Metaiodobenzylguanidine (MIBG) scintigraphy at various parts of the body in Parkinsonʹs disease and multiple system atrophy

We compared MIBG uptake at various parts of the body in controls and patients with Parkinsonʹs disease and multiple system atrophy. In the heart, MIBG uptake in Parkinsonʹs disease (early H/M: 1.668 ± 0.325, late H/M: 1.500 ± 0.402) was less than that in multiple system atrophy (early H/M: 2.395 ± 0.186, late H/M: 2.530 ± 0.391) and controls (early H/M: 2.635 ± 0.508, late H/M: 2.575 ± 0.635) (early: P < 0.0001, late: P < 0.0001). There were no significant differences in uptake by the lung, thyroid, or liver in the three groups. Only on early images, uptake in the shoulder in multiple system atrophy (early S/M: 0.473 ± 0.78) and Parkinsonʹs disease (early S/M: 0.470 ± 0.710) was decreased compared to that in controls (early S/M: 0.560 ± 0.118) (P = 0.0252). MIBG is reported to be taken up in the terminal part of sympathetic nerves and demonstrates sympathetic nerve activity, especially on late images. The cause of differences between the heart and other parts of the body remains unknown. We consider the following possibilities: (a) differences in the sympathetic nervous system between Parkinsonʹs disease and multiple system atrophy are more subtle in organs other than the heart; (b) the cause of MIBG uptake reduction by the heart in Parkinsonʹs disease involves factors in addition to sympathetic nervous system damage; and (c) MIBG uptake by organs other than the heart involves not only the sympathetic nervous system but also non-neuronal components. In conclusion, MIBG uptake by organs other than the heart cannot differentiate Parkinsonʹs disease from multiple system atrophy at present.