Veterinary Diagnostic Imaging

Veterinary Diagnostic Imaging 

Nikki Kilcullen R.T. (R) 

Radiography

  • A very short burst of x ray photons (waves) that create an image of the body 

  • X-rays are the oldest and most frequently used form of veterinary medical imaging 

  • Used to diagnose disease in the chest, abdomen, and musculoskeletal system. We also perform many special studies such as contrast studies of the gastrointestinal and urinary tract to diagnose obstructions.

HOW DO X-RAYS WORK: VIDEO

  • Are very high energy waves 

  • Can pass through many objects, but if an object's density is more, X-rays won’t pass

    • Tissues aren’t dense enough, but bones are dense enough, so that's why tissues don’t appear but bone does appear white on the film 

X-RAY Basics

  • An ray is a 2-dimensional grayscale representation of the anatomy

  • Pathology on an x ray is recognized when a density is seen in an abnormal lace

  • We cannot see all anatomy on radiographs: this is why we have CT and MRI

    • Air is black 

    • Fat is gray 

    • Soft tissue is white 

    • Bone is whitest

VIDEO NOTES:

  • Four Modalities of Diagnostic Imaging 

    • Radiograph 

    • Ultrasound 

    • CT scan 

    • MR

Small Animal Radiography

  • Lead apron - protects from X-ray waves

    • Due to scatter from the X-ray waves off of the table

The Importance of Orthogonal Views

  • Ventral/Dorsal

Always take more than one view 


Non-routine Radiograph 

  • Routine radiographs often consist of 2-4 views (DP and Lateral, Obliques) for limbs and 3 views (DP, right, and left later) for chest and abdomen 

  • When further imaging is required/beneficial, we can take more views on radiographs 

    • Using another imaging modality, like CT or MRI, can also be advantageous but is not always feasible or necessary

Comparative Anatomy

  • Homology 

Contrast Studies 

  • Can perform single (air) and double (air and barium/iohexol/omnipaque) contrast studies

Large Animal Radiography

  • Have to bring the X-ray to the animal

    • Portable X-ray tube


MISC:

  • Polydactyly

    • Extra digits


Fluoroscopy

  • A continuous series of very low dose x-ray images that let veterinarian see images of the inside of the body in motion (live x-rays)

  • Used to diagnose diseases that involve motion, such as collapse of the trachea during breathing, or disorders of swallowing 

  • Also, can be used intraoperatively

  • Colors are switched, (air;white, bone;gray, contrast material;black)

Cross-Sectional Imaging: Anatomy PLanes 

  • CT and MRI 

  • Can align planes 

    • Midsagittal (middle)

    • Transverse (middle, from front to back 

    • Front plan (vertically in half, but horizontal for animals)

Computed Tomography (CT)

  • Uses x-rays to produce multiple images of the inside of the body, and provides thin, cross sectional “slices” for viewing 

  • CT scans of internal organs, bone, soft tissue and blood vessels provide much more detail than conventional x-rays

  • Radiologists use this specialized equipment and expertise ot diagnose problems such as cancer, abnormalities of blood, vessels, trauma, and musculoskeletal disorders

  • VIDEO NOTES:

    • Take multiple images in succession, different layers of the body

    • When are they taken: taken after an accident, heart attack, or stroke, - to clarify what exactly happened, or to identify a tumor, or any treatment success

    • How do scans work: patient lies on table, slides in, integrated x-ray source rotates getting imaging of the body from every angle, creates signals that create images 

    • May be necessary to administer contrast medium to image more precisely, more reliable detection 

    • Almost all patients can be examined using CT, but because of radiation, pregnant folks should not be scanned unless absolutely necessary 

Equine and Large Animal CT

  • There are weight limits on small animal ct scanner - so don’t work for large animals 

  • CT scanner does the moving as opposed to the table 

Magnetic Resonance Imaging (MRI)

  • Uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of organs, soft tissues, and other internal body structures. The images can then be examined on a computer monitor or printed.

  • Does NOT use ionizing radiation (x-ray), but detects the motion of protons that are normally present in the body 

  • Detailed MR images allowing veterinary radiologists to better evaluate parts of the body and certain disease that may not be assessed adequately with other imaging methods such as x-ray, ultrasound, or CT

  • MRI is the most sensitive imaging test of the head (particularly in the brain) in clinical practice

Motion Artifact

  • Motion interferes with imaging sometimes 

  • Can be motion corrupt or motion corrected

Metal Artifact

  • Metal in the body won’t allow imaging to see through

    • Can also see a streaking affect from metal 

Ultrasound

  • The ultrasound probe generates inaudible high-frequency sound waves. The waves are reflected off the body structures and are detected by the probe. 

  • Ultrasound waves are:

    • Reflected by SOlid and gas: Bright 

    • Transmitted (not reflected) by Fluid: Darl

  • Does NOT use ionizing radiation (x-ray)

  • Images are captured in real-time, they can show the structure and movement of the body’s internal organs, as well as blood flowing through blood vessels. 

  • Patients usually have to be shaved for US so the hair doesn’t interfere

  • Can do US guided biopsies

  • ULTRASOUND guided FNA

    • US guided fine needle aspirations area safe and minimally invasive way to determine if a lesion is inflammatory, infectious, or neoplastic 

    • Precise and real time observation 

    • Bone and gas can prevent access to lesions 

  • Thing in probe called piezoelectric crystals, vibrations of these things cause the propagation of ultrasound waves 

So you want to be a Radiology/Ultrasound Technologist 

  • At most other veterinary hospitals the vet nurses are the ones who take the radiographs 

    • Required prerequisite courses, shadowing experience 

  • Human radiology and ultrasound technologist school is usually a 2 year certification track programs 

    • All schools have required prerequisite courses; some require an Associate’s Degree (then you can get your B.S. during x-ray school)

    • US school is separate from x-ray 

      • After US school you can specialize in: breast and/or Vascular Sonography 

      • After X-ray school you can specialize in other modalities 

        • Bone densitometry, Cardiac, and/or Vascular Interventional, Computed Tomography, Magnetic Resonance Imaging, Mammography, Registered Radiologist Assistant (RRA requires a master’s or doctorate), nuc

  • Veterinary Radiology 

    • Veterinary school is 4 years and at the end you will earn your DVM degree

    • Veterinary schools do not all have the same prerequisite requirements 

      • Most of them do not actually require a bachelor’s degree; you just need to meet the course requirements 

    • Most schools require shadowing experience or experience working in vet med 

      • If you think you want to be a DVM, get started shadowing sooner rather than later

    • After veterinary school you will have to do an internship so that you can apply for residency programs 

      • Sometimes you have to do more than one internship, internships are usually 1 year long 

      • Residencies are 3 years long