Qualitative elastography by endoscopic ultrasound in the restaging of the irradiated rectal tumor

Introduction: Qualitative endoscopic ultrasound elastography can identify fibrosis and differentiate it from residual tumor in the re-staging of patients with irradiated rectal tumors. Objective: To determine the usefulness of qualitative endoscopic ultrasound elastography in the re-staging of the irradiated rectal tumor. Methods: An observational and descriptive study (series of cases) was carried out in 31 patients with irradiated rectal tumor, restaged by means of Qualitative elastography by endoscopic ultrasound. To determine the usefulness of elastography, the following were calculated: sensitivity, specificity, positive predictive value, negative predictive value, Youden index and diagnostic agreement according to kappa, elastography and endoscopic ultrasound separately; these results were compared in both diagnostic tests. The histological study of the surgical specimen was the reference standard. Results: The concordance index of endoscopic ultrasound (77.4%), that obtained by elastography (87.1%). Endoscopic ultrasound showed greater sensitivity and negative predictive value than elastography, so the possibility of ruling out the presence of a tumor with a negative result was higher. Elastography had greater specificity (77.78%) and positive predictive value (90.91%) than endoscopic ultrasound (22.22 and 75.86%); it was most helpful in confirming the tumor diagnosis. Conclusions: The usefulness of qualitative elastography associated with endoscopic ultrasound, in the re-staging of the irradiated rectal tumor, consists in increasing the specificity of the study, thus allowing a better discernment between fibrosis and residual tumor.