Simultaneous Fluorodeoxyglucose Positron Emission Tomography (PET) and Magnetic Resonance (MR) in Visual Snow Syndrome

Completed

• Conditions: Visual Snow Syndrome
• Interventions: Diagnostic Test: simultaneous fluor-18 fluorodeoxyglucose (FDG) positron emission tomography with magnetic resonance imaging (PET/MRI)

• Registration Number: NCT05569733
• Lead Sponsor: Universitaire Ziekenhuizen KU Leuven

Brief 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.

Study Timeline

• Study Start: 2017-01-02
• Primary Completion: 2017-09-02
• Study Completion: 2022-02-01
• Status Verified: 2022-09
• Study First Submitted: 2022-09-27
• Study First Submitted QC: 2022-10-03
• Study First Posted: 2022-10-06
• Last Update Submitted: 2023-01-26
• Last Update Posted: 2023-01-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 22

Inclusion Criteria

• M/F, age 18-85,
• diagnosis of VSS by an experienced neurologist : dynamic, continuous, black and white tiny dots in the entire visual field lasting longer than 3 months, with at least two additional visual symptoms

Exclusion Criteria

• other underlying neurological conditions inclusive ophthalmological examinations

GROUP 2 : Controls

Inclusion Criteria:

• age 18-85 years, M/F, in general healthy condition
• normal neurological examination, Mini-Mental State Examination (MMSE) ≥ 28, Beck's Depression Inventory (BDI) score ≤ 9, and a normal structural volumetric MRI.

Exclusion Criteria:

• history of major internal pathology, neurological and/or psychiatric disorders (including psychosis, depression, and anxiety),
• history of frequent migraine attacks, substance abuse or current use of any central acting medication
• first-degree relatives with dementia.

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
controls	simultaneous fluor-18 fluorodeoxyglucose (FDG) positron emission tomography with magnetic resonance imaging (PET/MRI)	healthy, screened age-matched controls
VSS	simultaneous fluor-18 fluorodeoxyglucose (FDG) positron emission tomography with magnetic resonance imaging (PET/MRI)	Patients with visual snow syndrome

Primary Outcome Measures

Name	Time	Method
Group difference in regional brain volume assessed with volumetric magnetic resonance imaging.	at baseline	Visual, voxel- and volume-of-interest based assessment of MRI images
Group difference in regional brain metabolism as assessed with 18F-FDG positron emission tomography	analysis done immediately after imaging	Visual, voxel- and volume-of-interest based assessment of of FDG PET

Secondary Outcome Measures

Name	Time	Method
Discriminant analysis of PET metabolic differences	at baseline	Statistical discriminant analysis of FDG between VSS patients and controls
Visual scoring of PET metabolic differences	at baseline	Visual scoring of FDG between VSS patients and controls
Discriminant analysis of MR volumetric differences	at baseline	Statistical discriminant analysis of regional MR volumetry between VSS patients and controls
Visual scoring of MR volumetric differences	at baseline	Visual scoring of regional MR volumetry between VSS patients and controls