Clinical trial NCT01244386: Low-dose CT Using Iterative Reconstruction in Patients With Inflammatory Bowel Disease
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Inflammatory Bowel Disease
Crohn's Disease
Ulcerative Colitis
Keywords: Computed tomography
Iterative reconstruction
Automatic tube current modulation
Crohn's disease
Inflammatory bowel disease
Radiation dose optimization
C reactive protein
Lead sponsor: University College Cork
Sponsor class: OTHER
First posted: 2010-11-19
Enrollment: 250
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Patients under the care of the hospital gastrointestinal services including in-patients and outpatients.

Brief summary: The purpose of this study is to validate the use of a low-dose computed tomography (CT) protocol and facilitate reduced radiation doses in patients with inflammatory bowel disease (IBD). This is to be achieved using new computer software (Iterative Reconstruction and Automatic Tube Modulation) which will enable low-dose CT imaging at doses equivalent to that of an abdominal radiograph.

Detailed description: The increasing use of CT has prompted the development of new scanning protocols which reduce radiation doses to patients and minimise the likelihood of radiation related morbidity. The use of disease specific low-dose CT examinations is an emerging method of limiting radiation doses.

Research conducted in Cork University Hospital(CUH) by the current authors has identified a pressing need to reduce radiation doses in patients with IBD. A retrospective study of radiation doses in patients with Crohn's disease demonstrated that increasing numbers of CT exams are performed with average cumulative effective doses rising from 7.9 to 25mSv when the first 5-years of the 15 year study period were compared with the final 5-years. Eight-five percent of the dose during the final 5-year period was due to CT. Younger patients with more severe disease requiring surgery or steroids were more likely to undergo an increased number of exams. 15.5% of patients received cumulative effective doses of greater than 75mSv. This quantity of radiation exposure is associated with a 7.3% increase in mortality from cancer. In addition, patients with Crohn's disease are inherently predisposed to gastrointestinal and hepatobiliary carcinoma and small bowel lymphoma.

As an alternative to CT, IBD patients are frequently imaging with conventional abdominal radiography. The effective dose of a conventional abdominal radiograph (CAR) is approximately 10% that of a standard abdominal CT varying between 0.7 -0.1mSv. The current authors have also investigated the value of CAR. We retrospectively examined over 500 CAR's performed over a 16 year period in patients with IBD. Patients had an average of 3.5 CAR's performed but there were positive findings in less than 30% of exams. Many of these findings were non-specific requiring further investigation. For example separation of bowel loops on a plain radiograph has a wide differential diagnosis including abscess formation, presence of a phlegmonous mass, fibrofatty proliferation, bowel wall thickening and lymphadenopathy.

Patients with inflammatory bowel disease referred to CUH will undergo a modified abdominal CT protocol. The radiation dose of a standard CT abdomen and pelvis will be divided into 2 quotients. Patients will have a low-dose CT scan requiring approximately 10% of the dose of a standard abdominal CT. This equates to the radiation dose of a conventional abdominal radiograph. Patients will be imaged with a second CT exam using 90% of the standard abdominal CT dose ensuring a diagnostic study is acquired. Patients will be given oral and intravenous contrast agents as for a standard CT. Patients will have a C-reactive protein measured on the day of CT and will have their heights and weights also measured at the time of scanning. Patients will have a plain film of abdomen performed prior to CT.

Eligibility criteria: Inclusion Criteria:

* Adult patients requiring a CT abdomen for clinical purposes will be included

Exclusion Criteria:

* Pediatric patients

Primary outcomes:
measure: The adequacy of low dose CT in patients with Inflammatory bowel disease compared with standard dose CT
timeFrame: At the time of CT
Secondary outcomes:
measure: The correlation of C-reactive protein assay with CT disease severity in inflammatory bowel disease.
timeFrame: CRP sample on same day as CT
Other outcomes:
Locations:
city: Cork
country: Ireland
facility: Cork University Hospital
state: Co Cork
Study officials:
affiliation: University College Cork
name: Michael M Maher, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: University College Cork
name: Owen J O'Connor, MD
role: STUDY_DIRECTOR
affiliation: University College Cork
name: Fergus Shanahan, MD
role: STUDY_DIRECTOR
References:
citation: Desmond AN, O'Regan K, Curran C, McWilliams S, Fitzgerald T, Maher MM, Shanahan F. Crohn's disease: factors associated with exposure to high levels of diagnostic radiation. Gut. 2008 Nov;57(11):1524-9. doi: 10.1136/gut.2008.151415. Epub 2008 Apr 28.
citation: Kalra MK, Rizzo S, Maher MM, Halpern EF, Toth TL, Shepard JA, Aquino SL. Chest CT performed with z-axis modulation: scanning protocol and radiation dose. Radiology. 2005 Oct;237(1):303-8. doi: 10.1148/radiol.2371041227.
citation: Kalra MK, Wittram C, Maher MM, Sharma A, Avinash GB, Karau K, Toth TL, Halpern E, Saini S, Shepard JA. Can noise reduction filters improve low-radiation-dose chest CT images? Pilot study. Radiology. 2003 Jul;228(1):257-64. doi: 10.1148/radiol.2281020606. Epub 2003 May 15.
citation: Kalra MK, Maher MM, Rizzo S, Kanarek D, Shepard JA. Radiation exposure from chest CT: issues and strategies. J Korean Med Sci. 2004 Apr;19(2):159-66. doi: 10.3346/jkms.2004.19.2.159.
citation: O'Connor OJ, Vandeleur M, McGarrigle AM, Moore N, McWilliams SR, McSweeney SE, O'Neill M, Ni Chroinin M, Maher MM. Development of low-dose protocols for thin-section CT assessment of cystic fibrosis in pediatric patients. Radiology. 2010 Dec;257(3):820-9. doi: 10.1148/radiol.10100278. Epub 2010 Sep 27.