Abstract: An osteoporosis diagnosis yapparatus provided with a two-dimensional ultrasonic transducer array (3) comprising a number of cells (1.sub.1, 1.sub.2, . . . ). The ultrasonic transducer array (3) is applied to the skin covering a predetermined bone of a subject, and the individual cells sequentially emit a predetermined number of ultrasonic pulses through the skin while receiving echoes from the bone. The received echo data are processed so that they can be handled in a planewave problem, from which the information on the reflection from the bone is determined. This information is processed to obtain the acoustic impedance of a cortical bone and a cancellous bone, so as to check for the presence of osteoporosis. The information on the reflection from the bone can also be handled as an eigen-value problem, and, when the information is handled in such a manner, the shape determination of a bone becomes un necessary.

Abstract: The apparatus for diagnosing osteoporosis in the present invention radiates repeated ultrasonic pulses Ai toward cortical bone Mb in a subject and receives echoes Ae from the bone Mb. The received signal is converted to a digital echo signal by an A/D converter 8, and the echo level is detected by a CPU 11. The CPU 11 extracts the maximum echo level from the echo levels detected during the measurement period and calculates the acoustic impedance Zb of the cortical bone based on the maximum echo level which has been extracted. The bone density of the subject is calculated from the detected acoustic impedance Zb of the cortical bone using a predetermined recurrence formula. The acoustic impedance of bone is given by the square root of ?the elastic modulus.times.density! of bone, and since the elastic modulus of bone increases (or decreases) as bone density increases (or decreases), the elastic modulus of bone and bone density play a synergistic role in the acoustic impedance.

Abstract: The osteoporosis diagnosing apparatus of the invention radiates repeatedly an ultrasonic impulse Ai toward the bone Mb of an examinee and receives an echo Ae from the bone Mb. The received signal is converted into a digital echo signal through an A/D converter (8), and the echo level is detected by a CPU (11). The CPU (11) extracts maximum echo level from among the echo levels detected in a given period of measurement to thereby calculate a bone acoustic impedance Zb based on the extracted maximum echo level, and then calculate the bone density of the examinee based on the calculated acoustic impedance Zb. As the impedance Zb is expressed in the square root of the product of modulus of elasticity and density of a bone, decreased in both the modulus of elasticity and the density synergistically affect the impedance to remarkably decrease the same.