Small Animal Special Procedures and Diagnostic Imaging

Comprehensive vocabulary flashcards covering contrast media types, GI and urinary diagnostic procedures, and advanced imaging modalities including Ultrasonography, CT, MRI, and Fluoroscopy for veterinary medicine.

Positive-contrast agents

Substances that appear white (radiopaque) on a radiograph, used to increase radiographic contrast within an organ or system.

Negative-contrast agents

Substances that appear black (radiolucent) on a radiograph, such as air used in a pneumocystogram.

Barium sulfate

A positive-contrast agent used exclusively for the GI tract that can be administered orally or rectally.

Water-soluble organic iodides

Contrast agents used in intravascular studies or injected into body cavities, which are excreted through the kidneys.

Hyperosmolar

A solution, such as organic ionic iodine, that has a higher concentration than blood, causing water to move into vessels from extravascular tissues and red blood cells.

Esophagram

Contrast radiography of the esophagus used to identifying lesions or characterize findings, best evaluated with dynamic imaging like fluoroscopy.

Upper Gastrointestinal Study

A study where contrast medium is administered orally and images are taken during its transit through the stomach, small bowel, and colon.

Lower Gastrointestinal Study

Radiographic examination of the cecum, colon, and rectum through retrograde administration of contrast medium to evaluate lesions or masses.

Barium-Impregnated Polyethylene Spheres (BIPS)

Inert, low density, radiopaque spheres designed for evaluating gastric dysmotility and intestinal transit time in dogs and cats.

$5-mm$ BIPS

A specific size of Barium-Impregnated Polyethylene Spheres used to evaluate partial and complete obstruction.

$1.5-mm$ BIPS

A specific size of Barium-Impregnated Polyethylene Spheres used to mimic the passage of food through the GI tract.

Cystography

The study of the urinary bladder via retrograde infusion of contrast media through a urinary catheter.

Pneumocystogram

A negative-contrast study of the bladder performed by draining all urine and injecting air.

Double contrast study

A bladder study where positive contrast medium is instilled and then drained, followed by the re-instillation of air to reveal inflammation, calculi, or polyps.

Excretory Urography

A procedure primarily used to determine the size, shape, location, and integrity of the kidneys and collecting systems, assess relative kidney function, and indirectly evaluate renal failure.

Myelography

The injection of radiopaque contrast agent into the subarachnoid space in the cerebellomedullary cistern or lumbar region to evaluate the spinal cord.

Echogenicity

The appearance of tissues on ultrasound based on their ability to reflect sound waves, referring to the brightness on a B-mode display.

Anechoic

A structure that lacks internal echoes (echo-free) and appears very dark or black on ultrasound, such as the urinary bladder.

Hyperechoic

A tissue density that reflects back more intense sound waves and appears brighter than the surrounding tissues.

Hypoechoic

A tissue density that reflects fewer and less intense sound waves, making it appear darker than surrounding tissues.

Isoechoic

A term describing two structures that have relatively similar echogenicity toward each other.

Complex Echogenicity

A tissue that contains a mixture of hyperechoic and hypoechoic areas.

Attenuation

The loss of sound wave energy as it traverses tissue or medium due to absorption, reflection, or scattering.

Reverberation

An artifact where a sound wave is repeatedly reflected between two highly reflective surfaces, such as air and the ultrasound probe.

Near field

The area of a structure of interest that is closest to the ultrasound probe.

Far field

The area of a structure of interest that is farthest from the ultrasound probe.

B mode

The brightness mode in ultrasound imaging where pixels are classified as hyperechoic (bright) or hypoechoic (dark).

M mode

The motion mode in ultrasound where a cursor line is set over a B-mode image to display the motion of tissues over a two-dimensional scale.

Transducer (probe)

An ultrasound component that changes electrical energy into mechanical energy (sound waves) and converts reflected sound waves back into electrical impulses.

Piezoelectric crystals

Fragile components within an ultrasound transducer that can be damaged if the probe is dropped or jarred.

Fluoroscopy

A dynamic imaging modality that provides continuous real-time x-ray imaging of the patient.

Tomography

Making images of slices of the body; derived from the Greek words tomos (cut) and graph-o (to write).

Focal Plane

The section of a CT scan at which minimal blurring occurs.

Region of interest (ROI)

A fixed point in the anatomy of a patient used during CT imaging.

Gantry

The opening in the center of a CT machine through which the patient passes, containing the rotating x-ray tube and detectors.

Hounsfield units (HU)

A standardized scale for radio densities in CT images, where air is $-1000\,HU$ and water is $0\,HU$.

Scanogram

Also called a scout view, this is a radiograph-like image used by a CT operator to choose the regions to be included in a scan.

Projectile effect

The highest danger in an MRI room, where loose metal objects are violently pulled toward the magnet.

MR safe

Objects, devices, or implants made of materials like plastic, gold, sterling silver, or titanium that pose no known hazards in the MRI environment.

Signal Intensity

The term used for shades of gray in MRI; high intensity is bright (white) and low intensity is dark.

T1 images

MRI images where only one tissue type, FAT, appears bright.

T2 images

MRI images where two tissue types, FAT and WATER, appear bright.

Gadolinium

A contrast agent used in MRI to highlight infection, tumors, or vascular disease, typically seen on T1-weighted sequences.

Localizer

A low-quality, quick scan used at the start of an MRI to see anatomy and plan subsequent images.