Tissue Harmonic Imaging
Is It a Benefit for Bile Duct Sonography?
Dulia Ortega1,2,
Peter N. Burns3,
David Hope Simpson3 and
Stephanie R. Wilson1
1
Department of Medical Imaging, Toronto General Hospital, University Health
Network, 200 Elizabeth St., Toronto, Ontario, M5G 2C4 Canada.
2
Present address: Hospital Clinico Universidad de Chile, Servicio de
Radiologia, Santos Dumont 999, 4t. piso sector C, Santiago, Chile.
3
Department of Medical Biophysics, University of Toronto, Imaging Research,
Sunnybrook and Women's College Health Science Centre, 2075 Bayview Ave.,
Toronto, Ontario, M5G 2C4 Canada.
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Fig. 1. —Drawing of undistorted pressure wave (top) and of
pressure wave after undergoing nonlinear propagation (bottom).
Nonlinear effects cause high-pressure regions of sound wave to travel faster
than low-pressure regions and result in progressive distortion of transmitted
wave with generation of sound at higher harmonics of transmit frequency.
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Fig. 2. —Schematic cross-sections of conventional (outer) and
harmonic (inner) transmit beams at focus. Harmonic beam has narrower
main lobe and lower side lobes than conventional beam.
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Fig. 3. —Schematic shows conventional and harmonic sonography beams.
Conventional beam (top) is generated at transducer surface and can
produce reverberation artifacts in superficial tissues. Harmonic beam
(bottom) is generated below surface and is less susceptible to
reverberation artifacts.
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Fig. 4. —Schematic shows conventional beam (left) with
reverberations produced in superficial tissues. Harmonic beam
(right), generated in body, has fewer artifacts.
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Fig. 5A. —Lumen of common bile duct in 82-year-old man with jaundice.
Conventional sagittal sonogram (grade 1) of common bile duct and portal vein
shows each to have moderate artifact.
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Fig. 5B. —Lumen of common bile duct in 82-year-old man with jaundice.
Tissue harmonic image (grade 3) shows lumina of both bile duct and vein are
blacker and more echo-free with clearly defined margins.
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Fig. 6A. —Lumen of common bile duct in 47-year-old woman with jaundice.
Sagittal conventional sonogram (grade zero) of common bile duct shows dilated
common bile duct. Note extensive intraluminal artifactual echo.
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Fig. 6B. —Lumen of common bile duct in 47-year-old woman with jaundice.
Sagittal tissue harmonic image (grade 3) shows dilated duct as echo-free black
structure.
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Fig. 7A. —Length of visible common bile duct in 63-year-old woman with
choledocholithiasis. Sagittal conventional sonogram (grade 1) shows that
distal half of common bile duct is obscured.
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Fig. 7B. —Length of visible common bile duct in 63-year-old woman with
choledocholithiasis. Tissue harmonic image (grade 2) of same location as
A shows several centimeters of common bile duct that were previously
unvisualized.
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Fig. 8A. —Walls of common bile duct in 37-year-old woman with liver
transplant. Sagittal conventional sonogram (A) and tissue harmonic
image (B) show proximal common bile duct. Note uniform thickening of
walls of duct seen on both images. Both lumen of duct and several tiny cystic
spaces in small postoperative mass are clearer and blacker on tissue harmonic
image.
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Fig. 8B. —Walls of common bile duct in 37-year-old woman with liver
transplant. Sagittal conventional sonogram (A) and tissue harmonic
image (B) show proximal common bile duct. Note uniform thickening of
walls of duct seen on both images. Both lumen of duct and several tiny cystic
spaces in small postoperative mass are clearer and blacker on tissue harmonic
image.
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Fig. 9A. —Acoustic shadows in 55-year-old man with painful jaundice.
Sagittal conventional sonogram (grade 3) shows stone in distal duct and fairly
obvious acoustic shadow.
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Fig. 9B. —Acoustic shadows in 55-year-old man with painful jaundice.
Tissue harmonic image (grade 3) shows stone and acoustic shadow even more
clearly. Acoustic shadow has sharper walls, is more echo-free, and is better
defined than in A.
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Fig. 10A. —Metastatic tumor deposit from gastric carcinoma seen as
intraluminal mass in right hepatic duct in 83-year-old man with obstructive
jaundice. Conventional subcostal oblique sonogram (grade 1) of porta hepatis
shows dilated ducts in each lobe. Note vague suggestion of intraluminal
mass.
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Fig. 10B. —Metastatic tumor deposit from gastric carcinoma seen as
intraluminal mass in right hepatic duct in 83-year-old man with obstructive
jaundice. Tissue harmonic image (grade 3) clearly shows soft-tissue
intraluminal mass (arrow) without distal shadowing.
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Fig. 11A. —Normal-caliber duct in 35-year-old woman with possible
biliary colic. Conventional sagittal sonogram (A) and tissue harmonic
image (B) show duct distinctly. Each image received grade 2 for luminal
assessment and length of visible duct. However, when both images are placed
side by side, tissue harmonic imaging has more clarity.
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Fig. 11B. —Normal-caliber duct in 35-year-old woman with possible
biliary colic. Conventional sagittal sonogram (A) and tissue harmonic
image (B) show duct distinctly. Each image received grade 2 for luminal
assessment and length of visible duct. However, when both images are placed
side by side, tissue harmonic imaging has more clarity.
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Fig. 12A. —Tiny distal common bile duct stone in 55-year-old man with
painful jaundice. Conventional sagittal sonogram (A) and tissue
harmonic image (B) show small stone (arrow) distinctly.
However, tissue harmonic image shows longer length of common bile duct with
blacker lumen. Better definition of acoustic shadow distal to stone on tissue
harmonic image is related to increase in image contrast with increased
whiteness of echoes on either side of shadow.
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Fig. 12B. —Tiny distal common bile duct stone in 55-year-old man with
painful jaundice. Conventional sagittal sonogram (A) and tissue
harmonic image (B) show small stone (arrow) distinctly.
However, tissue harmonic image shows longer length of common bile duct with
blacker lumen. Better definition of acoustic shadow distal to stone on tissue
harmonic image is related to increase in image contrast with increased
whiteness of echoes on either side of shadow.
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Copyright © 2001 by the American Roentgen Ray Society.
