Measuring Colonic Transit Time
Are there any other means of identifying slow transit time than use of radiopaque markers?
Stam Tsoris, MD
Measuring colonic transit time is useful in evaluating patients with constipation, abdominal bloating, and refractory irritable bowel syndrome. It provides quantitative information about colonic transit, enables the identification and characterization of transit abnormalities, and allows assessment of the severity of the problem as well as the response to therapy.
Colonic transit time has been traditionally measured using radiopaque markers. The technique is simple and inexpensive and can be performed in any radiology department. Radiopaque markers may simply be cut from radiopaque tubes (eg, Levin tubes) or obtained commercially. Several methods have been suggested, including the single-marker bolus technique (ingestion of markers on a specific day followed by several x-rays until all markers are passed) or multiple-marker bolus technique (ingestion of markers each day for several days followed by a limited number or a single abdominal x-ray). Overall, radiopaque markers have been widely used to measure colonic transit. This technique provides valuable clinical information and has been proven to be reliable and reproducible. However, this test has a relatively long duration (5-7 days) and requires the patient to abstain from laxatives, enemas, and other medications known to affect gastrointestinal motility. These drawbacks have led to a desire to develop alternatives to this study.
Colonic scintigraphy can be used as an alternative to the radiopaque marker technique for measuring colonic transit time. This test involves administration of radioactive isotope and following its progression through the gastrointestinal tract with a large-field-view gamma camera. The test uses long half-life radionuclides indium 111-diethylenetriamine pentaacetic acid (In-DTPA) or iodine 131. A shorter half-life isotope, technetium 99m, can be added to measure gastric and small bowel transit. Several methods have been used to deliver the isotopes to the large intestine. These include using activated charcoal or a pH-sensitive methacrylate-coated capsule that dissolves and releases the isotope at alkaline pH in the distal ileum or simply dissolving the isotope (In-DTPA) in water. Overall, scintigraphy has been shown to be a reliable alternative for accurate quantitative measurement of colonic transit time. This technique may also provide additional information on segmental colonic transit. However, despite attempts to simplify the techniques and make them more applicable for clinical use, measurement of colonic transit time by scintigraphy is not yet widely available in clinical laboratories.
Are there any other means of identifying slow transit time than use of radiopaque markers?
Stam Tsoris, MD
Measuring colonic transit time is useful in evaluating patients with constipation, abdominal bloating, and refractory irritable bowel syndrome. It provides quantitative information about colonic transit, enables the identification and characterization of transit abnormalities, and allows assessment of the severity of the problem as well as the response to therapy.
Colonic transit time has been traditionally measured using radiopaque markers. The technique is simple and inexpensive and can be performed in any radiology department. Radiopaque markers may simply be cut from radiopaque tubes (eg, Levin tubes) or obtained commercially. Several methods have been suggested, including the single-marker bolus technique (ingestion of markers on a specific day followed by several x-rays until all markers are passed) or multiple-marker bolus technique (ingestion of markers each day for several days followed by a limited number or a single abdominal x-ray). Overall, radiopaque markers have been widely used to measure colonic transit. This technique provides valuable clinical information and has been proven to be reliable and reproducible. However, this test has a relatively long duration (5-7 days) and requires the patient to abstain from laxatives, enemas, and other medications known to affect gastrointestinal motility. These drawbacks have led to a desire to develop alternatives to this study.
Colonic scintigraphy can be used as an alternative to the radiopaque marker technique for measuring colonic transit time. This test involves administration of radioactive isotope and following its progression through the gastrointestinal tract with a large-field-view gamma camera. The test uses long half-life radionuclides indium 111-diethylenetriamine pentaacetic acid (In-DTPA) or iodine 131. A shorter half-life isotope, technetium 99m, can be added to measure gastric and small bowel transit. Several methods have been used to deliver the isotopes to the large intestine. These include using activated charcoal or a pH-sensitive methacrylate-coated capsule that dissolves and releases the isotope at alkaline pH in the distal ileum or simply dissolving the isotope (In-DTPA) in water. Overall, scintigraphy has been shown to be a reliable alternative for accurate quantitative measurement of colonic transit time. This technique may also provide additional information on segmental colonic transit. However, despite attempts to simplify the techniques and make them more applicable for clinical use, measurement of colonic transit time by scintigraphy is not yet widely available in clinical laboratories.
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