小肠疾病影像学诊断

Pattern of enhancement
Homogeneous
Mucosal
Layered
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Imaging findings on CT and MRI
• Bowel wall thickness
Normal bowel wall thickness： lumen distended， 1-2 mm； lumen collapsed, 3-4 mm Mild: 3-5 mm Moderate: 5-7 mm Marked: > 7mm One of the most common signs, but not specific Correlates well with the severity of the disease activity Measure when lumen distended well Black border artifacts can distort thickness measurements
Imaging findings on CT and MRI
• Stricture
A complication of Crohn disease
Imaging findings on CT and MRI
• Bowel wall enhancement
The result of increased vascular permeability and angiogenesis The most sensitive indicator of active Crohn disease Enhancement can be graded by comparing to the precontrast images Minor increased enhancement Moderate enhancement Marked enhancement No abnormal enhancement: equivalent to normal bowel wall
Imaging findings on CT and MRI
• Fat halo sign
Infiltration of the submucosa with fat, between the muscularis and the mucosa Confused with the fat ring sign of mesenteric panniculitis Nearly pathognomonic of inflammatory bowel disease (Crohn disease and ulcerative colitis)
Introduction--Crohn disease
• An inflammatory disease of the gastrointestinal tract that typically has an indolent course • Characterized by intestinal ulceration, strictures, and fistula formation • Commonly affects young adults, small bowel, particularly the terminal ileum • Small bowel involvement in Crohn disease is typically transmural, with skip lesions • CT and MRI
CASE DISCUSSION
Tang Chun Xiang 2016/5/25
Axial arterial phase
Axial arterial phase
Axial venous phase
Coronal arterial phase
Sagittal venous phase
Crohn disease
Depicting extraenteric involvement
Providing more detailed and comprehensive information about the extent and severity
Imaging findings on CT and MRI
• Comb sign • Fat halo sign • Bowel wall enhancement • Bowel wall thickness • Stricture and fistula • Mesenteric/intra-abdominal abscess (15%-20%) or phlegmon formation • Ulcerations and loss of haustration • Creeping fat
Introduction--Crohn disease
• CT and MRI
Useful for differentiating between active and fibrotic bowel strictures
Allowing visualization of the entire thickness of the bowel wall
Imaging findings on CT and MRI
• Comb sign
Prominence of the vasa recta adjacent to the inflamed loop of bowel Transmural extension of inflammation across the serosa and to engorgement of the hyperemic vasa recta surrounding the inflamed bowel segment Not pathognomic of Crohn disease