Phase contrast magnetic resonance velocity imaging is a powerful non-invasive technique to measure in vivo blood flow. Its sensitivity is usually restricted to prevent the measured phase from being 'wrapped' onto the range -�| to +�|.

Otherwise, the true phase must be estimated from the measured wrapped phase by a non-trivial phase unwrapping process. We investigate the performance of three different phase unwrapping algorithms.

Compared to the traditional approach, the sensitivity can be increased by a factor of up to five times, which has the potential to improve the accuracy of stress measurements at the vessel walls to predict cardiovascular risk.
 

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