123I-Ioflupane progression studies – avoiding pitfalls

Ioflupane (DaTSCAN) is a well established diagnostic tool for diagnosis of Parkinson’s disease (PD), as well as dementia with Lewy bodies (DLB). Ioflupane binds to the dopamine active transporters in the presynaptic membrane of the dopaminergic nerve terminals (DNT). Dopaminergic pathways in the brain are involved in various brain functions. Degeneration of dopaminergic neurons in […]Ioflupane (DaTSCAN) is a well established diagnostic tool for diagnosis of Parkinson’s disease (PD), as well as dementia with Lewy bodies (DLB). Ioflupane binds to the dopamine active transporters in the presynaptic membrane of the dopaminergic nerve terminals (DNT). Dopaminergic pathways in the brain are involved in various brain functions. Degeneration of dopaminergic neurons in the nigrostriatal pathway is one of the main pathological features of PD and DLB. In PD the pathologic process is postulated to start in the DNTs in the striata (putamen and caudate), progressing retrogradely, culminating in the loss of DNT in the pars compacta of the substantia nigra. The density of the dopamine active transporters (DaT) in the terminal axons is reduced with loss of DNTs, which is reflected in reduced ioflupane binding in the striata. Typically, DNT loss in PD is more marked in putamen than caudate, resulting in the typical abnormal ‘dot’-shaped appearance of the striata. However, in DLB, and to a lesser extent in atypical PD, the loss may be global with equal loss in putamen and caudate (balanced loss). In these patients the comma-shaped appearance is retained despite progressive and in some cases severe loss of DNT in the striata, thus visual appearance may appear ‘normal’ (comma-shaped). Then the visual assessment of ioflupane binding is difficult. Ioflupane uptake in the background (brain cortex and white matter) remains more or less the same regardless of the progression of the disease (PD or DLB), which serves as a basis for semiquantitative assessment of striatal uptake. Background corrected ratio of striatal uptake to occipital cortex is often used for semi-quantification (called striatal specific binding ratio, or striatal SBR).

The content on this page is provided by the individuals concerned and does not represent the views or opinions of RAD Magazine.