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Updated: Aug 29, 2026

Continuous Venous-Arterial Doppler Ultrasound During a Preload Challenge
Published on: January 20, 2023
BOLD signal sign and transient vessels volume variation
G Garreffa1, C Colonnese, M A Macrì
1Istituto Neurologico Mediterraneo Neuromed, Pozzilli, (IS), Italy.
Abstract:
The purpose of this work was to investigate the relation between BOLD signal sign and transient vessels volume variation induced by apnea. This stimulus consisting of breath holding after inspiration is able to induce a light slowing down in venous blood flow like in a sort of Valsalva maneuver. We observed diffuse negative BOLD responding areas at cortical level and a stronger negative response in correspondence of the main sinuses. These phenomena seem to be unrelated to a specific neural activity, appearing to be expressions of a mechanical variation in the hemodynamics. Our study suggests that particular care must be considered in the interpretation of fMRI findings, especially when patients with vascular-related cerebral diseases are involved.
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