Positron emission tomographic measurement of blood-to-brain and blood-to-tumor transport of 82Rb: the effect of dexamethasone and whole-brain radiation therapy
Unidirectional blood-to-brain and blood-to-tumor transport rate constants for rubidium 82 were determined using dynamic positron emission tomography in patients with primary or metastatic brain tumors. Regional influx rate constants (K1) and plasma water volume (Vp) were estimated from the time course of blood and brain radioactivity following a bolus injection of tracer. Eight patients were studied before and 24 to 72 hours after treatment using pharmacological doses of dexamethasone, and 6 additional patients with metastatic brain tumors were studied before and within 60 to 90 minutes after 200- to 600-rad whole-brain radiation therapy. Steroid treatment was associated with a 9 to 48% decrease in tumor K1 and a 21% mean decrease in tumor Vp. No consistent changes in K1 or Vp were observed in control brain regions. Tumor K1 and Vp did not increase in patients undergoing whole-brain radiation therapy, all of whom were taking dexamethasone at the time of study. These data suggest that corticosteroids decrease the permeability of tumor capillaries to small hydrophilic molecules (including those of some chemotherapeutic agents) and that steroid pretreatment prevents acute, and potentially dangerous, increases in tumor capillary permeability following cranial irradiation.
- Research Organization:
- Memorial Sloan-Kettering Cancer Center, New York, NY
- OSTI ID:
- 5964217
- Journal Information:
- Ann. Neurol.; (United States), Vol. 6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
BLOOD-BRAIN BARRIER
RADIONUCLIDE KINETICS
METASTASES
RADIOTHERAPY
RUBIDIUM 82
MEMBRANE TRANSPORT
BLOOD
DEXAMETHASONE
EMISSION COMPUTED TOMOGRAPHY
NEOPLASMS
PATIENTS
POSITRONS
ADRENAL HORMONES
ALKALI METAL ISOTOPES
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BODY FLUIDS
COMPUTERIZED TOMOGRAPHY
CORTICOSTEROIDS
DIAGNOSTIC TECHNIQUES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTARY PARTICLES
FERMIONS
GLUCOCORTICOIDS
HORMONES
HOURS LIVING RADIOISOTOPES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPES
KETONES
LEPTONS
MATERIALS
MEDICINE
MINUTES LIVING RADIOISOTOPES
NUCLEAR MEDICINE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PREGNANES
RADIOISOTOPES
RADIOLOGY
RUBIDIUM ISOTOPES
STEROID HORMONES
STEROIDS
THERAPY
TOMOGRAPHY
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550601 - Medicine- Unsealed Radionuclides in Diagnostics