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Imaging procedures, non-endoscopic

Imaging procedures, non-endoscopic

IBD Curriculum Topic 3.1

IBD Curriculum Topic 4.1

General advice

ECCO-ESGAR statement 2H (2013)

High radiation exposure and earlier age of exposure both increase the risk of radiation-induced cancer [EL 2]. Independent predictors of increased radiation exposure in IBD patients are: diagnosis of CD, need of steroids, IBD related surgery, increasing severity, upper gastrointestinal tract involvement, the first year following diagnosis and young age of disease onset [EL 2].

[2025] Diagnostics GL.2 - Recommendation 56

All cross-sectional imaging [IUS, MRE, and CT] reporting should include an indication, scan quality, and any uncertainties in interpretation. The description of all segments examined should be reported in detail and images stored and available in an electronic patient file. We recommend using a picture archiving and communication system for digital storage [EL3].

MRI

ECCO-ESGAR Imaging Statement 2D (2013)

MRI of the small bowel and colon requires fast imaging techniques and luminal distension [EL 2]. MR enterography/enteroclysis has similar diagnostic accuracy and similar indications to CT, but with the major advantage of not imparting ionizing radiation [EL 1].

[2025] Diagnostics GL.2 - Recommendation 52

MRE should be performed with a suitable oral contrast agent such as mannitol or PEG [EL3]. Contrast-enhanced images using intravenous gadolinium are suggested for assessment of perianal fistulizing disease [EL3]. Routine use of contrast-enhanced images using intravenous gadolinium may not be necessary in MRE studies [EL2].

[2025] Diagnostics GL.2 - Recommendation 44

In pregnant women with features of active IBD, we suggest IUS or MRE [without use of gadolinium] to evaluate the bowel [EL3]. Endoscopy should be reserved for situations where IUS or MRE are insufficient to make a therapeutic decision [EL5].

MRI is being used more frequently as it provides highly sensitive results without subjecting patients to radiation. It has become the established first line imaging modality for small bowel and pelvic Crohn’s disease.

Technique

The patient drinks ≈ 1L of oral contrast, (enteroclysis reserved for suspected proximal small bowel lesions or low grade stenosis). Then, the patient lies on a sliding table, which is advanced into the magnet. The exam lasts ≈ 20 to 30 minutes. IV contrast, based on gadolinium is often used to assess regional blood flow (a surrogate marker for disease activity) but cannot be given with significant renal impairment.

Outcomes

MR detects small bowel disease activity and strictures in 90% and 95% respectively. High cost / limited availability limits widespread use in some countries. The MaRIA score provides an objective score of disease activity, measuring wall thickening and wall signal intensity, contrast enhancement, oedema, ulceration, lymphadenopathy and presence of pseudopolyps.

Risk

MRI is contra-indicated in unstable patients, the first trimester of pregnancy, and those with implanted strongly ferromagnetic devices, including pacemakers. However, most modern metallic biomaterials are non-ferrous.

Ultrasound

ECCO-ESGAR statement 2H (2013)

High radiation exposure and earlier age of exposure both increase the risk of radiation-induced cancer [EL 2]. Independent predictors of increased radiation exposure in IBD patients are: diagnosis of CD, need of steroids, IBD related surgery, increasing severity, upper gastrointestinal tract involvement, the first year following diagnosis and young age of disease onset [EL 2].

[2025] Diagnostics GL.2 - Recommendation 54

IUS should be performed with an IUS-dedicated multifrequency probe [EL3]. Fasting is usually not required when performing IUS [EL3]. Routine use of oral contrast is not recommended but may be used in specific scenarios to increase visualization of the small bowel [EL3].

[2025] Diagnostics GL.2 - Recommendation 55

We recommend against the routine use of contrast-enhanced ultrasound to quantify bowel-wall perfusion [EL2]. We recommend against the routine use of real-time tissue elastography and shear wave elastography [EL2].

[2025] Diagnostics GL.2 - Recommendation 44

In pregnant women with features of active IBD, we suggest IUS or MRE [without use of gadolinium] to evaluate the bowel [EL3]. Endoscopy should be reserved for situations where IUS or MRE are insufficient to make a therapeutic decision [EL5].

Trans-abdominal ultrasound may be useful in expert hands to diagnose or assess Crohn’s disease.

Technique

Reflected sound waves allow the detection of bowel wall thickness. The technique is not able to view the entire intestine, and less effective in the obese. Colour doppler can distinguish active from fibrotic disease. Ingestion of an iso-osmolar polyethylene glycol solution can increase the accuracy of detecting lesions in the small bowel (SICUS, small intestine contrast ultra-sonography).

Outcomes

The technique is operator-dependent, with a quoted sensitivity of 73-96% and specificity of 90-100%.

Risk

Nil

CT

ECCO-ESGAR Imaging Statement 2C (2013)

CT of the abdomen and pelvis in order to assess the small intestine and colon requires luminal distension, and intravenous contrast administration. Radiation exposure is the major limitation. CT can be used to guide interventional procedures (e.g. abscess drainage) [EL 2].

CT can be used if MR is unavailable to assess small bowel Crohn’s disease, but provides significant radiation exposure. It is the investigation of choice for undiagnosed abdominal pain (usually in an emergency setting).

Technique

Administer oral contrast, reserving enteroclysis for suspected proximal small bowel lesions or low grade stenoses. IV contrast is administered unless renal dysfunction present. The examination is quick, taking a few minutes.

Outcomes

CT is useful for examining the small bowel, and for excluding the presence of extra-intestinal abscesses.

Risk

CT exposes patients to radiation, which should be minimized if possible; therefore MR (if available) is preferred.

Barium follow-through (BFT)

Technique

Plain radiographs are taken following oral barium ingestion.

Outcomes

Before the widespread availability of cross-sectional imaging, BFT was the standard investigation for small bowel Crohn’s disease but has significantly lower sensitivity so is little used now. It may be useful (particularly pre-operatively) for mapping stenosis and internal  fistulas.

Risk

It exposes patients to radiation so MR follow through is (if available) is preferred.