Noninvasive imaging of 99mtechnetium-labeled low density lipoprotein uptake by tendon xanthomas in hypercholesterolemic patients.

Technetium-labeled low density lipoproteins (Tc-LDL) appear to be useful for describing LDL biodistribution in normal and dyslipidemic subjects. We injected 99mTc-LDL into subjects with large tendon xanthomas secondary to homozygous familial hypercholesterolemia or sitosterolemia. Rapid (4 hours) accumulation of Tc-99m activity in xanthomas was observed, and this accumulation increased over a 24-hour period. No comparable accumulations of Tc-99m activity were noted in normal subjects or in a subject with heterozygous familial hypercholesterolemia who had very small tendon xanthomas. These findings support previous biopsy data indicating active uptake of LDL by macrophages within xanthoma and suggest that 99mTc-LDL imaging of xanthomas may be useful in studies of the effects of diet and drugs on the accumulation of lipoproteins by atherosclerotic plaques.