Low-density lipoprotein (LDL) uptake in gliomas was studied to find ou
t if LDL has potential as a drug carrier of boron, especially for boro
n neutron capture therapy. Single photon emission tomography (SPET) wa
s performed 2 h and 20 h after intravenous injection of autologous Tc-
99m-labelled LDL in four patients with untreated and five patients wit
h recurrent glioma. Tc-99m-LDL uptake was compared with the uptake of
Tc-99m-labelled human serum albumin (HSA), an established blood pool m
arker. The intra- and peritumoral distributions of radioactivity in th
e SPET images were not identical for radiolabelled LDL and HSA. The me
an LDL tumour to brain ratio, determined from transversal SPET slices
at 20 h post injection, was 1.5 in untreated and 2.2 in recurrent glio
mas; the corresponding ratios for HSA were 1.6 and 3.4. The brain to b
lood ratio remained constant at 2 h and 20 h in both types of tumours.
These data are not consistent with highly selective, homogeneous upta
ke of LDL in gliomas. However, the different tumoral distribution and
rate of uptake of Tc-99m-LDL, as compared with Tc-99m-HSA, indicate th
at the uptake of LDL is different from that of HSA and that further st
udies on the mechanism of LDL uptake in glioma are warranted.