Autonomic neuropathy along with cardiac denervation is one of the prognostic factors of diabetic patients. The aim of this study was to establish qualitative and quantitative assessment of diabetic cardiac denervation using [123I]metaiodobenzylguanidine (MIBG).
Methods: The study population consisted of 31 diabetic patients and 12 control subjects (C). Diabetic patients were classified into the following three groups according to their presentation of neuropathy: NO, without neuropathy; N1, mild neuropathy; N2, severe neuropathy. All subjects underwent triple-phase MIBG scanning, including dynamic planar imaging as well as early and delayed planar and SPECT imaging. Myocardial uptake ratios of MIBG and heart-to-mediastinum count ratios (H/M) were calculated as global uptake indices. Inferior-to-anterior count ratios and coefficients of variation were calculated as regional distribution indices. The washout rate of the inferior wall and whole myocardium were also studied.
Results: MIBG abnormalities were obvious in the inferior wall, which gradually spread to the adjacent segments. All indices of regional uptake showed a significant difference (p < 0.01) among the groups, while only the H/M of the late image showed significant differences in the two global uptake indices (p = 0.02). the washout rate of the inferior wall was enhanced with neuropathy.
Conclusion: Diabetic neuropathy involves an MIBG abnormality in its early stages. Since this abnormality occurs in the inferior segment, an inferior-to-anterior count ratio, an index of regional MIBG uptake could be suitable for the evaluation of this condition because of its superior sensitivity.