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Toronto Notes 2019 Abdominal Imaging Medical Imaging MI13
Figure 17. Axial abdominal computed tomography
CT and Bowel Obstruction
• causeofbowelobstructionrarelyfoundonplainfilms;CTisbestchoiceforimaging
• the“3,6,9”ruleisaveryusefulguidetodeterminingwhenthebowelisdilated;themaximumdiameter
of the bowel is 3 cm for small bowel, 6 cm for large bowel, and 9 cm for cecum; this can also be useful to distinguish small and large bowel, and to assess for ‘impending’ cecal perforation (e.g. post-untreated Ogilvie’s syndrome)
• closed-loopobstruction:anobstructionintwolocations(usuallysmallbowel)creatingaloopofbowel segment obstructed both proximally and distally; complications (e.g. ischemia, perforation, necrosis) may occur quickly
CT Colonography (virtual colonoscopy)
• emergingimagingtechniqueforevaluationofintraluminalcolonicmasses(i.e.polyps,tumours)
• twoCTscansoftheabdomen(proneandsupine)aftertheinstillationofcarbondioxideintoaprepped
colon
• computerreconstructionof2DCTimagesintoa3Dintraluminalviewofthecolon
• lesionsseenon3Dimagescorrelatedwith2Daxialimages
• indications:surveillanceinlow-riskpatients,incompletecolonoscopy,stagingofobstructingcolonic
lesions
Contrast Studies
Table 10. Types of Contrast Studies
Study
Cine Esophagogram
Barium Swallow Upper GI Series
Enterography and Enteroclysis (MRI or CT)
Organ
Cervical esophagus
Thoracic esophagus
Thoracic esophagus, stomach, and duodenum
Entire small bowel
Procedure Description
Contrast agent swallowed Recorded for later playback and analysis
Contrast agent swallowed under fluoroscopy, selective images captured
Double contrast study:
1. Barium to coat mucosa, then
2. Gas pills for distention Patient NPO after midnight
Enterography: patient drinks 1-2 L of sorbitol, psyllium, or barium solution to distend small bowel Enteroclysis: NJ tube used to pump barium, psyllium, or sorbitol contrast media directly into small bowel
Assessment
Dysphagia, swallowing incoordination, recurrent aspiration, post-operative cleft palate repair
Dysphagia, rule out GERD, post-esophageal surgery
Dyspepsia, investigate possible upper GI bleed, weight loss/anemia, post-gastric surgery
IBD, malabsorption, weight loss/anemia, Meckel’s diverticulum
Findings
Aspiration, webs (partial occlusion), Zenker’s diverticulum, cricopharyngeal bar, laryngeal tumour
Achalasia, hiatus hernia, esophagitis, cancer, esophageal tear
Ulcers, neoplasms, filling defects
Neoplasms, IBD, malabsorption, infection