Objectives To further validate the diagnostic utility of 18F-AV-133 vesicular monoamine transporter type 2 (VMAT2) positron emission tomography (PET) in patients with clinically uncertain parkinsonian syndromes (CUPS) by comparison to clinical diagnosis at 3 years follow-up.
Design, setting and participants In a previous study, we reported that 18F-AV-133 PET in community patients with CUPS changed diagnosis and management and increased diagnostic confidence. The current diagnosis of this cohort was obtained from the patient and treating specialist and compared with the diagnosis suggested 3 years earlier by the 18F-AV-133 PET. A second 18F-AV-133 PET was available in those with a discordant or inconclusive final diagnosis.
Study outcome measures The primary end point was the proportion of patients who had a follow-up clinical diagnosis, which was concordant with their initial 18F-AV-133 PET scan. Secondary end points were the proportion of patients who had the same diagnosis at follow-up as that reached after the initial scan and the stability of diagnostic changes made after the first scan.
Results 81 of the 85 patients previously recruited to the CUPS study had follow-up of which 79 had a clinical diagnosis and 2 remained CUPS. The diagnosis was in agreement with the initial 18F-AV-133 PET scan result in 74 cases. Five patients had a discordant diagnosis; one patient with rubral tremor had a severely abnormal scan that had worsened when rescanned; four cases with normal initial and repeat scans had a clinical diagnosis of Parkinson’s disease. Two patients with suspected genetic disorders remained classified as CUPS and both had normal scans. In the 24 CUPS cohort patients where 18F-AV-133 PET initially changed diagnosis, this change was supported by follow-up diagnosis in all but the one rubral tremor case.
Conclusion 18F-AV-133 PET is a useful tool in improving diagnostic accuracy in CUPS providing results and diagnostic changes that remain robust after 3 years follow-up.
- diagnostic accuracy
- molecular imaging
- parkinson-s disease
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Contributors SSX was involved in statistical analysis and wrote the manuscript. PKA, YL and VD were involved in the research project execution and statistical analysis. SB was involved in the research project organisation and execution. RSM and KY were involved in research project execution. VLV was involved in statistical analysis design, execution, review and critique. CCR was involved in research project conception, organisation and execution, statistical analysis review and critique and manuscript review and critique.
Funding This was an investigator-initiated study supported by a grant from Avid Radiopharmaceuticals. CCR has received research grants for imaging in dementia from Piramal Imaging, GE Healthcare, Cerveau, Astra Zeneca, Biogen and Navidea. He has been a consultant or paid speaker at sponsored conference sessions for Piramal Imaging, GE Healthcare, Astra Zeneca, Roche and Biogen. VLV has been a consultant or paid speaker at sponsored conference sessions for Piramal Imaging, GE Healthcare, Astra Zeneca and Novartis.
Competing interests A grant for this study was provided to Professor Rowe to support this study by Avid Radiopharmaceuticals, who developed and own the rights to 18 F-AV-133.
Patient consent Obtained.
Ethics approval Austin Health Human Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data available for sharing.
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