What are ultrasound waves: Audible sound waves lie between 20 and 20,000 Hz. Ultra sound uses sound waves with a far greater frequency between 1 and 30 MHz.
Superior (cephalad, cranial) Anatomical directions These terms are used both to describe the direction of movement of the transducer and to describe the relationship between various organs or structures. It is a standard labeling nomenclature used to show where structures lie in relation to each other. Superior (cephalad, cranial) Structure lying towards the patient's head Inferior (caudal) Structure lying closer to patient's feet Anterior (ventral) Structure lying towards the front of the patient Posterior (dorsal) Structure lying towards the back of the patient Right Patient's right side Left Patient's left side Medial Towards the patient's midline Lateral To the right or left of the patient's midline
Planes or body sections There are four main scanning planes: sagittal, transverse, coronal, and oblique. Scan planes can apply to either the whole body or an individual organ. Sagittal or longitudinal A lengthwise plane that divides a structure into left and right sides (often in the midline) Transverse A horizontal plane that divides a structure into superior and inferior part Coronal A lengthwise plane that divides a structure into anterior and posterior portions Oblique A plane that divides a structure at any angle which is not in the longitudinal, transverse, or coronal plane
IMAGE orientation To assist with orientation, most transducers have a notch or mark on the transducer that corresponds to a mark on the screen. Images are displayed on the ultrasound screen in a standardized way. Imagine standing at the foot of a bed and looking up at a large loaf of sliced bread. The captured image is projected as a slice, lifted onto the screen. IN TRANSVERSE SECTION : Anterior abdominal wall--- anterior aspect of image. Spine—posterior aspect of image Right side of body—left side of image Left side of body –right side of image IN SAGITTAL SECTION: Anterior abdominal wall--- anterior aspect of image. Spine—posterior aspect of image Head end—left side of image Foot end—right side of image
anterior anterior left Cephalad /cranial right Inferior / caudal A transverse image is orientated with the patient's right side to the left of the screen. Sagittal images are displayed with the patient's head to the left of the screen. Transverse Sagittal anterior anterior left Cephalad /cranial right Inferior / caudal posterior posterior
Role of Ultrasound To assess the: Size Capsular contour (smooth, coarse, lobulated) Parenchymal echogenicity Vascularity Biliary tree Masses or collections
Reduces portal vein caliber to its resting level Patient preparation: Elective hepatic scanning should be performed after an overnight fast or at least 6-8 hrs fasting which allows: GB distension Reduces portal vein caliber to its resting level Reduces the amount of swallowed gas in the upper GIT
Patient position for liver Right lobe: supine position /lateral decubitus with right side up. Left lobe: Supine position A liver ultrasound should include the following minimum images: Longitudinal Left lobe Caudate lobe IVC Porta hepatis Comparison to Rt Kidney Left hepatic vein Transverse Left portal vein Right portal vein Middle and Right hepatic vein
LEFT LOBE WITH LEFT HEPATIC VEIN
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