Imaging of the small bowel in Crohn's disease: A review of old and new techniques

Table 1 Main US features observed in Crohn’s disease (modified from Maconi et al[93])

Features	Crohn’s disease
Bowel wall
Thickening	4-14 mm
Echopattern	Variable
Vascularity	Variable
Contours	Variable
Stiffness	Often present
Haustra coli	Absent
Peristalsis	Often weak or absent
Location and extension
Site	Ileum 70%
Bowel involvement	Often divided into segments
Extra-intestinal alterations
Mesenteric hypertrophy	Common
Enlarged regional lymph nodes	Common
Fistulae and abscesses	Common

Table 2 Detection of strictures in Crohn’s disease: comparison between US and conventional radiology or surgery (prospective studies)

Author (ref)	Patients (n)	Comparator	Sensitivity	Specificity
Maconi et al[18]	98	Small bowel/ barium enema	74%	93%
Kohn et al[20]	44	Small bowel enema	82%	100%
Gasche et al[19]	33	Surgery/pathology	100%	91%
Parente et al[12]	211	Small bowel enema	79%	98%
	85 (operated)	Surgery	90%	100%

Adapted from Parente et al[22].

Table 3 Detection of intra-abdominal abscesses in Crohn’s disease: comparison between US and CT or surgery (prospective studies)

Author (ref)	Patients (n)	Comparator	Sensitivity	Specificity
Maconi et al[18]	58	CT scan	83%	94%
Gasche et al[19]	33	Surgery/pathology	100%	92%
Maconi et al[21]	128	Surgery	91%	87%

Adapted from Parente et al[22].

Table 4 Incremental yield of capsule endoscopy over the other modalities in patients with suspected Crohn’s disease (from Triester SL et al[63])

	Yield ofcapsuleendoscopy (%)	Yield of othermodalities(%)	% Incrementalyield for capsuleendoscopy (95% CI)	P
vs Small bowel radiography	43	13	24 (-0.3-0.51)	0.09
vs Ileoscopy	33	26	7 (-0.12-0.25)	0.48
vs CT enterography	70	21	40 (-0.03-0.83)	0.07

CT: Computed tomography.

Table 5 Incremental yield of capsule endoscopy over the other modalities in patients with established Crohn’s disease (from Triester SL et al[63])

	Yield ofcapsuleendoscopy(%)	Yield ofothermodalities(%)	% Incrementalyield for capsuleendoscopy(95% CI)	NNT	P
vs Small bowel radiography	78	32	51 (0.31-0.70)	2	< 0.001
vs Ileoscopy	86	60	26 (0.08-0.43)	4	0.002
vs CT enterography	68	38	30 (0.12-0.48)	-	< 0.01

CT: Computed tomography; NNT: Number needed to treat.

Table 6 Pros and cons of the different imaging techniques in the study of the small bowel in Crohn's disease

	PROs	CONs
Bowel ultrasound	-Non invasive, safe and well accepted -Widely available -Information about gut wall and extra-intestinal structures	-Operator dependent -False negative in case of superficial and rare lesions
Conventional radiology	-Exact anatomic location and extent of the lesions	-Limited information about trans-mural and peri-intestinal abnormalities -Radiation exposure
Entero MR	-Information about gut and extra-intestinal structures -Identification of active inflammation -Multiplanar sequences	-costly -Impossible to enter the magnet -IV infusion
Entero CT	-Information about gut and extra-intestinal structures -Mulitplanar sequences	-Radiation exposure -IV infusion -False negative in case of superficial and rare lesions
VCE	-Allows the complete evaluation of the small bowel -High diagnostic yield -Useful in indeterminate colitis -Well tolerated	-Unfeasible if significant stricture present -Not well established specificity of VCE findings
Double-balloon	-Allows the complete evaluation of the small bowel -Therapy and biopsies are feasible	-Invasive procedure requiring sedation and fluoroscopy -No data