Prolonged lung retention of iodine-123-MIBG in diabetic patients

Iodine-123-MIBG has been introduced as a biochemical marker in assessing pulmonary endothelial cell integrity and myocardial beta-adrenergic sympathetic innervation. The aim of this study was to evaluate 123I-MIBG lung uptake in diabetic patients with and without coronary artery disease.

Forty-four nonsmoking patients with normal respiratory function tests were included: 12 diabetics, 11 diabetics with coronary artery disease, 14 nondiabetic patients with coronary artery disease and 7 age-matched controls were imaged with 123I-MIBG and 201Tl scintigraphy. The lung retention of 123I-MIBG, cardiac sympathetic innervation (heart-to-upper mediastinum ratio of 123I-MIBG) and 201Tl lung-to-heart ratio were determined in all cases.

In diabetics with coronary artery disease, significantly prolonged lung retention and decreased cardiac uptake of 123I-MIBG were found. The lung retention of 123I-MIBG was inversely correlated with the heart-to-upper mediastinum ratio in this group. Lung-to-heart ratios of 201Tl were significantly increased in patients with coronary artery disease but there was no significant difference between diabetics and nondiabetics.

Prolonged lung retention of 123I-MIBG was associated with decreased cardiac sympathetic innervation in diabetic coronary artery disease patients. It seems that passive pulmonary congestion or cardiac dysfunction itself did not influence 123I-MIBG lung uptake. Increased lung extraction of 123I-MIBG is highly suggestive of ongoing pulmonary endothelial dysfunction together with ischemic events in diabetics.