Key result
Radiolabeled phenethylguanidines demonstrated improved myocardial kinetics compared to HED in nonhuman primates and avid accumulation in rat pheochromocytoma xenograft tumors in mice.
Why the study?
Do radiolabeled phenethylguanidines provide improved kinetics for quantifying cardiac nerve density and imaging adrenergic tumors compared to existing markers?
Do radiolabeled phenethylguanidines provide improved kinetics for quantifying cardiac nerve density and imaging adrenergic tumors compared to existing markers?
Radiolabeled phenethylguanidines demonstrate improved kinetics for quantifying cardiac nerve density and imaging adrenergic tumors in preclinical models, warranting further investigation.
May advance cardiac sympathetic imaging and adrenergic tumor detection; leaves open translation beyond animal models.
The norepinephrine transporter (NET) substrates [123I]-m-iodobenzylguanidine (MIBG) and [11C]-m-hydroxyephedrine (HED) are used as markers of cardiac sympathetic neurons and adrenergic tumors (pheochromocytoma, neuroblastoma). However, their rapid NET transport rates limit their ability to provide accurate measurements of cardiac nerve density. [11C]Phenethylguanidine ([11C]1a) and 12 analogues ([11C]1b-m) were synthesized and evaluated as radiotracers with improved kinetics for quantifying cardiac nerve density. In isolated rat hearts, neuronal uptake rates of [11C]1a-m ranged from 0.24 to 1.96 mL min-1 (g wet wt)-1, and six compounds had extremely long neuronal retention times (clearance T1/2 > 20 h) due to efficient vesicular storage. Positron emission tomography (PET) studies in nonhuman primates with [11C]1e, N-[11C]guanyl-m-octopamine, which has a slow NET transport rate, showed improved myocardial kinetics compared to HED. Compound [11C]1c, [11C]-p-hydroxyphenethylguanidine, which has a rapid NET transport rate, avidly accumulated into rat pheochromocytoma xenograft tumors in mice. These encouraging findings demonstrate that radiolabeled phenethylguanidines deserve further investigation as radiotracers of cardiac sympathetic innervation and adrenergic tumors.
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Raffel et al. (2007) studied Cardiac sympathetic innervation and adrenergic tumors (preclinical models). Radiolabeled phenethylguanidines ([11C]1a-m) vs. [11C]-m-hydroxyephedrine (HED) was evaluated on Neuronal uptake rates, retention times, myocardial kinetics, and tumor accumulation. Radiolabeled phenethylguanidines demonstrated improved myocardial kinetics compared to HED in nonhuman primates and avid accumulation in rat pheochromocytoma xenograft tumors in mice.
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