Interpretation of the ileocecal valve on computed tomography colonography: Analysis of normal cases and educational cases

Abstract

Background and Objectives: The ileocecal valve is a common pitfall in computed tomography (CT) colonography interpretation, resulting in false-negative and false-positive findings. Notably, studies on the features of the ileocecal valve using CT colonography are lacking. This study examined the characteristics of normal ileocecal valves on CT colonography and analyzed educational cases to assist clinicians with accurate interpretation.

Methods: Among participants who underwent CT colonography screening, we analyzed the characteristics of 188 normal ileocecal valves in the two-position images of 94 participants. A normal ileocecal valve was defined as a case in which a colonoscopy was performed within 18 months after CT colonography and no tumor or polyp was identified in the ileocecal valve. In addition, two educational cases were presented. The first was a false-positive case. The second case was a cancer case from a different cohort that was not a normal case.

Results: The morphology of the normal ileocecal valve was the papillary type in 53%. The mean size of the papillary type of ileocecal valve was 20.7 mm, with a maximum size of 33.0 mm. Eighteen percent of normal ileocecal valves exhibited irregularities or asymmetries such as unnaturally raised areas. In multiplanar reconstruction images, 88%, 7%, and 2% of the normal ileocecal valves exhibited a mix of low- and high-density areas to various degrees, nearly uniform low attenuation, and nearly uniform high density, respectively. Notably, a few cases showed nearly uniform high density in the supine position, and not in the second position. The first case presented was a false positive due to an enlarged ileocecal valve. This case was found to be lipomatosis as a normal variant of the ileocecal valve and was a mixture of low- and high-density areas. The second case presentation was a cancer case. In this case, the ileocecal valve was replaced by cancer, showing an irregular shape and uniform high density.

Conclusion: The presence of low-density areas in normal ileocecal valves aids in distinguishing them from lesions; however, the degree of low-density areas varies widely. Although the ileocecal valve exhibits morphological variation, the presence of uniform high-density areas is suggestive of a lesion. Knowledge of the characteristics of the normal ileocecal valve on CT colonography facilitates accurate interpretation.