According to US researchers who conducted meta-analysis of 33 prospective studies, ultrasound or MRI should be the imaging modality of choice in inflammatory bowel disease (IBD). While colonoscopy and barium examination can also be used, these methods are time consuming. Moreover, colonoscopy is invasive and may result in perforation in severe ulcerative colitis. Reported sensitivities and specificities of other options, such as ultrasonography, CT, MRI and scintigraphy, vary and, hence, are not extremely reliable.