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The International Atomic Energy Agency organized a technical meeting at its headquarters in Vienna, Austria, in 2022 that included 17 experts representing 12 countries, whose research spanned the development and use of radiolabeled agents for imaging infection. The meeting focused largely on bacterial pathogens. The group discussed and evaluated the advantages and disadvantages of several radiopharmaceuticals, as well as the science driving various imaging approaches. The main objective was to understand why few infection-targeted radiotracers are used in clinical practice despite the urgent need to better characterize bacterial infections. This article summarizes the resulting consensus, at least among the included scientists and countries, on the current status of radiopharmaceutical development for infection imaging. Also included are opinions and recommendations regarding current research standards in this area. This and future International Atomic Energy Agency-sponsored collaborations will advance the goal of providing the medical community with innovative, practical tools for the specific image-based diagnosis of infection.

Introduction: Recent studies show that porphyrin derivatives have interesting pharmacological and photodynamic properties and wide range of usage in photodynamic therapy treatment. This study describes the preparation, biodistribution and absorbed dose prediction of [111In] labeled 5, 10, 15, 20-tetra phenyl porphyrin (TPP) in human organs, based on rats' biodistribution data. Methods: Five rats were sacrificed at each exact time intervals (2, 4 and 24 h post injection) and the percentage of injected dose per gram of each organ was measured by direct counting from rats data from 12 harvested organs. The Medical Internal Radiation Dose (MIRD) formulation was applied to extrapolate from rats to human and to project the absorbed radiation dose for various organs in humans. Results: From rat data we estimated that injection of [111In] TPP into the humans would result in an estimated effective absorbed dose of 0.09 mSv/MBq in the whole body. While the highest effective absorbed dose for 111In-TPP was in the heart wall (0.22 mSv), the organs that received the next highest doses were the Kidneys (0.06 mSv), thymus (0.04 mSv) and lungs (0.03 mSv). Conclusions: The skin dose will four times higher compare to the other 111In compounds, which was due to magnificent skin uptakes. According to the fast wash-out, tumor avidity and the short half-life, [111In] can be a suitable candidate for labeling of photo dynamic therapy (PDT) agents as a tracer for accurate biological evaluation of other PDT agents such as Photofrin and its homologs. [ABSTRACT FROM AUTHOR]

To estimate the absorbed dose in normal organs and inflammated tissue following i.v. administration of [201Tl](III)-DTPA-HIgG by using biodistribution data in inflammation-bearing rats was attempted. The percentages of injected dose per gram of each organ were calculated. The medical internal radiation dose formulation was applied to calculate the absorbed dose for various organs. The inflammated tissue to blood activity concentration ratios were about 19 and 23.3 at 24 and 28 h post-injection, respectively. A 185-MBq injection of 201Tl-DTPA-HIgG into the human body, might result in an estimated absorbed dose of 14.4 mGy for the total body and the highest absorbed dose was in the kidney with 1195 (mGy) and second to the Spleen were the liver, the lungs and the adrenals, which received 250.5 (mGy), 58.64 (mGy) and 56.44 (mGy), respectively. Biodistribution of [201Tl](III)-DTPA-HIgG demonstrated significant inflammated tissue uptake and low muscle and blood uptake, allowing for imaging of inflammated tissues. [ABSTRACT FROM PUBLISHER]