Brain extraction and distribution of {sup 99m}{Tc}-bicisate in humans and in rats

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Journal of Cerebral Blood Flow and Metabolism

OSTI ID:68481

Knudsen, G M; Andersen, A R; Somnier, F E; Videbaek, C; Hasselbalch, S; Paulson, O B ^[1]

---

1. Univ. Clinic Rigshospitalet, Copenhagen (Denmark)

Blood-brain barrier (BBB) passage of the flow tracer ethylenediylbis-L-cysteine diethylester (bicisate, ECD) was measured repeatedly in five patients by means of the intravenous (i.v.) double-indicator technique using {sup 24}Na{sup +} as an intravascular cotracer. After i.v. injection, the arterial concentration curve of {sup 99m}{Tc}-bicisate was delayed and dispersed compared with that of the intravascular cotracer, presumably due to lung retention of the flow tracer. The corrected cerebral venous output curves were fitted using a three-compartment model with four parameters. At resting cerebral blood flow (CBF) values, the unidirectional brain extraction was 0.57 {+-} 0.05, the permeability-surface area product for passage from blood to brain (PS{sub 1}) was 0.48 {+-} 0.07 ml/g/min, and the distribution volume for bicisate was 0.74 {+-} 0.20 (mean {+-} SD). In a single patient, BBB transport after i.v. injection of bicisate was compared with that of a similar flow tracer, d,l-hexamethylpropyleneamine oxime (HM-PAO), and similar values were found for the two tracers. In 19 rats, the brain extraction of bicisate was measured by means of the intracarotid double-indicator technique. The brain extraction was measured at resting, decreased, and increased CBF values. Low CBF values were obtained by hyperventilation and high values by hypercapnia. The degree of backflux of tracer from brain to blood was evaluated by means of the three-compartment model and was found to be negligible in these experiments. The brain extraction was 0.70 {+-} 0.1 and PS{sub 1} was 0.94 {+-} 0.27 ml/g/min. During hypercapnia, CBF increased from 0.77 to 1.09 ml/g/min, leading to a significant decrease in brain extraction, from 0.70 to 0.56. During hyperventilation, CBF decreased from 0.77 to 0.54 ml/g/min, leading to a significant increase in brain extraction, from 0.70 to 0.74. PS{sub 1} remained constant despite changes in CBF or bolus size. 12 refs., 5 figs., 3 tabs.

• OSTI ID: 68481
• Journal Information: Journal of Cerebral Blood Flow and Metabolism, Journal Name: Journal of Cerebral Blood Flow and Metabolism Journal Issue: Suppl.1 Vol. 14; ISSN JCBMDN; ISSN 0271-678X
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BRAIN
METABOLISM
RADIOPHARMACEUTICALS
TECHNETIUM 99
TISSUE DISTRIBUTION