Search

The in vitro particle size of 99mTc-Sn-colloid preparation increases with the length of incubation time after reconstitution. It was found that the percentage of particles trapped (T) by a 1-micron filter as a function of time (t) could be represented by the logarithmic equation T = 5.3 + 15.7 ln t (r = 0.96). This material was applied to a crossover study involving 25 patients each of whom received preparations of the same reconstituted 99mTc-Sn-colloid that had been incubated for 15 min and (each patient received both) 5 h. It was found that there was a significant shift of radioactivity to the spleen and a significant decrease in background with the material that had been incubated longer. The 99mTc-Sn-colloid is adequate for the disclosure of space-occupying disease in the liver and spleen, but unreliable for drawing conclusions on the status of liver function based on the changes in splenic concentration.

Bone imaging using Tc-99m MDP was performed on a 68-year-old man with a newly diagnosed adenocarcinoma of the lung. The image unexpectedly showed increased activity in the heart area. Emergent echocardiography demonstrated impending pericardial tamponade. A malignant pericardial effusion was verified by pericardiocentesis.

Nonfunctional photomultiplier tubes produce subtle total body scan defects. The resultant scan shows bands of reduced activity which are far less obvious than those seen on a standard image.

The ribosomes of Entamoeba invadens trophozoites have sedimentation coefficients of 77, 53 and 36 S. Most of the ribosomal proteins are basic and their one- and two-dimensional electrophoretic patterns differ from the corresponding patterns of Escherichia coli and Saccharomyces cerevisiae. Two dozen bands were observed in the 10 000 to 100 000 molecular weight range following sodium dodecylsulfate-gel electrophoresis of amoebal ribosomal proteins. Long, thin pronase-sensitive structures were seen in electron micrographs of E. invadens ribosomal preparations.

Since the initiation of liver transplantation at our institution 9 yr ago, 73 patients ranging in age from 8 mo to 64 yr have undergone this procedure. In the immediate postoperative period and at various times thereafter as deemed necessary, radionuclide studies were performed using one of the iminodiacetic acid (IDA) derivatives labeled with 99mTc. Initially, these studies were performed using labeled PIPIDA with a shift to diisopropyl IDA when this latter agent became available. The IDA agent is administered as a bolus so that the "flow" and "pooling" may be viewed immediately after injection. This is followed by sequential imaging at various times up to 24 hr, with optional graphic tracings of hepatic and bowel patterns of uptake and clearance of radioactivity. An analysis of the initial portion of the IDA scan yields useful information regarding the arterial and portal venous supply of the liver. The rapidity of hepatic concentration and excretion provides a direct measure of hepatocyte function which is particularly helpful when used sequentially to follow the response of the liver to therapy for rejection or infection. The study is also used to assess the biliary system for obstruction or leaks.

The injection of Freund's adjuvant into the pericardial sac of 29 dogs resulted in chronic pericardial tamponade with persistent sodium retention. Micropuncture, clearance, and radioactive microsphere experiments were initiated 6--13 days after pericardial injection and 60 min after pericardiocentesis. Pericardiocentesis increased sodium excretion (from 12.2 to 41.3 microequiv./min) and mean arterial pressure (+ 20 mmHg (1 mmHg = 133.322 Pa)). Central venous pressure decreased 6.5 mmHg, as did hematocrit (from 45.7 to 39.8%) and plasma protein concentration (from 5.88 to 5.15 g%). Pericardiocentesis had no significant effect on renal blood flow (RBF), nor plasma flow. Redistribution of glomerular filtrate was suggested by the observation that superficial nephron glomerular filtration rate increased (from 91 to 108 nL/min) while glomerular filtration rate remained unaltered. Determination of intrarenal distribution of RBF revealed that cortical blood flow also distributed superficially. A significant increase in the fraction of RBF perfusing zone 1 (outer cortex) and a decrease in fractional perfusion of zones 2, 3 and 4 (juxtamedullary cortex) were observed in each experiment following pericardiocentesis. RBF distribution examined in a series of six animals prior to and during the development of pericardial tamponade showed the opposite effect. These results indicate that pericardiocentesis causes redistribution of both glomerular filtrate and RBF to superficial nephrons. The development of pericardial tamponade was associated with increased fractional juxtamedullary blood flow. These changes may have been the result of altered blood pressure, hematocrit, plasma protein concentration, or altered renal resistance.

To determine the value of scintigraphic perfusion studies in evaluating pancreas transplant patients, we reviewed 56 of these studies in 22 patients who had 27 transplants. Seventeen patients underwent two or more studies. The perfusion studies were performed with 20 mCi (740 MBq) of 99mTc-DTPA injected as a bolus followed by eight to 16 serial 2-sec images and a 500,000-count immediate static image. Images were evaluated for (1) the time and intensity of pancreatic peak radioactivity relative to the time and intensity of the iliac arterial peak; (2) relative pancreatic to iliac arterial intensity on the static image; and (3) size, homogeneity, and definition of the pancreas. Clinical diagnoses at the time of scintigraphy of normal function (n = 36), rejection (n = 13), pancreatitis (n = 6), or arterial thrombosis (n = 1) were based on insulin requirement, urine amylase, serum glucose, serum amylase, response to therapy, cultures, CT, MR, sonography, scintigraphy with 67Ga or 111In-WBCs, percutaneous drainage results, angiography, surgery, and pathologic examination of resected transplants. Three 99mTc-DTPA perfusion studies showed no pancreatic perfusion, four showed decreasing perfusion on serial studies, and five showed progressive loss of definition of the pancreas on serial studies. Of the three patients with no detectable perfusion, one had a normally functioning transplant, one had arterial thrombosis with transplant infarction, and one had severe rejection with minimal function. Decreasing perfusion was associated with rejection in three patients and pancreatitis in one. Decreasing definition was seen in four patients with rejection and one with pancreatitis. We conclude that perfusion scintigraphy is useful, primarily when performed serially, although nonspecific for evaluating pancreas transplants.

99mTechnetium mercaptoacetylglycine is a promising new renal radiopharmaceutical undergoing phase III trials in the United States. In a preliminary investigation of the efficacy and safety of mercaptoacetylglycine in 30 adult patients with suspected renal disease we used simultaneous imaging with orthoiodohippurate as the physiological "gold standard". Of these patients 11 had undergone renal transplantation. Factors, such as time to peak renal activity, clearance half-life and regional functional comparison, were similar by orthoiodohippurate and mercaptoacetylglycine imaging. Visual and quantitative analysis of angiograms and renograms was markedly facilitated with the use of mercaptoacetylglycine. Several morphological abnormalities were apparent only during mercaptoacetylglycine evaluation. No adverse effects, changes in vital signs or significant changes in clinical laboratory status were encountered. Since mercaptoacetylglycine combined an excellent technetium image with the pharmacokinetics of orthoiodohippurate, mercaptoacetylglycine may supplant all other agents for routine clinical use.

Following the introduction of In-111 oxine as a label for blood cells by McAffee and Thakur in 1976, these procedures have become increasingly important in the practice of nuclear medicine. Of particular interest are studies involving the use of labeled leukocytes for the detection of focal infection. The clinical utility of labeled platelets is less well developed, although the use of platelets to detect the formation of thrombi in blood vessels and on vascular grafts and prostheses is gaining prominence. This report summarizes the techniques presently employed at the University of Minnesota for the labeling of blood products, and their clinical use. Consideration also is given to the desired expertise and cost factors involved in the labeling of leukocytes and platelets.

The biodistribution of [54Mn]DTPA and [153Gd]DTPA dimeglumine were investigated and compared following i.v. administration to fasting anesthetized dogs. Unlike most previously reported metal ion-DTPA complexes, [54Mn]DTPA showed high uptakes in several organs including the liver, bile, pancreas, bowel, and kidney. This uptake was independent of the pH of the injected solution. Accumulation in these organs suggests a potential role for [Mn]DTPA as a paramagnetic contrast agent for NMR imaging. With the exception of the kidneys, [153Gd]DTPA showed no evidence of tissue specific uptake over the course of 4 hr, consistent with it being an extracellular ion that is cleared by glomerular filtration.

The pharmacokinetics of 54Mn administered as Mn-diethylenetriamine pentaacetic acid (DTPA) are being investigated to determine if tissue-specific uptake of manganese could be observed while increasing urinary excretion. This chelation and increased excretion should reduce toxicity. In order to obviate the need for repetitive quantitative nuclear magnetic resonance imaging (NMR) we have substituted tracer amounts of a radioisotope of manganese, Mn-54, for the stable ion. By 6 hours, 58 +/- 7% of the injected dose had been excreted in the urine. Peak liver accumulation occurred within 30 minutes (0.50 +/- 0.14% injected dose/g X kg body weight). The pancreas also showed a relatively high accumulation of tracer (0.25 +/- 0.04%/g X kg body weight), reaching a peak at 4 hours. The pancreas to liver ratios were highest at 6 hours (0.7). There was also a substantial accumulation of the manganese in bile. The blood concentration fell very rapidly with little tracer remaining in the blood at 1 hour. Based on these pharmacokinetics, imaging experiments were conducted before, immediately after, and 9 or 24 hours postinjection. These images showed enhanced kidneys and, later (at 9 hours), an excellent parenchymal-collecting system differentiation. The gallbladder was negatively enhanced. The liver showed either increased or decreased signal strength relative to skeletal muscle depending on the pulse sequence used. We conclude that Mn++, administered as Mn-DTPA, merits further investigation as an NMR contrast agent.

Intense muscle localization of Tc-99m MDP to upper extremity musculature was noted three days following weight lifting exercises. This phenomenon is due to an unknown mechanism although several causative factors have been suggested.

Transcatheter embolization by Ivalon particles for treatment of arteriovenous malformations has been an accepted therapeutic technique for many years. We describe a new and efficient radiolabeling technique of Ivalon particles using [99mTc]sulfur colloid. Continuous and dynamic monitoring of injected radiolabeled Ivalon particles is made possible by viewing the persistence scope of a portable gamma camera whose head is positioned over the patient undergoing therapeutic embolization. Therefore, if inadvertent pulmonary embolism or reflux migration of radiolabeled Ivalon particles has occurred, the angiographer is immediately aware of this potentially serious or fatal complication and can take corrective action. We describe two patients, each with an arteriovenous malformation, who had therapeutic embolization with radiolabeled Ivalon particles, one resulting in reflux migration and the other resulting in inadvertent pulmonary embolism.

Superimposition of nuclear medicine scintigrams and standard radiographs provides a unique opportunity for merging functional information intrinsic to nuclear medicine images with the high resolution anatomic detail of radiographs. A newly developed image processing system allows the merging of two separate films of greatly varying sizes to form a single composite image. Subsequent quantitative analysis of the composite image may be performed. Using the superimposition technique, [99mTc]DTPA aerosol ventilation scans (4.5 X 4.5 cm) were superimposed upon chest radiographs (35.6 X 43.2 cm) in 17 cystic fibrosis (CF) patients. Subsequent quantification of the area of nuclear scan ventilation and the radiographic lung area was then performed. A new quantitative radiologic index of ventilation, the aerosol penetration ratio (APR), was defined. Linear correlation of aerosol penetration ratio with residual volume (RV) as percent of total lung capacity (TLC) measured by body plethysmography was good. We conclude that the APR has validity as a physiologic parameter which localized regional excessive residual volume and correlates well with RV/TLC, the "gold standard" pulmonary function index of obstructive airway disease.

The procedure described in this article achieves the desired objective, but without the use of foreign bodies or any additional operation to obtain grafting material. Unlike many surgical approaches in use for treating chronic dislocation, there is no capsular violation. Six operations have been performed with this technique, and all have been successful.

In order to not only survive, but to carry out our mission in health care delivery, nuclear medicine procedures will have to be competitive with the many other techniques that are available for assessing cardiopulmonary structure or function. Our tests must also be shown to be cost-effective. According to the American Heart Association, cardiovascular diseases alone had an economic cost of 56.9 billion dollars in 1983. Of this enormous sum only a very small percentage could be attributed to the performance of diagnostic nuclear medicine examinations. In addition to the economic cost, cardiovascular diseases accounted for 51% of all deaths in 1980. Statistics from the U.S. Department of Health show that 8.26 million (26.3%) of the national noninstitutionalized handicapped are the result of heart conditions and hypertension. These statistics are especially tragic since cardiovascular disease tends to strike a large proportion of persons in their most productive working years. We must avoid becoming penny wise and pound foolish when we decide whether or not to perform diagnostic examinations. Information obtained from these tests can be used to evaluate the effectiveness of therapy (or lack thereof), determine those patients who are at greatest risk of subsequent events and, therefore, require the most intensive investigation and therapy, and similarly identify that population at very low risk of having subsequent cardiac events and, therefore, requiring little, if any, therapy and no further investigation. Is such an approach economically feasible? An estimated 1.5 million Americans will have a heart attack this year, and about 550,000 of them will die. Of these persons, 350,000 will die before they reach the hospital. This leaves 1,150,000 persons who will be hospitalized due to myocardial infarction. As an example, if every one of these patients had a GBP study, at an estimated cost of +350.00 per examination, the cost would be about +400,000,000 or 0.7% of the total cost of cardiovascular diseases. This figure would roughly double if either a 201Tl or GBP study was performed with stress. Thus, our examinations constitute only a small percentage of the overall cost of cardiopulmonary disease. If one of these tests results in even a day early CCU to general bed transfer, early discharge, deferment of angiography, or surgery, or long-term medical therapy, then they will be cost-effective. We believe that a strong case can be made for optimism about the continued growth and expansion of nuclear techniques.(ABSTRACT TRUNCATED AT 400 WORDS)