Ultrasonic-pathological comparison of the human arterial wall. Verification of intima-media thickness

Recent intravascular ultrasound experience challenges the accuracy of ultrasonic measurement of arterial wall thickness. We reevaluated the correlation between histological and sonographic measurements of intima-media thickness using standard transcutaneous vascular technology. Carotid and femoral arterial segments were imaged before and after fixation using a 7-MHz linear-array vascular transducer. Log compression and beam orientation were varied. Mean intima, media, and adventitia thicknesses were measured and compared with corresponding histological tunica. Tissue processing caused 2.5% shrinkage. Intraobserver reading error was 0.7% for histology and 5.4% for sonography. Ultrasound overestimated the thickness of the intima and adventitia and underestimated the thickness of the media. For combined intima-media thickness, the differences between histology and imaging were insignificant, averaging 4% for the carotid artery and 9% for the femoral artery in the far-wall projection. In the near-wall projection, sonographic intima-media thickness was 20% less than that determined histologically. We conclude that ultrasonography is limited mainly by axial resolution in quantifying the dimensions of individual arterial tunica but is capable of accurately measuring far-wall intima-media thickness.