Leah Stickler Kelly Flannery Imaging Sequences of Crohn’s Disease
Crohn’s disease, a form of Irritable Bowl Syndrome, is an ongoing symptomatic disease that has affected as many as 1.4 million people in the United States.7 Although it may occur at any age, the most common onset for IBS is between 15 to 30 years old.7 IBS can be broken down into two categories such as Crohn’s disease and ulcerative colitis.7 Crohn’s disease is one of the most difficult diseases to diagnose and uses a lot of distinctive tests such as X-ray, CT, MRI, Ultrasonography, and Nuclear Imaging. We will be investigating the optimum imaging sequences to analyze the cause, diagnosis, and treatments of Crohn’s disease. Crohn’s disease can incorporate any location of the gastrointestinal tract, but it usually affects the area in-between the small and large bowels.7 Although the cause of Crohn’s disease is widely unknown, there are numerous implicating factors. Genetics is proposed as it “is found among first-degree relatives, suggesting a strong genetic component” .7 Other factors that play a part in contributing to the disease can be environmental, for example, smoking and your diet.7 Infectious and Immunologic factors are also considered, such as preexisting infections as a child or the infectious bacterium, Mycobacterium avium paratuberculosis (MAP).3 The optimum imaging sequences to diagnose Crohn’s disease are plain radiography with barium studies, Computed Tomography, Magnetic Resonance Imaging, Ultrasonography, and Nuclear Imaging. To diagnose Crohn’s disease, a Gastroenterologist must “first obtain an accurate medical history from the patient, then perform a thorough physical examination and a series of other special investigations such as blood tests, “to check for anaemia, or high white blood cell count, which may indicate inflammation” or “stools may be examined for occult bleeding or infection”1. Plain radiography with barium contrast is then used to view the small intestine, and expose any inflammation of the lumen or irregularities.7 The major purposes of this procedure is to, “asses the presence of intestinal obstruction and evaluate pneumoperiotneum prior to further radiological workup”.7 An example of the findings associated with double contrast barium is apthoush ulcers, which is included in Figure 1.7 However, there are limitations to this procedure. This is because the, “slow passage of the contrast agent through the pylorus can result in nonvisualization”.7 For a patient with suspected or known Crohn’s disease, CT is superior to barium studies in diagnosing the complications of the disease. “The sensitivity of CT for Crohn’s disease is estimated to be 71%, with lower detection of early mucosal disease as compared with barium studies”.7 It is used to “directly demonstrate the bowel wall, adjacent abdominal organs, mesentery, and retroperitoneum”.7 Figure 2 demonstrates “small-bowel wall thickening, mesenteric inflammatory stranding, and mesenteric adenopathy”.7 CT also shows bowel involvement and extraluminal pathology by revealing abscesses, obstructions, and fistulas.7 Magnetic Resonance Imaging is important in “assessment of anorectal complications”.7 A technique used is fast-spin echo, which eliminates the need for holding one’s breath due to faster pulse sequences.7 This procedure detects pathological entities such as fistulas, sinus tract, and abscesses.7 Enterography and Enterclysis are two types of MRI imaging tests used to obtain images of your small bowel. Enterography is the digestion of an oral contrast dye to pinpoint irregularities such as inflammation or bleeding of the small intestine.4 Enteroclysis is a less common procedure involving the “placement of a nasoduodenal catheter under fluoroscopy”.4 Figure 3 shows “MRI enterography with coronal fat-saturated T2-weighted single-shot fast spin echo imaging demonstrate[ing] mesenteric edema and mural wall edema and thickening in a patient with active Crohn’s disease in the distal ileum”.7 “High-resolution imaging with the current MRI technology has increased the accuracy of assessing the grade and severity of patient with Crohn’s disease”.7 Some of the risks include kidney damage and a possible allergic reaction to dye”.5 MRI is a very common procedure in the treatment of Crohn’s disease because of its low dose of ionizing radiation. This is important because of the extensive amount of imaging needed for constant treatment, such as when you are diagnosed at a young age”.1 Occasionally, Ultrasonography and Nuclear Imaging can be used to detect Crohn’s disease. The gastrointestinal walls depict different layers with alternating echo variations.7 This allows you to use Ultrasonography as an alternative to CT to expose intraluminal and extraluminal manifestations.7 For example, Figure 4 shows a “sonogram of a thickened bowel wall [that] demonstrates the so-called pseudokidney appearance”.7 In rare occasions, Nuclear Imaging can be used to examine active bowel inflammation. In Nuclear Imaging, TC 99 is used as an efficient tag as it, “has better imaging characteristics and can be imaged much sooner after injection”. 7 In studies, a “leukocyte scan in active Crohn’s disease had a sensitivity of 76.1% and a specificity of 91.0%, as compared to CT sensitivity of 71.8% and specificity of 83.5%”. 7 Although Crohn’s disease is a constant struggle there is no known cure, therefore the objective of treatment is to induce remissions, maintain remissions, and minimize side effects of treatments to improve the quality of life.6 Crohn’s disease has a wide range of symptoms. Patients with mild symptoms may only require medication while more serious cases can undergo surgery.4 In conclusion, the imaging sequences of Crohn’s disease are used to analyze the symptoms and diagnose the disease. Plain radiography with barium studies is able to detect the presence of intestinal obstruction and is always done prior to Computed Tomography. Computed tomography shows bowel involvement and extraluminal pathology. Magnetic Resonance imagining uses a fast spin echo technique to detect pathological entities. Other less common modes of imaging for Crohn’s disease are Ultrasonography and Nuclear Imaging. Until a cure is found, new and improved ways of diagnosis and treatments are always encouraged. There are always enhanced medications on the rise, and the concept of molecular imaging (imaging at a cellular level) is a future prospect of better understanding this disease.2

Works Cited

1 “Crohn’s Disease.” Centre for Digestive Diseases. 2009. Web. 23 Nov, 2013. http://www.cdd.com.au/pages/disease_info/crohns_disease.html 2 Gee, Michael S., Sheth, Rahul A., “The Imaging of Inflammatory Bowel Disease: Current Concepts and Future Directions.” INTECH. 2012. Web. 23 Nov. 2013. http://cdn.intechopen.com/pdfs/41157/InTech-The_imaging_of_inflammatory_bowel_disease_current_concepts_and_future_directions.pdf 3 “Inflammatory Bowel Disease (IBD).” Centers for Disease Control and Prevention. 15 July 2011. Web. 23 Nov, 2013. http://www.cdc.gov/ibd/ 4 Kunipers, Ernst J., Wiarda, Bart M., “MR Enteroclysis of Inflammatory Small-Bowel Diseases” American Journal of Roentgenology 187.2. (2006): 592. Web. http://www.ajronline.org/doi/full/10.2214/AJR.05.0511 5 “MR Enterography” John Hopkins Medicine. Web. 23 Nov 2013. http://www.hopkinsmedicine.org/healthlibrary/test_procedures/gastroenterology/mr_enterography_135,61/ 6 Schoenfeld, Adam, Wu, George Y. “Crohn’s Disease Symptoms, Causes, Treatment.” Medicine.net. 2013. Web. 23 Nov. 2013. http://www.medicinenet.com/crohns_disease/page7.htm#how_is_crohns_disease_treated 7 Yunh-Hsin, Chen. “Imaging in Crohn’s Disease.” Medscape. 24 Oct,2013. Web. 20 Nov, 2013.
http://emedicine.medscape.com/article/367666-overview