Dear Colleagues,
Ct Enterography is rapidly becoming the mainstay screening small bowel examination. In the past, inch by inch examination of small bowel was performed utilizing eneteroclysis, an invasive examination requiring placement of a nasojejunal tube, with forceful administration of contrast agent to expand the bowel lumen and allow examination of the bowel wall. This examination has essentially been abandoned at most institutions due to patient discomfort.
The small bowel follow through involves intermittent fluoroscopic evaluation with passive ingestion of oral positive contrast. Complete evaluation of all small bowel loops (particularly the deep ileal loops of the pelvis) cannot be ensured and extraenteric findings which can provide valuable information in diagnosis are not visible. This markedly limits evaluation in diseases such as Crohn's where skip lesions occur, and mesenteric inflammation aids in localizing disease.
CT examination with positive contrast allows for visualization of extraenteric findings. However, positive contrast exhibits a higher Hounsfield measurement (denser) than the bowel wall which results in silhouetting of the mucosal surface, and bowel wall thickness is difficult to establish. Water provides excellent negative contrast however is absorbed quickly and often provides poor distension. Normal nondistended bowel can often appear to artificially enhance.
In my experience no contrast agent provides better delineation of the bowel than VoLumen(E-Z-EM, Westbury, NY). VoLumen is an LHV contrast agent (Low Hounsfield Value) barium solution that provides the benefits of negative contrast and contains sorbitol, a nonabsorbable sugar alcohol, which provides osmotic distention and resists absorption.
Combined with a multi-slice CT scanner and IV contrast, VoLumen provides a very powerful tool for small bowel evaluation - a superb screening tool for Crohn's disease, small bowel neoplasms, and occult blood loss. Alternative diagnoses can be excluded in patients with symptoms of Irritable bowel syndrome and strictures can be excluded prior to capsule endoscopy. Small bowel wall thickness and enhancement are optimally evaluated while the presence of extraenteric findings such as abscess, perienteric inflammation, desmoplastic reaction (as in carcinoid tumor), lymphadenopathy, and engorged vasa recta can be seen. Extraluminal findings such as intramural lesions, mural stratification, and extraluminal extension of mass can only be seen with CT. In addition, alternative causes for small bowel wall thickening such as mesenteric thrombosis can be investigated. Multiple cases of Celiac sprue have been identified with the overall abdominal overview CT provides.
CT Gastrography can be utilized in evaluation of gastric tumors for many of the same reasons. Oral contrast bolus timing is optimized for gastric distension.
At Marietta Imaging Center we offer both CT Enterography and Gastrography. I encourage your questions and can direct you toward multiple journal articles advocating CT Enterography and VoLumen use. You can contact me at the Imaging Center or via email at lindstrom.md@gmail .com. Please take a moment to peruse the attached images.
Sincerely,
Eric J. Lindstrom, MD
|
