Contents
Preface
Chapter 1 Basics of ultrasound1
Section 1 Fundamental physical principles of diagnostic ultrasound1
Section 2 Different modes of diagnostic ultrasound3
Section 3 Ultrasound generators and equipments6
Section 4 Clinical basis of diagnostic ultrasound6
Chapter 2 Echocardiography8
Section 1 Normal anatomy8
Section 2 Normal echocardiography9
Section 3 Evaluation of left heart function13
Section 4 Abnormal echocardiography15
Chapter 3 Digestive system39
Section 1 Liver39
Section 2 Gallbladder and biliary tract54
Section 3 Pancreas66
Section 4 Spleen71
Chapter 4 Urinary system and prostate76
Section 1 Kidney and ureter76
Section 2 Urinary bladder and prostate84
Chapter 5 Gynaecology88
Chapter 6 Obstetrics96
Section 1 Normal pregnancy96
Section 2 Abnormal pregnancy101
Chapter 7 Superficial organ111
Section 1 Eye111
Section 2 Thyroid gland116
Section 3 Breast122
Section 4 Scrotum125
Section 5 Cervical lymph node131
Chapter 8 Periphery and abdominal blood vessels134
Chapter 9 Interventional ultrasound in abdomen148
References152
內容試閱：
Chapter 1 Basics of ultrasound
Section 1 Fundamental physical principles of diagnostic ultrasound
1.1.1 Definition of ultrasound
Ultrasound is the name given to high-frequency sound waves, over 20 000 cycles per second 20 000Hz or 20kHz. These waves, inaudible to humans, can be transmitted in beams and are used to scan the body. Most diagnostic applications employ frequencies of 1 to 15 MHz.
1.1.2 Physical characteristics of ultrasound
1. Sound wave A wave is a propagation of energy that moves back and forth or vibrates at steady rate. Sound waves are mechanical oscillations that are transmitted by particles.
2. Wavelength λ and frequencyf
1 Wavelength λ: It represents the distance occupied by each cycle. It is the distance in the medium between consecutive particles.
2 Wave periodT: It is the time which is required to produce each cycle, depending on the frequency of transducer.
3 Frequencyf: It refers to the number of cycles completed per second which is determined by the number of oscillations per second of the vibrating source.
The relationship between f and T is:
f =1T
The unit of frequency is hertz Hz: 1oscillationsec=1cyclesec=1hertzHz;1000 oscillationsec=1kilocyclesec=1kilohertz 1kHz; 1 000 000 oscillationsec=1megacyclesec=1 megahertz 1MHz.
3. Velocity of sound c The velocity of sound is defined as the distance per second in medium the wave is propagating. Its unit is ms or cms. It is determined by density and elastic properties. In human body, the main determining factor is density. The larger the density is, the faster the velocity is. The velocity of sound differs greatly between air, bone, and soft tissue. But there is a small difference about 5% between fat, blood and organ tissue the liver, the kidney, the spleen,etc.. The mean velocity is about 1540cms. The relationship among c, f and λ is:
c=f×λ
The formula shows that the higher the frequency of ultrasound in human tissue, the shorter the wavelength.
4. Acoustic impedance Z It is resistance offered by tissue to movement of particles caused by ultrasound waves. It is defined as the products of velocityc and density ρ of the medium. The relationship among Z, c and ρ is:
Z=c×ρ
The acoustic impedance is one of the most fundamental physical parameter of sound wave. The different mediums have different kinds of acoustic impedance. The boundary between two mediums is called acoustic boundary. If the difference of acoustic impedance between two boundaries is larger than 0.1%, the reflection and refraction occur at the boundary.
5. Reflection, refraction and scatter Ultrasound can be reflected or refracted when it meets the boundary of two different mediums with different acoustic impedance.
1 Reflection: It refers to the change of direction of sound wave at a boundary of two different mediums with different acoustic impedance. On this occasion, a part of incident sound wave does not enter the second medium. It occurs at the interface where the dimension of the interface is much larger than the wavelength. The angle of incidence is equal to the angle of reflection.
2 Refraction: It refers to the change of direction of propagation of sound wave when it transmits across the boundary of two different mediums with different acoustic impedance. A part of incident sound wave enter the second medium but the direction changes.
3 Scatter: It occurs when the dimension of reflectors scatterers is much smaller than the wavelength of sound wave. The reflectors scatterers absorb the energy of sound wave and radiate the sound wave in different directions. The scatter is very important for B-mode and Doppler ultrasound because the micro-structures of solid organs and red blood cells are both scatterers.
In conclusion, the application of the diagnostic ultrasound relies on the different acoustic impedance among tissue and organs, which leads to reflection, refraction and scattering. Through a complex process, we can get different types of echogenicities by analyzing the information which reflection, refraction and scatter produce. The echogenicity is an important concept in diagnostic ultrasound will be discussed in detail later. In ultrasound scanning, the density of echogenicity depends on the difference of acoustic impedance between different boundaries. The larger the acoustic impedance is between two boundaries, the more the reflection is. With exception of air-tissue lung and bone in human body, the differences of acoustic impedance between other tissue are so small that only a small part of ultrasound wave is reflected at the different boundaries. When the ultrasound wave transmits to meet air-tissue lung or bone, the difference of acoustic impedance between two boundaries is huge, therefore causing nearly all reflection of ultrasound. So we can not utilize ultrasound to scan the lung and the bones.
6. Doppler effect When ultrasound is transmitted towards a stationary reflector, th
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