Ultrasound Imaging Using Coded Signals

Misaridis Th.

Table of contents :
Title……Page 1
Contents……Page 9
Preface……Page 13
Abstract……Page 15
Acknowledgements……Page 17
Nomenclature……Page 19
List of Figures……Page 23
List of Tables……Page 33
0.1 Potential advantages of coded excitation……Page 35
0.3 Thesis structure……Page 36
1.2 Signal basics……Page 39
1.3 Complex notation of narrowband signals……Page 41
1.4 Correlation integrals……Page 42
1.5 Waveform parameters and the uncertainty principle……Page 43
1.6 The time-bandwidth product (TB)……Page 45
2.1 Filtering using complex notation……Page 47
2.2 The matched filter……Page 48
2.3 Generalized matched filter……Page 50
2.4 Matched filter receiver in ultrasound imaging……Page 52
2.5 The ambiguity function and its properties……Page 54
2.6 Classification of pulse compression waveforms……Page 55
2.7 Resolution in a matched filter receiver……Page 60
2.8 Mismatched filtering……Page 62
2.9 Optimal filtering in speckle……Page 64
2.10 Appropriate compression waveforms and filters for ultrasound imaging……Page 66
3.1 The linear FM signal……Page 69
3.2 Spectrum of the linear FM signal……Page 70
3.3 Symmetry properties and their implications……Page 72
3.4 The matched filter response and the ridge ambiguity……Page 74
3.5 Mismatched filtering……Page 76
3.7 Non-linear FM modulation……Page 77
4.1 Weighting in time and frequency domain……Page 81
4.2 Weighting functions and tapering……Page 82
4.3 The effect of the ultrasonic transducer on pulse compression……Page 84
4.4 Fresnel ripples and paired-echoes sidelobes……Page 85
4.5 Amplitude and phase predistortion……Page 87
4.6 Proposed excitation/compression scheme……Page 88
5.1 Phase modulation……Page 95
5.2 Binary sequences……Page 97
5.3 Polyphase codes……Page 100
5.4 Hadamard matrices……Page 102
5.5 Sidelobe reduction for phase-encoded sequences……Page 103
5.6 Disadvantages of phase-coding for ultrasound imaging……Page 104
6.1 Intensity considerations……Page 105
6.2 Expected signal-to-noise ratio improvement……Page 107
6.3 Imaging with linear FM signals- Simulation results using Field II……Page 114
6.4 Imaging with non-linear FM signals……Page 118
6.6 Evaluation of resolution and compression……Page 119
6.7 Pulse compression and array imaging……Page 122
7.1 Experimental setup……Page 125
7.2 Phantom images with coded excitation……Page 130
7.3 Clinical images with coded excitation……Page 134
8.1 Waveform diversity for the FM signal……Page 139
8.3 Cross-correlation (CC) of binary codes……Page 143
9.1 Linear array coded imaging……Page 149
9.2 Other firing and coding strategies……Page 153
9.3 Synthetic transmit aperture (STA) imaging……Page 156
9.4 Literature review on SNR improvement methods in STA imaging……Page 159
9.5 Proposed STA coded imaging using Hadamard and FM space-time encoding……Page 160
9.7 Evaluation of SNR in coded STA imaging……Page 163
10.1 Pulse trains……Page 167
10.2 Ambiguity function of pulse trains……Page 168
10.3 FSK modulation and Costas arrays……Page 169
10.4 The linear FM pulse train (QLFM-FSK)……Page 174
10.6 A New Coding Concept……Page 175
10.7 Coherent processing of pulse trains……Page 180
10.8 Simulated images using pulse train excitation……Page 182
10.9 Possible alternative imaging strategies……Page 185
11 Conclusions……Page 187
A.1 Potential of coded excitation in medical ultrasound imaging……Page 189
A.2 An effective coded excitation scheme based on a predistorted FM signal and an optimized digital filter……Page 196
A.3 Clinical use and evaluation of coded excitation in B-mode images……Page 204
A.4 Space-Time Encoding for High Frame Rate Ultrasound Imaging……Page 212
Bibliography……Page 221
Index……Page 227