Abdominal Ultrasound
Imaging Control Buttons Depth The organ imaged should take up 3/4 of the screen Frequency = Penetration Use high frequencies (harmonics) for fluid filled and superficial structures If the far field (lower part) of the image loses detail (blurry, darkened, fuzzy, etc.) decrease the frequency for more penetration. You may also need to change to a lower frequency transducer Gain = Brightness Adjust the gain to see the borders of all structures clearly. This usually would be around 50-60%, but will differ with anatomy, depth, and frequency Map = Shades of gray The overall image will slightly change. Shades of gray will get brighter as your go up, or will get darker as you go down Use this function when the frequency and gain is at it s best, but still want to fine tune the image Transducers Linear (L14-5) Typically used for smaller animals and superficial structures. Can also be used to image the GI system in larger animals. Microconvex (MC9-4) Typically used for medium - large animals and all echocardiograms. Can also be used on smaller animals to image deeper organs (liver, right kidney, etc.) and when a large amount of gas is present. Curvilinear (C7-3) Typically used for large animals and deep structures NOTE: The choice of transducer is dependent on many factors such as body habitus, depth of organs imaged, and presence of gas. It is important to use multiple transducers and find what is right for that animal and organ being imaged.
Slide Move the transducer Scanning Movements Example: Slide Cranial - move the transducer toward the patients head Rotate/Twist Tilt To move from one plane to another Example: moving from a long axis image to a short axis image Hold the transducer in the same spot and point the transducer towards area of interest Example: Tilt the beam to the left to image the left (to image the left side of the body) or tilt the beam to the right (to image the right side of the body). Rock or Heel/Toe Apply more pressure to one end of the long axis of the transducer Example: rock the transducer to image underneath the rib cage - more pressure is placed on the end of transducer without the notch (heel of the transducer) Image Orientation Long Axis: Notch pointed to the patients head Ventral Short Axis: Notch pointed to the patients right side Ventral Cranial Caudal Patient s Right Patient s Left Dorsal Dorsal
Bladder Use the linear transducer with harmonics when possible Should appear anechoic (black) Be aware of pressure used - it can be compressed if too much pressure is used When excessive artifact is present try adjusting the gain, TGC, frequency, and/or map Be care not to darken the image too much or you could potentially miss debris or lesions Lesions vs debris- If echogenic material is noted on the dorsal side of bladder stand the animal upright and revaluate the echogenic material (lesions will stay at the dorsal portion of bladder and debris should move to the ventral portion since it is gravity dependent) Cranial Caudal (trigone) Cranial and Caudal (Rt - Lt) Short Axis - cranial to caudal Bounce on the bladder and look for floating debris Cranial Trigone
Prostate Follow the trigone caudal Intact Males: round to oval shaped Neutered Males: very small and may not always been seen If you suspect abnormality: take additional images with Color Long Axis Image Measurement of length and height Long Axis (Rt - Lt) Bladder Measurements
Left Kidney Increase the depth after scanning the bladder You may need to lower the frequency (or switch to a lower frequency transducer) after scanning the bladder Palpate the last rib: Kidney is located posterior and medial to the caudal aspect of spleen Renal Pelvis: Look for backwards C or U shape with a hyperechoic (bright) break in the cortex When the kidney is difficult to evaluate try using a lateral decubitus or standing position Long Axis Long Axis with measurement Short Axis at the Renal Pelvis Long Axis (Rt - Lt) Renal Pelvis
Left Adrenal Start at the cranial portion of the kidney and tilt the beam medial. The transducer beam should be pointing medial towards the aorta Look for the renal artery (the adrenal gland is located cranial to the artery). Use Color Doppler to follow the renal artery from the kidney If the dorsal position does not work, try to reposition the animal into a lateral recumbent positon You may have to rotate the transducer slightly to elongate the gland in a dorsal position Lateral recumbent position Slide lateral to the last rib and rotate the transducer so the back is pointing towards the animal s left knee (this is about a 30 angle from a long axis position) Long Axis Long Axis with measurement Long Axis (Kidney - Ao/CVC)
Use a high frequency when possible Spleen Cranial Spleen - locate the margins of the cranial spleen. Then increase depth and tilt the transducer towards the patients right (point the transducer to the patients left) until you see the spleen dive down on the screen. Standing the animal upright (especially larger animals) will allow for better visualization at times. Mid Spleen - Image should be taken at the hilum where the splenic vein can be seen (split screen with color) Splenic Tail - Cats: Slide caudal until you see the caudal margins Dogs: Once you find the caudal margins, follow all the way through to the tail of the spleen by sliding the transducer to the patients right. Mid Cranial Tail Mid
Spleen Long Axis Cranial Head Long Axis Body Long Axis Splenic Vein w/ Color Long Axis Caudal Tail Split Screen Liver and Spleen (do not change any settings for this image) Cranial half of spleen Caudal half of spleen Spleen Liver
Liver May need to increase depth, lower frequency, and/or switch transducers Make sure you can ALWAYS see the diaphragm Apply adequate pressure (usually more than you think) When a subcostal approach does not image well due to gas, body habitus, etc. try the following: Reposition the animal into a lateral recumbent position or standing position Use intercostal approach (especially in deep chested dogs). You can sometimes use both a left and right intercostal approach Left Lobe - Use the stomach as a landmark. The liver will appear more wedge shaped Mid Liver - Look for the portal vein as a landmark. Located just medial to the GB Right Lobe - Use the GB as a landmark. Long Axis Left Lobe Long Axis Mid Long Axis Right Lobe Long Axis - Right Lobe to Mid Liver Long Axis - Mid Liver to Left Lobe Left Lobe Mid Liver Right Lobe
Gallbladder Located just right of midline and surrounded by liver tissue Use a high frequency when possible (harmonics) Normal appearance: anechoic (black) To elongate the GB, rotate the transducer until you can see the neck and fundus (may not always be able to image both on the same image) Long Axis Fundus Image Long Axis Neck Image Video: If pathology is seen or if you cannot get the entire organ in one image Neck Fundus Fundus
Right Kidney Palpate the last rib Increase the depth so you do not miss the kidney. Readjust the depth once it is located You may need to lower the frequency or switch transducers Renal Pelvis: Look for backwards C or U shape with a hyperechoic (bright) break in the cortex When the kidney is difficult to evaluate try using a lateral decubitus or standing position Long Axis Long Axis with measurement Short Axis at the Renal Pelvis Long Axis (Rt - Lt) Renal Pelvis
Right Adrenal Start at the cranial portion of the kidney and tilt the beam medial. The transducer beam should be pointing medial towards the CVC/Aorta. Use color Doppler to follow the renal artery from the kidney If the dorsal position does not work, try to reposition the animal into a lateral recumbent positon You may have to rotate the transducer slightly to elongate the gland Lateral recumbent position: slide lateral to the rib cage (some animal s may require a more lateral approach than others) and tilt the beam of the transducer until you locate the CVC Long Axis Long Axis with measurement Long Axis (Kidney - Ao/CVC)
Duodenum Use linear transducer in harmonics when possible Duodenum is larger than the rest of the small intestine Using the Rt. Kidney as your landmark, you may need to either tilt lateral or slightly medial depending on the position of the transducer on the abdomen. The duodenum should lengthen across the screen. Long Axis Long Axis with measurement Short Axis If pathology is seen
Pancreas Normal tissue may not always be seen Right Limb - Duodenum is the landmark. When scanning from a lateral approach the pancreas can be seen dorsal to the duodenum Short Axis - start at the right kidney and slide cranial following the duodenum Left Limb - Triangle of landmarks: greater curvature of the stomach, cranial spleen, and left kidney Follow the splenic vein from the spleen Long Axis Right Limb Short Axis Right Limb Long Axis Left Limb If pathology is seen Left Limb Landmarks
Stomach Use a high frequency when possible (harmonics) Start at the sternal notch and apply pressure to the heal of the transducer To elongate the stomach rotate the transducer to an oblique angle (about 45 ) Standing the animal upright can shift the gas making it easier to visualize portions of the stomach If you are concerned about a stomach mass, stand the animal upright and re-evaluate Long Axis Images of greater/lesser curvatures Short Axis Image Video: Long Axis lesser curvature (from the body of stomach to the pylorus) Long Axis greater curvature (from the body of stomach to the patient s left) Empty Stomach
Small Intestine Use the linear transducer in harmonics when possible Apply more gel! All the small intestine should be similar in size Scan the abdomen systematically Short Axis Right (Cranial - Caudal) Short Axis Mid (Cranial - Caudal) Short Axis Left (Cranial - Caudal) Images and measurements should be taken if there is any concern for GI disease or abnormalities are visualized
Iliacs at Aortic bifurcation Use the linear transducer in Harmonics when possible Normal lymph nodes may not always be seen Characteristics: Well defined, smooth, and fusiform to oval shaped Isoechoic or slightly hypoechoic (slightly darker) to surrounding fatty tissue When using a high frequency transducer you may also see a hyperechoic (bright) central line representing the hilum Patient is scanned in a lateral decubitus position, transducer in a vertical position. Start dorsal, near back musculature and slowly slide ventral until Aorta appears. Slide caudal on Aorta until you see it bifurcate into iliac vessels. Fan through the bifurcation Lateral/Medial Right Iliac Video (fan through the vessel at Aortic bifurcation) Left Iliac Video (fan through the vessel at Aortic bifurcation) If large lymph nodes are seen images should be taken (measure the largest) Left Iliac With Color Normal Lymph Node Right Iliac
Imaging Abnormalities When abnormalities are noted on an exam additional images should be taken in addition to the protocol Additional Images for Lesions Long AND Short Axis Images If lesion is small use split screen Image with measurements Smaller lesions can be measured on split screen Image with color Doppler Multiple lesions on the same organ that have similar appearance Measure the largest 2 lesions and include images of the others Make sure that on your video that the lesions are included Large masses May need to take 1-2 additional videos Try to locate the organ it is originating from (this may be difficult at times depending on location and size) Abdominal Fluid Capture an image of any ascites that you note Use organs as landmarks if only a small amount is seen so the specialist can document where the fluid is seen on reports Fluid-filled Intestine Can be a normal finding or a sign of an abnormality Follow intestine until you no longer see the fluid or until you scan come across an abnormal/suspicious area