Computed tomographic evaluation of pectus excavatum in 14 cats

Abstract

Pectus excavatum (PE) is one of the most frequently reported chest deformities. However, limited studies are available with regard to its CT scan findings in cats. In the present research computed tomographic images of the thoraxes of 14 cats diagnosed with PE has been reviewed. This is one of the first studies exploring the use of CT to characterise PE in animals. The aim of this study was to present characteristic CT features of PE in cats. The introduction of new criteria for better assessing thoracic wall deformity–a correction index (CI) and an asymmetry index (AI)–was also proposed. The study revealed a high variety of morphological features of PE in cats. It was demonstrated that among the 14 cats: cranial PE (an atypical location) occurred in seven cats while seven cats had typical (caudal) PE, long PE occurred in five cats, while short PE had nine cats. Of the 14 cats included in the study eight showed symmetric PE, and asymmetric PE was found insix. Thoracic asymmetry was found in six cats. Six cats had sternal torsion. Based on the Vertebral Index moderate or severe PE was revealed in 11 animals. In the group of cats studied the CI ranged from 12.20 to 32.11. The magnitude of AI did not exceed 10% in any of the cats studied. The study confirmed statistically significant differences in the CI values between groups of cats with different degrees of PE severity (p = 0.02). CT examination showed many PE features that have not been discussed so far. The main benefit of CT examination is its ability to reveal asymmetric PE, thoracic asymmetry and sternal torsion. CI and AI provided a clinically useful tool to quantify thoracic wall deformity in order to obtain comparable results between cats with PE.

Sternal Abnormalities on Thoracic Radiographs of Dogs and Cats

“…A large proportion (67%) of affected cats in our study population had an atypical location of pectus excavatum, in which the dorsal deviation affects the cranial and mid-section of the sternum. This was also reported in a recent publication on computed tomographic features of pectus excavatum in cats, in which half the cats had the atypical form of the disorder [ 11 ]. That study found mild pectus excavatum in only 21.5% of cats, whilst most of the cats included had moderate or severe pectus excavatum.…”

“…Moreover, computed tomography would allow a better representation of the anatomy. For instance, computed tomography was reported to be useful for evaluation of thoracic asymmetry and sternal torsion in cats with pectus excavatum, which cannot be done with radiography [ 11 ]. In addition, the use of intravenous iodinated contrast medium in computed tomography would allow for better characterization of potential soft tissue abnormalities, such as inflammation [ 18 ].…”

“…The vertebral index was calculated as a measure of severity of pectus excavatum using the vertebra overlying the deviation at the most depressed point of the thoracic wall [ 11 , 12 , 22 ]. The severity of pectus excavatum was characterized as mild if the vertebral index was >9, moderate if the vertebral index was 6–8.99, and severe if the vertebral index was <6, as previously described [ 11 , 23 ]. The type of pectus excavatum was determined based on the anatomical location of the deformity of the sternum and rib cartilage.…”

“…Congenital malformation of the sternum can consist of dorsal or ventral deviations (pectus excavatum and pectus carinatum, respectively), as well as numeric or shape changes, such as cleft sternum. Sternal malformations sometimes form a part of a larger congenital defect with expansion to the adjacent thoracic and abdominal structures as well as diaphragmatic cupula [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Acquired sternal abnormalities include neoplasia [ 14 ], traumatic or pathological fracture and luxation [ 15 , 16 , 17 ], infection [ 18 , 19 , 20 ], and degenerative disease of the intersternebral cartilage [ 21 ].…”