Quantification of brain perfusion with tracers retained by the brain

Conference · Tue Dec 31 04:00:00 EST 1991

OSTI ID:139696

Pupi, A; Bacciottini, L; De Cristofaro, M T.R.; Formiconi, A R; Castagnoli, A ^[1]

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1. Univ. of Florence (Italy)

Almost a decade ago, tracers, labelled with {sup 123}I and {sup 99m}Tc, that are retained by the brain, started to be used for studies of regional brain perfusion (regional cerebral blood flow, rCBF). To date, these tracers have been used for brain perfusion imaging with SPECT in brain disorders as well as for physiological activation protocols. Only seldom, however, have they been used in protocols that quantitatively measure rCBF. Nevertheless, comparative studies with perfusion reference tracers have repeatedly demonstrated that the brain uptake of these brain-retained tracers is correlated to perfusion, the major determinant of the distribution of these tracers in the brain. The brain kinetics of {sup 99m}Tc HMPAO, which is the tracer most commonly used, was described with a two-compartment tissue model. The theoretical approach, which is, in itself, sufficient for modeling quantitative measurements with {sup 99m}Tc HMPAO, initially suggested the possibility of empirically narrowing the distance between the brain`s regional uptake of the tracer and rCBF with a linearization algorithm which uses the cerebellum as the reference region. The value of this empirical method is hampered by the fact that the cerebellum can be involved in cerebrovascular disease (i.e. cerebellar diaschisis) as well as in several other brain disorders (e.g. anxiety, and dementia of the Alzheimer type). It also was proposed that different reference regions (occipital, whole slice, or whole brain) should be selected in relation to the brain disorder under study. However, this approach does not solve the main problem because it does not equip us with a reliable tool to evaluate rCBF with a high predictive value, and, at the same time, to reduce intersubject variability. The solution would be to measure a quantitative parameter which directly reflects rCBF, such as the unidirectional influx constant of the freely diffusible flow-limited tracers. 45 refs., 3 figs., 1 tab.

• Research Organization: Brookhaven National Lab., Upton, NY (United States)
• OSTI ID: 139696
• Report Number(s): CONF-9110368--; ON: TI92014827
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOCHEMICAL REACTION KINETICS
BLOOD FLOW
BRAIN
CEREBELLUM
DIAGNOSTIC USES
DISTRIBUTION
IODINE 123
LIGANDS
MENTAL DISORDERS
PERFUSED TISSUES
RADIOPHARMACEUTICALS
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
TECHNETIUM 99
UPTAKE