May/June 2013 Today’s Veterinary Practice 59
ImagIng EssEnTIalsPeer reviewed
Small animal Spinal RadiogRaphy SeRieS
Thoracic Spine radiographyDanielle Mauragis, CVT, and Clifford R. Berry, DVM, Diplomate ACVR
Spinal radiographs are indicated for:
• Evaluation of traumatic injuries
• Neck and back pain
• Pain or neurologic issues associated with
thoracic or pelvic limb lameness isolated to
these regions.
Each radiographic projection is a separate study and
should be radiographed as such. High quality, correctly
positioned and collimated radiographs are required in
order to provide an accurate assessment of the area of
interest, especially for surgical planning.
Measuring the thoracic spine
Measure the thickest portion of the spine
that is within the area of collimation.
Follow these precautions
as a general rule, general anesthesia or heavy
sedation is necessary to evaluate the spine
because, in most cases, spinal images taken
in nonsedated patients are nondiagnostic.
In addition, the presence or absence of disk
space narrowing cannot be determined from
a nonsedated animal’s radiographs due to
unavoidable positioning artifacts.
If a back injury (fracture) is suspected, DO
nOT flex or extend the spine of the injured dog
or cat, and DO nOT turn the patient for an or-
thogonal image. If possible, a horizontal beam
image is done for the ventrodorsal projection.
imaging essentials provides
comprehensive information on small
animal radiography techniques. This article
is the second in a 3-part series covering
cervical, thoracic, and lumbar spine
radiography.
The following anatomic areas
have been addressed in previous
columns; these articles are available at
todaysveterinarypractice.com (search
“Imaging Essentials”).
• Thorax
• scapula, shoulder, and humerus
• abdomen
• Elbow and antebrachium
• Pelvis
• Carpus and manus
• stifle joint and crus
• Tarsus and pes
| ImagIng EssEnTIals
Today’s Veterinary Practice May/June 201360
routine Views
Lateral and ventrodorsal views are considered the
minimum orthogonal radiographs for the spine. Due to
the angled, divergent nature of the x-ray beam, the area
of the spine in the center of the field of collimation will
be the area that provides the correct anatomic detail and
intervertebral disk space widths.
A routine thoracic spine study includes:
1. Lateral image of the thoracic spine
2. Ventrodorsal image of the thoracic spine
3. Lateral image of the thoracolumbar spine
4. Ventrodorsal image of the thoracolumbar spine.
lateral projection: thoracic spine
For the lateral projection, position the patient in lateral recumbency (Figure 1). • Tape the thoracic limbs together evenly
and pull cranially, keeping the sternum and vertebrae equidistant to the table. • a foam wedge may be placed under the
cubital joints and/or sternum in order to maintain laterality of the patient; wedges are typically needed for large-breed and/or barrel-chested dogs.• Tape the pelvic limbs together evenly and pull
caudally, keeping the patient in lateral position.• The thoracic spine should be aligned with
the horizontal line of the collimated field of view (FOV). To accomplish this alignment, the pelvis of the dog or cat may need to be shifted ventrally. To determine whether or not the patient is
aligned in a lateral position and parallel to the table, gauge the superimposition of the iliac wings by palpating the wings to ensure they are even.
lateral collimation
For the lateral projection, the FOV should:• Include the dorsum just above the spinous
processes• Exclude the sternum and ventral third of the
thoracic cavity.
For all patients:• Palpate the vertebrae of the thoracic spine by
following the ribs dorsally to where they meet
the vertebral bodies; place the horizontal line of the FOV at this plane.• accommodate the contour of the thoracic
spine from a ventral position cranially to a more dorsal position caudally.• Place the radiographic marker to the caudal
right or left of the patient to keep it from overlapping with important anatomic areas.
Ventrodorsal projection: thoracic spine
For the ventrodorsal projection, position the patient in dorsal recumbency (Figure 2). • If a trough is used, place the entire thoracic
spine within the trough to eliminate edge artifacts. • Extend the skull and neck and align with the
manubrium; the skull and cervical spine should also be aligned in a straight line cranially. • align the sternum over the thoracic spine; it
should be superimposed onto the thoracic spine on the final image. • Tape the thoracic limbs either together or
individually and pull cranially. • Tape the pelvic limbs individually and pull
caudally.
Ventrodorsal collimation
For the ventrodorsal projection, the FOV should: • Include the thoracic vertebral bodies,
B
a
Figure 1. Dog positioned for lateral projection of the tho-
racic spine (A) and corresponding radiograph (B).
May/June 2013 Today’s Veterinary Practice 61
ImagIng EssEnTIals |
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with only the rib head and proximal rib bodies visualized.• Exclude the lateral body
wall and mid zone to periph-eral portion of the middle and caudal lung fields.
For all patients:• Palpate the manubrium and
the xiphoid of the sternum; collimate just cranial to the manubrium and 3 finger widths caudal to the xiphoid. • Place the center of the FOV
halfway in between these landmarks, with the horizon-tal line of the FOV placed midline.• Place the radiographic
marker on the soft tissues of the ventrum at the most lateral edge of the colli-mated FOV.
lateral projection: thoracolumbar
Junction
Due to x-ray beam divergence, it is neces-sary to include a projection of the thora-columbar (T-l) junction for a spinal radio-graphic survey that includes the thoracic and lumbar spine.
For the thoracolumbar junction lateral pro-jection, position the patient in lateral recum-bency (Figure 3). • Tape the thoracic limbs together evenly and
pull cranially in the same manner as a lateral thoracic radiograph, keeping the sternum and vertebrae equidistant to the table. • a foam wedge may be placed under the
elbows in order to maintain laterality of the patient. • Tape the pelvic limbs together evenly and
pull caudally, keeping the patient in lateral position. To determine whether or not the patient is
aligned in a lateral position and parallel to the table, gauge the superimposition of the iliac wings by palpating the wings to ensure eveness.
lateral collimation
For the lateral projection, the FOV should include T10 through l3, including spinous
processes of the re-spective vertebrae. • Palpate the junc-
tion between the last thoracic ver-tebral body (T13) and the first lumbar vertebra (l1) by following the caudal border of the last rib dor-sally to the point where it joins the vertebral column.• Place the center of
the FOV 2 finger widths caudal to this space. • Place the radio-
graphic marker to the caudal right or left of the patient to keep it from overlapping with important ana-tomic areas.
Ba
Figure 2. Dog positioned for
ventrodorsal projection of the
thoracic spine (A) and corre-
sponding radiograph (B).
B
a
Figure 3. Dog positioned for lateral
projection of the thoracolumbar spine
(A) and corresponding radiograph (B).
| ImagIng EssEnTIals
Today’s Veterinary Practice May/June 201362
aDDitional Views
Ventrodorsal oblique projection: thoracic spine
Subtle lesions, fractures, and intervertebral disk disease
are a few of the conditions that may require a ventrodor-
sal oblique projection of the spine (Figure 5).
• From the straight ventrodorsal position of the thoracic
spine, obliquely rotate the patient to the left approxi-
mately 10° to 15°; then take the radiograph.
• Rotate the patient to the right approximately 10° to 15°
and take a second radiograph.
Collimate as described for the ventrodorsal projection of
the thoracic spine (page 60). The ventrodorsal oblique tho-
racic spine projection requires a larger collimated FOV on the
lateral aspect due to the curvature of the spine in that region.
QualitY control
To make certain the desired technique has been achieved,
use the following guidelines to determine whether the ap-
propriate anatomy is included in the images.
thoracic spine
For the lateral projection of the thoracic spine:
• The cranial border should include the caudal aspect of
Ventrodorsal projection:
thoracolumbar Junction
For the thoracolumbar junction ventro-dorsal projection, position the patient in dorsal recumbency (Figure 4). • If a trough is used, place the entire
thoracic spine within the trough to eliminate edge artifacts.
• Extend the skull and neck and align with the manubrium.
• align the sternum over the thoracic spine; it should be superimposed with the thoracic spine on the final image.
• Tape the thoracic limbs either together or individually and pull cranially.
• Tape the pelvic limbs individually and pull caudally.
Ventrodorsal collimation
For the ventrodorsal projection, the FOV should: • Include the thoracic vertebral bodies,
with only the immediate rib heads and soft tissues visualized.
• Exclude the lateral body wall and lungs of the thoracic cavity.
For all patients:• Palpate the xiphoid of the sternum and
the curve of the last rib in the lateral body wall. • Place the center of the FOV halfway in between
these landmarks, with the horizontal line of the
FOV placed midline.• Place the radiographic marker on the soft tissues
of the ventrum at the most lateral edge of the colli-mated FOV.
Ba
Figure 4. Dog positioned for ventrodorsal projection of the thora-
columbar spine (A) and corresponding radiograph (B).
the cervical spine (C7).
• The caudal border should, at least, include lumbar
vertebra 1 (L1).
• For the lateral position, the rib heads should be
superimposed at the vertebral body level.
For the ventrodorsal projection of the thoracic
spine:
• The cranial border should include the caudal
aspect of the cervical spine at the level of C7.
• The caudal border should, at least, include lumbar
vertebra 1 (L1).
• The spinous processes should be superimposed over
the thoracic vertebral bodies.
thoracolumbar Junction
For the lateral projection of the thoracolumbar junc-
tion:
• The cranial border should include the caudal
aspect of the thoracic spine near the level of thoracic
vertebra 11 (T11).
• The caudal border should, at least, include lumbar
vertebra 3 (L3).
May/June 2013 Today’s Veterinary Practice 63
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a
Figure 5. Dog positioned for ventrodorsal
oblique projection of the thoracic spine, with
the sternum obliqued toward the right (A) and
corresponding radiograph (B). Ventrodorsal
oblique projection of the thoracic spine, with
the sternum obliqued toward the left (C) and
corresponding radiograph (D).
c D
B
For quality control of any diagnostic image, follow a simple 3-step approach: 1. Is the technique adequate (appropriate
exposure and development factors)?2. Is the correct anatomy present within the
image? 3. Is the positioning anatomically correct
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ImagIng EssEnTIals |
• For a true lateral position, the rib heads should be
superimposed at the vertebral body level.
For the ventrodorsal projection of the thoracolumbar
junction:
• The cranial border should include the caudal aspect
of the thoracic spine at the level of T11.
• The caudal border should, at least, include L3.
• The spinous processes should be superimposed over
the thoracic and lumbar vertebral bodies.
• In a straight dorsoventral projection, the dorsal spi-
nous processes should have a tear drop appearance. n
Suggested Reading
Burk rL, Feeney dA. Small Animal Radiology and Ultrasonography: A
Diagnostic Atlas and Text, 3rd ed. Philadelphia: Saunders elsevier, 2003.
Keely JK, McAllister H, Graham JP. Diagnostic Radiology and
Ultrasonography of the Dog and Cat, 5th ed. Philadelphia: Saunders
elsevier, 2011.
Sirois M, Anthony e, Mauragis d. Handbook of Radiographic Positioning for
Veterinary Technicians. Clifton Park, NY: delmar Cengage Learning, 2010.
Thrall de (ed). Textbook of Veterinary Radiology, 5th ed. Philadelphia:
Saunders elsevier, 2008.
Thrall de, robertson id. Atlas of Normal Radiographic Anatomy and
Anatomic Variants in the Dog and Cat. Philadelphia: elsevier Saunders,
2011.
Danielle Mauragis,
CVT, is a radiology techni-cian at University of Florida College of Veterinary Medi-cine. She teaches veteri-nary students all aspects of the physics of diagnos-tic imaging, quality control of radiographs, positioning of small and large animals, and radiation safety. Ms.
Mauragis coauthored the Handbook of Radio-graphic Positioning for Veterinary Technicians (2009) and was the recipient of the Florida Veteri-nary Medical Association’s 2011 Certified Veterinary Technician of the Year Award. This award recognizes an individual for the many outstanding contributions that person has made to the overall success of a veterinary practice operated or staffed by an FVMA member veterinarian.
Clifford R. Berry, DVM, Diplomate ACVR, is a pro-fessor in diagnostic imaging at the University of Florida College of Veterinary Medi-cine. His research inter-ests include cross-sec-tional imaging of the thorax, nuclear medicine applica-tions in veterinary medicine, and molecular imaging ap-
plications of imaging in human and veterinary medi-cine. Dr. Berry has been a faculty member at North Carolina State University and University of Missouri. He received his DVM from University of Florida and completed a radiology residency at University of California–Davis.
Terry Marie Curtis, DVM, MS,
Diplomate ACVB, is head of the
Clinical Behavior Service at the
University of Florida College of
Veterinary Medicine and also
makes house calls in Florida
and South Georgia for behavior-
related cases. Dr. Curtis is the
author of a number of peer-re-
viewed articles, including book
chapters in veterinary Clinics of North America and
Blackwell’s Five-Minute veterinary Consult (5th ed).
She regularly lectures at the NAVC Conference, is co-
ordinator for its day-long behavior symposium, and
has appeared on ABC’s Nightline and NBC’s Today
Show. Dr. Curtis received her DVM from University of
Florida and completed her veterinary behavior resi-
dency and MS in psychology at University of Georgia.
have you seen how to enhance Your
pet’s enVironMent?
This practical 1-page client handout: • Highlights signs of stress in pets
• Provides suggestions for environmental enrichment
• lists helpful links for additional ideas.
It is available for download and use in your
clinic at todaysveterinarypractice.com. select
resources; then go to client aids & handouts.
reluctant to emerge for food, attention, or litter box use
• One or more cats is particularly focused on another cat
or cats (ie, bullying behavior)
• If a behavior issue continues to manifest despite the
owner implementing the solutions provided by his or
her veterinary team
• Any combination of the above. n
References
1. wolfe rC. The Social Organization of the Free Ranging Domestic Cat (Felis
catus). Phd dissertation, University of Georgia, 2001.
2. Beaver Bv. Feline Behavior: A Guide for Veterinarians. Philadelphia: wB
Saunders, 1992, pp 181-182.
3. Pachel C, Neilson JC. Comparison of feline water consumption between
still and flowing water sources: A pilot study. J Vet Behav Clin Appl Res
2010; 5(3):130-133.
4. Chon e. The effects of queen (Felis sylvestris)-rearing versus hand-rearing
on feline aggression and other problematic behaviors. Intl Vet Behav Meet
Proc, 2005, pp 201-202.
5. Neilson JC. Feline house soiling: elimination and marking behaviors. Vet
Clin North Am Small Anim Pract 2003; 33(2):296.
6. Panaman r. Behaviour and ecology of free-ranging female farm cats (Felis
catus L). Zeitschriftfür Tierpsychologie 1981; 56:59-73.
7. Feldman HN. Methods of scent marking in the domestic cat. Can J Zool
1994; 72:1093-1099.
8. Hart BL, Barrett re. effects of castration on fighting, roaming, and urine
spraying in adult male cats. JAVMA 1973; 163(3):290-292.
9. Beaver Bv. Feline Behavior: A Guide for Veterinarians. Philadelphia: wB
Saunders, 1992, p 209.
On YOuR BEsT BEHaVIOR |
(Behavior continued from page 70)
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