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Biomedical subjects

C L Partain

Publications and source records attributed to C L Partain.

At least 73 records · Page 4Linked to original sources
PubMed1984

Intravascular contrast agents suitable for magnetic resonance imaging.

Two paramagnetic chelates, chromium EDTA and gadolinium DTPA, were evaluated as potential intravenous contrast agents for magnetic resonance imaging (MR) using a 0.5-T superconducting scanner. After evaluating both agents in vitro, in vivo studies were conducted in dogs to document changes in renal appearance produced by contrast injection. Acute splenic and renal infarction were diagnosed with contrast-enhanced MR and confirmed by gamma camera imaging following administration of Tc-99m-labeled DMSA and sulfur colloid. The authors conclude that intravenous paramagnetic contrast agents presently offer the best mechanism for assessment of tissue function and changes in perfusion with MR.

Animals↗
PubMed1984

Magnetic resonance imaging of multiple sclerosis: a study of pulse-technique efficacy.

Forty-two patients with the clinical diagnosis of multiple sclerosis were examined by proton magnetic resonance imaging (MRI) at 0.5 T. An extensive protocol was used to facilitate a comparison of the efficacy of different pulse techniques. Results were also compared in 39 cases with high-resolution x-ray computed tomography (CT). MRI revealed characteristic abnormalities in each case, whereas CT was positive in only 15 of 33 patients. Milder grades 1 and 2 disease were usually undetected by CT, and in all cases, the abnormalities noted on MRI were much more extensive than on CT. Cerebral abnormalities were best shown with the T2-weighted spin-echo sequence (TE/TR = 120/1000); brainstem lesions were best defined on the inversion-recovery sequence (TE/TI/TR = 30/400/1250). Increasing TE to 120 msec and TR to 2000 msec heightened the contrast between normal and abnormal white matter. However, the signal intensity of cerebrospinal fluid with this pulse technique obscured some abnormalities.

Adult↗
PubMed1984

Current perspectives on medical imaging.

Advances in biomedical technology have expanded the potential of medical imaging. Selected aspects of developments in sonography, nuclear medicine, nuclear magnetic resonance and digital imaging are addressed, stressing the wide scope permitted by these newer modalities.

Angiography↗
PubMed1984

Paramagnetic contrast agents in magnetic resonance imaging: research at Vanderbilt University.

Experimental studies in animals have demonstrated the application of particulate and chelated paramagnetic oral contrast agents in magnetic resonance imaging (at 0.5 tesla). The ability of a soluble paramagnetic species, ferrous gluconate, to improve imaging studies of the pancreas presently is being evaluated in clinical trials. Two paramagnetic metal ion chelates, Cr EDTA and Gd DTPA, have been evaluated extensively as potential intravascular contrast agents. Renal function, tissue vascularity, abnormalities of the blood-brain barrier, and infarction of myocardial tissue may all be assessed with IV contrast enhanced magnetic resonance imaging. The contrast materials tested all represent first generation compounds. Improved relaxation characteristics, toxicity, distribution, and flexibility will result from development of second generation agents, primarily within the particulate and chelate classes.

Animals↗
PubMed1984

Congenital absence of the gallbladder: another cause of false-positive hepatobiliary image.

Hepatobiliary imaging with the various technetium-labeled IDA compounds is more than 90% sensitive and specific for the diagnosis of acute cholecystitis. Causes of false-positive studies include chronic cholecystitis, cystic-duct obstruction by tumor, prolonged fasting, the nonfasting state, pancreatitis, alcoholism, parenteral hyperalimentation, and severe intercurrent illness. A case of congenital absence of the gallbladder is submitted as another cause of a false-positive scan.

Aged↗
PubMed1984

Evaluation of intrathoracic goiter with I-123 scintigraphy and nuclear magnetic resonance imaging.

Iodine-123 thyroid scintigraphy allows the diagnosis of a functioning retrosternal goiter in a patient with a mediastinal mass. The case report of a 60-yr-old lady demonstrates this. The correlative values of nuclear magnetic resonance imaging and thyroid scintigraphy in the initial evaluation and continued management of patients with thyroid mediastinal mass are presented. In addition, this observation demonstrates the ability of nuclear magnetic resonance to identify retrosternal thyroid tissue. This may obviate the need for TCT evaluation, which involves both ionizing radiation and iodinated contrast enhancement.

Female↗
PubMed1983

Evaluation of left ventricular performance using digital subtraction angiography.

Cardiac applications for digital subtraction angiography appear promising, but few correlative studies with contrast ventriculography have been done. Left ventricular volume, ejection fraction, and regional wall motion by digital subtraction angiography were evaluated after intravenous injection of 40 ml of iodinated contrast medium and after left ventricular injection of 5 to 10 ml of contrast medium. A film-based system of the authors' own design was used. Results were compared with those after direct left ventricular injection of 40 ml of contrast medium. The ventriculograms after intravenous injection were of diagnostic quality in 9 of 12 studies, and there were close correlations between intravenous and direct-injection studies for left ventricular ejection fraction (r = 0.89, n = 9, and p = 0.001) and for left ventricular volume (r = 0.91, n = 18, and p less than 0.001). Regional wall motion scores showed close correspondence in 83% of sectors. After small-volume left ventricular injections, the ventricular image was enhanced considerably by digital subtraction. Correlations between small- and large-volume ventriculograms were close for left ventricular ejection fraction (r = 0.91, n = 8, and p = 0.002) and for left ventricular volume (r = 0.96, n = 16, and p less than 0.001). There was close correspondence of wall motion scores in 87% of sectors. Thus, digital subtraction angiography improves the visibility of the left ventricle after either intravenous or small-volume direct left ventricular injection. Digital images produce excellent estimates of left ventricular volume and should have considerable usefulness for the study of cardiac performance and anatomy.

Adult↗
PubMed1983

Radionuclide stroke count ratios for assessment of right and left ventricular volume overload in children.

The ratio of left ventricular to right ventricular stroke counts measured by radionuclide angiography has been used in adults to estimate the severity of left-sided valvular regurgitation. The validation of this technique in children for assessment of right and left ventricular volume overload is reported herein. Radionuclide stroke count ratios in 60 children aged 0.5 to 19 years (mean 11) were determined. Based on their diagnoses, the patients were divided into 3 groups: (1) normal--40 patients with no shunts or valvular regurgitation, (2) left ventricular volume overload--13 patients with mitral or aortic regurgitation, or both, and (3) right ventricular volume overload--7 patients, 2 with severe tricuspid regurgitation, 3 with atrial septal defects, and 2 with total anomalous pulmonary venous drainage. The radionuclide stroke count ratio clearly differentiated these groups (p less than 0.05): normal patients had a stroke count ratio of 1.04 +/- 0.17 (mean +/- 1 standard deviation), the left ventricular volume overload group had a stroke count ratio of 2.43 +/- 0.86, and the right ventricular volume overload group had a stroke count ratio of 0.44 +/- 0.17. In 22 of our 60 patients, radionuclide stroke count ratios were compared with cineangiographic stroke volume ratios, resulting in a correlation coefficient of 0.88. It is concluded that radionuclide ventriculography is an excellent tool for qualitative and quantitative assessment of valvular regurgitation in children.

Adolescent↗
PubMed1983

Renal allograft recovery subsequent to apparent "hyperacute" rejection based on clinical, scintigraphic, and pathologic criteria.

An unusual case is described in which in spite of clinical, scintigraphic and histologic findings strongly supportive of a diagnosis of "hyperacute rejection," recovery of renal function occurred. These findings are in contrast to the current literature in which it is generally accepted that a renal allograft showing neither pertechnetate transit nor hippurate concentration warrants allograft nephrectomy irrespective of the etiology. Scintigraphic evaluation included both dynamic studies after a bolus administration of Tc-99m pertechnetate and serial renogram collections after the intravenous administration of I-131 Hippuran.

Adult↗
PubMed1983

Lymphoscintigraphy as an adjunctive procedure in the perioperative assessment of patients undergoing microlymphaticovenous anastomoses.

Microlymphaticovenous anastomoses provide a potential for reducing lymphedema of the upper extremity complicating radical mastectomy or irradiation. Lymphoscintigraphy is a valuable investigative modality in the perioperative evaluation of patients undergoing this surgical procedure. The radionuclide studies provide information regarding structural change and physiologic derangement with a low radiation dose to the patient. It is a simple, painless procedure requiring minimal skill and no surgical intervention. In addition, a reproducible method for preparing a radiocolloid suitable for lymphatic imaging using an approved drug as a precursor has been developed.

Arm↗
PubMed1983

Work in progress: radionuclide imaging of indium-111-labeled eosinophils in mice.

Eosinophils isolated from peritoneal exudates were labeled with indium-111-oxine and injected intravenously into sensitized mice. They became localized at sites of inflammation produced by intradermal injections of schistosomal antigen or Toxocara canis larvae, whereas labeled neutrophils did not. Intense uptake of eosinophils by normal spleen, liver, and bone marrow was noted, with tracer distribution effectively complete by 5 hours after injection. Indium-111-eosinophil studies appear to be quite sensitive to parasitic inflammatory reactions; in contrast, nonspecific inflammation such as that induced by turpentine causes localization of eosinophils, but to a lesser extent. This technique may be useful in the study of parasitic and allergic disease.

Animals↗
PubMed1983

Work in progress: potential oral and intravenous paramagnetic NMR contrast agents.

The potential use of paramagnetic compounds as nuclear magnetic resonance (NMR) contrast agents was examined in vitro. The T1 relaxation times for serial dilutions of Cu2+, Cr3+, Fe3+, and Mn2+ ions in saline, gadolinium oxalate (a potential oral contrast agent) in suspension, and chromium EDTA (a potential intravenous contrast agent) in solution were determined. The effect on T1 of increasing the concentration of oxygen in solution was also examined. The relative magnitude of the decrease in T1 was, as expected, proportional to both the concentration of the paramagnetic substance and its effective magnetic moment. Thus NMR has the potential to detect differences in tissue oxygenation. By incorporating paramagnetic metal ions into insoluble compounds or stable complexes, toxicity can be dramatically reduced while maintaining a significant paramagnetic effect. Highly insoluble paramagnetic compounds or stable paramagnetic ion complexes can thus be utilized as effective NMR contrast agents with significantly diminished toxicity.

Administration, Oral↗
PubMed1983

Radionuclide angiographic evaluation of right and left ventricular function during exercise after repair of transposition of the great arteries. Comparison with normal subjects and patients with congenitally corrected transposition.

We assessed the incidence, clinical significance and etiology of ventricular dysfunction after intraatrial repair of d-transposition of the great arteries in 11 patients, mean age 9 +/- 3 years, who had had Mustard operations. We compared the results to 15 patients who were considered to have normal ventricular function, two patients who had Rastelli operations and five patients with congenitally corrected transposition. Gated equilibrium radionuclide angiography with supine exercise stress testing was used to assess these children. We found no significant difference between our patient groups in exercise capacity, heart rate, or blood pressure response to exercise. However, we found a high incidence of right ventricular dysfunction in the patient groups, manifested by an abnormal right ventricular ejection fraction response to dysfunction in the patient groups, manifested by an abnormal right ventricular ejection fraction response to exercise in six of 11 patients with a Mustard repair, both patients with a Rastelli repair and all five with congenitally corrected transposition. In addition, the left ventricular response to exercise was abnormal in 10 of 11 patients who had undergone a Mustard repair, both patients with a Rastelli repair, and two of five patients with congenitally corrected transposition. We conclude that biventricular dysfunction is frequently present after intraatrial repair of d-transposition of the great arteries. Despite this dysfunction, no significant decrease in exercise tolerance is found in childhood.

Adolescent↗
PubMed1983

Nuclear magnetic resonance of iron and copper disease states.

The tissue levels of paramagnetic ions are an important factor in the determination of T1 values as observed by nuclear magnetic resonance (NMR) imaging. The increased levels of iron present in human disease states such as hemochromatosis lead to decreased T1 values. The mean liver T1 of three patients with iron storage disease was determined to be 130 msec, significantly different from the value of 154 msec, the mean for 14 normal controls. Whether NMR will be able to detect the increased copper levels in liver and brain in Wilson disease remains for further clinical trials to evaluate. NMR imaging, however, does serve as a noninvasive method for the diagnosis of states of iron overload and as a technique to follow progression of disease or response to medical therapy.

Abdomen↗
PubMed1983

Paramagnetic agents for contrast-enhanced NMR imaging: a review.

The use of paramagnetic agents for contrast enhancement may extend the diagnostic potential of nuclear magnetic resonance (NMR) imaging. Proton relaxation is enhanced in targeted organ systems after either oral or intravenous administration of suitable paramagnetic agents. A decrease in T1 and T2, the spin-lattice and spin-spin relaxation times, can then be observed as an increase in signal intensity on NMR imaging. Initial investigations have focused on development of agents incorporating either paramagnetic ions or stable free radicals. Principles in development and application are illustrated with examples from experiments using the Vanderbilt Technicare 0.5 T NMR imager.

Animals↗