An analysis of technetium ( 99 mTcO 4−) kinetics: The effect of perchlorate and iodide pretreatment

• Published in: The International journal of applied radiation and isotopes 1969-01, Vol.20 (6), p.437-445
• Main Authors: Welch, M.J., Adatepe, M., Potchen, E.J.
• Format: Article
• Language: English
• Subjects: BIOLOGICAL HALF-LIFE; BLOOD; BODY; BRAIN; BRAIN/scanning of human, using technetium-99, effects of iodide or perchlorate pretreatment on; CHOROID; CORRELATION; DISTRIBUTION; Humans; IODIDES; Iodides - pharmacology; IODIDES/effects on technetium-99 uptake by blood following brain scans; Kinetics; MAN; MAN/scanning of brain in, using technetium-99, effects of iodide or perchlorate pretreatment on; METASTABLE STATES; N28530 -Life Sciences-Medicine-Radiodiagnosis; Perchlorates - pharmacology; PERCHLORATES/effects on technetium-99 uptake by blood following brain scans; PERCHLORIC ACID; PERTECHNETATES; RADIOACTIVITY; RADIODIAGNOSIS; Radionuclide Imaging; RETENTION; SAMPLING; SCINTIGRAPHY; Technetium - blood; Technetium - metabolism; Technetium - urine; TECHNETIUM 99; TECHNETIUM ISOTOPES Tc-99/use for brain scanning in man, effects of pretreatment with iodide or perchlorate on; TIME; TISSUES; TRACER TECHNIQUES; URINE
• ISSN: 0020-708X
• DOI: 10.1016/0020-708X(69)90134-3

Pretreatment with perchlorate or iodide prior to technetium brain scanning has been advocated to reduce the radioactivity emanating from the choroid plexus. By blocking tissue technetium uptake this pretreatment may alter the blood background significantly. The kinetics of technetium blood disappearance and body distribution were evaluated in multiple blood samples withdrawn from 21 patients who were having technetium brain scans. The patients were divided into three groups; (1) control; (2) pretreated with perchlorate; and (3) pretreated with iodide. The activity of the blood was plotted against time and trends were found to fit a model: ▪ The tissue compartment appears almost completely blocked by the perchlorate or iodide and the rate constant are found to be k 1 = 0·19 hr −1, k 2 = 1·47 hr −1, k 3 = 1·7 hr −1. From these observations we conclude that equimolar perchlorate and iodide have similar effects on technetium body distribution kinetics and almost completely block a large segment of tissue accretion. These observations provide useful dosimetric data for assessing the effect of iodide or perchlorate pretreatment upon the biologic half life (tissue residence) of pertechnetate and suggest that the optimal time for brain scintiscanning in patients pretreated with perchlorate of iodide is somewhat later than that usually performed shortly after the intravenous injection of technetium. Le prétraitement au perchlorate ou à l'iodure a été recommandé avant le balayage au technétium de la cervelle, afin de réduire la radioactivité sortant du plexus choroidique. En bloquant l'absorption du technétium par le tissu ce prétraitement peut produire une variation signifiante de la base du sang. On a évalué la kinétique de la disparaissance du technétium hors du sang et de sa distribution dans le corps dans un nombre d'échantillons de sang tirés de 21 personnes recevant des balayages de cervelle au technétium. Les sujets se divisèrent en trois groupes: (1) contrôle; (2) prétraités au perchlorate et (3) prétraités à l'iodure. On traça l'activité du sang contre le temps et on trouva que les tendances accordait un modèle: ▪ Le compartiment tissu parait presque entièrement bloqué par le perchlorate ou l'iodure et on trouve pour les constantes de taux k 1 = 0,19 hr −1, k 2 = 1,47 hr −1, k 3 = 1,7 hr −1. D'ici on déduit que le perchlorate et l'iodure équimolares ont de pareils effets sur la kinétique de la distribution du technétium dans le corps et bloqient presque co