The oesophagus

image of The oesophagus
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The oesophagus is a tubular structure connecting the pharynx to the stomach, and is bound at each end by a sphincter. The cranial sphincter is composed of the paired thyropharyngeal and cricopharyngeal muscles. This chapter discusses Radiographic anatomy; Interpretive principles; and Diseases.

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Image of 9.1
9.1 Left lateral view of the dorsocaudal thorax of a 9-year-old Rottweiler bitch. Note the faintly visible tubular soft tissue opacity of the oesophagus (arrowed). This can be a normal finding on left lateral radiographs, particularly in deep-chested dogs.
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9.2 Right lateral view of the dorsocranial thorax of an 8-year-old male Dalmatian. Note the summation of the dorsal tracheal wall and draping of the ventral wall of the oesophagus, resulting in a soft tissue stripe called the tracheal stripe sign (arrowed), indicative of gas in the oesophagus.
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9.3 Right lateral view of the cranial thorax of a 6-year-old male English Bulldog. Note the tortuous path (gas opacity) of the oesophagus in the thoracic inlet area. It represents a redundant oesophagus and is an incidental finding in this breed. A small amount of contrast medium helps visualize the ventral deviation of the oesophagus.
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9.4 Normal oesophagram of a mature dog. Note the longitudinal linear pattern of barium trapped between the mucosal folds.
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9.5 Normal oesophagram of a mature cat. The cranial section of the thoracic oesophagus has the same longitudinal contrast medium pattern as that of the dog (see Figure 9.4 ); however, the caudal section of the thoracic oesophagus consists of smooth muscle, which throws the mucosa into a characteristic striated herringbone appearance.
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9.6 Right lateral view of the thorax of a 3-month-old German Shepherd Dog bitch with congenital megaoesophagus. The survey radiograph illustrates that a markedly gas-distended oesophagus can easily be missed. Several hallmark features for megaoesophagus can be detected with close scrutiny: thin soft tissue lines representing the oesophageal wall (arrowed) and ventral depression of the trachea and the cardiac silhouette. Note also the gas-distended stomach. Follow-up thoracic radiograph 1 month later. Autocontrast is present within the megaoesophagus due to the presence of soaked kibble. Food had accumulated secondarily to the severe loss of oesophageal peristalsis.
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9.8 VD thoracic radiograph of a 4-year-old Boerboel bitch with an acquired megaoesophagus. Note the reduced radiopacity of the dilated craniodorsal and caudodorsal mediastinum due to the gas-filled megaoesophagus. It is indented on the left by the aorta and the right by the azygos vein (white arrows). The soft tissue stripes, representing the oesophageal wall, converge at the oesophageal hiatus (black arrows).
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9.9 Right lateral view of the thorax of a 3-month-old Irish Setter puppy with congenital megaoesophagus. Oral contrast medium mixed with a small amount of soft food has been used to distend the oesophagus. This procedure was used to rule out a vascular ring anomaly. The risks of aspiration should be considered before undertaking this procedure.
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9.10 Right lateral view of the dorsocaudal thorax of a 3-month-old Samoyed 1 hour after oral contrast medium was administered. Note the prolonged retention of contrast medium in the terminal oesophagus and irregular outline of the oesophageal wall (arrowed) consistent with oesophagitis.
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9.11 Close-up of a right lateral oesophagram of a mature cat with an iatrogenic mid-thoracic oesophageal stricture. It extends over three intercostal spaces. The oesophagus can only distend up to rib width in this area. Note also the pooling of contrast medium cranial to the stricture.
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9.12 Oesophagram of a 4-year-old Boerboel bitch with a craniodorsal mediastinal abscess. The resulting large perioesophageal mass (M) produced ventral deviation of the trachea and oesophagus. It also resulted in a perioesophageal stricture, illustrated by the thinned and deviated oesophageal column of contrast medium (arrowed), outlining the ventral extent of the mass.
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9.13 Thoracic radiographs of a 2-year-old male German Shepherd Dog with a history of regurgitation after eating solids since a puppy. Right lateral view of the cranioventral thorax. A small amount of gas can be seen in the oesophagus (white arrow). A marked oesophageal dilatation due to ingesta accumulation can be seen cranial to the heart and the mineral debris (black arrow) is seen dorsal to the sternum. The latter might be the only indication for the presence of a diverticulum. DV view. White arrows outline the soft tissue opacity of the diverticulum cranially to the heart. Also note the presence of the normal left aortic arch (black arrows). Oesophagram. Ingesta and barium accumulate in the diverticulum cranial to the heart. There is no constriction to suggest a vascular ring anomaly. Fluid tended to pool in this location and food accumulated until the distension was filled, then moved rapidly to the stomach.
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9.14 VD view of the caudal thorax of an 11-year-old Boxer bitch diagnosed with an oesophageal leiomyosarcoma. Note the relatively well defined, slightly irregular soft tissue opacity in the terminal oesophagus area (T) and the gas-dilated oesophagus cranial to it (arrowed).
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9.15 Right lateral view of the mid dorsal thorax of a mature dog. The trabeculated appearance of the structure at the heart base is consistent with a bony foreign body. Note also the small amount of cranial oesophageal air, causing a tracheal stripe sign.
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9.16 Right lateral oesophagram of an immature dog. Note the multiple filling defects in the oesophagus caused by radiolucent foreign bodies.
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9.17 Right lateral view of the thorax of a 6-week-old Great Dane bitch (slightly rotated). The oesophagus is markedly gas distended with a constriction at the fourth rib visible as a thin soft tissue band. Note also the accumulation of mineral debris and ingesta in the cranial oesophageal diverticulum and the markedly gas distended caudal oesophagus. There is also gas in the stomach. Findings are consistent with a vascular ring anomaly.
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9.18 DV view of the cranial thorax of a 5-week-old Boerboel bitch with a history of regurgitating solids. Note the moderate focal leftward curvature of the trachea near the cranial border of the heart (arrowed) consistent with a vascular ring anomaly. This sign is reportedly present in 100% of PRAA cases. The focal narrowing of the trachea is present in 74% of DV/VD radiographs of dogs with this condition.
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9.19 Oesophagram of an 8-week-old Staffordshire Bull Terrier in right lateral recumbency. Note the prominent linear filling defect at the level of the fourth intercostal space as well as the cranially dilated oesophagus consistent with a vascular ring anomaly.
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9.20 DV view of the terminal oesophagus in a mature dog. In cases of suspected infection, it is always essential to follow the left outline of the aorta (white arrows). A second bulge in this area (black arrows) is consistent with an oesophageal granuloma and/or aortic aneurysm secondary to infection.
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9.21 Right lateral view of the dorsocaudal thorax of a 4-year-old Labrador Retriever bitch. Survey radiograph. An ill defined faint soft tissue opacity can be seen in area of the terminal oesophagus (G). Note the slightly irregular outline of the dorsal aortic arch consistent with aortic aneurysm (arrowed). Pneumo-oesophagram, resulting in an air-dilated oesophagus, highlighting the oesophageal granuloma (G).
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9.22 Oesophagram showing a small dorsal oesophageal wall filling defect consistent with a granuloma. Note also the thoracic spondylitis (arrowed), considered to be pathognomic for infection. Caudally there is also spondylosis deformans.
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9.23 Transverse CT image obtained immediately caudal to the carina of an 8-year-old neutered male Dalmatian (window level −215 HU, window width 1996 HU (lung window)). A granuloma is visible in the oesophagus (arrowed). The mineralization within is indicative of malignant transformation (osteosarcoma or fibrosarcoma). Note also the small amount of gas within the remaining oesophagus dorsal to the mass. The aorta (A) also contained a very small amount of mineralization. The heart (H) is also identified.
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9.24 Sagittal ultrasound image of a normal oesophagus crossing the diaphragm from the thoracic cavity into the abdomen in a 6-month-old mixed breed dog with a small amount of pleural effusion (P). The oesophagus is shown by the arrowheads. The liver (L) is seen in the near field. Transverse ultrasound image of the terminal oesophagus of a 7-year-old male Staffordshire Bull Terrier using the liver (L) as acoustic window. Compare the 5 × 4 cm bilobed medium echogenicity of the granuloma (callipers) to the normal oesophagus shown in (a). The arrow points to the ventral oesophageal wall.
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9.25 Thoracic radiographs of an 8.5-year-old German Shepherd Dog previously diagnosed with idiopathic megaoesophagus and now presented with rapid deterioration. Right lateral view. A well defined soft tissue opacity can be seen in the oesophagus with a markedly gas-distended oesophagus (arrowed) cranially. In addition, the lack of a cranial abdominal gastric silhouette, ventral displacement of the trachea and the cardiac silhouette are consistent with a gastro-oesophageal intussusception. On occasion rugal folds will be seen entering the caudal oesophagus and further assist with the diagnosis. DV view. Rightward displacement of the trachea can be seen. Arrows indicate the gastro-oesophageal intussusception.
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9.26 Oesophagram of a 3-month-old male Shar Pei. Note the abrupt cessation of the contrast medium passage, a large soft tissue opacity in the oesophagus and the absence of the gastric silhouette in the cranial abdomen, which are consistent with a gastro-oesophageal intussusception.
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