EARLY in the course of sodium pertechnetate Tc 99m (TcO4-) human brain scanning there was noted an occasional appearance of regional uptake in the midhemisphere.1 Witcofski et al2 identified this uptake to be in choroid plexus and subsequently demonstrated in vivo the ability of rabbit choroid plexus to concentrate TcO4from blood.3 The suppression of this uptake by the perchlorate ion (ClO4-) was also demonstrated.
Employing a ventriculocisternal perfusion (VCP), the in vivo studies presented here demonstrate the remarkable ability of the rabbit choroid plexus to concentrate TcO4- present in the ventricular fluid. To determine the relative affinity of choroid plexus for TcO4- and the iodide ion (I-), carrierfree sodium iodide I 131 was included in the perfusion fluid. The rates of removal of these ions from the ventricular fluid were measured, and the choroid plexus and brain tissue concentrations
Oldendorf WH, Sisson WB, Iisaka Y. Affinity of Ventricular 99mTc Pertechnetate and Iodide Ions for Choroid Plexus. Arch Neurol. 1970;23(1):74–79. doi:10.1001/archneur.1970.00480250078011
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