PMID- 12760554
OWN - NLM
STAT- MEDLINE
DCOM- 20030910
LR  - 20191210
IS  - 0278-0062 (Print)
IS  - 0278-0062 (Linking)
VI  - 22
IP  - 3
DP  - 2003 Mar
TI  - Robust estimation of ultrasound pulses using outlier-resistant de-noising.
PG  - 368-81
AB  - A different approach to the problem of estimation of the ultrasound pulse 
      spectrum, which usually arises as a part of ultrasound image restoration 
      algorithms, is presented. It is shown that this estimation problem can be 
      reformulated in terms of a de-noising problem. In this formulation, the 
      log-spectrum of a radio-frequency line (RF-line) is viewed as a noisy measurement 
      of the signal that needs to be estimated, i.e., the ultrasound pulse 
      log-spectrum. The log-spectrum of the tissue reflectivity function (i.e., tissue 
      response) is considered as the noise to be rejected. The contribution of the 
      paper is twofold. First, it provides statistical description of the reflectivity 
      function log-spectrum for the case, when the samples of the reflectivity function 
      are independent identically distributed (i.i.d.) Gaussian random variables. 
      Moreover, it is shown that the problem of the pulse spectrum recovery is 
      essentially a de-noising problem. Consequently, it is suggested to solve the 
      problem within the framework of the de-noising by wavelet shrinkage. Second, a 
      computationally efficient algorithm is proposed for the pulse-spectrum 
      estimation, which can be viewed as a modified version of the classical Donoho's 
      three-step de-noising procedure. This modification is necessary, because of 
      specific properties of the noise to be rejected. It is shown, that whenever the 
      samples of the reflectivity function can be assumed to be i.i.d. Gaussian random 
      variables, the samples of its log-spectrum obey the Fisher-Tippet distribution. 
      For this type of noise, straightforward implementation of the standard de-noising 
      can cause serious estimation errors. In order to overcome this difficulty, an 
      outlier-resistant de-noising is performed. The unique properties of this modified 
      de-noising algorithm allow estimating the pulse spectrum adaptively to its 
      properties, as they are continuously influenced by the frequency-dependent 
      attenuation process. The performance of the proposed algorithm is examined in a 
      series of computer-simulations. It is shown that this algorithm, developed on the 
      assumption of the "Gaussian" reflectivity function, remains applicable for 
      broader classes of distributions. The results obtained in a series of in vivo 
      experiments reveal superior performance of the novel approach over some of 
      alternative estimation techniques, e.g., cepstrum-based estimation.
FAU - Michailovich, Oleg
AU  - Michailovich O
AD  - Department of Biomedical Engineering, Technion-Israel Institute of Technology, 
      Haifa.
FAU - Adam, Dan
AU  - Adam D
LA  - eng
PT  - Comparative Study
PT  - Evaluation Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Validation Study
PL  - United States
TA  - IEEE Trans Med Imaging
JT  - IEEE transactions on medical imaging
JID - 8310780
SB  - IM
MH  - Adult
MH  - *Algorithms
MH  - Artifacts
MH  - Computer Simulation
MH  - Echocardiography/methods
MH  - Heart
MH  - Humans
MH  - Image Enhancement/*methods
MH  - Linear Models
MH  - Male
MH  - Models, Biological
MH  - Phantoms, Imaging
MH  - Quality Control
MH  - *Signal Processing, Computer-Assisted
MH  - Stochastic Processes
MH  - Ultrasonography/instrumentation/*methods
EDAT- 2003/05/23 05:00
MHDA- 2003/09/11 05:00
CRDT- 2003/05/23 05:00
PHST- 2003/05/23 05:00 [pubmed]
PHST- 2003/09/11 05:00 [medline]
PHST- 2003/05/23 05:00 [entrez]
AID - 10.1109/TMI.2003.809603 [doi]
PST - ppublish
SO  - IEEE Trans Med Imaging. 2003 Mar;22(3):368-81. doi: 10.1109/TMI.2003.809603.