This document provides an outline for a course on ultrasound for small animals. It discusses ultrasound physics including how ultrasound works, transducer frequencies and imaging modalities. It covers getting ready for scans such as patient preparation and positioning. It also discusses applications of ultrasound in private practice for emergency FAST exams, general internal medicine, and single organ studies.

1. INTRODUCTION TO SMALL ANIMALINTRODUCTION TO SMALL ANIMAL
UltrasoundUltrasound
Jeff King, DVM and Edgar Elguezabal

2. COURSE OUTLINECOURSE OUTLINE
 Ultrasound PhysicsUltrasound Physics
 How Does it Work?How Does it Work?
 Frequency & TransducersFrequency & Transducers
 Imaging ModalitiesImaging Modalities
 Imaging ArtifactsImaging Artifacts
 Getting Ready To ScanGetting Ready To Scan
 ““Buttonology”Buttonology”
 Patient Preparation & PositioningPatient Preparation & Positioning
 The Complete Abdominal ScanThe Complete Abdominal Scan
 Applications Of Ultrasound In PrivateApplications Of Ultrasound In Private
PracticePractice

4. Ultrasound PHYSICS - IUltrasound PHYSICS - I
 Soundwaves emitted from the transducer are reflectedSoundwaves emitted from the transducer are reflected
back at different amounts depending on the type ofback at different amounts depending on the type of
tissue.tissue.
 The computer in the machine processes theseThe computer in the machine processes these
reflections into an image.reflections into an image.

5. Usefulness of USUsefulness of US

6. Ultrasound Physics - IIUltrasound Physics - II
 Fluid reflects few sound waves, and willFluid reflects few sound waves, and will
appear black.appear black.
 Tissues reflect a variable amount of soundTissues reflect a variable amount of sound
waves and will appear in shades of gray.waves and will appear in shades of gray.
 Bone and Tissue Interfaces reflect largeBone and Tissue Interfaces reflect large
amounts of sound waves and will appearamounts of sound waves and will appear
white.white.
 Descriptive Terms – anechoic – black;Descriptive Terms – anechoic – black;
hypoechoic – darker; isoechoic – equal;hypoechoic – darker; isoechoic – equal;
hyperechoic - brighterhyperechoic - brighter

7. Transducer FrequenciesTransducer Frequencies
 1-18 megahertz (million cycles per second).1-18 megahertz (million cycles per second).
 Low Frequency – 1-5 MHzLow Frequency – 1-5 MHz
• More depth of penetration into the bodyMore depth of penetration into the body
• Use for medium to large sized patients orUse for medium to large sized patients or
Deeper structuresDeeper structures
• Provides moderate resolution (detail)Provides moderate resolution (detail)
 High Frequency – 7.5-18 MHzHigh Frequency – 7.5-18 MHz
• Less depth of penetration into the body.Less depth of penetration into the body.
• Use for medium to small pets orUse for medium to small pets or
superficial structures.superficial structures.
• Provides high resolution (detail)Provides high resolution (detail)

9. Transducer SelectionTransducer Selection
With experience transducer frequencyWith experience transducer frequency
selection becomes more intuitive.selection becomes more intuitive.
Body condition will influence resolutionBody condition will influence resolution
significantly.significantly.
Thin and well hydrated image the bestThin and well hydrated image the best
Obese and dehydrated will image poorly.Obese and dehydrated will image poorly.
Choose the transducer frequency toChoose the transducer frequency to
maximize image quality…maximize image quality…

10. TRANSDUCERS/PROBESTRANSDUCERS/PROBES
 Digital Ultrasound machines utilizeDigital Ultrasound machines utilize
Piezoelectric Crystals that convert electricalPiezoelectric Crystals that convert electrical
to sound energy.to sound energy.
 The returns are processed by the computerThe returns are processed by the computer
in the machine to create the image displayedin the machine to create the image displayed
on the screen.on the screen.
 Most transducers are capable of imaging at aMost transducers are capable of imaging at a
variety of frequencies.variety of frequencies.

11. Convex TransducerConvex Transducer
 Micro-convex transducer–Micro-convex transducer–
Curved footprint that yieldsCurved footprint that yields
a triangular image.a triangular image.
• Preset @ 5, 6.5, 8,10 MHzPreset @ 5, 6.5, 8,10 MHz
• Best for abdominal surveyBest for abdominal survey
and cardiac/thoracicand cardiac/thoracic
studies.studies.

12. Linear TransducerLinear Transducer
• Linear/TrapezoidLinear/Trapezoid
Transducer – straightTransducer – straight
footprint that yields afootprint that yields a
rectangular image.rectangular image.
• Preset to image @ 5,Preset to image @ 5,
7.5, 10 ,13, 18MHz7.5, 10 ,13, 18MHz
• Best for imagingBest for imaging
abdominal details orabdominal details or
small parts.small parts.

14. Ultrasound PHYSICSUltrasound PHYSICS
Imaging ModalitiesImaging Modalities
 B-Mode (Brightness)B-Mode (Brightness)
• Yields a 2-D image.Yields a 2-D image.
• Utilized for imaging tissueUtilized for imaging tissue
or organ structure, sizeor organ structure, size
and contour.and contour.
 M-Mode (Motion)M-Mode (Motion)
• Yields a swept 2-DYields a swept 2-D
image.image.
• Utilized for preciseUtilized for precise
measurements of cardiacmeasurements of cardiac
walls and chambers.walls and chambers.

15. Ultrasound PHYSICSUltrasound PHYSICS
Technique-dependent ArtifactsTechnique-dependent Artifacts
• Noise caused by excess gain.Noise caused by excess gain.
• Solution: turn down the overall gainSolution: turn down the overall gain

16. Descriptive TerminologyDescriptive Terminology

17. Appearance of TissuesAppearance of Tissues

18. Ultrasound PHYSICSUltrasound PHYSICS
TTechnique-dependent Artifactsechnique-dependent Artifacts
• Low gain artifactLow gain artifact
• Solutions: select another frequency, increase theSolutions: select another frequency, increase the
far gain, apply more alcohol/acoustic gel.far gain, apply more alcohol/acoustic gel.

19. EnhancementEnhancement

20. ShadowingShadowing

21. Liver and DiaphragmLiver and Diaphragm

22. Kidney and SpleenKidney and Spleen

23. Pregnancy = Puppies!Pregnancy = Puppies!

24. Ultrasound PHYSICSUltrasound PHYSICS
Technique-Dependent ArtifactsTechnique-Dependent Artifacts
• Electrical interference can occur from other equipment inElectrical interference can occur from other equipment in
the facility. Causes a variety ofthe facility. Causes a variety of “60 cycle noise” on the“60 cycle noise” on the
image screen.image screen.
• Solutions: move power cord to a different outlet, turn offSolutions: move power cord to a different outlet, turn off
the interfering equipment (dental scaler, clippers, etc.).the interfering equipment (dental scaler, clippers, etc.).

25. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Shadowing: caused by soundwaves hitting aShadowing: caused by soundwaves hitting a
highly reflective object, ex. uroliths, choleliths.highly reflective object, ex. uroliths, choleliths.
• Very helpful in detecting mineral densities.Very helpful in detecting mineral densities.
• Solution: recognize, scan from a different angle.Solution: recognize, scan from a different angle.

26. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Edge-shadowing: caused by refraction of soundwaves atEdge-shadowing: caused by refraction of soundwaves at
fluid- tissue interface at the edges of round structures,fluid- tissue interface at the edges of round structures,
ex. Urinary bladder, renal medulla and diverticula.ex. Urinary bladder, renal medulla and diverticula.
• Very helpful in detecting fluid structures.Very helpful in detecting fluid structures.
• Solution – recognize.Solution – recognize.

27. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Reverberation: caused by soundwaves interfacing with two tissuesReverberation: caused by soundwaves interfacing with two tissues
having markedly different acoustic properties, ex. bowel gas, poorhaving markedly different acoustic properties, ex. bowel gas, poor
skin contact, metallic objects.skin contact, metallic objects.
• Solutions: shave better, apply more alcohol/gel, change angle ofSolutions: shave better, apply more alcohol/gel, change angle of
transducer, rotate patient.transducer, rotate patient.
• Classic: Comet Tail:Classic: Comet Tail:

28. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Enhancement: caused by soundwaves travellingEnhancement: caused by soundwaves travelling
through fluid-filled structures, ex. urinary or gallthrough fluid-filled structures, ex. urinary or gall
bladder, cyst, seroma/hematoma.bladder, cyst, seroma/hematoma.
• Very helpful in detecting fluid structures.Very helpful in detecting fluid structures.
• Solutions: recognize, reduce overall or far gain.Solutions: recognize, reduce overall or far gain.

29. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Mirror-image: Caused by curved, stronglyMirror-image: Caused by curved, strongly
reflective interfaces, ex. diaphragm-lung.reflective interfaces, ex. diaphragm-lung.
• Solutions: possibly change angle of probe, rotateSolutions: possibly change angle of probe, rotate
patientpatient

30. Ultrasound PHYSICSUltrasound PHYSICS
Inherent Sonographic ArtifactsInherent Sonographic Artifacts
• Side-lobe: caused by minor beams ofSide-lobe: caused by minor beams of
soundwaves travelling out at different anglessoundwaves travelling out at different angles
from the primary beam. Occurs with curvedfrom the primary beam. Occurs with curved
surfaces, fluid and air.surfaces, fluid and air.
• Solution: reduce overall gain, adjust down TGCSolution: reduce overall gain, adjust down TGC

31. GETTING READY TO SCANGETTING READY TO SCAN
 Give yourself enough time to scan withoutGive yourself enough time to scan without
disturbances.disturbances.
 Pick an assistant who is capable ofPick an assistant who is capable of
restraining a patient without asking toorestraining a patient without asking too
many questions.many questions.
 Scan in a darkened room on a table whereScan in a darkened room on a table where
the assistant is across from you.the assistant is across from you.
 For abdominal studies a 8-12 hour fastedFor abdominal studies a 8-12 hour fasted
patient is ideal.patient is ideal.

32. GETTING READY TO SCANGETTING READY TO SCAN
 Shave the ventral abdomen like you wouldShave the ventral abdomen like you would
do for an exploratory surgery.do for an exploratory surgery.
 Apply sprayed alcohol to the skin toApply sprayed alcohol to the skin to
displace air.displace air.
 Apply Ultrasound gel to the transducer.Apply Ultrasound gel to the transducer.
 Maximize patient comfort with v-troughs,Maximize patient comfort with v-troughs,
towels, foam padding, calm environment,towels, foam padding, calm environment,
compassion.compassion.

33. GETTING READY TO SCANGETTING READY TO SCAN
 Imaging can be performed in dorsal, left or rightImaging can be performed in dorsal, left or right
lateral recumbency.lateral recumbency.
 Stressed or struggling patients need to beStressed or struggling patients need to be
sedated when safe.sedated when safe.
 Panting can lead to aerophagia which canPanting can lead to aerophagia which can
increase GIT gas.increase GIT gas.
 Resist the temptation to focus on the obviousResist the temptation to focus on the obvious
lesion.lesion.
 Be systematic and complete in your approach toBe systematic and complete in your approach to
a abdominal studya abdominal study..

34. SYSTEMATIC APPROACHSYSTEMATIC APPROACH
Mid-caudal
Left-caudal
Left-cranial
Mid-cranial
Right-cranial
Right-caudal
 Bladder, urethra, aorta, iliac lymphBladder, urethra, aorta, iliac lymph
node, prostate, testes.node, prostate, testes.
 L kidney, l adrenal, tail of spleen, LL kidney, l adrenal, tail of spleen, L
ovary/uterine horn.ovary/uterine horn.
 L side of the liver, left limbL side of the liver, left limb
pancreas, stomach, head ofpancreas, stomach, head of
spleen.spleen.
 Liver, gall bladder, biliary tract,Liver, gall bladder, biliary tract,
hepatic hilus, portal vein, cranialhepatic hilus, portal vein, cranial
VC, pylorus.VC, pylorus.
 Right side of the liver, right kidney,Right side of the liver, right kidney,
r adrenal, main body of pancreas.r adrenal, main body of pancreas.
 Duodenum, ileum, jj, RDuodenum, ileum, jj, R
ovary/uterine horn, colon,ovary/uterine horn, colon,
mesenteric root, ileocecalcolicmesenteric root, ileocecalcolic
junction.junction.

35. APPLICATONS OF Ultrasound INAPPLICATONS OF Ultrasound IN
PRIVATE PRACTICEPRIVATE PRACTICE
 Ultrasound HAS GREAT VALUE IN INTERNAL MEDICINE WORKUPS WHEN MINIMUMUltrasound HAS GREAT VALUE IN INTERNAL MEDICINE WORKUPS WHEN MINIMUM
DATABASE DATA DO NOT GIVE A DEFINITIVE DIAGNOSIS.DATABASE DATA DO NOT GIVE A DEFINITIVE DIAGNOSIS.
 EMERGENCY FAST ABDOMEN: blunt or penetrating trauma, bloat, spleen torsion, foreignEMERGENCY FAST ABDOMEN: blunt or penetrating trauma, bloat, spleen torsion, foreign
bodies, pyometra; to quantify and locate fluid pockets and to obtain a fluid sample; quickbodies, pyometra; to quantify and locate fluid pockets and to obtain a fluid sample; quick
assessment of the liver, spleen, kidneys, bladder, GI tract.assessment of the liver, spleen, kidneys, bladder, GI tract.
 EMERGENCY FAST THORAX; blunt or penetrating trauma, effusions and fluid sampling,EMERGENCY FAST THORAX; blunt or penetrating trauma, effusions and fluid sampling,
masses, pneumothorax, heart disease.masses, pneumothorax, heart disease.
 GENERAL INTERNAL MEDICINE PRACTICE: GI foreign body vs inflammation vs pancreatitis;GENERAL INTERNAL MEDICINE PRACTICE: GI foreign body vs inflammation vs pancreatitis;
ascites assessment and sampling; location of masses; bladder uroliths, , prostatic disease,ascites assessment and sampling; location of masses; bladder uroliths, , prostatic disease,
cystitis, neoplasia; differentiation of diffuse liver diseases via biopsy; kidney, ureters; pyometra;cystitis, neoplasia; differentiation of diffuse liver diseases via biopsy; kidney, ureters; pyometra;
cystocentesis; GI wall thickening; lymphadenopathy; adrenal measurements; hernias; ocular andcystocentesis; GI wall thickening; lymphadenopathy; adrenal measurements; hernias; ocular and
retrobulbar diseases; characterize types of heart disease.retrobulbar diseases; characterize types of heart disease.
 SINGLE ORGAN STUDIES:SINGLE ORGAN STUDIES:
 Skin/muscle masses/abscesses/cysts – characterize, margins, guided FNA, drainageSkin/muscle masses/abscesses/cysts – characterize, margins, guided FNA, drainage
 Thyroid/parathyroidThyroid/parathyroid
 TestesTestes
 Bicipital tendon, cruciate, joint effusionsBicipital tendon, cruciate, joint effusions
 Early pregnancy detection (day 21 in dogs) and fetus countEarly pregnancy detection (day 21 in dogs) and fetus count
 Discounted Wellness ExamsDiscounted Wellness Exams