European Nuclear Medicine Guide
[111In]In-DTPA in solution (orange/apple juice);
[111In]InCl2 adsorbed onto amberlite IR-120H resin in a capsule;
Alternatively, [67Ga]Ga-citrate (in solution) can be used.
These are non-absorbable compounds which are used to show gastrointestinal transit over a period of days. There is no significant tracer uptake, and all activity is excreted in the faeces.
Colonic transit is measured as part of assessment of gastrointestinal motility disorders such as chronic constipation and irritable bowel syndrome.
Pregnancy is a relative contra-indication.
There is extensive literature on methodology and clinical studies of colonic transit in various conditions. It is used in adjunct with other manometric and radiological examinations of the gastrointestinal tract. Objective assessment of the extent of constipation and colonic transit delay is particularly important if surgery is being considered for severe colonic transit delay.
The suggested activities to administer are
[111In]In-DTPA in solution (orange/apple juice): 3.7-37 MBq
[111In]InCl2 adsorbed onto amberlite IR-120H resin in a capsule: 3.7 MBq;
[67Ga]Ga-citrate: 3 MBq
No recommendations are given for paediatric nuclear medicine.
The effective dose for [67Ga]Ga-citrate is 100 µSv/MBq [15]
The effective dose for [111In]In-DTPA is: 21 µSv/MBq.
The effective dose for 111In-non absorbable markers is: 320 µSv/MBq.
Caveat
“Effective Dose” is a protection quantity that provides a dose value related to the probability of health detriment to an adult reference person due to stochastic effects from exposure to low doses of ionizing radiation. It should not be used to quantify the radiation risk for a single individual associated with a particular nuclear medicine examination. It is used to characterize a certain examination in comparison to alternatives, but it should be emphasized that if the actual risk to a certain patient population is to be assessed, it is mandatory to apply risk factors (per mSv) that are appropriate for the gender, the age distribution and the disease state of that population."
Various methods have been used to assess colonic transit. The simplest method is visual assessment, but this is usually accompanied by calculation of percent remaining activity in various segments of the colon at various time points, and one would expect 70% excretion by 48 h in normal transit [16]. Another method used in calculation of geometric centre to quantify the progression of the bolus activity [17].
Patients should ideally be off any medication affecting the gut motility one week before the test until the end of the test period.
Joint SNMMI-EANM guidelines are available at http://snmmi.files.cms-plus.com/docs/jnm129973_clean.pdf.
Standardized protocols for HIDA scintigraphy should be available within every nuclear medicine department based on consensus guidelines [14].
A usual protocol would include data acquisition using a low energy, high-resolution collimator on a 128x128 matrix with initial image acquisition performed dynamically whenever possible from the time of injection to 60 min. Delayed images at 2 and 4 h are obtained in cases of suspected cholecystitis and non-visualization of the gallbladder. Anterior or right anterior oblique views are taken to include the liver and duodenum with additional views as needed. In post-operative imaging, it is important to tailor the study to individual patients taking account of the type of surgery performed. Delayed acquisitions (up to 24 h) with additional views (e.g. lateral or decubitus) are routinely obtained to demonstrate delayed bile drainage and to exclude small bile leaks or fistulae. Drainage catheters and bags should be included in the field of view as tracer uptake within these may be the only sign of a biliary leak. Hybrid imaging using a single photon-emission computed tomography/ computed tomography (SPECT/CT) camera can also improve the diagnostic confidence and specificity of the technique.