Abdominal and Pelvic US Course - PDF

ABDOMINAL AND PELVIC US COURSE BASIC AND  DR. NAHLA EL GIZAWY.  MD RADIODIAGNOSIS 2004.  Master hospital management 2012.  Diploma TQM 2013. Objectives history and definition. Define piezoelectric effect. Define frequency and wave length. Define band width. Define attenuation and relation...

ABDOMINAL AND PELVIC US COURSE BASIC AND  DR. NAHLA EL GIZAWY.  MD RADIODIAGNOSIS 2004.  Master hospital management 2012.  Diploma TQM 2013. Objectives history and definition. Define piezoelectric effect. Define frequency and wave length. Define band width. Define attenuation and relation to frequency. Define resolution. Basic transducers. Sector and linear probes. Types of display. Useful artifacts Is ultrasound waves safety ?  Sound is a mechanical wave it is a series of pressure waves propagating through a medium. One cycle of the acoustic wave is composed of a complete positive and negative pressure change. What is ultrasound is the use of high frequency sound in medical field either diagnostic or therapeutic. Frequency exceeding the upper limit of human hearing 20.000HZ =20KHZ. History -1880 s Piezoelectric effect discovered. -1940 s SONAR used in war. -1950 used in diagnostic medical field.  The source of the ultrasound wave is the piezoelectric crystal, which is placed in the transducer. This crystal has the ability to transform an electrical current into mechanical pressure waves (ultrasound waves) and vice versa. The production of ultrasound waves is based on the so-called ‘pulse- echo-principle PULSE – ECHO PRINCIPLE - Pulse (crystals) of sound send to the tissues Interaction – bioeffect. -Echo from tissues to transducer( ---crystals) again to processed and displayed as images.  Once the ultrasound wave is generated and travels through the medium, the crystal switches from ‘sending’ into ‘listening’ mode and awaits returning ultrasound echoes. Actually over 99% of the time is spent “listening”. This cycle is repeated several million times per second. Returning sound waves are converted into images on the ultrasound monitor.  Why we choose 7MHZ for Breast US exam and 5 MHZ for abdomen US exam. Wave length IS the distance traveled during each cycle. This mean -increase frequency - decrease wave length - decrease the distant This mean transducers with high frequency pulse of low distant so for superficial use. Frequency Definition: Is the number of cycles per unit of time Transducers are named by frequencies. Frequency unites: - one cycle/sec= Hz. - one Thousand Hz= One KHz. - one Million Hz= One MHz - 7.5 Mhz transducer i.e crystals give pulse with frequency 7,milion 500 ,00o cycle /sec.  Diagnostic ultrasound used for common medical imaging uses frequencies between 2 and 20 million Hertz (Megahertz, MHz). Lower frequencies are able to penetrate deeper into tissue. In contrary higher frequency ultrasound. This is a very important principle when choosing your probes and frequencies Transducers frequencies - 2.5 Mhz Deep abdomen. - 3.5 Mhz General abd. pelvis - 5.5 Mhz vascular - 7.5 Mhz breast thyroid - 10 Mhz superficial MSK. Band width Now transducers manufactured with a band of Range of frequencies this band width. More than one operating frequencies: - 2 - 5 Mhz for abdomen scanning. - 7 - 13 Mhz for superficial scanning. Frequency transducers High frequency transducers: Low frequency transducers: - Good resolution. - Less resolution. - Less penetration - More penetration - For superficial use. - More penetration. Probes Several different types of probes are commonly used Knobology: IS THE SCIENCE AND ART OF USING THE DIFFERENT KNOBS AVAILABLE ON AN ULTRASOUND MACHINE, TO ACQUIRE AND OPTIMISE IMAGES FOR PROPER DIAGNOSIS Ultrasound Knobology and Settings: Step-by-Step Approach. KnobologyStep 1: Power Button; Knobology Step 2: Switch to the Correct Ultrasound Probe/Transducer; Knobology Step 3: Application Preset; Knobology Step 4: Depth; Knobology Step 5: Gain (Overall) Knobology Step 6: Near/Far Field Gain and Time Gain Compensation (TGC) Knobology Step 7: Focus  Freeze Frequency Gain Depth Focus GAIN TOTAL GAIN TGC Time gain compensation Compensate for attenuation of the sound  Freeze Frequency Gain Depth Focus Ultrasound Modes The most important mode for the ultrasound-beginner is the “B-mode”. B-mode stands for ‘brightness mode’ and provides structural information utilizing different shades of gray (or different Ultrasound Modes M-mode stands for ‘motion mode’. It captures returning echoes in only one line of the B-mode image but displays them over a time axis. Movement of structures positioned in that line can now be visualized. Often M-mode and B-mode are displayed together on the ultrasound monitor. Doppler mode examines the characteristics of direction and speed of tissue motion and blood flow and presents it in audible, color or spectral displays. Color Doppler ultrasound is also called color-flow ultrasound. It is able to show blood flow or tissue motion in a selected two-dimensional area. Direction and velocity of tissue motion and blood flow are color coded and superimposed on the corresponding B-mode image Power Doppler Unlike color Doppler, common power Doppler does not examine flow velocity or the direction of flow. It looks at the amplitudes of the returning frequency shifts and is able to detect even states of very low flow This is of use when examining vascular emergencies such as testicular or ovarian torsion.  Image Interpretation Anechoic / Echolucent Hyperechoic / Echogenic Hypoechoic Complete absence Opposite of hypoechoic, of returning Structure has very few structure appears brighter sound waves, area is black. echoes and appears than surrounding tissue. darker than surrounding tissue. Useful artifacts The ability to differentiate solid from cystic Acoustic shadowing and acoustic enhancement. YET. Shadowing Diminished sound or loss of sound posterior to strongly reflecting or attenuating structures Like bone or solid malignant tumors. Enhancement Increased transmition of the sound wave posterior to cysts. Your Machine Functions This section will list several important machine functions. On / Off - Remember where to switch the machine on before going into the patient’s room! Select / Change Probes - Select a specific probe. Set - Press to select from an activated menu; press to select/fixate a measurement point. Preset Menu - Select from preset menus such as general abdominal / vascular / procedures / OB or others. Use the scroll ball to navigate the menu. Scroll - Use the scroll ball (or in some machines a touch pad) to move the curser within the image or navigate through menus. After freezing an image-moving the scroll ball will display the last few images just right before you pushed the freeze button (these images are called cine-loops) Gain - Changes overall strength of returning echoes, functions as an amplifier. TGC - Changes strength of returning echoes in a certain depth. Depth Adjustment - Increases or decreases the depth of the ultrasound beam. Freeze - Push to freeze the current image. Print / Save - Will print a frozen image and/or save an image to a hard drive. Measurement / Cursor - After activating the first measurement button – a marker will appear on the screen. Use the scroll button to place it over the desired area. By pushing ‘set’ or ‘mark’ - the first cursor will be placed there and second cursor will appear. Use the scroll ball and the set button to complete the process. Additional measurements can be obtained by pushing the cursor button again. Some machines will have extra measurement buttons. Change Mode - Pushing the M-mode button will change the machine to M-mode, Doppler button to Doppler mode, color Doppler to color, etc. Most machines are set up so that a “dual” screen appears when certain modes are selected (B-Mode combined with Doppler or M-Mode etc.). Focus - Will change or add focal zones to the image. Change Paper - Most printers are designed in a very similar way: Push ‘open’ button on printer and insert new roll as shown inside the printer door, manually close the printer. Start printing! Is ultrasound waves safety? No confirmed harmful biological effects from ultrasound YET