18F-DPA714 PET in MRI-negative autoimmune encephalitis: a supportive approach to aiding neuroinflammation

Huanyu Meng1,2, Yuanqi Qi1, Mengmeng Zhang3

  • 1Department and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, China.

Abstract

Insights

18F-DPA714 PET imaging detected neuroinflammation in most autoimmune encephalitis (AIE) patients with negative MRI scans. This neuroinflammation biomarker correlated with disease severity and predicted brain volume loss, supporting its use in AIE assessment.

Area of Science:

  • Neuroimaging
  • Nuclear Medicine
  • Neurology

Background:

  • Conventional magnetic resonance imaging (MRI) has limitations in detecting abnormalities in autoimmune encephalitis (AIE).
  • 18F-DPA714 is a potential PET tracer for neuroinflammation, targeting the translocator protein (TSPO).

Purpose of the Study:

  • To evaluate the utility of 18F-DPA714 PET in identifying neuroinflammation in patients with MRI-negative autoimmune encephalitis (AIE).
  • To assess the correlation between 18F-DPA714 uptake, clinical severity, and treatment response in AIE.

Main Methods:

  • Retrospective analysis of 60 MRI-negative possible AIE patients and 10 healthy controls who underwent 18F-DPA714 PET.
  • Abnormal PET uptake was defined using a standardized uptake value ratio (SUVR) threshold derived from controls.
  • Clinical severity was assessed using modified Rankin Scale (mRS) and Clinical Assessment Scale for Autoimmune Encephalitis (CASE); 34 patients had follow-up imaging.

Main Results:

  • 18F-DPA714 PET showed abnormal uptake in 65% of MRI-negative AIE patients, particularly in the occipital lobes.
  • Uptake patterns correlated with specific symptoms, and baseline PET activity (SUVRmax, SUVRmean) significantly correlated with baseline mRS and CASE scores.
  • Follow-up PET activity correlated with mRS and CASE, with decreased uptake paralleling clinical improvement and higher baseline activity predicting greater brain volume loss.

Conclusions:

  • 18F-DPA714 PET is effective in detecting neuroinflammation in a significant proportion of MRI-negative AIE patients.
  • Quantitative 18F-DPA714 uptake correlates with AIE disease severity and may predict treatment response and subsequent brain volume loss.
  • 18F-DPA714 PET/MR shows promise as an adjunctive tool for assessing disease activity and outcomes in MRI-negative AIE.

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