Simultaneous Fluorodeoxyglucose Positron Emission Tomography (PET) and Magnetic Resonance (MR) in Visual Snow Syndrome
Condition: Visual Snow Syndrome
MeSH terms: Syndrome
Study type: Observational

Summary: 
      Visual snow syndrome (VSS) is a neurologic condition where patients experience tiny
      flickering dots in their entire visual field. It has been reported that the brain consumes
      more glucose in the lingual gyrus (a subdivision of the occipital cortex) and that this also
      shows increased volume of grey matter (neurons and supporting cells). In this study, the
      investigators apply fluor-18 fluorodeoxyglucose positron emission tomography with magnetic
      resonance imaging (18F-FDG PET/MR) in patients with VSS and compare this to healthy controls.
      Aside from an analysis in each brain volume element (voxel), the accuracy of classifying
      groups based on a volume-of-interest (VOI) analysis of both PET and MR is studied, Lastly,
      this is also compared to a visual assessment of the PET and MR images.
    

Detailed description: 
      Aim : Prospective measurement of brain glucose metabolism and structural integrity in the
      brain of subjects with visual snow syndrome (VSS). Voxel-based and volume-of interest
      comparison to age matched healthy controls retrospectively obtained on the same simultaneous
      PET/MR imaging system.

      Hypothesis : 1/ VSS patients show overactivation of parts of the visual system, in particular
      the lingual gyrus, which is likely related to larger volume of the gyrus on structural
      imaging. 2/ Discrimination of VSS patients versus controls can be done by visual read of FDG
      PET and/or volume-of-interest based discriminant analysis.

      Methods : Recruitment through neurology practice specialised in VSS, detailed history taking
      and assessment of in/exclusion criteria, scanning with simultaneous18F-FDG PET/MR Signa GE
      Healthcare.

      Analysis : visual assessment, group-based voxel and volume-of-interest based analysis (FDG
      PET, volumetry T1 MRI) with appropriate statistics and corrections for multiple regional
      comparisons. Discriminant analysis on VOI based data. Dual observer scoring of visual data
      and assessment of accuracy, sensitivity and specificity of visual image analysis compared to
      clinical final diagnosis.
    

Intervention name(s): simultaneous fluor-18 fluorodeoxyglucose (FDG) positron emission tomography with magnetic resonance imaging (PET/MRI)
Intervention type(s): Diagnostic Test
Intervention description(s): All subjects fast at least for 4 hours prior to 18F-FDG injection. 18F-FDG is injected intravenously (150 megabecquerel (MBq)) in standard ambient conditions, supine in a dark, noise free room with eyes and ears open. 18F-FDG PET images are acquired for 20 min on a simultaneous GE Signa 3 Tesla (3T) PET/MR scanner with integrated Time-of-Flight (TOF) (GE Healthcare, Chicago, USA). Simultaneous with the 18F-FDG PET/MR acquisition, zero-echo-time (ZTE) MR data are acquired for attenuation correction and a 3D volumetric T1-weighted BRAVO MR sequence using a vendor supplied high-resolution 8-channel phased array head coil (GE Healthcare, Milwaukee, USA).
Intervention MeSH terms: Fluorodeoxyglucose F18
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Group 1 : Visual Snow Syndrome patients Group 2 : Healthy Controls
      
Keywords: FDG PET; PET/MR; volumetry; visual analysis; discriminant analysis