Introduction: Gorge carcinoma or carcinoma of esophagus is one of the most commonly occurring malignancies in developing countries. In these patients, dysphagia for liquids is one of the most common complaints, resulting in unwillingness of the patient to swallow contrast containing liquid. The objective of the study was to find an alternative technique to the currently existing techniques for evaluating esophageal carcinoma.
Materials and methods: Twenty patients with endoscopically proved cases of esophageal cancer were examined with CT thorax using AIR (negative) as a contrast agent-negative contrast computed tomography scan. Only the mid- and lower third esophageal malignant cases were included in the study. Upper third esophageal malignancy and lesions causing complete obstruction were excluded from the study. All cases were scanned using single-slice Somatom-4 (Siemens). NECT scan was done after intravenous injection of Buscopan. A total of 450-600 ml of air is introduced through a 14G Ryle's tube, both manually and as a continuous flow. IV contrast is given simultaneously, and a CECT scan is done. Multiplanar reconstructions were done in all patients.
Results: Significant distension of the normal esophagus was noted. However, very minimal distension of the esophageal lumen was noted at the carcinomatous site--called the "streak sign" as air is seen as a thin streak within the narrowed lumen. In some cases, intraluminal polypoid growth could be seen. No significant complications were noted except for throat irritation. We conclude that usage of air as negative contrast in identifying carcinoma of mid- and lower third esophagus is safe, cost-effective, and feasible and can be used as an alternative technique in patients who are not readily willing to swallow liquid contrast.