Direct Assessment of Wall Shear Stress by Signal Intensity Gradient from Time-of-Flight Magnetic Resonance Angiography

Biomed Res Int. 2017:2017:7087086. doi: 10.1155/2017/7087086. Epub 2017 Aug 16.


The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p < 0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (β = 0.96, p < 0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p < 0.001 for all β values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice.

MeSH terms

  • Cardiovascular Diseases / diagnosis*
  • Cardiovascular Diseases / diagnostic imaging
  • Cardiovascular Diseases / physiopathology
  • Carotid Arteries
  • Carotid Artery, Common / diagnostic imaging
  • Carotid Artery, Common / physiopathology
  • Carotid Stenosis / diagnosis*
  • Carotid Stenosis / diagnostic imaging
  • Carotid Stenosis / physiopathology
  • Contrast Media / therapeutic use
  • Humans
  • Hydrodynamics
  • Magnetic Resonance Angiography / methods*
  • Magnetic Resonance Imaging / methods*


  • Contrast Media