What is CT (Computed Tomography) enterography?

CT Enterography: Definition and Clinical Applications

CT enterography is a specialized CT examination that uses large volumes of neutral oral contrast to optimally distend the small bowel, combined with thin-slice CT imaging and intravenous contrast to visualize the small bowel wall and lumen in detail. 1

Key Technical Specifications

• Oral Contrast Administration:

  • 1300-1800 cc of neutral contrast (near water density)
  • Administered over 30-60 minutes before imaging
  • Imaging conducted at 60 minutes after contrast administration 1, 2

• Technical Parameters:

  • Thin collimation (2-3 mm slice thickness)
  • Multiplanar reconstruction
  • Intravenous contrast administration
  • Imaging timed between enteric and portal phases (50-70 seconds after IV contrast) 1

• Imaging Coverage:

  • Abdomen, pelvis, and perineum (including anal sphincter complex) 1

Advantages Over Standard CT

• Enhanced Small Bowel Visualization:

  • Neutral contrast allows evaluation of mucosal enhancement
  • Detects subtle inflammation that would be obscured by positive contrast agents
  • Provides optimal distention of bowel lumen 1, 2

• Superior Diagnostic Performance:

  • Sensitivity for Crohn's disease: 75-90%
  • Specificity for Crohn's disease: >90% 1

Clinical Applications

• Primary Applications:

  • Diagnosis and evaluation of Crohn's disease
  • Assessment of small bowel inflammation beyond the reach of colonoscopy
  • Detection of transmural disease with normal-appearing mucosa
  • Evaluation of suspected small bowel bleeding 1

• Disease Characterization:

  • Active inflammation: wall thickening, mural stratification, hyperenhancement
  • Strictures: persistent luminal narrowing with upstream dilation
  • Penetrating complications: fistulas, sinus tracts, abscesses 1

Limitations and Pitfalls

• Technical Challenges:

  • Inadequate small bowel distention due to insufficient ingestion
  • Gastric retention or rapid small bowel transit
  • Frequently collapsed jejunal segments 3

• Interpretive Challenges:

  • Peristaltic contractions mimicking pathology
  • Transient intussusception
  • Opaque intraluminal debris (especially problematic when evaluating GI bleeding) 3

• Patient Considerations:

  • Requires patient ability to tolerate large volumes of oral contrast
  • Uses ionizing radiation
  • Cannot detect isolated mucosal abnormalities (e.g., aphthous ulcers) 3, 4

CT enterography has become a first-line imaging modality for small bowel disorders, particularly Crohn's disease, offering comprehensive evaluation of bowel wall pathology and extraenteric complications in a single examination.