Abstract: The schedule memory unit 23 memorizes a time schedule set in advance for saving images. The avascularization unit 30 compresses the subject's brachial region to avascularize the brachial artery, releases the avascularization after a predetermined period of time, and simultaneously transmits a decompression start signal to the controller 17. The controller 17 stores an ultrasonic image in the image storage unit 22 at a point in time when a period of time specified by the time schedule has elapsed after the decompression start signal was received. The vascular diameter measuring unit 18 determines the vascular diameters based on the ultrasonic tomography images of a blood vessel at rest and after the release of the avascularization which are stored in the image storage unit 22. Based on those diameter values, the largest vascular diameter deducing unit 20 and the % FMD calculation unit 21 perform the deduction of the largest after-release vascular diameter and the calculation of the % FMD, respectively.

Abstract: An ultrasonograph having a vascular diameter measurement means for taking an ultrasonic tomography image of a blood vessel and then measuring a vascular diameter based on the image, including: an ultrasonic probe 11 having an ultrasonic oscillator 11a for an ultrasonic beam scan, the oscillator being rotatable in the direction orthogonal to the ultrasonic beam's scan direction; a multi-section imaging means for tilting the oscillator 11a at predetermined intervals to perform an ultrasonic beam scan by the oscillator 11a at each position in order to take a tomography image of the blood vessel 50 at a plurality of sections; an imaging position determiner for comparing the results of the measurement of the vascular diameter based on each taken tomography image, and determining the position where an image presenting the largest vascular diameter has been taken as the largest vascular diameter imaging position; and a largest vascular diameter acquisition means for tilting the oscillator 11a to the position determi