Objective: This study investigated the impact of I123-FP-CIT single photon emission computed tomography (SPECT) for the diagnosis of patients with clinically uncertain parkinsonian syndrome (CUPS) on changes in diagnosis, medical management, and healthcare utilization.

Background: Parkinson’s disease (PD) is a Parkinsonian syndrome (PS) characterized by nigrostriatal dopaminergic degeneration (NSDD). It is typically diagnosed based on clinical features including bradykinesia with resting tremor and/or rigidity. Patients presenting with atypical or ambiguous symptoms, or without satisfactory response to levodopa, may lead to a clinically uncertain diagnosis. I123-FP-CIT SPECT is indicated for helping to differentiate between non-dopaminergic degenerative conditions like essential tremor and conditions associated with NSDD like PD.

Method: This was a retrospective single-center study of adult patients first identified with CUPS at a movement disorders clinic between 3/17–2/19. All patients were evaluated and treated by a single neurologist per routine clinical practice and 1-year follow-up was collected from clinical records. Patients who had a I123-FP-CIT SPECT to assist with a definitive diagnosis were identified from imaging referrals. Patients with CUPS and without SPECT were identified from referrals that did not have a scan due to patient fear or discomfort, and from clinical records of patients with CUPS that were not referred for a scan due to non-clinical reasons such as lack of insurance coverage.

Results: The population included 81 patients with I123-FP-CIT SPECT and 12 controls. [Table 1] No complications related to I123-FP-CIT were reported. The proportions of patients with a diagnosis change within 1 year was similar (29.6% I123-FP-CIT vs. 33.3% controls), but the first change was made significantly later in the control group (226.5±119.2 vs. 47.5±21.4 days). The total number of clinic visits was similar (4.0±1.2 I123-FP-CIT vs. 4.1±1.4 controls), but only 12.3% of I123-FP-CIT patients had clinically uncertain diagnoses beyond their first CUPS visit compared to 83.3% of controls.

Conclusion: I123-FP-CIT SPECT is a safe diagnostic tool that can assist physicians in making an accurate and timely diagnosis in patients with CUPS. This may allow for more appropriate treatment earlier in the clinical course.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/diagnostic-utility-of-i123-fp-cit-single-photon-emission-computed-tomography-for-patients-with-clinically-uncertain-parkinsonian-syndrome/