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Biomedical subjects

D P Swanson

Publications and source records attributed to D P Swanson.

14 recordsLinked to original sources
PubMed1991

Acute reactions to intravascular contrast media: types, risk factors, recognition, and specific treatment.

Acute, potentially life-threatening systemic reactions to contrast media are less frequent with lower osmolality, nonionic contrast agents, but they are not totally eliminated. Severe reactions remain a reality in all radiology departments. Typical reactions to contrast media include nausea and/or vomiting, scattered to extensive urticaria, bronchospastic reaction, hypotension (isolated) with compensating tachycardia, anaphylactoid reaction, vagal reaction, cardiovascular collapse, convulsion, and seizure. For each type of reaction, rapid recognition and initiation of specific corrective therapy enhance response and minimize side effects of drugs. Specific drugs for treating each reaction type are reviewed, including recommended dose, contraindications, and alternative choices. An approach to the high-risk patient and prevention of acute systemic reactions is discussed and pretreatment protocols are outlined.

Anaphylaxis↗
PubMed1979

A simple model for anatomic bone scanning studies.

A simple anatomic model for studying the scintigraphic appearance of various skeletal structures is described. The technique makes use of the fact that technitium pyrophosphate uptake in bone occurs by chemisorption to the surface of crystals in the bone matrix. By soaking clean bones in solutions of technetium pyrophosphate they can be rendered radioactive and subsequently studied by various imaging techniques.

Bone and Bones↗
PubMed1979

Adrenal imaging with iodomethyl-norcholesterol (I-131) in primary aldosteronism.

Twenty consecutive patients with primary aldosteronism (PAl) underwent dexamethasone suppression (DS) imaging with 6beta-[131I]-iodomethyl-19-norcholesterol (NP-59): A) to establish the value of the adrenal scan in distinguishing aldosteronomas from bilateral hyperplasia; b) to determine its ability to locate aldosteronomas when present; and c) to compare the efficacy of NP-59 in this current series against that reported previously with NM-145 in PAl. Ten of twenty patients had an aldosteronoma, five had histologically confirmed hyperplasia, and five had presumed hyperplasia. With NP-59, nine of ten tumors were correctly located (90%) , correct distinction between tumor and hyperplasia was possible in 90%, and a locating DS scan was specific for tumor in 90%. In a combined series of different patients with PAl imaged with NM-125, 21 of 25 tumors were correctly located (84%), tumor was distinguished from hyperplasia in 86%, and the specificity of the localizing scan was 92%. The imaging delay required from tracer injection to attainment of an interpretable scan averaged 2.7 days with NP-59 and 4.8 days with NM-145. In summary, no significant differences were noted in the clinical results achieved with these two agents. The preferred agent is NP-59, since the study can be completed with less average time delay than is possible with NM-145.

Adosterol↗
PubMed1979

Imaging the adrenal medulla with an I-131-labeled antiadrenergic agent.

Tissue distributions of four antiadrenergic agents labeled with iodine-125 have been determined in dogs. [125I] ortho-iodobenzldimethyl-2-hydroxyethyl ammonium and [125I] ortho-iodobenzyldimethylethyl ammonium show highly selective uptake in the adrenal medulla. Studies of molecular structure-distribution indicate that both the nature of the cationic head and the ring position of the iodine atom greatly influence adrenal specificity. Distinct images of dogs' adrenal medulla have been obtained 4 days after i.v. injection of 1.5 mCi of [131I] ortho-iodobenzyldimethyl-2-hydroxyethyl ammonium.

Adrenal Medulla↗
PubMed1979

The normal dexamethasone-suppression adrenal scintiscan.

To establish the parameters of adrenal imaging under dexamethasone suppression (DS), 18 normotensive, normal male volunteers underwent dexamethasone-suppression adrenal scintiscanning. Five control groups were established and given dexamethasone, either 8 mg for 2 days or 4 mg for 7 days before 6 beta-[131I]iodomethyl-norcholesterol (NP-59) administration. NP-59 was given in doses of 2, 1, or 0.5 mCi. Early visualization (3--5 days) of the adrenals was noted in the groups on the 8 mg DS regimen with either 1 or 2 mCi of NP-59. Late visualization (5--7 days) was noted in the groups that received 4 mg DS and either 2, 1, or 0.5 mCi of NP-59, respectively. The normal adrenal will demonstrate uptake of NP-59 under DS, and the duration of DS before imaging is the critical factor as to when discernible adrenal visualization will occur. The documentation of the noraml suppression interval on these DS regimens provides a basis for the correct diagnostic interpretation of adrenal hyperfunction as seen on the dexamethasone-suppression NP-59 adrenal scan.

Adosterol↗
PubMed1979

Iodine-131: optimal therapy for hyperthyroidism in children and adolescents?

To assess the medium- to long-term effects of I-131 therapy of hyperthyroidism in children and adolescents, we studied 51 patients (age range 6--18; boys, 43 girls) treated with I-131 for Graves' disease with hyperthyroidism at the University of Michigan Medical Center (1951--1972). Patients received total doses ranging from 3 to 81.6 mCi. The mean followup period was 14.6 +/- 7.9 yr. Hyperthyroidism was effectively treated in 49 within 1 to 12 mo. One patient failed to respond to three treatment doses, and hyperthyroidism recurred in two patients: 2 and 11 yr after initial therapy. Of these three patients, two were treated by thyroidectomy and one was retreated successfully with I-131. There were no cases of thyroid cancer, other malignancies or leukemia. The patients' reproductive histories and the health of their offspring were as in the general population. At the time of study, the prevalence of hypothyroidism was 92%, with no recurrent goiters or thyroid nodules. Iodine-131 is found to be safe and effective treatment of hyperthyroidism in children and adolescents and should be the preferred mode of therapy.

Adolescent↗
PubMed1978

Adrenal imaging agents: rationale, synthesis, formulation and, metabolism.

In this introductory paper on radionuclide adrenal imaging, the rationale, synthesis, formulation, and metabolism of two clinically well-established and one promisinmg adrenocortical imaging agents are reviewed. Their present clinical utility is reviewed in a separate presentation in this issue. Progress to date in developing a positive imaging agent of the adrenal medulla and tumors of chromaffin tissue will be given brief consideration because there is, as yet, no clinically successful radiolabeled adrenal medulla imaging agent.

Adrenal Glands↗
PubMed1978

Normal adrenal asymmetry: explanation and interpretation.

Although adrenal imaging with 19-iodocholesterol provided much useful diagnostic information, spatial resolution was less than ideal. With the greater target-to-background ratios afforded by NP-59, differences between the right and left adrenal glands--in terms of position, configuration, and depth-related activity--can now be defined. Analysis of the scintigrams of 21 individuals with no evidence of adrenal disease has allowed us to characterize the normal degree of adrenal asymmetry. Appreciation of this asymmetry is necessary if the potential for greater diagnostic accuracy afforded by NP-59 is to be realized.

Adrenal Glands↗
PubMed1978

Imaging the adrenal glands with radiolabeled inhibitors of enzymes: concise communication.

Although radioiodinated cholesterols furnished the first noninvasive imaging of the adrenal glands, it would be desirable to decrease the time for imaging and decrease the radiation dose. The relative tissue distributions of two radiolabeled enzyme inhibitors [3H] metyrapol and I-125-SKF-12185 were studied in dogs and man. Their percentage uptakes and target-to-nontarget ratios were similar. The adrenals of three dogs were imaged sharply at 2 hr after injection with 4--6 mCi of I-131-SKF-12185, confirmed by subsequent imaging with 1 mCi of I-131-6-beta-19-nor cholesterol at 5 days after injection. The use of 1 mCi of I-123-SKF will permit imaging of the adrenals in 1--2 hr and will decrease the radiation dose in the human to 0.76 rads to the adrenal, 0.18 rads to the ovaries and 1.7 rads to the liver.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Diagnostic interventions in nuclear medicine.

Diagnostic interventions in nuclear medicine may be defined as the coadministration of a nonradioactive drug or application of a physical stimulus or physiologic maneuver to enhance the diagnostic utility of a nuclear medicine test. The rationale for each interventional maneuver follows from the physiology or metabolism of the particular organ or organ system under evaluation. Diagnostic inference is drawn from the pattern of change in the biodistribution of the tracer in response to the intervention-induced change in metabolism or function. In current practice, the most commonly performed interventional maneuvers are aimed at studies of the heart, genitourinary system, hepatobiliary system, and gastrointestinal tract. The single most commonly performed interventional study in the United States is the stress Thallium-201 myocardial perfusion scan aimed at the diagnosis of coronary artery disease. The stress portion of the study is accomplished with dynamic leg exercise on a treadmill and is aimed at increasing myocardial oxygen demands. Areas of myocardium distal to hemodynamically significant lesions in the coronary arteries become ischemic at peak stress due to the inability of the stenotic vessel to respond to the oxygen demand/blood flow needs of the myocardium. Ischemic areas are readily recognized as photopenic defects on scans obtained immediately after exercise, with "normalization" upon delayed imaging. Diuresis renography is aimed at the differential diagnosis of hydroureteronephrosis. By challenging the urinary tract collecting structures with an augmented urine flow, dilated, unobstructed systems can be differentiated from systems with significant mechanical obstruction. Obstructed systems have a low ability to respond even after effective diuresis, resulting in a characteristic prolonged retention of the radiotracer. Hepatobiliary interventions are most commonly employed in the clinical setting of suspected acute cholecystitis. Administering a cholecystogogue before a hepatobiliary tracer promotes visualization of the gallbladder by causing it to go through a contraction/filling cycle in which the filling phase occurs during maximum exposure to the radionuclide. This maneuver can convert a false positive study that suggests the presence of acute cholecystitis to a true negative study. Other gastrointestinal interventions are aimed at enhancing the detection of gastroesophageal reflux and gastrointestinal bleeding. Many new interventions have been developed that are currently aimed at research problems rather than clinical problems.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Gland Diseases↗