Comparison of high-resolution ultrasound and MR-enterography in patients with inflammatory bowel disease

Table 1 Contingency table of all evaluated 250 cases (patient based) n (%)

Any bowel wall changes (including unspecific changes such as “accentuated wall”, etc.)	Ultrasound
	Negative	Positive
Magnetic resonance enterography
Negative	21 (8.4)	28 (11.2)
Positive	38 (15.2)	163 (65.2)

Negative findings means no bowel wall change found in the modality (magnetic resonance enterography or ultrasound) report.

Table 2 Influence of the experience of the ultrasound examiner on diagnosis

Pathological changes	Ultrasound examiner with moderate experience (%)	Ultrasound examiner with high experience (%)
MRI found more lesions than ultrasound
Stenosis (n = 72)	62	38
Abscess (n = 16)	46	46
Fistula (n = 32)	59	41
Ultrasound found more lesions than MRI
Stenosis (n = 8)	0	100
Abscess (n = 4)	50	50
Fistula (n = 2)	0	100

The percentage indicates the ratio of moderate or experienced ultrasound examiners in this scenario. MRI: Magnetic resonance imaging.

Table 3 Contingency table of all evaluated 250 cases (patient based) n (%)

Statement “inflammation” or “bowel wall affection” in the report	Ultrasound
	Negative	Positive
Magnetic resonance enterography
Negative	83 (33.2)	6 (2.4)
Positive	132 (52.8)	29 (11.6)

Negative findings means no bowel wall affection or inflammation assessed based on the report (magnetic resonance enterography or ultrasound).

Table 4 Diagnostic performance of ultrasound and magnetic resonance enterography regarding bowel wall changes, diagnosis of bowel inflammation, stenosis, abscess, fistula and indirect inflammation signs such as local lymphadenopathy and fat injection or comb sign n (%)

	Bowel wall changes	Diagnosis “bowel wall inflammation”	Stenosis	Abscess	Fistula	Local lymph-adenopathy	Mesenteric fat injection/comb sign
US = MRE (no pathological change)	21 (8)	83 (33)	150 (60)	221 (84)	211 (88)	187 (75)	182 (73)
US = MRE (pathological change)	163 (65)	29 (12)	20 (8)	9 (4)	5 (2)	4 (2)	4 (2)
US > MRE	28 (11)	6 (2)	8 (3)	4 (2)	2 (1)	15 (6)	4 (2)
MRE > US	38 (15)	132 (53)	72 (29)	16 (6)	32 (13)	44 (18)	60 (24)

US: Ultrasound; MRE: Magnetic resonance enterography. In “US = MRE” the number (and percentage) of cases, when both modalities found the same amount of pathological features (patient based) are identical. For “US > MRE” the reports based on ultrasound described more pathological changes compared to the MRE, while for “MRE > US” more findings in the MRE reports were detected (because of truncation the percentage values in a column can exceed 100%).

Table 5 Possible explanations for misdiagnosis of all evaluated features (wall affection, stenosis, abscess, fistula, lymph nodes and indirect inflammation signs) for ultrasound and magnetic resonance enterography for all 250 evaluated cases

	HR-US	MRE
Reduced imaging quality (obesity, breathing artifacts, residual bowel gas, etc.)	25	7
Region difficult to access (lesser pelvis)	72	N/A
Subtle findings	15	31

Magnetic resonance enterography (MRE) missed most of the diagnoses made by ultrasound (US) because of subtle US findings (n = 31), while the most common reason for a misdiagnosis based on the US report was an anatomical region difficult to assess (n = 72).