What is the accuracy of nuclear imaging in ulcerative colitis (UC)?

Updated: Feb 23, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Answer

Answer

Radionuclide-labeled WBC scanning using 111In is an accurate, quantitative, and noninvasive method for assessing the degree of bowel inflammation in cases of IBD; it is also useful in assessing response to therapy. Fecal collection or total body counts of radioactivity may be used.

The use of 99mTc HMPAO WBC scanning has several advantages over the111 In scanning, including a reduction in the radiation dose and better image resolution. The 99mTc HMPAO WBC technique may be used in combination with single-photon emission CT (SPECT), which allows visualization of the entire bowel as distinct from overlying structures. Tc-99m HMPAO WBC SPECT permits measurement of segmental and total bowel uptake. [33]

Technetium-99m HMPAO-labeled leukocyte scintigraphy has been found to correlate well with colonoscopy in the assessment of both the extension and severity of ulcerative colitis. Use of 2-hour scintigraphic imaging decreases the number of false-positive results. [34]

Tolia and associates compared 111In-labeled WBC scanning and colonoscopy in 19 children and adolescents with chronic IBD; they compared the degree to which the 2 diagnostic modalities correlated with histologic diagnosis. [35] The data suggested that the usefulness of scans is limited to patients in whom standard diagnostic procedures are contraindicated. The sensitivity of 111In scanning was 18%, its specificity was 62.5%, and its accuracy for colonic disease was only 37%. In comparison, the sensitivity and specificity of colonoscopy were 100% and 57%, respectively; its accuracy was 84%.


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