Computed Tomography and Magnetic Resonance Enterography: From Protocols to Diagnosis

Abstract

Both Magnetic Resonance Enterography (MRE) and Computed Tomography Enterography (CTE) are crucial imaging modalities in the diagnosis and treatment of inflammatory bowel disease (IBD). CTE is often used in acute scenarios, such as when complications (such as abscesses, perforations, or bowel obstructions) are suspected. It can also help determine the degree and extent of pathological processes. Although CTE is rapid, generally accessible, and offers precise images that are useful in emergencies, it does expose patients to ionizing radiation. Nevertheless, MRE is very useful in assessing perianal illness and the small intestine, and it is frequently used in patients who need repeated follow-ups or are pregnant to minimize radiation exposure. Moreover, MRE can demonstrate oedema, fistulas, abscesses, and the thickening of the bowel wall. In addition, MRE offers superior soft tissue contrast resolution without ionizing radiation, which helps identify complications such as fistulas and abscesses. With their respective advantages and disadvantages, both approaches play essential roles in assessing IBD. The primary goal of this review is to provide an overview of the technical specifications, benefits, drawbacks, and imaging findings of CTE and MRE.

Keywords: Crohn’s disease; computed tomography enterography; inflammatory bowel disease; magnetic resonance enterography.

Figure 1

A 52-year-old male underwent CTE for bowel evaluation with a known history of Crohn’s disease. The patients reported multiple episodes of diarrhea, with increased laboratory inflammatory indexes. CT coronal multiplanar reconstruction on the portal venous phase is reported in (A,B). The most critical findings in (A) are diffuse and multiple small bowel wall thickening (red arrows) associated with comb sing (yellow arrow), peri-visceral oedema (green arrow), and enlarged nodes (purple arrow). In (B), it is possible to detect a significant thickening of a small bowel loop (red arrow), with homogeneous contrast enhancement, associated with a slight dilation of the upstream bowel portion.

Figure 2

A 44-year-old male suspected of Crohn’s disease underwent MRE for the evaluation of bowel loops. The patients reported multiple episodes of constipation and diarrhea, with laboratory inflammatory indexes in range. Coronal T2WI (A) and T1WI (B) after contrast media administration. The most important finding is the thickening of the terminal ileum (A—yellow arrows), characterized by increased contrast enhancement (B—yellow arrow). Notably, the enhancement pattern is known as trilaminar, considering the lack of enhancement of the submucosal layer. The reported findings align with Crohn’s disease in the activity phase.

Figure 3

A 49-year-old man with Crohn’s disease involving the neo-terminal ileum. Coronal FIESTA (A) and SSFSE T2WI (B) show a thickened neo-terminal ileum with an increased T2 signal. Axial DWI (b = 1000) (C) image at the same level reveals increased intramural signal, indicating restricted diffusion, and the post-contrast axial T1WI (D) demonstrates intensely, layered pattern enhancement (mural stratification), consistent with active inflammation.

Figure 4

A 56-year-old man suffering from Crohn’s disease affecting the mid-distal section of the ileum with stenotic/substenotic and ecstatic features. Coronal (A) and axial (B) T2WI SSFSE images show multiple wall thickenings with a high T2 signal at the level of the ilium. The axial DWI (b = 1000) (C) image reveals increased intramural signal intensity, indicating restricted diffusion of the multiple thickened tracts. Coronal (D) and axial (E) post-contrast T1WI demonstrate intense wall structure multilayer enhancement.