Retention of (/sup 99m/Tc)-d,l-HM-PAO in the human brain after intracarotid bolus injection: a kinetic analysis

Journal Article · Wed Nov 30 23:00:00 EST 1988 · J. Cereb. Blood Flow Metab.; (United States)

DOI:https://doi.org/10.1038/jcbfm.1988.28· OSTI ID:6514904

Lassen, N A; Andersen, A R; Friberg, L; Paulson, O B

(99mTc)-d,l-HM-PAO (HM-PAO) was injected rapidly into the internal carotid artery and its retention in the brain was recorded by external scintillation cameras in eight human subjects. A model is described based on three compartments: the lipophilic tracer in the blood pool of the brain, the lipophilic tracer inside the brain, and the hydrophilic form retained in the brain. The retention curve initially drops abruptly, corresponding to the nonextracted fraction of the injectate leaving the brain; it then falls exponentially towards the asymptotic level of the fractional steady-state retention R. Cerebral blood flow (F) was measured using the xenon-133 intracarotid injection method. The first-pass extraction E of HM-PAO was calculated from F using an empiric regression equation. The residue curves for the whole brain after intracarotid HM-PAO injection were analyzed to yield a retention fraction (R') and the brain clearance backflux constant of lipophilic HM-PAO (k). From the kinetic model and the measured values of R', k, and F, the following parameter values could be calculated: the average retained fraction of all tracer supplied to the brain, R = 0.38 +/- 0.05 (mean +/- SD), the conversion rate constant (lipophilic to hydrophilic tracer) in the brain k3 = 0.80 +/- 0.12 min-1, the efflux rate constant (brain to blood) k2 = 0.69 +/- 0.11 min-1, the conversion/clearance ratio alpha = k3/k2 = 1.18 +/- 0.25, the influx (blood clearance) constant K1 = 0.45 +/- 0.11 ml/g/min, and the brain/blood partition ratio lambda = K1/k2 = 0.67 +/- 0.23 ml/g. Using the kinetic model and assuming constancy of alpha, an algorithm was developed that corrects for the blood flow dependent backflux of HM-PAO and results in a more linear relation between regional cerebral blood flow (rCBF) and HM-PAO distribution.

• Research Organization: Bispebjerg Hospital (Denmark)
• OSTI ID: 6514904
• Journal Information: J. Cereb. Blood Flow Metab.; (United States), Journal Name: J. Cereb. Blood Flow Metab.; (United States) Vol. 8:6; ISSN JCBMD
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ALGORITHMS
AMINES
ANIMALS
ARTERIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BLOOD FLOW
BLOOD VESSELS
BLOOD-PLASMA CLEARANCE
BODY
BRAIN
CARDIOVASCULAR SYSTEM
CAROTID ARTERIES
CENTRAL NERVOUS SYSTEM
CLEARANCE
COMPUTERIZED TOMOGRAPHY
COUNTING TECHNIQUES
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DRUGS
EMISSION COMPUTED TOMOGRAPHY
EVEN-ODD NUCLEI
HOURS LIVING RADIOISOTOPES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MAN
MATHEMATICAL LOGIC
MATHEMATICAL MODELS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
ORGANS
OXIMES
PRIMATES
RADIOISOTOPES
RADIOPHARMACEUTICALS
RETENTION
SCINTILLATION COUNTING
TECHNETIUM 99
TECHNETIUM ISOTOPES
TOMOGRAPHY
VERTEBRATES
XENON 133
XENON ISOTOPES
YEARS LIVING RADIOISOTOPES