A method for characterizing a blood vessel, having adventitia, media, and intima regions surrounding a lumen, by measuring the apparent intima-media thickness, the method comprising: producing an ultrasound image of a blood vessel, the ultrasound image having a longitudinal direction corresponding to an axial direction of a blood vessel, a lateral direction orthogonal thereto, and comprising pixels each associated with a numerical value representing an intensity; locating an initial adventitia pixel; selecting a series of two or more positions in the longitudinal direction in the ultrasound image each associated with a column of pixels across the blood vessel, proceeding column by column and beginning with the columns of pixels next to the initial adventitia pixel, and finding for each position in the longitudinal direction an adventitia pixel, having the greatest value of intensity in a column of pixels associated with the longitudinal position, wherein a search for finding the adventitia pixel is limited to a small region centered or otherwise registered with respect to a lateral location of an adventitia pixel in an adjacent column, and wherein finding adventitia pixels further comprises identifying a line passing through at least two adventitia pixels, and wherein a search for finding other adventitia pixels is limited to a region limited with respect to the line; defining an adventitia datum by a first curve fit to the adventitia pixels located in the columns of pixels; defining a lumen datum by a second curve that passes through a pixel in a first group of contiguous pixels with intensity values below a lumen threshold in each column found as a result of a search from the adventitia toward a center of the lumen; defining a media datum by a third curve that passes through pixels representing a local minima of intensity in each column that is positioned between the lumen datum and the adventitia datum; locating the lumen-intima boundary, extending along the longitudinal direction, as the lateral location of local steepest ascent of intensity in a traverse from the lumen datum toward the media datum; locating the media-adventitia boundary, extending along the longitudinal direction, as the lateral location of local steepest ascent in intensity in a traverse from the media datum toward the adventitia datum; and calculating the intima-media thickness as the lateral distance between the lumen-intima boundary and the media-adventitia boundary. producing an ultrasound image of a blood vessel, the ultrasound image having a longitudinal direction corresponding to an axial direction of a blood vessel, a lateral direction orthogonal thereto, and comprising pixels each associated with a numerical value representing an intensity; locating an initial adventitia pixel; selecting a series of two or more positions in the longitudinal direction in the ultrasound image each associated with a column of pixels across the blood vessel, proceeding column by column and beginning with the columns of pixels next to the initial adventitia pixel, and finding for each position in the longitudinal direction an adventitia pixel, having the greatest value of intensity in a column of pixels associated with the longitudinal position, wherein a search for finding the adventitia pixel is limited to a small region centered or otherwise registered with respect to a lateral location of an adventitia pixel in an adjacent column, and wherein finding adventitia pixels further comprises identifying a line passing through at least two adventitia pixels, and wherein a search for finding other adventitia pixels is limited to a region limited with respect to the line; defining an adventitia datum by a first curve fit to the adventitia pixels located in the columns of pixels; defining a lumen datum by a second curve that passes through a pixel in a first group of contiguous pixels with intensity values below a lumen threshold in each column found as a result of a search from the adventitia toward a center of the lumen; defining a media datum by a third curve that passes through pixels representing a local minima of intensity in each column that is positioned between the lumen datum and the adventitia datum; locating the lumen-intima boundary, extending along the longitudinal direction, as the lateral location of local steepest ascent of intensity in a traverse from the lumen datum toward the media datum; locating the media-adventitia boundary, extending along the longitudinal direction, as the lateral location of local steepest ascent in intensity in a traverse from the media datum toward the adventitia datum; and calculating the intima-media thickness as the lateral distance between the lumen-intima boundary and the media-adventitia boundary.