Low-dose CT Using Iterative Reconstruction in Patients With Inflammatory Bowel Disease

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.

Study Overview

• Status: Unknown
• Conditions: Crohn's Disease; Ulcerative Colitis; Inflammatory Bowel Disease

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.

• Study Type: Observational
• Enrollment (Anticipated): 250

Contacts and Locations

Study Locations

• Ireland
  • Co Cork
    • Cork, Co Cork, Ireland
      • Recruiting
      • Cork University Hospital
      • Contact: Michael M Maher, MD; Phone Number: + 353 86 1731929; Email: m.maher@ucc.ie

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients under the care of the hospital gastrointestinal services including in-patients and outpatients.

Description

Inclusion Criteria:

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

Exclusion Criteria:

• Pediatric patients

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Inflammatory bowel disease; Patients with inflammatory bowel disease requiring CT for clinical purposes will be studied.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The adequacy of low dose CT in patients with Inflammatory bowel disease compared with standard dose CT	Radiation dose of a standard CT abdomen and pelvis will be divided into 2 quotients. A low-dose CT scan acquired using automatic tube current modulation (ATM) requiring 10% the dose of a standard abdominal CT and equating to that of a conventional abdominal radiograph. High noise index will be used ensuring reduced mAs. Increased image noise will be overcome by the IR filter. A second CT using 90% of the standard abdominal CT dose will ensure a diagnostic study is acquired.	At the time of CT

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The correlation of C-reactive protein assay with CT disease severity in inflammatory bowel disease.	The severity of inflammatory bowel disease will also be quantified based on the CT appearances. The disease severity as measured by CT will be correlated with C-reactive protein measured on the day of imaging.	CRP sample on same day as CT

Collaborators and Investigators

• Sponsor: University College Cork
• Investigators: Principal Investigator: Michael M Maher, MD, University College Cork; Study Director: Owen J O'Connor, MD, University College Cork; Study Director: Fergus Shanahan, MD, University College Cork

Publications and helpful links

General Publications

• 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.
• 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.
• 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.
• 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. Erratum In: J Korean Med Sci. 2004 Jun;19(3):487. Shephard JA [corrected to Shepard JA].
• 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.

Study record dates

Study Major Dates

• Study Start: June 1, 2010
• Primary Completion (Anticipated): December 1, 2011
• Study Completion (Anticipated): December 1, 2011

Study Registration Dates

• First Submitted: November 18, 2010
• First Submitted That Met QC Criteria: November 18, 2010
• First Posted (Estimate): November 19, 2010

Study Record Updates

• Last Update Posted (Estimate): November 19, 2010
• Last Update Submitted That Met QC Criteria: November 18, 2010
• Last Verified: November 1, 2010

More Information

Terms related to this study

• Keywords: Computed tomography; Crohn's disease; Inflammatory bowel disease; C reactive protein; Iterative reconstruction; Automatic tube current modulation; Radiation dose optimization
• Additional Relevant MeSH Terms: Digestive System Diseases; Gastrointestinal Diseases; Gastroenteritis; Inflammatory Bowel Diseases; Crohn Disease; Intestinal Diseases
• Other Study ID Numbers: 10-CT-Crohn's