Erythrocyte survival in chronic renal failure. Role of secondary hyperparathyroidism.

The human erythrocyte (RBC) is a target organ for parathyroid hormone (PTH) and the hormone increases RBC osmotic fragility and induces their hemolysis. The present study was undertaken to examine whether elevated blood levels of PTH affect RBC survival, and therefore whether PTH, being an extracorpuscular factor, is responsible for the shortened RBC survival in chronic renal failure. 51Cr-labeled RBC survival was elevated in six normal dogs, in six animals with chronic renal failure and secondary hyperparathyroidism (NPX), and in six thyroparathyroidectomized dogs (NPX-TPTX) with comparable degree and duration of chronic renal failure. In the normal dogs, 51Cr-labeled RBC survival ranged between 22 and 35 (25.6 +/- 1.9) d. In the NPX dogs, 51Cr-labeled RBC survival was shortened and the values ranged between 16 and 20 (18.4 +/- 0.6) d, a value significantly (P less than 0.01) lower than normal dogs. In NPX-TPTX dogs, 51Cr-labeled RBC survival ranged between 20 and 33 (25.2 +/- 1.8) d, a value not different from that in normal dogs but significantly higher (P less than 0.01) than that in NPX animals. Our data demonstrate that excess blood levels of PTH and not other consequences of the uremic state are responsible for the shortened RBC survival in chronic renal failure.

Radiopharmaceuticals. 16. Halogenated dopamine analogs. Synthesis and radiolabeling of 6-iododopamine and tissue distribution studies in animals.

A simple halogenated derivative of dopamine, 6-iododopamine (1), has been synthesized using two different methods. These synthetic sequences have been applied to the radiolabeling of 1 with carbon-11, iodine-131, and iodine-123. The tissue distribution of 1 in mice, dogs, and rats was determined. The ratio of radioactivity (%/g) in the adrenal medulla-kidney in dogs increases from 3.45 at 2 h postinjection to 33.3 at 24 h postinjection. Thyroid uptakes in mice, dogs, and rats show that in vivo deiodination of 1 is not significant.

Imaging of medullary thyroid carcinoma and hyperfunctioning adrenal medulla using iodine-131 metaiodobenzylguanidine.

Scintigraphy with radiolabeled metaiodobenzylguanidine was performed in a patient with MEN Type IIa having a pheochromocytoma of the right adrenal gland, adrenomedullary hyperplasia of the left adrenal gland and a primary medullary thyroid carcinoma. The scintigraphic findings demonstrate visualization of all the above mentioned pathologies.

A clinical comparison of Xe-127 and Xe-133 for ventilation studies.

Xenon-133 and xenon-127 were compared by performing ventilation studies with both radionuclides in 19 patients with a variety of lung diseases. Assessment of the counting rate over the chest, relative to the radioactivity in the lungs, permitted the evaluation of each isotope in terms of usable photons detected by a scintillation camera with a large field of view and appropriate collimation. A greater photon yield was obtained with Xe-127. Markedly improved resolution was shown by measurement of a line phantom, but was not apparent on subjective appraisal of scintiphotos except in the washout phase. Xenon-127 appears to be preferable to Xe-133 because of the higher counting rates, lower patient radiation dose, and longer shelf life. In addition, a prior perfusion study using a Tc-99m radiopharmaceutical does not affect the quality of a Xe-127 ventilation study. The use of Xe-127 therefore permits the selection for ventilation studies of only those patients with suspected pulmonary embolism, and eliminates unnecessary radiation exposure. A further improvement in image quality obtained with Xe-127 should be possible with certain modifications of the scintillation camera that would permit use of the 375-keV photopeak along with the 172- and 203-keV gamma energies. Charcoal traps designed for Xe-133 will require additional shielding and longer storage time when used for Xe-127. Xenon-127, however, might be used again after appropriate processing.

Thallium-201 for medical use. II: Biologic behavior.

Thallium-201 has been evaluated for myocardial imaging by determining its distribution and assessing its imaging properties. Organ distribution with time was studied in goats, chosen for their large size and easy operability. Myocardial imaging was performed in living and sacrificed goats and also in two anesthetized dogs, without infarction. Infarcts were made by ligature at open chest surgery on the goats and the infarcts subsequently confirmed histologically. The myocardium of normal and infarced, young and old goats was cut into blocks and the isotope distribution measured and compared with that in the lungs, liver, spleen, and kidney in normal goats. The renal medulla-to-cortex concentration ratio in goats was studied and is approximately five. The heart uptake exceeds 3% for 100 min whereas contiguous organs have less than one-half of the myocardial concentration, and blood clearance is rapid. One problem may prove to be inhomogeneity of uptake of thallium in the "normal" myocardium, showing a standard deviation of 1u% in a young goat and 29% in an old goat. In view of the good myocardial uptake, however, this work strongly suggests the trial 201Tl in patients.

Osteosarcoma presenting as intestinal obstruction.

Osteosarcoma commonly presents with osseous and pulmonary metastases. We present an unusual case of extraosseous metastatic abdominal chondroblastic osteosarcoma presenting as intestinal obstruction.

Radiopharmaceuticals. XIX. 11C-labeled octylamine, a potential diagnostic agent for lung structure and function.

After intravenous injection, 11C-octylamine - HC1 is rapidly sequestered by the rabbit lung. The initial lung uptake during the first minute was 70 +/- 6% of the administered dose, and 40% of the injected dose remained after 15 min. Approximately 12% of the administered radioactivity is exhaled as 11CO2 during the first 30 min.

Thallium-201 for medical use. Part 3: Human distribution and physical imaging properties.

Studies were undertaken to determine the biologic distribution of thallium-201 in man. The disappearance from the blood is extremely rapid and intracellular deposition is nearly immediate. The biologic half-time of thallium was measured by both the Brookhaven whole-body counter and the Donner whole-body scanner, with excellent agreement. The effective whole-body half-time of thallium-201 is about 57 hr. Concentration of activity was seen in the heart, kidneys, large bowel, and thyroid. The whole-body radiation dose is 0.21 rads/mCi.

Thallium-201 for medical use. I.

Thallium-201 merits evaluation for myocardial visualization, kidney studies, and tumor diagnosis because of its physical and biologic properties. A method is described for preparation of this radiopharmaceutical for human use. A critical evaluation of 201Tl and other radiopharmaceuticals for myocardial visualization is given.

Rapid detection of acute appendicitis with Tc-99m-labeled intact polyvalent human immune globulin.

BACKGROUND: Acute appendicitis remains problematic for emergency clinicians. A rapid and definitive test is needed for detecting acute appendicitis before surgical intervention. The purpose of this clinical trial was to determine the efficacy of Tc-99m-labeled intact polyvalent human immune globulin (Tc-99m IgG) in the evaluation of acute appendicitis. STUDY DESIGN: Thirty-five patients with clinically suspected acute appendicitis were evaluated with Tc-99m IgG. After the intravenous injection of 25 mCi (92.5 MBq) of Tc-99m IgG, anterior flow, single photon emission computerized tomography (SPECT) and planar delayed images of the abdomen were obtained. Any abnormal focal uptake of Tc-99m IgG in the right lower quadrant was considered to be a positive scan. RESULTS: Twenty-one patients with a positive Tc-99m IgG scan underwent laparotomy and were found to have acute appendicitis. Of the 14 patients who had negative scans, 7 underwent surgery. In this series, Tc-99m IgG study yielded 21 true-positive, 12 true-negative, and 2 false-negative results with a sensitivity, specificity, and accuracy of 91%, 100%, and 94%, respectively. The positive and negative predictive values were 100% and 86%, respectively. There were no false-positive results. CONCLUSIONS: Tc-99m IgG scintigraphy can provide the clinicians a simple, rapid, and definitive test for the diagnosis of acute appendicitis.

Metal isotopes used as radioactive indicators of ocular melanoma.

We studied radioactive metal compounds to determine their localization in malignant Greene melanoma in the eye of the Syrian golden hamsters. Scintigraphy of an ocular melanoma was achieved with several radioactive metals: radioactive indium(111In)-bleomycin, radioactive gallium (67Ga)-citrate, and radioactive lead (203Pb)-tris. The 111In-bleomycin had the highest tumor uptake (5.45% dose/g), but not the highest tumor-to-background ratios. The 67Ga-citrate had a maximum tumor uptake of 4.87% dose/g at 48 hours. The 111In-chloride had a melanoma uptake of 2.26% dose/g, while with 203Pbtris the uptake was 1.61% dose/g. These uptake ratios compare favorably with that of radioactive phosphorus (32P)-2.21% dose/g. Noninvasive localization of malignant melanoma in the eye was accomplished with metal isotopes. Detailed analysis of in vitro uptake date by tumor and background tissues revealed the optimum time for scanning and precluded unnecessary trials.

Microautoradiographic studies on the cellular localization of radiothallium.

201Tl-chloride and 204Tl-nitrate were similarly distributed in organs of mice 10 min and 60 min after intravenous injection. Autoradiographic studies were carried out with 204Tl-nitrate in rats (injected intraperitoneally) as well as in mice and dogs (injected intravenously). Thallium localized in the cells of proximal and distal convoluted tubules and collecting tubules of the kidney. In the intestines, it was distributed mostly in the cells of the smooth musculature and surface epithelium of the villi. Some silver grains were seen in the goblet cells and in the lumen as well. It localized in the sarcoplasm of the myocardium and the skeletal muscle cells. In thyroid, most of the thallium was seen in the colloidal part of the follicle. In testes, silver grains were seen in and around the cells of Sertoli and in the lumen of the seminiferous tubules. Some localized concentration in the interstitial cells of the testes was also observed.

Circumferential quantitative analysis of planar 201T1 myocardial scintigraphy in the diagnosis of coronary artery disease.

Methodology for the computer analysis of 201T1 myocardial perfusion images has been developed by several laboratories. Substantial evidence of the advantage of this approach over visual inspection alone has been reported. The currently available computer analyses use different algorithms to analyze 201T1 kinetics in the myocardium. The authors evaluated and compared two widely used software programs, Medical Data System (MDS): a mean-count profile, and the Cedars Sinai (CS): a maximal-count profile, of planar 201T1 scintigraphy for their ability to detect coronary artery disease (CAD).

B-cell immunoblastic sarcoma as a cause of a photopenic lesion on bone scintigraphy: an initial description.

Photopenic metastatic lesions on bone scintigraphy have been previously reported. However, this finding is not emphasized for B-cell immunoblastic sarcoma. We report a case of B-cell immunoblastic sarcoma, which presented as an aggressive pancoast tumor with extensive rib destruction. Bone scintigraphy findings demonstrated a photopenic lesion with high gallium avidity. Correlative chest radiograph and CT scan are described.

Reproducibility of ventilation studies.

Differences in ventilation patterns were observed in several instances in two consecutive ventilation studies with 127 Xe and 133Xe gas involving a group of 20 patients with COPD and other pulmonary disorders. Included were differences in the distribution of a tracer gas bolus during the initial inspiration, the distribution of gas tracer after equilibration and during gas washout, artifacts external to the lung, and variations in the half-time for gas washout. The observed discrepancies are clinically significant and could lead to erroneous or ambiguous diagnoses.

Gallium-67 uptake in cutaneous lesions of mycosis fungoides.

The literature on gallium imaging in mycosis fungoides is limited and conflicting. A case of mycosis fungoides with increased uptake of Ga-67 in clinically noninfected skin lesions is reported. The literature regarding mycosis fungoides and gallium imaging is reviewed.

Chronic berylliosis. Demonstration by gallium-67 imaging and magnetic resonance imaging.

Ga-67 is known to localize in the lungs in a wide spectrum of pulmonary pathology. The nonspecific affinity of Ga-67 uptake in both inflammatory and neoplastic entities limits its utility in terms of pulmonary disease differential diagnosis. However, Ga-67 lung imaging has proven to be helpful in evaluating the extent of inflammatory activity, as well as in assessing responses to therapy. A case of active chronic berylliosis, a disorder in which Ga-67 uptake has not been previously reported is presented. There is diffuse bilateral Ga-67 pulmonary activity before therapy. Subsequent to steroid therapy, a marked decrease in pulmonary gallium uptake activity was noted with only residual hilar and mediastinal adenopathy noted.

Dermatofibrosarcoma protuberans of the toe. Findings on multiple imaging modalities.

Dermatofibrosarcoma protuberans occurs early in life, is an unusual soft tissue tumor, and is uncommonly seen distal to knees. The authors present a rare case of dermatofibrosarcoma protuberans of the toe with different imaging modalities.

Direct comparison of Tc-99m DTPA and Tc-99m HMPAO for evaluating brain death.

Portable cerebral perfusion studies provide a quick and accurate alternative to traditional confirmatory examinations (such as four-vessel angiography and electroencephalography) to determine brain death. The authors retrospectively analyzed 26 cerebral perfusion studies using both Tc-99m DTPA and Tc-99m HMPAO. The flow agents gave identical results. Additionally, the delayed-phase Tc-99m HMPAO images gave the same results for brain death (14 positive and 12 negative) as the flow images from either agent. Because the Tc-99m HMPAO delayed images can be used for diagnosis, many technical problems become less crucial. Unlike Tc-99m DTPA, Tc-99m HMPAO normally visualizes the gray matter of the cerebellum, midbrain, and medulla. These areas must be evaluated to ensure that they meet the strict criteria for brain death. These differences and the present study suggest that Tc-99m HMPAO is a superior agent for cerebral perfusion studies to determine brain death.

A comparison of Tc-99m-labeled human serum albumin and in vitro labeled red blood cells for blood pool studies.

A comparison of Tc-99m-labeled human serum albumin (HSA) and in vitro labeled red blood cells (RBC) was carried out in five subjects. The disappearance of radioactivity from the blood was more rapid for HSA (T 1/2, 281.6 minutes, range 202.1--318.3) than for RBC (T 1/2, 1719.8 minutes, range 767.6--5059.5). Urinary excretion was twice as great for HSA. Ratios of activity in heart blood pool to lung and liver were considerably greater for RBC up to 2 hours after administration. The results indicate that labeled RBC are superior to labeled HSA for blood pool imaging.