecting the current imaging protocols and pharmacological agents for performing cardiac stress testing and new codes that recognize combinations of ventricular function measurements in patients undergoing myocardial perfusion imaging with technetium-99m agents.

American Medical Association↗
PubMed1992

Quantitation of metastatic tumor burden from human colon tumor xenografts using radiolabelled monoclonal antibody 17-A fragments.

In realistic models of human tumor xenograft metastasis, the metastatic foci arise in perivascular sites and rarely grow to sizes which are easily quantifiable by visual inspection. As an alternative approach, we have used monoclonal antibody (MAb) 17-1A F(ab')2 fragments labelled with radioiodine (125I) to study the differential accumulation of label in xenografts and metastatic tumor sites as well as in noninvolved tissues of NIH Swiss nude mice receiving HT-29 human colon tumor cells. Images of the whole-body distribution and sites of localization were determined using a pinhole-collimated Angergamma camera. Radioactivity was determined in tissue samples using a well scintillation system, and pharmacokinetics were assessed during the initial 72 h after injection of antibody fragments. The half-life of 125I-F(ab')2 fragments in the blood, 8.6 h, was similar in nontumor-bearing control and tumor-bearing mice. The half-life in subcutaneous tumor xenografts was 30.1 h. The tumor xenograft to tissue activity ratios per unit weight (radiolocalization indices) at 72 h were: blood 90, lung 65, pancreas 50, muscle 35, spleen 20, liver and mesenteric lymph node 10. All subcutaneous xenografts were successfully imaged, and images of 5 of 9 mice (55%) appeared to demonstrate the presence of metastatic tumor by differential and focal accumulation of MAb fragments after 48 or 72 h in the lung (2 cases) or abdominal cavity (3 cases). Necropsy and subsequent histological and biodistribution studies confirmed the presence of metastatic tumor in these sites and identified tumor in several additional sites. The smallest volume of metastatic tissue in liver or lung determined at necropsy which appeared to have been detected by imaging was about 20 mm3. Generally, for mice with metastatic tumors, the radioactivity per unit weight of metastatic tumor-bearing organs compared to tumor-free organs was 2- to 7-fold greater. The results indicate that a radiolocalization index of > or = 2 is generally necessary for metastatic tumor detection by imaging although this is influenced by the extent of anatomical location of the tumor. It was possible to predict the tissue distribution of the fragments from the planar image for the amounts of radioactivity (approximately 1 mCi/kg body weight) employed in this study. These results demonstrate the utility of this approach to quantitate the metastatic burden arising from human colon tumor xenografts in this experimental model.

Animals↗
PubMed1988

Brain structure and function in sexual molesters of children and adolescents.

Sixteen men incarcerated in a state psychiatric facility pursuant to sexual molestation of children and/or adolescents were evaluated by computed tomography (CT) head scans and regional cerebral blood flow (rCBF) estimation. Compared with controls, child molesters were found to have thinner and less dense skulls and lower rCBF values. Variations from control values in rCBF and characteristics of CT head scans for the sex offenders suggest a role for cerebral dysfunction in the etiology of their aberrant behavior.

Adult↗
PubMed1984

Single coronary artery with the right coronary artery arising from the first septal perforator.

A 50-year-old woman with chest pain and an exercise thallium-201 scintigram positive for focal ischemia was found on coronary arteriography to have a heretofore unreported variant of single left coronary artery with the right coronary artery originating as a branch from the first septal perforator. Proximally, the aberrant vessel coursed through the ventricular septum at the level of the right ventricular outflow tract. A conus artery was absent and this is a possible basis for the focal basal ventricular ischemia and the patient's symptoms.

Coronary Vessel Anomalies↗
PubMed1983

Regional cerebral blood flow in schizophrenics. Tests using the xenon Xe 133 inhalation method.

Measurements of intrahemispheric and bilateral regional cerebral blood flow (CBF) for gray and white matter were compared in 29 schizophrenic patients and 22 normal controls, using the xenon Xe 133 inhalation method. Results showed significantly lower CBF values for all brain regions in the schizophrenic group, and post hoc comparisons showed relatively greater reduced gray-matter CBF values in the anterior areas of the brain. There was also a left-hemisphere frontal loss similar to that reported previously, although it was in the context of a generalized loss in anterior functioning. Interhemispheric comparison within both groups showed no differences between homologous regions for gray matter, and greater white-matter CBF values in the right hemisphere than in the left hemisphere. The findings support a hypothesis of a bilateral anterior deficit in schizophrenia.

Adolescent↗
PubMed1983

Hypovolemic pregnant women and their risk determinants.

Among hypovolemic pregnant women there is a high risk of premature labor, fetal growth retardation, and/or hypertension. Arterial wave velocity was determined and Evan's blue disappearance rates measured in hypovolemic gravidas with complications. It appeared that those hypovolemic gravidas without increased cardiac performance are more likely to give birth prematurely, while those with increased cardiac performance and delayed in vivo mixing of Evan's blue dye develop hypertension.

Electrocardiography↗
PubMed1981

Red blood cell volume in preterm neonates.

In the high-risk neonate, the direct determination of the red cell volume by radionuclide dilution technique appears to be the singularly definitive method of defining treatment efficacy, and is thus a useful evaluation and management tool for the pediatrician. For effective patient management, the red blood cell(RBC) volume of 69 preterm and term neonates was determined. The method utilized, Tc-99m-labeled RBCs, provided a fast and accurate answer with a large reduction in the absorbed radiation dose. In the population studied within a high-risk newborn ICU, the mean RBC volumes between the preterm and term neonates were without significant difference. Grouping and analysis of the RBC volume data with respect to birth weight, gestational ages, and 1- and 5-minute Apgar scores revealed on statistical difference. The mean value found in our population, 32.2 +/- 9.2 ml/kg, however, does differ from those previously reported in which the determinations were made using an indirect estimation from the plasma compartment.

Apgar Score↗
PubMed1981

Evaluation and testing of in vitro labeled technetium Tc-99m red blood cells in two animal models for neonatal RBC volume determinations.

The present study was designed to evaluate the red blood cell (RBC) radiolabeling technique utilizing the short half-lived radionuclide technetium-99m and to compare the results with the well-recognized standard chromium-51 method. The procedure was evaluated in a canine and a newborn lamb model utilizing dual radionuclide labeling and counting techniques. With the express purpose of providing a significant radiation dose reduction, the procedure presented was adapted for utilization in a neonatal patient population. Statistical analysis of the data revealed that there was no significant difference in the radiolabeling efficiency for the two methods (Cr-51, 86.6%; Tc-99m, 92.4%). Assessment of the in vitro stability for technetium-99m RBCs showed that less than a 4% loss of radiolabel from the RBC was seen in a 4-hr time span in the canine model (15 min, 90.5%; 2 hr, 88.9%; 4 hr, 86.6%) when compared to the 15 min equilibrium sample. Evaluation of newborn lamb RBC volumes showed that the technetium-99m RBC volume did not significantly differ from the chromium-51 labeling technique (Cr-51, 24.0 ml/kg; Tc-99m, 23.2 ml/kg). Summarization of the whole-body radiation dose showed that greater than a 30-fold reduction in absorbed dose was achieved in the newborn (Cr-51, 30.0 mrad; Tc-99m, 0.9 mrad). The modified procedure presented for the radiolabeling of the RBC with the short half-lived radionuclide technetium-99m provides a technique comparable to the utilized standard chromium-51 RBC method, yet with a large reduction in absorbed radiation dose. This procedure is presented as a superior technique for the determination of pediatric RBC volumes.

Animals↗
PubMed1980

Clinical decision-making with treadmill testing and thallium 201.

Fifty patients were prospectively evaluated for myocardial ischemia utilizing treadmill testing and thallium-201 imaging. By coronary angiography, 43 had significant coronary stenosis and seven were normal. The sensitivity, specificity, accuracy and predictive value of treadmill testing alone (81 per cent, 71 per cent, 80 per cent and 95 per cent) did not statistically differ from that of thallium-201 imaging (70 per cent, 86 per cent, 72 per cent and 97 per cent). Combined treadmill testing and thallium-201 imaging (84 per cent, 71 per cent, 80 per cent and 98 per cent) did not significantly affect the results of treadmill testing alone. Thallium-201 imaging failed to identify a number of patients with high risk lesions. The high prevalence of disease, the presentation of typical angina, preselection bias, multiple lead monitoring and exclusion of patients with abnormalities on the resting electrocardiogram probably accounted for failure of thallium-201 imaging to improve the results obtained with treadmill testing. The use of thallium-201 imaging in certain subsets of patient (resting electrocardiographic abnormalities, nondiagnostic treadmill testing, atypical chest pain or asymptomatic patients with abnormalities on treadmill testing) may be of value. However, the use of thallium-201 imaging as a routine screening procedure for myocardial ischemia in patients with typical angina, without due consideration of the prevalence of the disease in the population, is not justified.

Angina Pectoris↗
PubMed1979

Myocardial accumulation of labeled phosphate in malignant pericardial effusion.

Recognition of the presence of a malignant pericardial effusion is important because of the insidious onset and life-threatening potential. This report presents data on three patients with metastasizing carcinoma of the breast, all admitted with a presumptive clinical diagnosis of malignant pericardial effusion. Two of the three revealed a diffuse concentration of Tc-99m PPi within the myocardium. In these cases the diagnosis was confirmed by identification of malignant cells in the pericardial fluid. We suggest that the use of labeled phosphate agents may allow early recognition of myocardial involvement in patients with disseminated neoplasm that results in malignant pericardial effusion.

Aged↗
PubMed1978

Characteristics of red blood cell survival from subjects with hereditary elliptocytosis.

Hereditary elliptocytosis is an intrinsic red cell abnormality and 12% of elliptocytic individuals demonstrate hemolysis. Using tracer kinetic methodology (51Cr labeled RBC's) the destructive phase of erythropoesis was assessed in two healthy subjects receiving labeled donor red blood cells from individuals with hereditary elliptocytosis. The red blood cell survival time of transfused elliptocytes was significantly decreased in both recipients, with a survival half-time (T 1/2) of 19 days in one recipient and 20 days in the other (N 27 days). Abnormal splenic sequestration was also demonstrated. The decreased survival of transfused cells suggests that caution should be exercised in utilizing patients with hereditary elliptocyosis as donors in blood banking operations even in the absence of evidence of hemolysis.

Blood Transfusion↗