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Fig 2: Dorsoventral radiograph of the nasal cavity and paranasal sinuses (a) and transverse CT image at the level of M2 (the 10’s) in a Quarter Horse (right is to the left). Radiography shows that the left PM4 (tooth 208 in the Triadan system) is fractured (arrow) and there is an increase of opacity within the left rostral maxillary sinus (asterisks). Computed tomography showed an abscess with granular appearance within the left conchal (arrowheads) and left rostral maxillary sinuses secondary to a fractured PM4 (208) (not shown).
TABLE 3: Radiographic sensitivity, specificity, positive and negative predictive values for identifying sinus involvement confirmed by CT in horses of Group A
Rostral maxillary Caudal maxillary Conchofrontal Sphenopalatine Ventral conchal
Sensitivity (%) 67.9 (57.9–77.8)
75 (65.7–84.3) 65.2 (55.0–75.4) 16.7 (8.7–24.6) 43.5 (32.9–54.1)
Specificity (%) 92.9 (87.4–98.4)
95 (90.3–99.7) 96.7 (92.9–100) 100 (96.5–100) 100 (96.5–100)
PPV = positive predictive values, NPV = negative predictive values.
stylohyoid (n = 1) and petrous temporal (n = 1) bones, fluid accumulation within the tympanic bulla (n = 2) and luxation of the temporohyoid articulation (n = 2) (Fig 4). In all cases the condition was unilateral. Incidentally, a hyperattenuating, rounded and well-defined soft tissue mass lateral to the temporomandibular joint (TMJ) was found in one horse. Histological diagnosis was melanoma. There was one case of otitis media and externa.
Computed tomography findings included the presence of fluid accumulation within the tympanic bulla and tissue thickening of the external ear canal. Computed tomography allowed identification of
abnormalities in the TMJ in 2 cases. Computed tomography findings in the first one included permeative lysis of the mandibular articular surface with periarticular new bone formation and associated soft tissue swelling. Histological diagnosis was osteomyelitis and infectious arthritis. The second horse was the botryomycosis case previously described, showing marked osteolysis of both articular surfaces. Radiographic findings in the first case consisted of mild
© 2015 EVJ Ltd
periarticular new bone formation, while the botryomycosis case presented a large bony mass at the level of the zygomatic arch. Computed tomography findings for the nasofrontal suture
exostosis included endosteal and periosteal elevation adjacent to widened and irregular sutures between the frontal, maxillary, nasal and lacrimal bones. Computed tomography dacryocystography showed a focal narrowing of the nasolacrimal duct due to the new bone formation in the area of the affected sutures, resulting in partial obstruction of both nasolacrimal ducts.
Soft tissue disease (Group C) Six horses were included in this group; 3 retrobulbar masses, one acute subdural haematoma, one nuchal ligament bursitis and one parotid mucocele. Radiographs were not performed in any of the horses included in this group. Retrobulbar masses appeared as a well-defined, rounded
and homogeneous structure in the retrobulbar space with an average CT attenuation value of 47 HU. Mass effect and
PPV (%)
82.6 (74.5–90.7) 85.7 (78.2–93.2) 88.2 (81.4–95.1) 100 (96.5–100) 90.9 (84.8–97.1)
NPV (%)
85.3 (77.7–92.8) 90.5 (84.2–96.8) 88.1 (81.1–94.9) 81.5 (73.2–89.8) 82.2 (74.0–90.4)
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