Front Matter

510 Canine Sports Medicine and Rehabilitation

Nuclear scintigraphy

In canine sports medicine and rehabilitation,
nuclear scintigraphy may be very useful in
localization of lameness attributable to bone
lesions that are not apparent on radiographs.
Studies have been performed in dogs that high-
light this clinical application, including locali-
zation of occult lameness, diagnosis of medial
coronoid disease, and bone injuries in racing
Greyhounds (Tobin et  al., 2001; Schwarz et  al.,
2004; Van Bruggen et al., 2010). In these studies,
radiography was inconclusive in identifying
the source of the pathological changes in
question.
Nuclear scintigraphy is a visual representa-
tion of physiological processes rather than an
image of an anatomic structure. After intrave-
nous injection of a radiopharmaceutical, tech-
netium‐99 m methyl‐diphosphonate, labeled
to target phosphate in bone, the dog is placed
in front of a gamma camera. The gamma

camera uses scintillation material to pick up

energy produced by decay of the isotope dis-

tributed in the tissues being studied (Driver,

2003). An image is produced from the pro-

cessing of these gamma‐emissions showing

the uptake of the radiopharmaceutical. The

radiopharmaceutical itself is composed of a

radionucleotide and a pharmaceutical.

Technetium‐99 is the most common isotope

used in bone scintigraphy due to its ideal

half‐life and ability to bind well to diphos-

phate salts. Diphosphate salts are the primary

pharmaceutical used because they localize to

bone by binding to hydroxyapatite crystals

that are exposed during bone remodeling

(Driver, 2003). When increased uptake of the

radiopharmaceutical is observed, it reflects

increased activity in that area of bone related

to  blood flow and osteoblastic activity. This

increased activity, indicating potential pathol-

ogy, can be observed before bone changes are

apparent radiographically.

Fatty replacement

myotendinous

junction

Tear

Figure 20.9 T2‐weighted sagittal image of the

shoulder. The yellow arrow indicates the tear in the

supraspinatus tendon at the insertion. The red arrow

indicates fatty replacement of the normal tendon at

the myotendinous junction. Source: Image courtesy

of Dr. Pat Gavin.

Figure 20.10 Cross‐sectional image of the

supraspinatus tendon at the insertion on the greater

tubercle. The tendon is enlarged at 0.92 cm^2 in cross‐

sectional area. Enlargement of the tendon is causing

compression of the biceps tendon within the bicipital

groove (blue arrow). The hypoechoic tear is indicated

by the red arrow. A hyperechoic area of mineralization

or fibrosis is indicated by the yellow arrow.