Basic Ultrasonography Quiz

Basic Ultrasonography

• Ultrasound uses sound waves to create images of internal structures.
• A current is applied to piezo-electric crystals within a transducer.
• This causes the crystals to vibrate, emitting sound waves.
• Sound waves reflect off tissues and organs, returning to the transducer.
• The returning waves generate an electrical signal.
• The signal is amplified and displayed as an image.

Interactions with Tissues

• Reflection: Sound waves reflect off tissues (echoes).
• Refraction: Sound waves change direction due to differing tissue velocities.
• Diffraction: Sound waves change direction through openings or around barriers.
• Attenuation: Loss of sound wave energy through scatter and absorption.

Ultrasound Probes

• Linear Array: Crystals in a line, producing rectangular images with a large footprint and no near-field artifact.
• Curved Array: Crystals in a curve, producing fan-shaped images with some near-field artifact and a smaller footprint.
• Phased Array: Crystals in a line, offering greater depth with fan-shaped images and smaller footprints. These probes can electronically steer the beam.

Frequency

• High Frequency: Better axial resolution, more rapid beam attenuation, poorer penetration.
• Low Frequency: Poorer axial resolution, less rapid beam attenuation, better penetration.
• Axial resolution is the ability to determine two points along the path of the beam.

Depth

• Sound waves from deeper structures are weaker due to attenuation.
• Time Gain Compensation (TGC) controls brightness levels at different depths.

Focus / Focal Zone

• Area of optimal image quality, often marked by a triangle.
• Focusing improves lateral resolution.
• Lateral resolution is the ability to determine two points perpendicular to the beam
• A narrow beam results in better lateral resolution

Ultrasound Artifacts

• Reverberation: Parallel bright lines caused by multiple reflections of sound waves.
• Mirror Image: Artifact at a curved reflective surface, appearing as a mirrored image.
• Acoustic Enhancement: Bright areas deep to fluid or air pockets caused by reduced attenuation.
• Poor Probe Contact: Artifact due to inadequate coupling gel.
• Acoustic Shadowing: Distal shadowing caused by highly reflective structures.
• Edge Shadowing: Acoustic shadow distal to a lateral aspect of cystic structures.
• Slice Thickness: Artifact, where the beam is wider than the cystic structure, mimicking a tissue interface.

Echogenicity

• Isoechoic: Structures with the same shade of gray as surrounding tissue.
• Hypoechoic: Structures with a darker shade of grey than surrounding tissue.
• Hyperechoic: Structures with a lighter shade of grey than surrounding tissue.
• Anechoic: Structures that appear black.

Echotexture

• Homogeneous: Uniform distribution of grey shades or dot sizes within the structure.
• Heterogeneous: Non-uniform distribution of grey shades or dot sizes within the structure.

Describing a Lesion

• Location, echotexture, measurements, outline, number, size (LEMONS).
• Echogenicity, echotexture and artifacts

Abdominal Ultrasound

• Indications (Elective): Any condition involving an abdominal organ, tumor identification/description, staging of neoplasia, intra-abdominal biopsy, reproductive tract investigations.
• Indications (Emergency): POCUS (point-of-care ultrasound) to identify free fluid (often post-trauma)
• Scanning areas: diaphragmatic hepatic (DH), hepato-renal (HR), spleno-renal (SR), cysto-colic (CC).

Benefits of Abdominal Ultrasound

• Non-invasive and safe.
• No general anesthesia required.
• Excellent morphological information and resolution.
• Comprehensive information from all major organs.
• Real-time sampling of tissues possible.
• Relatively inexpensive.

Disadvantages of Abdominal Ultrasound

• Limited functional information.
• Difficulty detecting diffuse disease.
• Sampling may be necessary for disease classification.
• Patient clipping is required.
• Sedation may be necessary.
• Gas interferes with sound transmission.
• Technically demanding to acquire high-quality images.
• Images might not be immediately interpretable by specialists.

Patient Preparation for Abdominal Ultrasound

• Withhold food (ideally 8 hours), drink is allowed.
• Clip the fur of the patient.
• Wash the patient to remove stray hairs.
• Apply liberal amounts of coupling gel.
• Sedation as required.
• Patient should be placed in lateral recumbency.

Patient Preparation (General)

• Allow plenty of examination time
• Use a darkened, quiet room
• Ensure the table is at the correct height
• Providing a vet bed or similar to patient to ensure comfort.
• Sufficient nursing support

Scanning Areas

• Systematic approach is crucial.
• Right lateral recumbency is often used to assess the left side; left lateral recumbency the right side.
  • List of organs easily assessed in each position.

Ultrasound Guided Techniques

• Abdominocentesis, Cystocentesis (sample collection)
• Fine Needle Aspiration (FNA), Trucut biopsy, liver/spleen biopsy for histology.
• Preparing the skin aseptically, applying spirit to skin, protecting probe in glove with coupling gel.

Echocardiography

• Indications: Heart murmurs, ECG abnormalities, radiography abnormalities, hypertension, dyspnoea, syncope, arterial thromboembolism and pre-breeding screening.

Patient Preparation for Echocardiography

• Clip the fur over the heart region.
• Patient in lateral recumbency.
• Placement of the ultrasound probe onto the thorax: the probe is angled into the space between the 3rd-6th or 5th-7th intercostal space depending on the side of the heart

Echocardiography: Standard Views

• Right parasternal long-axis view
• Right parasternal short-axis view (Chordae tendineae, Papillary muscles, Mitral valve, Aortic valve)
• Subcostal view
• Left apical 4- and 5-chamber views

Thoracic Ultrasound

• General view: Normal lung with smooth hyperechoic line.
• Ribs: Hyperechoic line with a distal acoustic shadow.

TFAST

• 5-point assessment: Chest tube insertion site (x2), pericardium (x2), diaphragmatic/hepatic region.
• Uses: Evaluate for pleural space and pericardial effusion in trauma cases.
• Fluid = hypoechoic; absence of the 'glide sign' suggests air.

Vet BLUE assessment

• 4-areas: Caudodorsal, middle, perihilar, and cranial lung lobes.