On all imaging modalities, diverticular sacs are visualized as rounded and oval saccular outpouchings extending beyond the bowel wall. Multidetector computed tomography (CT) is the main imaging modality for diverticular disease and its complications; however, it is not infrequent that it is diagnosed or suspected on other modalities. In the context of suspected diverticulitis, a contrast-enhanced CT is currently the initial study recommended. Magnetic resonance imaging (MRI) can effectively diagnose diverticular disease and may be the initial diagnostic study in the context of pregnant women with suspected diverticulitis. Ultrasonography may be the initial diagnostic study in the context of pregnant women with suspected diverticulitis if MRI is not readily available. Abscesses can be intramural, pericolic or distant to the site of diverticulitis. Free perforation that is not contained by the mesocolon or walled off into an abscess is the most important finding on CT to indicate the need for surgery. Colovesical fistula is the most common type of diverticulitis-related fistula. Acute diverticulitis can lead to infection of the mesenteric venous vessels, leading to septic thrombosis and hepatic abscesses. Colon carcinoma in a segment affected by diverticulosis can be impossible to differentiate from a diverticulitis, with diagnosis uncertainty on CT reported up to 25%.