Real-Time Volumetric Flow Measurements with Complex-Difference MRI

Richard B. Thompson, Elliot R. McVeigh

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Blood flow in large vessels can be noninvasively evaluated with phase-contrast (PC) MRI by encoding the spin velocity to the image phase. Conventional phase-difference processing of the flow-encoded image data yields velocity images. Complex-difference processing is an alternative to phase-difference methods, and has the advantage of eliminating signal from stationary spins. In this study, two acquisitions with differential flow encoding are subtracted to yield a single projection that contains signal from only those spins moving in the direction of the flow-encoding gradients. The increase in acquisition efficiency allows real-time flow imaging with a temporal window as short as two acquisition lengths (60 ms). Validation of the complex-difference method by comparison with conventional gated-segmented PC-MRI in a flow phantom yielded a correlation of r > 0.99. Peak arterial flow rates in the popliteal artery and desending aorta measured in vivo with the complex-difference method were 0.92 ± 0.06 of the values measured with conventional PC imaging. Real-time in vivo volumetric flow imaging of transient flow events is also presented.

Original languageEnglish (US)
Pages (from-to)1248-1255
Number of pages8
JournalMagnetic Resonance in Medicine
Issue number6
StatePublished - Dec 2003
Externally publishedYes


  • Complex-difference
  • Flow
  • MRI
  • Phase-contrast
  • Real-time

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology


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