Transcutaneous very-high-resolution ultrasound to quantify arterial wall layers of muscular and elastic arteries: Validation of a method

Background: High-resolution ultrasound (HRU) is used to measure carotid intima-media thickness (IMT). We postulated that very-high-resolution ultrasound (VHRU, 25–55 MHz) provides more detailed information on arterial morphology. Methods: Rabbit and pig arterial specimens and artificial elastin membranes were studied with HRU and VHRU, and compared to histology. Bilateral carotid, brachial, radial, ulnar, femoral, and tibial arteries were imaged in vivo in 15 humans to determine the precision of VHRU and in 53 teenagers to compare VHRU to HRU. Results: The assessment of IMT, adventitia thickness (AT) and combined intima-media-adventitia thickness (IMAT) in muscular arteries was accurate and precise by VHRU with the exception that the AT of the smallest arteries was not delineated with 25 MHz. VHRU was accurate and precise for IMAT in small and for IMT in large elastic arteries and allowed to qualitatively assess elastin fibers of the media. HRU was accurate for IMT of large muscular and elastic arteries only. Intima thickness (IT) was grossly overestimated by both VHRU and HRU. Conclusion: Transcutaneous VHRU provides a noninvasive method of quantifying elastic and muscular arterial AT, IMT and IMAT in children and adults, but neither VHRU nor HRU is able to assess IT in non-diseased vessels.