The present disclosure generally relates to using high frequency ultrasound to assess blood volume changes in a subject. A baseline blood volume value can be determined based on a weight of a subject or based on an initial/previous assessment test value. An image taken with the high frequency ultrasound can be retrieved. A test blood volume value can be measured in a field of view of the image. For example, the test blood volume can be determined based on a destruction/replenishment of a contrast agent during imaging by the high frequency ultrasound. A change in blood volume in the subject can be estimated by comparing the test blood volume value to the baseline blood volume value. The estimate of the change in blood volume can be used to assess a condition of the subject.
