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Diagnostic imaging features of normal anal sacs in dogs and cats

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ABSTRACT

This study was conducted to provide normal reference features for canine and feline anal sacs using ultrasound, low-field magnetic resonance imaging (MRI) and radiograph contrast as diagnostic imaging tools. A total of ten clinically normal beagle dogs and eight clinically normally cats were included. General radiography with contrast, ultrasonography and low-field MRI scans were performed. The visualization of anal sacs, which are located at distinct sites in dogs and cats, is possible with a contrast study on radiography. Most surfaces of the anal sacs tissue, occasionally appearing as a hyperechoic thin line, were surrounded by the hypoechoic external sphincter muscle on ultrasonography. The normal anal sac contents of dogs and cats had variable echogenicity. Signals of anal sac contents on low-field MRI varied in cats and dogs, and contrast medium using T1-weighted images enhanced the anal sac walls more obviously than that on ultrasonography. In conclusion, this study provides the normal features of anal sacs from dogs and cats on diagnostic imaging. Further studies including anal sac evaluation are expected to investigate disease conditions.

No MeSH data available.


Dorsal (A, B and E) and transverse (C and D) low-field MRI T1-weighted images of canine (A–C) and feline (D and E) anal sac. Increased signal intensity of anal sac tissue was identified on T1-weighted enhanced images (B). Asterisks, fat of ischiorectal fossa; arrow, levator ani muscle; arrow heads, external sphincter muscle; dagger, anal sac contents; r, rectum.
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Figure 5: Dorsal (A, B and E) and transverse (C and D) low-field MRI T1-weighted images of canine (A–C) and feline (D and E) anal sac. Increased signal intensity of anal sac tissue was identified on T1-weighted enhanced images (B). Asterisks, fat of ischiorectal fossa; arrow, levator ani muscle; arrow heads, external sphincter muscle; dagger, anal sac contents; r, rectum.

Mentions: The anatomic appearance of the anal sacs on low-field MRI was similar to that of ultrasonography in the same section. However, low-field MRI provided more distinct features than ultrasonography, with wide range images of the anal sacs and adjacent structures (panels A and C in Fig. 5).


Diagnostic imaging features of normal anal sacs in dogs and cats
Dorsal (A, B and E) and transverse (C and D) low-field MRI T1-weighted images of canine (A–C) and feline (D and E) anal sac. Increased signal intensity of anal sac tissue was identified on T1-weighted enhanced images (B). Asterisks, fat of ischiorectal fossa; arrow, levator ani muscle; arrow heads, external sphincter muscle; dagger, anal sac contents; r, rectum.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037300&req=5

Figure 5: Dorsal (A, B and E) and transverse (C and D) low-field MRI T1-weighted images of canine (A–C) and feline (D and E) anal sac. Increased signal intensity of anal sac tissue was identified on T1-weighted enhanced images (B). Asterisks, fat of ischiorectal fossa; arrow, levator ani muscle; arrow heads, external sphincter muscle; dagger, anal sac contents; r, rectum.
Mentions: The anatomic appearance of the anal sacs on low-field MRI was similar to that of ultrasonography in the same section. However, low-field MRI provided more distinct features than ultrasonography, with wide range images of the anal sacs and adjacent structures (panels A and C in Fig. 5).

View Article: PubMed Central - PubMed

ABSTRACT

This study was conducted to provide normal reference features for canine and feline anal sacs using ultrasound, low-field magnetic resonance imaging (MRI) and radiograph contrast as diagnostic imaging tools. A total of ten clinically normal beagle dogs and eight clinically normally cats were included. General radiography with contrast, ultrasonography and low-field MRI scans were performed. The visualization of anal sacs, which are located at distinct sites in dogs and cats, is possible with a contrast study on radiography. Most surfaces of the anal sacs tissue, occasionally appearing as a hyperechoic thin line, were surrounded by the hypoechoic external sphincter muscle on ultrasonography. The normal anal sac contents of dogs and cats had variable echogenicity. Signals of anal sac contents on low-field MRI varied in cats and dogs, and contrast medium using T1-weighted images enhanced the anal sac walls more obviously than that on ultrasonography. In conclusion, this study provides the normal features of anal sacs from dogs and cats on diagnostic imaging. Further studies including anal sac evaluation are expected to investigate disease conditions.

No MeSH data available.