1. NUR INANI BINTI MOHD RUZLAN A140714

2. Tissue harmonic imaging is a technique in ultrasonography that provides images of better quality as compared to conventional ultrasound technique. It exploits non-linear propagation of ultrasound through the body tissues The high pressure portion of the wave travels faster than low pressure resulting in distortion of the shape of the wave. This change in waveform leads to generation of harmonics (multiples of the fundamental or transmitted frequency) from tissue.

3. Time step 1 contains a wave of single frequency As the wave travels into the tissue (time step 2), it becomes distorted Additional frequency components are created that are integer multiples of the initial frequency. These components are called “harmonic frequencies” As the wave continues to travel, it becomes highly distorted (time step 3) and very rich in harmonic frequencies. Although many harmonic frequencies are produced with nonlinear wave propagation, the amplitudes of the higher harmonics are extremely small Therefore, current technology uses only the second harmonic (2f), which is twice the nominal transmitted frequency

4. Frequency spectrum of the transmitted and received waves. The fundamental wave (f) is generated at the transducer surface and attenuates linearly as it is transmitted through the body. The harmonic wave (2f) is generated as the fundamental wave travels through the body. The harmonic wave increases exponentially in intensity before attenuating within the deeper tissues. Harmonic imaging uses only the harmonic frequency in the echo signal received by filtering out the transmitted frequency spectrum in the signal.

6. These harmonic wave which are generated within the tissue, increase with depth to a point of maximum intensity and then decrease with further depth due to attenuation Hence the maximum intensity is achieved at an optimum depth below the surface

8. improved axial resolution due to shorter wavelength better lateral resolution due to improved focusing with higher frequencies less artifact than with conventional US due to relatively small amplitude of the harmonic waves, which reduces detection of echoes from multiple scattering events side lobes are less likely to occur and degrade the image.

9. did not have any additional benefit over conventional US for demonstrating a lesion, improving diagnostic confidence, or altering clinical management minority of lesions that were better demonstrated with conventional US. For patients with diffuse fatty infiltration in the liver, penetration of the ultrasound beam was better on conventional US images

10. Right renal mass in an obese patient. Solid mass in the lower pole of the right kidney is seen equally well on the harmonic (a) and conventional(b) US images. Clinical management was not altered because a did not contribute information in addition to that in b. ab