Measurement of flow with NMR imaging using a gradient pulse and phase difference technique

Area of Science:

• Medical Imaging
• Biophysics
• Cardiovascular Science

Background:

• Accurate measurement of blood flow is crucial for diagnosing and monitoring various cardiovascular conditions.
• Conventional imaging techniques may have limitations in precisely quantifying flow dynamics.

Purpose of the Study:

• To describe and validate a novel nuclear magnetic resonance (NMR) imaging method for determining flow velocity.
• To assess the accuracy and potential clinical utility of this NMR flow measurement technique.

Main Methods:

• A modified spin-echo imaging sequence incorporating balanced gradient pulses was utilized.
• Phase shifts in NMR images were analyzed to determine flow velocities orthogonal to the image plane.
• In vitro validation with a water phantom and in vivo studies on human carotid and femoral arteries were performed.

Main Results:

• In vitro experiments showed excellent agreement between NMR-measured flow rate and actual volume flow rate.
• In vivo measurements in volunteers demonstrated general agreement with Doppler ultrasound velocity data.
• The method's ability to track rapid flow changes is dependent on careful gradient profile design.

Conclusions:

• The described NMR imaging technique provides accurate flow velocity measurements.
• The method is compatible with existing NMR hardware and holds promise for clinical use in vascular assessment.
• Further optimization of gradient design may enhance the tracking of dynamic flow changes.