Author + information
- Received September 4, 1991
- Revision received November 8, 1991
- Accepted November 21, 1991
- Published online July 1, 1992.
- Geoffrey R. Lockwood, MSc∗,
- Linda K. Ryan, BSc,
- Avrum I. Gotlieb, MD,
- Eva Lonn, MD,
- John W. Hunt, PhD,
- Peter Liu, MD and
- F.Stuart Foster, PhD
- ↵∗Address for correspondence: Geoffrey R. Lockwood, MSc, Sunnybrook Health Science Center, Reichmann Research Building, Room S118, 2075 Bayview Avenue, Toronto, Ontario, Canada M4N 3M5.
High resolution (125-μm lateral, 55-μm axial) images of 16 muscular (femoral) and 15 elastic (common carotid) human arteries were made in vitro with use of a prototype 45-MHz intravascular imaging system. Four distinct regions of scattering, excluding plaque, were identified in the ultrasound images corresponding histologically to the adventitia, media, thickened intima and elastic laminae, both internal and external. Arterial samples imaged under pressure and in a collapsed state underwent dimensional changes but exhibited similar levels of backscatter amplitude.
All the elastic arteries displayed a prominent echogenic media, whereas all the muscular arteries displayed an echolucent media. Scattering from the internal elastic lamina in muscular arteries provided an excellent landmark for defining the location and extent of intimal thickening or plaque. In elastic arteries the internal elastic lamina could not be distinguished from the echogenic media; consequently, the boundary between the media and intimal layer was indistinct.
Differences in the relative concentration and organization of collagen and elastin were found to provide a consistent explanation for the differences in scattering that were observed between individual layers within an artery as well as between muscular and elastic arteries.
☆ This work was funded by the Medical Research Council of Canada, Ottawa, Ontario, Canada and by a grant to Dr. Foster from the National Cancer Institute of Canada, Toronto, Ontario.
- Received September 4, 1991.
- Revision received November 8, 1991.
- Accepted November 21, 1991.