Pitfalls in establishing the diagnosis of deep venous thrombophlebitis by indium-111 platelet scintigraphy.

Forty-seven 111In-platelet scintigraphs (In-PS) were analyzed retrospectively to identify sources of diagnostic error and to optimize the diagnostic criteria for active deep venous thrombophlebitis (DVT). The results of In-PS were compared with contrast venography, additional diagnostic studies, and clinical outcome. Three patterns of platelet localization emerged as the best predictors of active DVT: (a) focal or (b) linear 4-hr localization, or (c) an asymmetric blood-pool pattern on 4-hr imaging that evolved into a focal or linear pattern by 16 to 24 hr. All false-positive studies had abnormal patterns confined to the inguinal region at 24 hr. All patients with false-negative studies had received heparin between 4 and 24 hr. The potential pitfalls encountered in the evaluation of the iliac, femoral, and popliteal veins are reviewed and the importance of delayed imaging in selected cases is emphasized.

Uses and limitations of positron emission tomography in clinical pharmacokinetics/dynamics (Part I).

Positron emission tomography (PET) involves imaging the biodistribution and tissue localisation of small amounts of radiolabelled biomolecules or drugs. In Part I of this article, the applications of pharmacokinetics in PET are discussed in order to derive quantitative measures of physiological function. Part II will examine the use of PET imaging as a tool to study the pharmacokinetics and pharmacodynamics of specific drugs.

Uses and limitations of positron emission tomography in clinical pharmacokinetics/dynamics (Part II).

Positron emission tomography (PET) involves imaging the biodistribution and tissue localisation of small amounts of radiolabelled biomolecules or drugs. In Part I of this article, which appeared in the previous issue of the Journal, the applications of pharmacokinetics in PET were discussed in order to derive quantitative measures of physiological function. Part II examines the use of PET imaging as a tool to study the pharmacokinetics and pharmacodynamics of specific drugs.

Radiopharmaceutical-related pitfalls and artifacts.

The primary goal of this review article is to increase the reader's knowledge and understanding of problems associated with the radiopharmaceuticals commonly used in daily practice. To achieve this objective, problems related to the commonly used radiopharmaceuticals are divided into pitfalls and artifacts related to radiopharmaceutical preparation (technetium-99m [99mTc]-labeled and non-99mTc-labeled radiopharmaceutical) and those related to radiopharmaceutical administration. For the radiopharmaceutical formulation-associated pitfalls and artifacts, problems are discussed in terms of factor categories, such as factors associated with radionuclides, factors associated with components, factors associated with preparation procedures, and miscellaneous factors. As for the pitfalls and artifacts caused by radiopharmaceutical administration, these problems are categorized into errors associated with administration technique and nontechnical errors. Clinical manifestations (ie, appearance upon imaging) from the numerous literature-based examples are presented. The effect of the causative factors and the reason each factor can result in radiopharmaceutical preparation and administration problems are discussed. In addition, the possible preventive actions are presented for each group. However, the cause of some pharmaceutical related problems may not be easily recognized, and thus it is difficult to develop preventive and/or corrective plans for these cases.

Dosimetry of [15O]water: a physiologic approach.

Earlier dosimetry estimates for [15O]water assumed its instantaneous equilibrium with total body water. This assumption leads to an underestimation of the absorbed doses to organs with high blood flows, since the biodistribution of this short-lived radiopharmaceutical is dependent upon blood flow to organs. We have developed a physiologically based whole body blood flow model (WBBFM) using a commercially available icon-driven mathematical simulation software package and applied it to the reevaluation of [15O]water dosimetry in humans. The WBBFM uses multiple parallel compartments to represent organs, heart chambers, the injection site for [15O]water, and blood sampling sites (arterial and venous). Input values to the WBBFM include organ blood flows, organ masses, organ water volumes, organ:blood partition coefficients, injected activity and S-values of [15O]. The WBBFM is based on the same assumptions that are used in calculating regional blood flow using [15O]water and simulates the human body closely in its physiologic response. The activity in each organ is derived from the simulation and is used to calculate absorbed doses. The WBBFM calculated absorbed doses in microGy/MBq (mrad/mCi) to various organs are as follows: heart--2.66 (9.84), kidneys--2.20 (8.15), thyroid--1.83 (6.78), brain--1.66 (6.13), ovaries--1.25 (4.61), breast--1.24 (4.59), and small intestine--1.03 (3.83). These values are approximately two- to threefold higher than the earlier estimates of Kearfott [J. Nucl. Med. 23, 1031-1037 (1982)] and similar to the recent findings of Herscovitch et al. [J. Nucl. Med. 34, 155P (1983)]. We believe this approach yields more realistic dosimetry estimates for [15O]water. Accordingly, we have revised the amount of [15O]water administered during regional blood flow studies at our institution. The relative ease and accuracy of this approach suggests its usefulness in dosimetry estimation for other freely diffusible radiopharmaceuticals.

Analysis of the practice of nutrition support pharmacy specialists.

In 1988 the Board of Pharmaceutical Specialities (BPS) recognized nutrition support pharmacy practice (NSPP) as one of four specialty areas in pharmacy. The BPS appointed a specialty council to develop and manage the process for board certification of qualified specialists. One step was to identify and validate activities performed by the specialists. This was accomplished by conducting a study that delineated the role of these practitioners and also provided information for developing a blueprint for a certification examination. The results revealed the types of practice settings, education, and training for specialists, and the distribution of professional time devoted to nutrition support activities.

Technetium-99m radiopharmaceutical preparation problems: 12 years of experience.

OBJECTIVE: Chemical reactions involved in preparing 99mTc radiopharmaceuticals occasionally result in products of substandard purity. A retrospective examination of preparation problems that occurred in the author's institution was conducted to better define the incidence, recognize patterns and identify causes of substandard 99mTc radiopharmaceutical products. METHODS: All 99mTc radiopharmaceutical preparation and quality control testing records for the years 1986-1997 were reviewed, and preparation factors associated with substandard products were identified and examined. RESULTS: Fifty of 20,972 (0.2%) 99mTc products had substandard radiochemical purity; none were administered to patients. Twenty-eight of the 50 substandard products (56%) involved macroaggregated albumin with the remainder divided among in vitro red blood cells, exametazime, disofenin, sestamibi, mertiatide and sulfur colloid. Thirty-three of the 50 (66%) involved 99mTc-pertechnetate obtained as the first elution of a new generator and/or 99mTc-pertechnetate more than 12 hr old. Several of the substandard products involved other preparation factors and/or human error. CONCLUSION: The majority of substandard 99mTc radiopharmaceutical products involved the use of 99mTc-pertechnetate containing excessive amounts of 99Tc and/or oxidizing impurities to prepare products containing relatively small amounts of stannous. Although substandard products are an infrequent occurrence, radiochemical purity testing should be performed routinely on all 99mTc radiopharmaceuticals before patient administration.

Nuclear pharmacy, Part II: Nuclear pharmacy practice today.

OBJECTIVE: Nuclear pharmacy is a specialty within the profession of pharmacy that focuses on the proper use of radiopharmaceuticals. This article reviews various features of contemporary nuclear pharmacy practice. After reading this article the nuclear medicine technologist should be able to: (a) describe nuclear pharmacy training and certification; (b) discuss nuclear pharmacy practice settings; (c) discuss nuclear pharmacy practice activities; (d) list professional organizations; and (e) describe activities associated with job satisfaction. In addition, the reader should be able to discuss regulatory issues of current concern.

Dosimetry of technetium-99m red blood cells labeled in vivo.

Mean organ doses received from Tc-99m red blood cells labeled in vivo were calculated by the MIRD method using biodistribution data reported in the literature. The organ receiving the greatest dose was found to be the heart, followed closely by the bladder and stomach. Relatively high doses are also received by the blood, spleen, and lungs. Intermediate absorbed doses are received by the thyroid and kidneys, whereas organs with small blood concentrations and the remainder of the body receive the smallest doses. The major portion of the absorbed doses delivered to the stomach and the thyroid is due to the presence of free pertechnetate.

Fetal dosimetry from pulmonary imaging in pregnancy. Revised estimates.

Fetal dose estimates from Tc-99m MAA and Tc-99m DTPA aerosol were calculated using two methods. These calculations show that the average fetal dose decreases as gestational age (or fetal size) increases. Although the resultant dose estimates exceed those previously reported by severalfold, the risk to mother and fetus from undiagnosed pulmonary embolism far outweighs the risk to the fetus from the radiation exposure.