Radio-labeled metaiodobenzylguanidine (MIBG) is considered an established s
ympathetic neuron imaging agent capable of scintigraphically visualizing th
e organs richly innervated by the sympathetic nervous system. Its clinical
applications now include cardiac and pulmonary adrenergic imaging. The quan
titative determination of global and/or regional abnormalities of MIBG hear
t uptake has been demonstrated to be very useful in several clinical settin
gs representing one of the major determinants of adverse prognosis. The pre
sence and the severity of autonomic neuropathy are known as important progn
ostic factors in patients with diabetes. MIBG scintigraphy is able to non-i
nvasively assess and characterize the adrenergic abnormalities of the cardi
ac innervation also in these patients. In order to evaluate whether 123I-MI
BG is able to reveal abnormalities of myocardial adrenergic function in dif
ferent groups of diabetic patients, we performed 123I-MIBG scintigraphy in
control subjects and in normotensive Type 1 diabetic patients with and with
out autonomic neuropathy (N+ and N- patients), selected according to result
s of cardiovascular reflex tests, Regional abnormalities of adrenergic inne
rvation were revealed in 10% of control subjects, in 70% of N- patients and
in 100% of N+ patients. The finding of a higher than expected prevalence o
f MIBG regional abnormalities in patients without signs or symptoms of auto
nomic neuropathy allows to hypothesize that cardiac autonomic nervous damag
e occurs earlier than previously known in diabetic patients whose cardiovas
cular tests are still completely normal. (C) 2000, Editrice Kurtis.