DocumentCode :
1402766
Title :
Optical-Flow-Based B-Mode Elastography: Application in the Hypertensive Rat Carotid
Author :
Zakaria, Toufik ; Qin, Zhao ; Maurice, Roch Listz
Author_Institution :
Lab. of Biorheology & Med. Ultrasonics, Centre Hospitalier de l´´Univ. de Montreal (CRCHUM), Montreal, QC, Canada
Volume :
29
Issue :
2
fYear :
2010
Firstpage :
570
Lastpage :
578
Abstract :
Ultrasound elastography is now used worldwide in tissue characterization. The primary premises of elastography are that speckle kinematics reproduces underlying tissue kinematics and that tissue motion can be inferred from speckle tracking. This implicitly assumes that speckle pattern is a material property that can be tracked with respect to time and space. It is then convenient to express the motion of such a material property in terms of total derivative, also known as optical flow (OF) equations. The present paper introduces a new iterative OF-based elastography (OFBE) method devoted to B-mode data. The first OFBE iteration computes axial and lateral displacement fields. Such displacement fields are used for data rigid registration, prior to the second OFBE iteration which computes the 2-D strain tensor. The OFBE method was validated in the common carotid artery of rat hypertension models. The effect of aging on carotid stiffness was investigated in female recombinant inbred rats (RI-17, (n = 2)) in the first experiment. The outcomes of low/high-salt diets were examined in young male Dahl salt-sensitive rats (SS, n = 6; SM12, n = 6; SM9, n = 6) in the second experiment. Good concordance was observed between left and right carotid axial strain measurements with 11.4% relative error, whereas 4.6% relative error occurred between diastolic and systolic axial strain measurements. Old (80 and 85 weeks) RI-17 carotids were determined to be twice as stiff with 5.70 ?? 0.97% (strain ?? std) as young carotids (30 and 34 weeks) with 13.26 ?? 2.73%, p < 0.001. Carotid axial strain measurement also indicated that salt diets had a significant impact on SS (p=0.008) and SM12 (p < 0.001) but not on SM9 (p = 0.881) rats.
Keywords :
biomechanics; biomedical measurement; biomedical ultrasonics; blood vessels; displacement measurement; elasticity; image sequences; iterative methods; medical image processing; speckle; Dahl salt sensitive rats; OFBE method; axial displacement fields; carotid stiffness; diastolic axial strain; hypertensive rat carotid artery; iterative optical flow based elastography; lateral displacement fields; optical flow based B-mode elastography; optical flow equations; speckle kinematics; speckle tracking; systolic axial strain; tissue kinematics; ultrasound elastography; Adaptive optics; Capacitive sensors; Hypertension; Kinematics; Material properties; Rats; Speckle; Strain measurement; Tracking; Ultrasonic imaging; B-mode elastography; carotid artery; engineered rat models; hypertension; optical flow equations; small animal imaging; strain tensor; Age Factors; Animals; Blood Pressure; Carotid Arteries; Diet; Disease Models, Animal; Elasticity Imaging Techniques; Female; Hypertension; Male; Movement; Normal Distribution; Rats; Rats, Inbred Dahl; Rats, Transgenic; Shear Strength; Signal Processing, Computer-Assisted; Sodium Chloride;
fLanguage :
English
Journal_Title :
Medical Imaging, IEEE Transactions on
Publisher :
ieee
ISSN :
0278-0062
Type :
jour
DOI :
10.1109/TMI.2009.2038694
Filename :
5405640
Link To Document :
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