Apparatus and method for diagnosing osteoporosis

摘要

PCT No. PCT/JP96/03489 Sec. 371 Date Jul. 29, 1997 Sec. 102(e) Date Jul. 29, 1997 PCT Filed Nov. 28, 1996 PCT Pub. No. WO97/19641 PCT Pub. Date Jun. 5, 1997The 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 modulusxdensity] 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. The acoustic impedance Zb of bone is thus a good index for assessing bone density.