Abstract
Aim Diagnosing movement disorders can be challenging owing to their similar clinical
presentations with other neurodegenerative and basal ganglia disorders, like idiopathic
Parkinson's disease (IPD), essential tremors (ET), vascular parkinsonism, multiple
system atrophy (MSA), and progressive supranuclear palsy (PSP). Technetium-99m labeled
tropane derivative (99mTc-TRODAT-1) imaging can help in diagnosing Parkinson's disease
at an early stage to help early initiation of the treatment. The current study aimed
to evaluate the role of 99mTc-TRODAT-1 imaging in differentiating IPD and Parkinson-plus
syndromes (PPS).
Material and Methods We have analyzed 38 patients, referred to our department for 99mTc-TRODAT imaging.
These patients were thoroughly evaluated in the movement disorder clinic at our institute
and had a possible/ probable diagnosis of IPD, Hoehn and Yahr (H&Y) stage I/II (n = 28) or PPS (PSP [n = 06] and MSA [n = 04]). Striatal uptake ratio (SUR) was calculated in all the patients and data was
statistically analyzed.
Results The mean age of IPD, PSP, and MSA groups was 56.5 ± 12.15, 65.2 ± 11.1, and 51.2 ± 3.9
years, respectively. On qualitative evaluation, all patients had reduced striatal
uptake on 99mTc-TRODAT imaging, with 31/38 patients showed a greater reduction in
putaminal uptake compared with the caudate nucleus. On semiquantitative evaluation,
mean total SUR was 0.58 ± 0.27, 0.53 ± 0.31, and 0.91 ± 0.20 in IPD, PSP, and MSA
groups, respectively. The total SUR was lowest in the PSP group followed by IPD, but
MSA had relatively higher SUR, although the difference was not statistically significant.
Among the IPD patient group, 25/28 patients (89.3%) experienced a greater reduction
in SUR values in the striatum contralateral to the side, where motor symptoms first
manifested at disease onset.
Conclusion 99mTc-TRODAT is a potential imaging biomarker for the evaluation of presynaptic dopaminergic
dysfunction in patients with movement disorders. In our study cohort, mean SUR values
were lowest for the PSP group followed by IPD and MSA group, which was in concordance
with previous studies. However, the difference between SUR values in these two groups
was not statistically significant. The present study emphasizes that the capacity
of 99mTc-TRODAT-1 imaging alone for diagnosing IPD from PPS is constrained, although
it offers a precise approach for distinguishing patients with IPD from those with
essential tremors, drug-induced, or psychogenic parkinsonism. Consequently, more specific
imaging biomarkers are needed to effectively differentiate between patients with IPD
and those with PPS.
Keywords
99mTc-TRODAT-1 - idiopathic Parkinson's disease - Parkinson-plus syndrome - movement
disorders - parkinsonism
