Subharmonic contrast intravascular ultrasound for vasa vasorum imaging.
The feasibility of subharmonic contrast intravascular ultrasound (IVUS) imaging was investigated using a prototype nonlinear IVUS system and the commercial contrast agent Definity . The system employed a mechanically scanned commercial catheter with a custom transducer element fabricated to have sensitivity at both 15 and 30 MHz. Experiments were conducted at a fundamental frequency of 30 MHz (F30; 25% bandwidth), with on-axis pressures ranging from 0.12 to 0.79 MPa, as measured with a needle hydrophone. In vitro characterization experiments demonstrated the detection of 15 MHz subharmonic signals (SH15) when pressure levels reached 360 kPa. The formation of SH15 images was shown, with tissue signals suppressed to near the noise floor and contrast to tissue ratios were improved by up to 30 dB relative to F30. In vivo experiments were performed using the atherosclerotic rabbit aorta model. Following the bolus injection of contrast agent upstream of the imaging catheter, agent was detected within the aorta, vena cava and within the perivascular space. These results provide a first in vivo demonstration of subharmonic contrast IVUS and suggest its potential as a new technique for imaging vasa vasorum.
Goertz
David E
DE
Biomedical Engineering Department, Erasmus Medical Centre, Rotterdam, The Netherlands. goertz@sri.utoronto.ca
Frijlink
Martijn E
ME
Tempel
Dennie
D
Bhagwandas
Vijay
V
Gisolf
Andries
A
Krams
Robert
R
de Jong
Nico
N
van der Steen
Antonius F W
AF
D000818:Animals; D001018:Aortic Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media; D005240:Feasibility Studies; D005466:Fluorocarbons; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008863:Microspheres; D019047:Phantoms, Imaging; D011817:Rabbits; D014463:Ultrasonography; D014651:Vasa Vasorum / Q000000981:diagnostic imaging*
D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren