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Diagnostic impact of [18F]flutemetamol amyloid imaging in young-onset dementia

      Background

      In young onset dementia, approximately one out of three patients has an atypical clinical presentation, which substantially complicates correct nosological diagnosis. In vivo detection of amyloid pathology can be useful in the diagnostic process. The present study aimed to examine the diagnostic impact of the amyloid-PET imaging agent [18F]flutemetamol in assessing patients with young onset dementia.

      Methods

      The present study included 200 patients visiting our tertiary memory clinic and diagnosed with young onset dementia (age <70 years). Patients were enrolled when physician’s diagnostic confidence was <90% after a full routine diagnostic work-up for dementia. All patients underwent a [18F]flutemetamol PET scan which was visually assessed as amyloid positive or negative. Scans were performed 90-110 minutes after injection of 185 MBq [18F]flutemetamol. Before and after disclosing PET results to the physician, clinical diagnosis and confidence in this diagnosis were determined. In addition, the impact on healthcare management plan, including medication and care, and request for additional investigations was assessed.

      Results

      [18F]Flutemetamol scans were positive in 107 out of 137 (78%) patients with a pre-PET AD diagnosis and in 20 out of 63 (32%) patients diagnosed with a non-AD dementia prior to PET. Overall, confidence in diagnosis increased in 87% of the patients, on average from 69±12% to 89±15% after disclosing PET results (p<0.001). In 68 (34%) patients, [18F]flutemetamol PET results led to a change in patient healthcare management (i.e. medication changed in 61 patients and care plan altered in 22 patients). A positive PET scan resulted in change of management plans (either medication, care, or both) nine times more often than a negative PET scan (n=61 vs. n=7; p<0.001). For 43 (22%) patients, additional ancillary investigations were planned after PET results were disclosed, predominantly when PET results were negative (n=33; p<0.001). In patients with a pre-PET AD diagnosis and a positive PET scan, additional ancillary investigations were less often requested compared to patients with a negative PET scan (p<0.001).

      Conclusions

      [18F]Flutemetamol PET increased physician’s overall confidence in clinical diagnosis. In addition, it altered diagnostic work-up and healthcare management plan of young onset dementia patients visiting a tertiary memory clinic.