Online Journal
IF値: 0.677(2017年)→0.966(2018年)


Journal of Medical Ultrasonics

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1996 - Vol.23

Vol.23 No.05

Original Article(原著)

(0341 - 0348)


MTI Filter in Non-equally Spaced Pulse Transmission for Non-aliasing Ultrasonic Pulsed Doppler Measurement

西山 久司1, 片倉 景義2

Hisashi NISHIYAMA1, Kageyoshi KATAKURA2

1(株)日立製作所本社, 2(株)日立製作所情報通信事業部

1Head Office Hitachi, Ltd., 2Telecommunications Division Hitachi, Ltd.

キーワード : MTI filter, Non-aliasing, Nyquist frequency, Pulsed Doppler, Non-equally spaced pulse transmission

Non-equally spaced pulse transmission in pulsed Doppler ultrasonography is a method for measuring velocity of blood flow that is not subject to the Nyquist limit; transmission of non-equally spaced ultrasonic pulses to a blood vessel in vivo makes it possible to measure blood velocity that exceeds the Nyquist limit unambiguously and without aliasing. For removal of clutter from the imaged blood vessel, a new design principle, that of a moving target indication (MTI) filter capable of processing non-equally spaced pulse transmission sequences, is discussed. Two approaches toward delay time in the MTI filter are proposed: Sum-PRT-MTI and Respective-PRT-MTI; addition times and respective times between two pulse repetition times (PRT) must be applied for this purpose. A phase comparator was used to test the proposed method analytically with model Doppler signals. The method was also verified experimentally using computer-simulated Doppler signals to which white noise had been added. We then compare the proposed MTIs for color flow mapping (CFM) and discuss the characteristics of these filters.