1. TISSUE HARMONIC IMAGING NUR FASHIHA BINTI AZMAN A140944 DIAGNOSTIC IMAGING AND RADIOTHRAPY /2

2. WHAT IS TISSUE HARMONIC IMAGING New grayscale imaging technique a technique in ultrasonography that provides images of better quality as compared to conventional ultrasound technique

3. Generation of tissue harmonic generated by the passage of the ultrasound beam as it passes through tissue. More tissue travel, more harmonic generated Production of harmonic is propotionally to the square of the fundemental intensity Harmonic generated prodominantlyby the main transmit beam

4. Artifact reduction with tissue harmonic Reduce artifact in several way : – Decrease the scattered from the body wall – Reduced artifact from weak echoes – Less near field haze from body wall reverberation Result in less noisy images, making cyst appear clearer and improving the visualization of pathologic condition and normal tissue

5. 1. Decrease effect of the body wall Sound not travel in constant velocity through the body wall – cause the significant and scattering of transmitted the ultrasound beam Fundamental – beam pass 2 times Tissue harmonic – beam pass body wall one time – tissue harmonic signal produce in the tissue from within the body

6. 2. Reduced artifact from the weak echoes Use inverse square law concept The weak wave produce a little or no harmonic, while the strong wave produce more harmonic Detect harmonic - weak echoes will eliminate Side lobe, scatter, grating lobe reduce Result better image

7. 3. Decrease the body wall reverberation Eliminate reverberation artifact from the body wall Harmonics do not develop in the first few centimeters, but many artifacts do. In particular, multiple reverberations between the transducer and the body wall layers cast a ‘haze’ that overlies the image. Because in reality these artifacts are mis-registered echoes from the near field, they do not contain harmonics and disappear in the tissue harmonic image.

8. IMAGE FORMATION IN TISSUE HARMONIC IMAGING Image formed only from the higher frequency harmonic sound. Echoes from fundamental frequency is rejected Technique to detect harmonic and eliminate the unwanted fundamental echoes – Filtration – Single line pulse inversion – Side by side phase cancellation – Pulse encoding

9. Filtration

10. Pulse inversion

11. ADVANTAGES Improve contrast resolution Reduced noise and clutter Improved lateral resolution Reduce the slice thickness Reduce the artifact Improve noise to signal ratio

12. reference http://radiopaedia.org/articles/tissue- harmonic-imaging http://radiopaedia.org/articles/tissue- harmonic-imaging Tissue harmonic imaging article-updated, Philips W. Rall M.D http://www.docstoc.com/docs/77145952/Har monic-Imaging-(PowerPoint) http://www.docstoc.com/docs/77145952/Har monic-Imaging-(PowerPoint)