The esophagus can be a difficult organ to image. Commonly used diagnostic imaging modalities, such as radiography, esophagography, ultrasonography, and endoscopy, have limitations for evaluation of the esophagus.1–3 In dogs, positive-contrast esophagography is frequently used to identify pathological esophageal lesions, but there is a risk patients may aspirate the contrast agent (eg, barium) or that the contrast agent may obscure visibility of small nodules.3 Ultrasonographic evaluation of the thoracic portion of the esophagus is hampered by the interposition of aerated lungs. Results of 1 study1 suggest that endoscopic ultrasonography may be useful for assessing esophageal wall integrity, but that modality is currently not readily available in most clinical settings. Endoscopy is a noninvasive atraumatic technique that allows visual inspection of the esophageal lining and biopsy of visible lesions, but it cannot be used to identify or evaluate periesophageal abnormalities, such as lesions located in the adjacent lymph nodes or lesions located in the muscular or submucosal layers of the esophagus, or to accurately describe the location and extent of lesions for surgical planning.2
Computed tomography is useful for evaluation of the location, severity, and extent of esophageal lesions as well as surrounding structures, and it is often used to glean information about lesion size and surrounding structures during tumor staging and surgical resection planning.4–9 The entire length of the esophagus can be evaluated with CT. In CT images, the esophagus appears as a round or ovoid shape with a soft-tissue density in the cervical and thoracic regions and has a more triangular shape at its most caudal aspect.10 However, the esophagus is a collapsible organ and is generally in a collapsed state. Collapse of the esophageal lumen or contraction of the muscular wall during the acquisition of standard unenhanced or contrast-enhanced CT images limits the information that can be obtained in regard to the extent and invasiveness of lesions. Several techniques can be applied to overcome that drawback, including use of oral effervescent granule contrast agents, an oxygen bag, or CO2 to achieve esophageal distention.5,7–9,11,12 In human medicine, the use of CO2 to distend the esophageal lumen is considered superior to other alternatives. That technique requires a continuous supply of CO2 to distend and maintain a pressure of 10 to 20 mm Hg within the esophageal lumen throughout the CT scan.5,9
The introduction of multidetector CT has made CT much more readily available in veterinary practice, and CT is frequently used to evaluate the gastrointestinal tracts of veterinary patients.13,14 A poorly distended gastrointestinal lumen can obscure luminal lesions such as nodules and masses, thereby decreasing the diagnostic efficacy of most imaging modalities including CT, and techniques such as CT-pneumocolonography and hydro-CT have been developed to circumvent that obstacle.15–17 In veterinary species, insufflation of gas through an orogastric or endotracheal tube is commonly used to distend the esophageal lumen and facilitate the delineation of intraluminal and mural masses during diagnostic imaging.3,4,10 However, detailed data regarding the optimal insufflation pressure to achieve continuous and consistent esophageal distention in dogs are currently unavailable.
The objective of the study reported here was to assess the feasibility of EICT for evaluation of the entire extent of the esophagus in dogs. We hypothesized that EICT, by which CO2 was insufflated into the esophagus during CT scanning, would be a feasible and noninvasive method for evaluation of the entire esophagus and its surrounding structures. A secondary objective was to determine whether images acquired by EICT could be used for MPR and virtual endoscopy.
Supported by the Research Institute for Veterinary Science, Seoul National University.
Esophageal insufflation CT
Yushin Medical Co Ltd, Bucheon, South Korea.
Aquilion 64, Toshiba Medical Systems Corp, Ωtawara, Japan.
Endoflator, Karl Stortz, Tuttlingen, Germany.
Omnipaque 300, GE Healthcare, Cork, Ireland.
INFINITT, Infinitt Healthcare Co Ltd, Seoul, South Korea.
Vitrea 2, Vital Images Inc, Minnetonka, Minn.
SPSS Statistics for Windows, version 23.0, IBM Corp, Armonk, NY.
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