Biologic System Evaluation with Ultrasound

130 Pages·1992·5.159 MB·English

by  James F. Greenleaf Ph.D, Chandra M. Sehgal Ph.D. (auth.)

Biologic System Evaluation with Ultrasound
James F. Greenleaf Chandra M. Sehgal
Biologic System
Evaluation with
Ultrasound
With 59 Illustrations
Springer-Verlag
New York Berlin Heidelberg London Paris
Tokyo Hong Kong Barcelona Budapest
James F. Greenleaf, Ph.D
Department of Physiology and Biophysics
Mayo Clinic Foundation
Rochester, MN 55905, USA
Chandra M. Sehgal, Ph.D.
Associate Professor
Department of Radiology
University of Pennsylvania
Philadelphia, PA 19104, USA
Library of Congress Cataloging-in-Publication Data
Greenleaf, James F.
Biologic system evaluation with ultrasound 1 James F. Greenleaf,
Chandra M. Sehgal
p. em.
1. Ultrasonics in biology. 2. Ultrasonics in medicine.
1. Sehgal, Chandra M. II. Title.
[DNLM: 1. Computer Graphics-congresses. 2. Computer Simulation
congresses. 3. Models, Structural-congresses.
4. Ultrasonography-congresses. QY 26.5 G814b]
QP82.2.U37G74 1992
616.07'543-dc20
DNLMIDLC
for Library of Congress 92-2266
Printed on acid-free paper.
© 1992 Mayo Foundation.
Softcover reprint of the hardcover 1st edition 1992
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responsibility for any errors or omissions that may be made. The publisher makes no warranty,
express or implied, with respect to the material contained herein,
Production managed by Christin R. Ciresi; manufacturing supervised by Jacqui Ashri.
Camera-ready copy provided by the authors.
987654321
ISBN -13: 978-1-4613-9245-3 e-ISBN -13: 978-1-4613-9243-9
DOl: 10.1007/978-1-4613-9243-9
Preface
This book is the outcome of a course that we taught at the 1988 Ultra
sonics Symposium in Chicago, IL. The book is meant for engineers who are
not acquainted with current methods of ultrasonic analysis of tissues. Some
engineers already in the field of ultrasonics may find the book useful as a
reference. The concept of associating the scattering hierarchy with a biologi
cal hierarchy was developed from work by Wagner and Insana et al. Al
though their concepts of scattering are more sophisticated than those in this
book, the hierarchy idea lended itself well to unifying the scattering con
cepts used herein. The book begins with two chapters of introduction. The
second chapter describes relationships between the biological and scattering
hierarchies used later in the book. The third chapter describes scattering
using graphical contexts in the spatial and Fourier domains. The fourth
through sixth chapters describe Class 0 (absorption and speed), Class 1
(speckle), Class 2 (resolved point), Class 3 (specular), and Class 4 (motion)
scattering and their association with the biological hierarchy (molecules,
cells, tissues, organs, and function). The seventh chapter describes instru
ments used for biologic system evaluation and the eighth chapter describes
computed tomographic methods of imaging. The book could not have been
done without the greatly appreciated and extensive assistance given by my
secretary, Ms. Elaine C. Quarve, and graphics artist, Ms. Christine A.
Welch. Editing was done in the Editorial Department by Dr. Carol L.
Kornblith and Ms. Mary K. Horsman. We hope this book contributes to a
better understanding of biologic system evaluation with ultrasound.
J.E Greenleaf and C.M. Sehgal
Contents
Preface ...................................................... v
1 Scattering vs. Biologic Hierarchies ............................ 1
1.1 Introduction .......................................... 1
1.2 Organization of Book .................................. 2
Bibliography ............................................... 2
2 Biologic Material Hierarchy .................................. 5
2.1 Introduction .......................................... 5
2.2 Molecules ........................................... 5
2.3 Cells ................................................. 6
2.4 Tissues ............................................... 9
2.4.1 Inflammation................................... 9
2.4.2 Fibrosis ........................................ 10
2.4.3 Neoplasm ...................................... 11
2.4.4 Other Diseases .................................. 12
2.5 Organs............................................... 12
2.6 Function (Organ Systems) ............................... 12
2.6.1 Heart .......................................... 13
2.6.2 Other Organs ................................... 14
2.7 Summary ............................................. 15
Bibliography ............................................... 15
3 Graphic Description of Scattering ............................. 17
3.1 Introduction .......................................... 17
3.2 Wave Equation ........................................ 18
3.3 Relationships Between the Fourier Transforms of P and Q ... 20
3.3.1 First-Order Approximations: Born and Rytov ........ 20
3.3.2 Fourier Relationships ............................ 21
3.3.3 Orthogonal Incidence ............................ 22
3.3.4 Nonorthogonal Incidence ......................... 24
3.4 Inverse Diffraction Tomography ......................... 25
3.4.1 Backscattering Analysis .......................... 26
3.4.2 Echography .................................... 27
viii Contents
3.5 1tansmission Tomography .............................. 28
3.6 Graphic Depiction of Scattering Classes ................... 29
3.7 Discussion ............................................ 31
Bibliography ............................................... 31
4 Class 0 Scattering .......................................... 35
4.1 Introduction .......................................... 35
4.1.1 Molecular Interactions ........................... 35
4.1.2 Macroscopic Interactions ......................... 35
4.1.3 Tissues ........................................ 35
4.2 Class 0 Scatterers ...................................... 36
4.2.1 Absorption of Ultrasound ........................ 36
4.2.2 Sound Speed and Acoustic Nonlinearity (BI A) ....... 51
4.2.3 Conclusions .................................... 57
Bibliography ............................................... 59
5 Class 1, 2, and 3 Scattering .................................. 63
5.1 Introduction .......................................... 63
5.2 Model-Based Scatter Analysis ........................... 64
5.2.1 Signal Analysis ................................. 64
5.2.2 RF Analysis .................................... 64
5.2.3 Statistical Analysis of Envelope-Detected Signal ...... 69
5.3 Thxture-Based Scatter Analysis ........................... 74
5.3.1 Classification ................................... 74
5.3.2 Gray-Level Run-Length Thxture Analysis ............ 75
5.3.3 Markovian Statistics for Thxture Analysis .......... 77
Bibliography ............................................... 78
6 Class 4 Scattering .......................................... 81
6.1 Introduction .......................................... 81
6.2 M-Mode Ultrasound ................................... 81
6.3 Doppler Methods ...................................... 82
6.3.1 Various Thchniques .............................. 84
6.3.2 Doppler 1tacings ................................ 87
6.3.3 Doppler Color Flow Mapping ..................... 88
6.3.4 Color Doppler for Induced Motions ................ 92
6.4 Correlation Methods for Measuring Motion ............... 93
6.4.1 Speckle 1tacking ................................ 94
6.4.2 Time Domain Correlation ........................ 94
6.5 Summary ............................................. 96
Bibliography ............................................... 96
7 Backscatter-Imaging Instruments ............................. 99
7.1 Introduction .......................................... 99
7.2 1tansducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 99
Contents ix
7.2.1 Piezoelectrics ................................... 99
7.2.2 Lenses ......................................... 100
7.2.3 Construction ................................... 100
7.3 Beams ............................................... 101
7.3.1 Lateral Resolution ............................... 101
7.3.2 Axial Resolution ................................ 102
7.3.3 Resolution Cell ................................. 104
7.4 Mechanical Scanning ................................... 104
7.5 Lensless Beamforming .................................. 104
7.5.1 Phased Array ................................... 104
7.5.2 Annular Array .................................. 106
7.5.3 Diffractionless Array ............................ 106
7.6 Effect of Scattering Class on Image ....................... 107
7.6.1 Class 0 Absorption and Speed ..................... 107
7.6.2 Class 1 Speckle .................................. 107
7.6.3 Class 2 Resolved Scatterers ........................ 108
7.6.4 Class 3 Specular Scatterers ........................ 108
7.6.5 Class 4 Motion .................................. 109
7.7 Conclusion ........................................... 110
Bibliography ............................................... 110
8 Computed Transverse Imaging ............................... 113
8.1 Computed Tomography ................................. 113
8.1.1 Reconstruction From Transmission Projections ...... 113
8.1.2 Reconstruction From Reflections .................. 117
8.2 Diffraction Tomography ................................ 118
8.3 Scattering-Class Comments ............................. 120
Bibliography ............................................... 120
Index ........................................................ 125
1
Scattering vs. Biologic Hierarchies
1.1 Introduction
The approach taken in this book toward ultrasonic scattering as a method of
noninvasive evaluation of biologic systems is to divide the problem into separate
scatteringl classes. The concentration or size of scattering centers relative to the
resolution ce1l2 of the imaging system is used to develop a hierarchy of scattering
classes that correlates with a hierarchy of biologic classes. Class 0 scattering
occurs when there are only absorption or speed or perhaps nonlinearity variations
present as scattering terms. Class 1 scattering occurs when the concentration
of scatterers per resolution cell is high (25 or higher). This occurs in tissues
such as blood or liver and results in speckle, the fine-grained noise familiar from
laser light. Class 2 scattering occurs when the concentration of scatterers is less
than about 1 per resolution cell. This can happen simultaneously with Class 1
scattering. Oass 3 scattering occurs when the scatterers are large relative to the
resolution cell and cause specular or mirror-like reflection. We include a final
type of scattering, Oass 4, which is associated with motion causing Doppler
shifts in the returned signal.
This hierarchy of scattering can be associated directly with biologic com
ponents in the following way.
1. Class 0 scattering is associated with molecules as solutes in solvents such
as water, the most common molecule in the body.
2. Class 1 scattering is associated with cells, depending on their concentration.
Cells are the basic unit of life and are assembled in groups as tissues and
organs throughout the body.
3. Class 2 scattering is associated with tissues in which the structural archi
tecture (connective tissue) or other components such as lipids are scattered
throughout the tissue in concentrations lower than 1 per resolution cell.
These elements scatter independently and cause scattering distinguishable
from speckle produced by the cell components themselves.
4. Class 3 scattering is caused by the borders of the. organS and vessels and
is often specular in nature.
The tenn "scattering" describes the part of the ultrasonic pressure field that when added to
the original field results in the measured field Both the real (speed) and the imaginary (absorption)
part of the refractive index can cause a scattered field [1, 2].
2 The resolution cell is related to the size of the acoustic pulse used to probe the object. It has
dimensions in the axial direction that depend on the bandwidth of the system and in the transverse
direction that depend on the center frequency and the aperture of the system [3].
2 J. F. Greenleaf and C. M. Sehgal
Macromolecular Macroscopic
(Size: < 10' -10' A) (Size: >0.01 mm)
!
/Classo~
Absorption Sound speed Class I Class 2 Class 3
Equilibrium which There should be Rayleigh Diffractive Geometric
can be perturbed by intermolecular bonding (cell) (soft tissue: fat globules) (organ surfaces)
pressure must exist ka« I ka=1 ka»1
~
(I) At low PK ....; ' (2) At high PKW.;, Tissue inhomogeneities
-bonds vibrate as -bonds vibrate as should have different
harmonic oscillator anharmonic oscillator acoustic impedance than
-medium is linear -medium nonlinear the surrounding medium
Figure 1.1. Depiction of scattering and biologic hierarchies used to describe ultrasound
methods for evaluating biologic systems.
5. Class 4 scattering is caused by motion that produces a Doppler shift which
is associated with ultrasonic signals scattering from interfaces within blood,
heart, hmg, and gut which move to accomplish their fimction.
1.2 Organization of Book
The book is formulated to describe the field of biologic system evaluation with
ultrasound by using the scattering and biologic hierarchies described in Figure
1.1.
This book gives an overall view of ultrasonic imaging to the engineer or
physicist who is unfamiliar with the field. It can also be used by the physician
as a technical reference. We begin with a description of biologic systems, their
hierarchic nature, their normal operation, and some of their pathologic features.
Next, a very general description of scattering is used to explain the elements of
scattering in a graphic context. Then, in three chapters, the scattering hierarchy
is described in detail, with applications to biologic systems. Next, some typical
backscattering imaging instruments are described with reference to the scattering
classes that are used by the clinician to evaluate various pathologic conditions.
Finally, some transmission imaging methods are described.
Bibliography
[1] 1. F. Greenleaf, "An inverse view of scattering," Proceedings IEEE
Ultrasonics Symposium, vo1. 2, no. 2, pp. 821-824, 1984.
Scattering VS. Biologic Hierarchies 3
[2] A. J. Devaney, "Inverse source and scattering problems in ultrasonics,"
IEEE Transactions on Sonics and Ultrasonics, vol. SU-30, no. 6, pp. 355-
364, 1983.
[3] R. F. Wagner, M. F. Insana, and D. G. Brown, "Unified approach to the
detection and classification of speckle texture in diagnostic ultrasound,"
Optical Engineering, vol. 25, pp. 738-742, June, 1986.