Nuclear Gastrointestinal Scans

1. Nuclear Gastrointestinal Scans
Dr Muhammad Qasim Khan

2. • Nuclear scans are tests that involve the use of harmless
radioactive materials. The radioactive materials are ingested as
part of a meal or in a drink or are given by vein (intravenously).
The small amount of radiation produced by these materials is
used to produce images of internal structures.

3. • After the materials are in the body, doctors use a special
radiation-sensing scanner or camera, called a gamma camera, to
show where the materials are in the body. Different types of
scans with different nuclear materials are used depending on the
purpose of the test and which part of the body needs to be
imaged.

4. 1. Bleeding scans
2. Gastric emptying
3. Meckel scans

5. 1. Bleeding scans
• Bleeding scans use 99mTc-labeled red blood cells, or occasionally
99mTc-labeled colloid, to determine the origin of lower
gastrointestinal hemorrhage before surgery or angiography.
• Active bleeding sites are identified by focal areas of tracer that
conform to bowel anatomy, increase with time, and move with
peristalsis.

6. • Bleeding scans are useful mainly for
colonic bleeding in patients with significant hemorrhage
An unprepared bowel, in whom endoscopic visualization is difficult.

7. 2. Gastric emptying
• Gastric emptying can be measured by having the patient ingest a
radiolabeled meal (solid or liquid) and observing its passage out of
the stomach with a gamma camera. Because this test cannot
differentiate physical obstruction from gastroparesis, further
diagnostic studies typically are done if emptying is delayed.
• The test also is useful in monitoring response to promotility drugs
(eg, metoclopramide, erythromycin). The results of this test can be
affected by use of opioids or other drugs that alter gastrointestinal
motility.

8. • Specialized motility centers can also evaluate small intestine and
whole gut transit. The small intestine transit test takes place over a 2-
day period and the whole gut transit test takes place over a 4-day
period. These tests are useful in patients with suspected motility
disorders, severe constipation, or colonic inertia.

9. • The simplest approach for interpreting a gastric emptying study is to
report the percent retention at defined times after meal ingestion,
usually 2 and 4 hours, with normal being <60% remaining in
the stomach at 2 hours and <10% remaining at 4 hours

10. 3. Meckel scans
• A Meckel scan identifies ectopic gastric mucosa by using an injection
of 99mTc pertechnetate, which is taken up by mucus-secreting cells of
the gastric mucosa. Focal uptake outside of the stomach and in the
small bowel indicates a Meckel diverticulum.

11. Thank you…