Diagnosis may be made with a double-contrast barium esophagram. This test shows nodularity, irregular narrowing, ulceration, abrupt angulation or stiffness of the esophagus. Endoscopy is more sensitive for detection of esophageal cancer because it allows for direct visualization of the affected area and biopsy and/or brush cytology of affected tissue. Additionally, EUS or endoscopic ultrasound, a highly technical, low-risk procedure, allows imaging at close proximity to detect subtle mucosal changes. Screening endoscopy is performed on patients who are at increased risk of developing esophageal cancer such as those with Barrett's esophagus.