Objective: To examine the diagnostic utility (or misuse) of DAT scanning in a University Hospital practice – is there unnecessary utilisation of DAT scanning when compared to published guidelines or when a diagnosis of Parkinson’s Disease (PD) is clinically evident?

Background: DAT scans are FDA approved to evaluate suspected pre-synaptic dopaminergic insufficiency. While data is limited, previous studies have concluded that DAT scanning can have a significant impact on diagnosis and management, even within tertiary centres.

Method: DAT scans performed between 2016 to end 2018 (three years) from the nuclear medicine department in St Vincent’s University Hospital were assessed. We then conducted a retrospective chart review. The European Association of Nuclear Medicine Neuroimaging (EANM) 2009 guidelines were taken as the standard from which appropriateness of scanning was measured. Gold standard for diagnosis of PD or Parkinsonism was either by clinical diagnosis by a movement disorder specialist or diagnosis as per the Movement Disorder Society (MDS) clinical diagnostic criteria for PD.

Results: Patient records from 398 scans were analysed. Of these, full records were available for 318. 262 (82.4%) were within the recommended ordering guidelines. 170 (53.5%) were ordered by neurologists, of which 134 (78.8 %) were deemed appropriate. 148 (46.5%) were ordered by non-neurologists (73% geriatricians) of which 128 (86.5%) were deemed appropriate. In appropriate scans Parkinsonism was apparent in 67 patients prior to scanning (25.6%). In these cases PD was not diagnosed prior to scanning, either by MDS criteria or by a movement disorder specialist. Management changed in 71 (27.1%). Where it was unchanged, this was most commonly due to medication being started prior to the scan and a clinical response already being noted. In those patients where management changed, 14 of these were due to a change in suspected diagnosis. 31 patients (9.7%) were diagnosed with a Parkinson’s Plus disorder.

Conclusion: 82.4% of scans performed in our department adhered to existing guidelines. Within these management changed in 27%, with diagnosis changing in 4.4%. Parkinsonism was evident in 25.6% of appropriate scans. In patients with Parkinsonism, could dopaminergic therapy be trialled, as a clear response to therapy is included in the diagnostic criteria for PD?

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MDS Abstracts - https://www.mdsabstracts.org/abstract/appropriateness-of-dat-scan-ordering-in-a-university-hospital-practice/