Caspr2 antibody-associated limbic encephalitis: contribution of visual aided analysis of 18 F-FDG PET images using normal database comparison

Rev Esp Med Nucl Imagen Mol (Engl Ed). Mar-Apr 2020;39(2):92-95. doi: 10.1016/j.remn.2019.08.008. Epub 2019 Nov 26.
[Article in English, Spanish]


Early immunotherapy is of paramount importance for a positive outcome in patients suffering acute encephalitis of autoimmune origin (AIE). A new approach for early diagnosis based on clinical presentation and complementary tests has been proposed, but not all these tests show positive findings in the first weeks. While common forms of AIE (anti-LGI-1 and anti-NMDAR antibodies) exhibit consistent 18Fluor-fluorodeoxiglucose (FDG-PET) patterns in many cases, the anti-Caspr2 form of AIE is infrequent and FDG-PET patterns have not been well characterized. In our experience, FDG-PET in anti-Caspr2 limbic encephalitis shows medial temporal hypermetabolism and diffuse cortical hypometabolism, even in the absence of findings in these tests. However, it is necessary to standardize PET image analysis by means of visual and voxel-based methods compared to normal databases to define the areas of pathological metabolism that may go unnoticed when using visual analysis exclusively.

Keywords: (18)F-FDG PET/CT; (18)F-FDG PET/TC; Caspr2; Encefalitis autoinmune; Encefalitis límbica; Limbic encephalitis; autoimmune encephalitis.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Antibodies / blood
  • Antibodies / cerebrospinal fluid
  • Fluorodeoxyglucose F18* / metabolism
  • Humans
  • Limbic Encephalitis / diagnostic imaging*
  • Limbic Encephalitis / immunology*
  • Limbic Encephalitis / metabolism
  • Magnetic Resonance Spectroscopy
  • Male
  • Membrane Proteins / immunology*
  • Memory Disorders / etiology
  • Nerve Tissue Proteins / immunology*
  • Neuropsychological Tests
  • Positron Emission Tomography Computed Tomography / methods*
  • Positron Emission Tomography Computed Tomography / standards
  • Radiopharmaceuticals* / metabolism


  • Antibodies
  • CNTNAP2 protein, human
  • Membrane Proteins
  • Nerve Tissue Proteins
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18