Stephen Dragotakes

Redistribution of regional and organ blood volume and effect on cardiac function in relation to upright exercise intensity in healthy human subjects.

To determine the effect of relative exercise intensity on organ blood volume and its relation to cardiac function, changes in relative blood volume and cardiac function were monitored with radionuclide techniques in 14 healthy volunteers. After labeling the subjects red cells with technetium 99m, we acquired data at rest, zero-load cycling, and at 50%, 75%, and 100% of maximal oxygen uptake. From rest to zero-load cycling, leg blood volume decreased 32 +/- 2% (mean +/- SEM), whereas relative end-diastolic blood volume increased 9.6 +/- 1.2%, and lung blood volume increased 18 +/- 2%, suggesting that the lungs may act as a blood volume buffer during periods of acutely increased venous return. With relative increasing exercise, leg blood volume stabilized, and then the blood volume in the abdominal organs decreased, further augmenting cardiopulmonary blood volume; leg blood volume and abdominal blood volume decreased by 23 +/- 2% and 19 +/- 2% from baseline, respectively, whereas thoracic blood volume increased 38 +/- 4%. In the abdomen, large decreases in blood volume were observed in the spleen (46 +/- 2%), kidney (24 +/- 4%), and liver (18 +/- 4%). In contrast, lung blood volume increased 50 +/- 4%, with the upper lung fields increasing more than the lower. Blood sampling revealed an increase in the hematocrit level by 4.3 +/- 0.4 units at peak exercise that paralleled the decrease in splenic blood volume (r2 = -0.64, p less than 0.001), suggesting a role for the spleen in augmenting cardiovascular performance by the release of concentrated red blood cells into general circulation. We conclude that upright exercise results in marked blood volume shifts from the legs and abdominal organs to the heart and lungs in a dynamic process correlating closely with oxygen consumption.

Detection of acute inflammation with 111In-Labeled nonspecific polyclonal IgG

The detection of focal sites of inflammation is an integral part of the clinical evaluation of the febrile patient. When anatomically distinct abscesses are present, lesion detection can be accomplished by standard radiographic techniques, particularly in patients with normal anatomy. At the phlegmon stage, however, and in patients who have undergone surgery, these techniques are considerably less effective. While radionuclide methods, such as Gallium-67 (67Ga)-citrate and Indium-111 (111In)-labeled WBCs have been relatively successful for the detection of early inflammation, neither approach is ideal. In the course of studies addressing the use of specific organism-directed antibodies for imaging experimental infections in animals, we observed that nonspecific polyclonal immunoglobulin G (IgG) localized as well as specific antibodies. Preliminary experiments suggested that the Fc portion of IgG is necessary for effective inflammation localization. Since polyclonal IgG in gram quantities has been safely used for therapy in patients with immune deficiency states, we decided to test whether milligram quantities of radiolabeled IgG could image focal sites of inflammation in humans. Thus far, we have studied a series of 84 patients with suspected lesions in the abdomen, pelvis, vascular grafts, lungs, or bones/joints. In 48 of 52 patients with focal lesions detected by surgery, computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound (US), the IgG scan correctly localized the site, while 31 patients without focal inflammation had no abnormal focal localization of the radiopharmaceutical. Four patients had false negative scans and one patient had a false positive scan. For this small series, the overall sensitivity and specificity were 92% and 95%, respectively. In this report, we review our experience with this exciting new agent.

The Future of USP Monographs for PET Drugs

1Washington University School of Medicine, St. Louis, Missouri; 2Committee on Pharmacopeia, Society of Nuclear Medicine and Molecular Imaging, Reston, Virginia; 3University of New Mexico Health Sciences Center, Albuquerque, New Mexico; 43D Imaging, LLC, University of Arkansas for Medical Sciences, Little Rock, Arkansas; 5Beth Israel Deaconess Medical Center, Boston, Massachusetts; 6Mayo Clinic, Rochester, Minnesota; 7University of Washington, Seattle, Washington; 8Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsyvania; 9Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts; 10Brigham and Women’s Hospital, Boston, Massachusetts; 11Duke University Medical Center, Durham, North Carolina; 12University of Iowa, Iowa City, Iowa; 13Seifert and Associates, Los Angeles, California; 14University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania; 15Ron Weiner Services, Sherman Oaks, California; and 16Siemens PETNET Solutions, Knoxville, Tennessee

The Role of the Practice of Nuclear Pharmacy in Positron Emission Tomography

As nuclear medicine evolved from an obscure research tool to a mainstream clinical diagnostic and therapeutic modality, so has the role of the practice of pharmacy in nuclear medicine also evolved. A similar evolution is unfolding today in the practice of positron emission tomography (PET). The skills of many diverse professionals, including pharmacists, are essential for the safe and efficient operation of a modern PET facility. The importance of the role of pharmacists in PET has been increasing as the use of PET radiopharmaceuticals has matured from research to clinical to commercial arenas. While it is clear that pharmacists can contribute clinical and technical skills to the operation of a PET center, perhaps one of the most important factors influencing the increased role of pharmacists in PET is their expertise and experience in the drug regulatory process. The commercial distribution of PET radiopharmaceuticals, primarily [18F]2-fluorodeoxyglucose (FDG), is currently being performed by a variety of corporate and institutional facility partnerships, with the likelihood of several new players entering the marketplace in the near future. This factor has served to dramatically increase the role for nuclear pharmacy in PET. The practice of nuclear pharmacy is a well-established component of PET. The role of nuclear pharmacists in PET is complementary to the many other professionals currently practicing in this specialty. With the rapidly increasing clinical demand for FDG imaging, it is likely that the number of facilities and institutions entering into the commercial distribution of PET radiopharmaceuticals will also increase. Such growth will also serve to solidify and expand the role for the practice of nuclear pharmacy in PET.