VICTR: Venous transit time imaging by changes in T₁ relaxation

Area of Science:

• Neuroimaging
• Cerebrovascular Physiology
• Medical Physics

Background:

• Cerebral venous abnormalities are common in neurological diseases.
• Current MRI techniques for assessing venous hemodynamic function are limited.
• Venous transit time (VTT) is a novel circulatory measure reflecting blood flow dynamics.

Purpose of the Study:

• To develop a noncontrast MRI technique for measuring VTT.
• To assess the validity and reliability of the developed technique.
• To compare the novel technique with existing contrast-based methods.

Main Methods:

• Development of a novel MRI sequence: venous transit time imaging by changes in T1 relaxation (VICTR).
• Validation of VTT measurements using anatomical flow trajectories and a caffeine-induced vasoconstriction challenge.
• Comparison of VICTR MRI-derived VTT with a gadolinium-based contrast agent bolus-tracking method.

Main Results:

• VICTR MRI reliably measured VTT with high test-retest reliability (ICC=0.964).
• VTT increased significantly after caffeine ingestion, consistent with vasoconstriction.
• VTT measured by VICTR MRI strongly correlated with contrast-based methods (R=0.84).
• VTT was inversely correlated with cerebral blood flow and venous oxygenation.

Conclusions:

• VICTR MRI is a novel, noncontrast technique for measuring brain VTT.
• This technique offers a promising tool for evaluating cerebral venous hemodynamics.
• VICTR MRI may aid in the diagnosis and management of neurological diseases involving venous abnormalities.