Tau and amyloid-β (Aβ) aggregates have been suggested to play a role in the development of dementia in Parkinson's disease (PD). Positron emission tomography (PET) with [18F]FDDNP and the determination of cerebrospinal fluid (CSF) levels of these proteins constitute a means to visualize in vivo Aβ and tau brain accumulation. Information about longitudinal changes of these CSF and PET biomarkers in PD with regard to progression to dementia is lacking. We assessed the cross-sectional and longitudinal associations of CSF and PET biomarkers of tau and Aβ with PD-related cognitive dysfunction in 6 healthy-controls (HC), 16 patients with PD without dementia (PDND), and 8 PD with dementia (PDD). All subjects underwent comprehensive neuropsychological testing, [18F]FDDNP PET, and CSF Aβ-tau determination. After 18 months, the PDND group was re-assessed clinically and by neuropsychological, PET, and CSF determinations. Cross-sectionally, PDD had higher [18F]FDDNP binding in lateral temporal regions and lower levels of CSF Aβ levels compared to PDND, with a congruent correlation between the [18F]FDDNP binding and CSF Aβ levels. Longitudinally, higher baseline lateral temporal [18F]FDDNP binding was associated to longitudinal worsening in cognitive performances and progression to dementia among subjects classified as PDND at baseline, who additionally disclosed at follow-up an increase in lateral-temporal FDDNP binding, as well as a reduction in CSF Aβ and an increase in CSF tau levels. These results confirm the relevance of these CSF and PET biomarkers to PDD, being specifically the first to show [18F]FDDNP PET as a dementia risk biomarker in PD, along with longitudinal CSF and PET changes over time.
The main indication for C-choline PET/CT in prostate cancer patients is the early localization of biochemical recurrence after radical treatment. However, any C-choline uptake should be assessed in terms of physiological distribution and patterns of tumor spread. Therefore, tracer-avid lesions in unexpected sites should be carefully addressed because the diagnosis of other malignancies has important therapeutic implications. We present a patient with biochemical recurrence of prostate cancer treated with radiotherapy. C-choline PET/CT showed local recurrence and inguinal lymph node uptake. Because of its location beyond typically prostatic lymphatic spread, resection was performed. Histology confirmed a diffuse large B-cell lymphoma.
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