Kinetic and metabolic considerations in the use of (I-125) HIPDM as a tracer for quantitative measurement of regional cerebral blood flow

Conference · Sun Jan 01 04:00:00 EST 1984 · J. Nucl. Med.; (United States)

OSTI ID:6594212

Lucignani, G; Nehlig, A; Blasberg, R; Patlak, C S; Anderson, L; Kung, H F; Fieschi, C; Fazio, F; Sokoloff, L

The kinetics of cerebral uptake and the metabolism of radioactive iodine labeled HIPDM (N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-(I-125)iodobenzyl) -1,3-propanediamine)(I-125)HIPDM were studied in vivo in male adult Sprague-Dawley rats in order to evaluate the potential usefulness of this compound for quantitative measurement of regional cerebral blood flow (rCBF). The first pass extraction fraction of (I-125)HIPDM in brain was found to be about 80%. The arterial concentration of unmetabolized (I-125)HIPDM following an i.v. pulse drops rapidly and represents only 30% of the blood sample total radioactivity at 60 minutes, whereas 92% of the radioactivity in brain tissue at the same time is in unaltered (I-125)HIPDM. The rate constant for (I-125)HIPDM transport across the blood-brain barrier (BBB) was calculated on the basis of a distribution model in which bi-directional exchange of the tracer between brain tissue and vascular space is assumed. A kinetic model and an operational equation have been derived for determination of rCBF with this molecule. The model and equation take into account the three following factors: (a) incomplete first pass extraction; (b) HIPDM metabolism; (c) bi-directional flux of tracer across the BBB. The observations suggest that this molecule might be of potential usefulness for rCBF measurements with single photon emission tomography, provided that all these factors are evaluated in man.

• Research Organization: Lab. of Cerebral Metabolism, National Institute of Mental Health, Bethesda, MD
• OSTI ID: 6594212
• Report Number(s): CONF-840619-
• Conference Information: Journal Name: J. Nucl. Med.; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

550501 -- Metabolism-- Tracer Techniques
550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
551001 -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOMEDICAL RADIOGRAPHY
BLOOD FLOW
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
CHEMICAL ANALYSIS
COMPUTERIZED TOMOGRAPHY
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DISTRIBUTION
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
EMISSION COMPUTED TOMOGRAPHY
EVALUATION
IN VIVO
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEDICINE
METABOLISM
NERVOUS SYSTEM
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANS
QUANTITATIVE CHEMICAL ANALYSIS
RADIOISOTOPE SCANNING
RADIOISOTOPES
RADIOLOGY
RADIOPHARMACEUTICALS
RATS
REACTION KINETICS
RODENTS
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
TISSUE DISTRIBUTION
TOMOGRAPHY
UPTAKE
VERTEBRATES