CT Enterography: Negative oral contrast and Scanning Protocol

CT Enterography Standards

Comprehensive Preparation, Acquisition & Interpretation Guide

Created by Dr. Sharad Maheshwari

I. Ingestion Timeline

1.5L - 2.0L Target

1

T-60m

2

T-30m

3

Scan

II. Acquisition Strategy

Anti-peristaltic: Administer 20mg IV Buscopan immediately before scan to ensure bowel stillness and optimal wall assessment.

Phase 1

Plain Scan

Phase 2

Late Arterial

Phase 3

Venous Phase

Select a phase to view clinical utility and radiation dose considerations.

Radiation Stewardship (ALARA)

Evidence suggests that for routine Crohn's follow-up, skipping the plain and arterial phases significantly reduces radiation without compromising diagnosis of abscesses or strictures.

RESEARCH: Single-Phase Venous is sufficient in >85% of cases.

Protocol Consistency

Essential for longitudinal assessment. Changes in wall thickness or comb sign must be compared to baseline using identical phases.

Neutral Contrast Rule

Neutral contrast (Mannitol/Water) is strictly preferred to assess mural enhancement; positive contrast masks hypervascularity.

Image Interpretation Toolkit

Reporting Expectations Checklist

Small Bowel Segments

Bowel Distension

Assess loop distribution and adequacy of luminal diameter.

Wall Characteristics

Thickness, enhancement pattern, and mural stratification.

Strictures

Identify transition points and pre-stenotic dilatation.

Complications

Fistulae & Abscesses

Check for entero-enteric fistulae or fluid collections.

Inflammatory Masses

Assess for phlegmon or mesenteric conglomerate loops.

Extra-luminal / Solid Organs

Mesenteric Findings

Fat stranding, Comb sign (engorged vasa recta), Lymphadenopathy.

Solid Abdominal Organs

Explicit assessment of Liver, Spleen, Kidneys, and Peritoneum.

Neutral Agent Efficacy Chart

Created by Dr. Sharad Maheshwari

AJR Am J Roentgenol Radiology RSNA-Aligned