123I-FP-CIT SPECT (DaTSCAN®) allows to detect presynaptic dopamine neuronal denervation. It is recommended to differentiate neurodegenerative parkinsonism from secondary parkinsonian syndromes or from essential tremor, and to distinguish patients with suspected dementia with Lewy bodies and those with other subtypes of dementia. The aim of this retrospective study was to evaluate the relevance of 123I-FP-CIT SPECT prescriptions, the profile of prescribers and the evolution of the prescription rate over a ten-year period.

the investigators included 723 patients in this retrospective study between February 2009 and May 2019, in the nuclear medicine Department of Avicenne University Hospital. No patients were excluded. Demographic, clinical, brain imaging, and 123I-FP-CIT SPECT data were collected from medical records. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Ethics Committee (CLEA-2019-75).

Regarding the relevance of the indications, the investigators have defined three groups: " inappropriate ", "uncertain " and " relevant ", also respectively named (a), (b) and (c) groups.

In the "inappropriate" group (a), the investigators placed prescriptions with no indication, 123I-FP-CIT SPECT requested to confirm a PS clinically evident, and those prescribed for isolated cognitive-behavioral disturbances with no PS or differential diagnosis mentioned.

In the "uncertain" group (b), the investigators did not have sufficient data to determine with certainty whether this was an inappropriate or relevant indication.

In the "relevant" group (c), the prescriptions concerned the differential diagnosis between neurodegenerative parkinsonism and secondary parkinsonian syndromes (for instance post-neuroleptics) or other doubtful disorders (Alzheimer's disease, essential tremor), clinically uncertain PS (such as an isolated asymmetric resting tremor without akinesia or lead-pipe rigidity) and PD of atypical evolution.

Data were presented as mean (standard deviation) for numeric variables and as count (percentage) for categorical variables. To compare demographic, clinical and paraclinical data, and the distribution of prescribers between the three groups (i.e. inappropriate (a), uncertain (b) and relevant (c)), one-factor analysis of variance (ANOVA) was used for numerical variables and Fisher's exact test for categorical variables. To identify which groups differed from each other, post hoc comparisons were made using the Tukey test for numeric variables and the Fisher pairwise exact test followed by the Benjamini-Hochberg correction to account for multiple testing, for categorical variables. For all tests, the significance level was set at p < 0.05. All data were analyzed using R software (version 3.6.1, R Core Team).

Inclusion Criteria:

• Parkinsonian patients who benefited from a 123I-FP-CIT SPECT

Exclusion criteria:

Adult Parkinsonian patients who benefited from a 123I-FP-CIT SPECT ,