Stroke, Vol 12, 745-750, Copyright © 1981 by American Heart Association
MD Ginsberg, AH Lockwood, R Busto, RD Finn, JA Campbell and TE Boothe
Positron emission tomography (PET) makes it possible to employ an in vivo
autoradiographic paradigm to measure regional cerebral blood flow (rCBF) in
man. In this study, we synthesized the positron-emitting
radiopharmaceutical 11C-iodoantipyrine (11C-IAP) and validated its
suitability as a CBF tracer. 11C ( T and one-half 20.4 min) was produced by
the (p,alpha) nuclear reaction on 14N. 11C-methyl iodide was used to
methylate 3-methyl-1-phenyl-2-pyrazolin-5-one to form 11C- antipyrine,
which was iodinated. Radiochemical purity of the 11C-IAP product was 93-98%
except as described below. rCBF was measured with 11C-IAP in nitrous
oxide-anesthetized Wistar rats by the method of indicator fractionation,
and values were compared with rCBF values measured with simultaneously
administered commercially produced 14C- IAP. rCBF was studied over a range
of arterial Pco2 values (31-58 mm Hg, mean 43.0 +/- 3.5). Mean rCBF data
for the 2 tracers agreed to within 4.8% for cerebral hemispheral samples,
3.8% for cerebellum, and 5.3% for brainstem. Mean values (+/- SEM) for rCBF
using 11C-IAP were 1.67 +/- 0.20 ml gm-1 min-1 for cerebral hemispheres;
1.32 +/- 0.17 for cerebellum; and 1.50 +/- 0.21 for brainstem. When
chromatographic analysis revealed tracer impurity, rCBF, as measured with
11C-IAP, fell consistently below values obtained with 14C-IAP. The data
indicate that 11C-IAP, when properly synthesized and submitted to
batch-by-batch quality control, may be suitable for measuring rCBF in man
by emission tomography.
ARTICLES
11C-Iodoantipyrine for the measurement of regional cerebral blood flow by positron emission tomography. Validation studies