SP10:Gastrointestinal Tract Scintigraphy

Question 1

Which of the following pairs of radiopharmaceuticals are used for simultaneously studying gastric emptying of both liquids and solids?
(a)99mTc sulfur colloid chicken livers and 111In DTPA scrambled eggs

(b) 99mTc albumin colloid scrambled eggs and 99mTc colloid in milk
(c) 99mTc sulfur colloid scrambled eggs and 111In DTPA in water
(d) 111In DTPA scrambled eggs and 99mTc sulfur colloid in water

Answer 1

(c) To simultaneously image gastric emptying of liquids and solids, two radionuclides are necessary, so choice (b) is incorrect. Choice (a) contains two solids and so is incorrect. The most common practice is to use 99mTc sulfur colloid with whatever solid meal is preferred by the given laboratory along with 111In in liquid.

Question 2

What structure is outlined by the ROI on Fig. 1?
(J shaped)
(a)Esophagus

(b) Stomach
(c) Common bile duct
(d) Duodenum

Answer 2

(b) Figure 1 shows the stomach outlined by regions of interest for the purpose of calculating the percentage of emptying over time.

Question 3

Which of the following radiopharmaceuticals can be used to study the spleen?
(a)51Cr-labeled damaged red blood cells

(b) 99mTc-labeled damaged red blood cells
(c) 99mTc sulfur colloid
(d) All of the above
(e) (b) and (c) only

Answer 3

(d) Damaged red blood cells are removed from circulation largely by the spleen, so tagged damaged erythrocytes as well as tagged colloids can be used to image the spleen.

Question 4

How is a radiopharmaceutical administered when a LeVeen shunt is evaluated?
(a)By intravenous injection

(b) By intraperitoneal injection
(c) By subcutaneous injection
(d) By intrathecal injection

Answer 4

(b) A LeVeen shunt routes ascites from the peritoneum to the superior vena cava; therefore, the radioisotope is injected into the peritoneal space.

Question 5

The ejection fraction of the gallbladder can be evaluated using:
(a)Cimetidine

(b) Dipyridamole
(c) Cholecystokinin
(d) Dobutamine

Answer 5

(c) Cholecystokinin, or CCK, is a hormone secreted by the duodenum, which causes the gall bladder to contract and secrete bile. Sincalide is a synthetic form of CCK that can be used before radiopharmaceutical injection in patients who have fasted for extended periods of time or who receive parental nutrition to empty the gall bladder, allowing the radiopharmaceutical to localize there. When used it should be injected over 5-10 min to ensure that spasm is not induced. It can also be used to determine gallbladder ejection fraction (normal is >50%).

Question 6

If no gallbladder is seen at 1 h following injection of 99mTc DISIDA, what should be done?
(a)Cimetidine should be given.

(b) Images should be taken at 24 h.
(c) Images should be taken at 4 h.
(d) The exam should be ended.

Answer 6

(c) Patients should fast 2-4 h before hepatobiliary imaging. The gallbladder may not be visualized in patients who have recently eaten and in patients who have fasted for extended periods. The use of morphine can hasten visualization of the gallbladder by increasing bile flow to the gallbladder relative to the intestine. For patients in an extended fast, sincalide may be used. If there is no gallbladder seen 1 h following injection of radiopharmaceutical, delayed images should be obtained.

Question 7

While performing a liver scan with sulfur colloid, the technologist notices that lung uptake is present. This is probably due to:
(a)Free pertechnetate in the sulfur colloid preparation

(b) Too much Al3+ ion in the pertechnetate that was used for labeling
(c) Lung metastases
(d) Patient being injected in the supine position

Answer 7

(b) Lung activity on a liver/spleen scan using 99mTc sulfur colloid may be the result of clumping of particles, a particle that is too large or too much Al3+ ion in the technetium used to prepare the kit.

Question 8

The function of a LeVeen shunt is to:
(a)Treat hydrocephalus

(b) Drain peritoneal fluid into the inferior vena cava
(c) Drain peritoneal fluid into the superior vena cava
(d) Divert CSF flow

Answer 8

(c) A LeVeen shunt routes ascites from the peritoneum to the superior vena cava; therefore, the radioisotope is injected into the peritoneal space.

Question 9

A technologist received a request to perform a scan with 99mTc albumin colloid to rule out acute cholecystitis. What should he or she do next?
(a)Check if albumin colloid is available

(b) Alert the nuclear medicine physician to the problem
(c) Change the order to 99mTc IDA
(d) Perform the study as ordered

Answer 9

(b) The technologist who sees that the exam ordered is inappropriate for addressing the question asked by the referring physician should alert the departmental physician in charge so that the situation can be resolved. It is irresponsible to perform the exam as ordered, but beyond the responsibility of the technologist to change the order.

Question 10

When performing a SPECT study of the liver and spleen, the camera should be positioned:
(a)So that the costal margin is at the bottom of the detector face

(b) So that it touches the left side of the patient when rotating
(c) So that it touches the right side of the patient when rotating
(d) As close as possible but without touching the patient during rotation

Answer 10

(d) The camera rotation should be as close as possible to the patient without touching him or her. Any IV poles catheter bags, or other attachments should be carefully placed to avoid entanglement during rotation. The detector head should be level, and the arms should ideally be positioned above the head.

Question 11

Radiocolloids are cleared from the circulation by:
(a)Liver parenchymal cells

(b) Hepatocytes
(c) Kupffer cells
(d) Hemangiomas

Answer 11

(c) Radiocolloids are cleared largely by the liver’s Kupffer cells but also by the spleen and the bone marrow. The smallest particles tend to be sequestered by the bone marrow, the largest by the spleen. In certain hepatic conditions, colloid shift may be present; this manifests as greater clearance by the spleen and bone marrow relative to the liver.

Question 12

Which radiopharmaceutical is commonly used to image cavernous hemangioma?
(a)99mTc albumin colloid

(b) 99mTc RBCs
(c) 99mTc IDA
(d) 99mTc pertechnetate
(e) 99mTc sulfur colloid

Answer 12

(b) Cavernous hemangioma is a common vascular malformation which often causes no symptoms in patients. It can be evaluated using 99mTc-labeled red blood cells. Increased activity is seen on initial perfusion images which decreases on delayed static images. Large hemangiomas may show inhomogeneous uptake due ot thromboses. SPECT has a much greater sensitivity for detecting cavernous hemangioma than does planar imaging.

Question 13

Colloid shift refers to:
(a)Small colloid particles clumped together to form large particles which localize in the lungs

(b) 99mTc sulfur colloid changing into albumin colloid
(c) Increased uptake of colloid in the spleen and bone marrow relative to the liver
(d) The redistribution of colloid within the liver over time

Answer 13

(c) In certain hepatic conditions, colloid shift may be present; this manifests as greater clearance by the spleen and bone marrow relative to the liver.

Question 14

Which of the following does not involve the use of labeled RBCs?
(a)Blood pool imaging of the liver

(b) GI bleed imaging
(c) Spleen imaging
(d) Meckel’s diverticulum
(e) Both (a) and (d)

Answer 14

(d) The listed choices a, b, and c can all be performed using labeled erythrocytes. 99mTc pertechnetate is taken up by gastric mucosa. Meckel’s diverticulum is a congenital outpouching of the intestine which may contain ectopic gastric mucosa, so imaging with 99mTc pertechnetate can be useful for diagnosis.

Question 15

Cimetidine:
(a)Prevents the gallbladder form contracting

(b) Prevents the release of pertechnetate from gastric mucosa
(c) Increases uptake of pertechnetate in the gastric mucosa
(d) Decreases peristalsis

Answer 15

(b) Cimetidine inhibits release of pertechnetate from the gastric mucosa. It may be administered to patients 1-2 days prior to performing an exam to improve sensitivity of detection of Meckel’s diverticulum.

Question 16

The approximate time for half of the activity to empty from the stomach during a solid phase gastric emptying exam is:
(a)25 min

(b) 40 min
(c) 90 min
(d) 180 min

Answer 16

(c) The half time for solid gastric emptying is dependent on the type of meal used but is about 90 min for scrambled eggs, a commonly used meal.

Question 17

Esophageal reflux studies are usually performed with both solid and liquid phases.
(a)True

(b)False

Answer 17

(b)Esophageal reflux studies typically use a radiopharmaceutical in liquid.

Question 18

Which imaging study is acquired while an abdominal binder is inflated to increasing pressures?
(a)Meckel’s diverticulum study

(b) Gastric emptying study
(c) Esophageal transit study
(d) Esophageal reflux study
(e) Gastrointestinal bleeding study

Answer 18

(d) A common protocol for an esophageal reflux study involves an abdominal binder to increase pressure over time while imaging. This pressure, together with the supine positioning, and the addition of acid into the radiopharmaceutical all seek to provoke reflux.

Question 19

An appropriate adult dose and radiopharmaceutical for a Meckel’s diverticulum is:
(a)10 mCi of 99mTc pertechnetate

(b) 300 uCi of 99mTc sulfur colloid in water
(c) 300 uCi of 99mTc albumin colloid in 150 ml of orange juice
(d) 20 mCi of 99mTc-labeled red blood cells
(e) 6 mCi of 99mTc albumin colloid

Answer 19

(a) Only the first choice lists 99mTc pertechnetate. 99mTc pertechnetate is taken up by gastric mucosa. Meckel’s diverticulum is a congenital outpouching of the intestine which may contain ectopic gastric mucosa, so imaging with 99mTc pertechnetate can be useful for diagnosis.

Question 20

A patient with a bilirubin level of 35 mg/dl is scheduled for hepatobiliary imaging. The best radiopharmaceutical to use would be:
(a)99mTc pertechnetate

(b) 99mTc disofenin
(c) 99mTc mebrofenin
(d) 99mTc sulfur colloid
(e) 99mTc-labeled RBCs

Answer 20

(c) The uptake and distribution following injection of a hepatobiliary imaging agent depend in part on the patient’s bilirubin level. Increased level of bilirubin is associated with decreased excretion of the radiopharmaceutical.

Question 21

If 15 min after injection of 8 mCi of 99mTc disofenin, the liver is not visualized, but the heart and kidneys are, what is the most likely reason?
(a)Too little DISIDA was injected.

(b) The liver is not functioning properly.
(c) The gallbladder is obstructed.
(d) The patient is taking morphine.
(e) The patient has a very low bilirubin level.

Answer 21

(b) Iminodiacetic acids (IDAs) are cleared from the blood by the hepatocytes before they are secreted into the canaliculi. If the liver is not seen but there is cardiac and renal activity at 15 min after injection, this likely indicates that there is a problem of liver function.

Question 22

A synthetic form of cholecystokinin is:
(a)Glucagon

(b) Cimetidine
(c) Pentagastrin
(d) Sincalide
(e) Mebrofenin

Answer 22

(d) Cholecystokinin, or CCK, is a hormone secreted by the duodenum, which causes the gall bladder to contract and secrete bile. Sincalide is a synthetic form of CCK that can be used before radiopharmaceutical injection in patients who have fasted for extended periods of time or who receive parental nutrition to empty the gall bladder, allowing the radiopharmaceutical to localize there. When used it should be injected over 5-10 min to ensure that spasm is not induced. It can also be used to determine gallbladder ejection fraction (normal is >50%).

Question 23

What are the possible effects on a hepatobiliary scan if the patient has eaten 2 hr before the study?
(a)A false positive

(b) Nonvisualization of the gallbladder within an hour
(c) Intermittent contraction of the gallbladder
(d) All of the above
(e) (a) and (b) only

Answer 23

(e) If there is insufficient fasting, radiopharmaceutical may not be able to enter the gallbladder, resulting in a false positive.

Question 24

If the maximum counts obtained from an ROI about the gallbladder are 285,000 and the minimum counts obtained from the same ROI are 187,000, what is the ejection fraction of the gallbladder?
(a)22%

(b) 34%
(c) 52%
(d) 66%
(e) 73%

Answer 24

(b) Images pre- and post-CCK or fatty meal are used to draw regions of interest for calculation of gallbladder ejection fraction. The formula used to calculate gallbladder ejection fraction is (net maximum counts-net minimum counts/Net maximum counts) x 100%. Since there is no mention of background counts in the question, one assumes that the numbers given are in net counts. ((285,000-187,000/285,000)x100%=34%)

Question 25

Is the ejection fraction (maximum counts obtained from an ROI about the gallbladder are 285,000 and the minimum counts obtained from the same ROI are 187,000) within the normal range?
(a)Yes

(b)No

Answer 25

(b) Many authors state that normal gallbladder ejection fraction is >50%, although this varies among labs. Some consider ejection fractions of 30-50% to be equivocal; other recent sources state that anything >35% is normal.

Question 26

What will be visualized in the first hour of a normal hepatobiliary scan?
(a)Common duct

(b) Gallbladder
(c) Duodenum
(d) All of the above
(e) (a) and (b) only

Answer 26

(d) Within an hour, a normal hepatobiliary scan (e.g., with 8 mCi 99mTc DISIDA) is expected to show the liver, the common bile duct, the gallbladder, and the small intestine.

Question 27

Cholesystokinin is a hormone secreted by the duodenum that stimulates gallbladder contraction.
(a)True

(b)False

Answer 27

(a) Cholecystokinin, or CCK, is a hormone secreted by the duodenum, which causes the gall bladder to contract and secrete bile. Sincalide is a synthetic form of CCK that can be used before radiopharmaceutical injection in patients who have fasted for extended periods of time or who receive parental nutrition to empty the gall bladder, allowing the radiopharmaceutical to localize there. When used it should be injected over 5-10 min to ensure that spasm is not induced. It can also be used to determine gallbladder ejection fraction (normal is >50%).

Question 28

Morphine given during a hepatobiliary scan can:
(a)Constrict the sphincter of Oddi

(b) Enhance gallbladder filling
(c) Shorten the study time
(d) All of the above
(e) (b) and (c) only

Answer 28

(d) As morphine enhances the muscle tone of the sphincter of Oddi, pressure will increase in the bile ducts and may result in gallbladder filling. This may be an alternative to delayed imaging.

Question 29

Sulfur colloid is best for gastrointestinal bleeding studies if:
(a)Bleeding is intermittent.

(b) Bleeding is active.
(c) The bleeding site is in the right upper quadrant.
(d) Delayed images will be planned.
(e) None of the above.

Answer 29

(b) 99mTc sulfur colloid is rapidly cleared from the blood stream, and the patient must be actively bleeding while sulfur colloid is intravascular for the bleed to be visualized. Delayed imaging is therefore not possible, but repeat studies can be undertaken within a relatively short time. Increasing liver and spleen activity may complicate the detection of bleeding in these areas.

Question 30

Which of the following would not be useful in further examining a suspicious area of activity when evaluating a patient for lower GI bleed with 99mTc-labeled red blood cells?
(a)Delayed imaging to visualize a change in configuration of the activity

(b) Delayed imaging to visualize increasing activity
(c) Use of cine mode
(d) Anterior obliques
(e) None of the above

Answer 30

(e) The use of cine mode, oblique imaging, and delayed imaging is useful in the detection of GI bleeds.

Question 31

Potassium perchlorate should not be administered to pediatric patients undergoing scanning for Meckel’s diverticulum with 99mTc pertechnetate.
(a)True

(b)False

Answer 31

(a) Most scans to rule out Meckel’s diverticulum are performed on pediatric patients, in whom potassium perchlorate may be given to reduce thyroid uptake of pertechnetate. However, it also blocks secretions from gastric mucosa and may result in a false-negative scan.

Question 32

Which is the method of choice for labeling red blood cells with 99mTc if the goal is to have the least amount of free pertechnetate in the resulting dose?
(a)In vitro.

(b) In vivo.
(c) Modified in vivo.
(d) The amount of free pertechnetate will be the same in all cases.

Answer 32

(a) Labeling the cells in vitro will result in the highest labeling efficiency, i.e., the least amount of pertechnetate. Free technetium will cause increased activity in the kidneys and gastric mucosa and may interfere with image interpretation.

Question 33

Why is the labeling efficiency important for imaging of GI bleeding with 99mTc RBCs?
(a)A small decrease in labeling efficiency may lead to a false-negative result.

(b) If the patient is actively bleeding, the radiopharmaceutical must be prepared as quickly as possible.
(c) 99mTc pertechnetate will be taken up by the Kupffer cells.
(d) Free pertechnetate is secreted by the stomach and the kidneys.

Answer 33

(d) Free technetium will cause increased activity in the kidneys and gastric mucosa and may interfere with image interpretation.

Question 34

When performing a gastric emptying study, it is important to scan the patient in the erect position to promote emptying.
(a)True

(b)False

Answer 34

(b) The patient can be imaged supine using continuous dynamic acquisition. Newer guidelines recommend images be obtained at hour intervals, up to 4 hours, either erect or supine (depending on patient condition).

Question 35

Which of the following studies does not require any fasting prior to the examination?
(a)Gastric emptying study

(b) Hepatobiliary scan
(c) Esophageal transit
(d) Gastroesophageal reflux study
(e) Gastrointestinal bleeding scan

Answer 35

(e) No fasting is necessary before scanning to rule out a GI bleed; some fasting is required for all of the other exams listed.

Question 36

Symptoms of cholecystitis may include:
(a)Pain the right upper quadrant

(b) Back pain
(c) Nausea
(d) All of the above
(e) (a) and (c) only

Answer 36

(d) Symptoms of both acute and chronic cholecystitis include nausea and pain, which can be limited to the abdomen but sometimes extends to the back and right scapular area.

Question 37

In order to reach the duodenum, bile must pass through the gallbladder.
(a)True

(b)False

Answer 37

(b) Bile is produced in the liver and then enters the biliary canaliculi. From there approximately two-thirds of bile bypasses the gallbladder and enters the duodenum. The remaining bile is stored in the gallbladder until it is needed and secreted.

Question 38

A positive urea breath indicates the presence of Helicobacter pylori based on:
(a)The body’s inability to produce urea in the presence of H. pylori

(b) The fact that H. pylori needs a carbon-rich environment in which to survive
(c) The inability of radioactive carbon to exist in the form of carbon dioxide
(d) The ability of H. pylori to break up urea into nitrogen and carbon

Answer 38

(d) In this test, patients receive urea labeled with 13C or 14C orally. Helicobacter pylori produces urease, which breaks down the labeled urea into carbon dioxide and ammonia. The carbon dioxide is transported by blood into the lungs and can be detected in the breath.

Question 39

Urea normally leaves the body:
(a)In the urine

(b) In the stool
(c) As exhaled carbon dioxide
(d) When 13C has decayed to background levels

Answer 39

(a) Urea is produced in the liver as a result of the breakdown of ammonia from protein and is reabsorbed from blood in the kidneys before being excreted in the urine.

Question 40

When performing GI bleeding scan using 99mTc-labeled RBC, which of the following is correct?
(a)Dynamic images are obtained at 1 min/frame for 60 min.

(b) If positive findings of active bleeding are observed by the technologist, he/she can stop the imaging acquisition at that time point.
(c) If positive findings of active bleeding are observed by the technologist, he/she can stop the imaging acquisition and immediately restart a second part of imaging so that the first part imaging can be reviewed by a physician.
(d) If the test is negative in the 60 min period of imaging, the patient should be sent back to the floor, but delayed imaging can be performed later if there is evidence of active bleeding later.
(e) Both (a) and (c)
(f) Both (a) and (d)

Answer 40

(e) GI bleeding imaging is normally for 60 min but can be longer. If more imaging is needed, it should be performed continuously. Delayed imaging after interruption often does not help.

Question 41

Poor 99mTc RBC labeling may be caused by:
(a)Heparin

(b) Iodinated contrast
(c) Doxorubicin
(d) Lidocaine
(e) All of the above

Answer 41

(e) other medicines that affect Tc-99m RBC labeling include the following: methyldopa, hydralazine, quinidine, etc.

Question 42

When performing Meckel’s scan to detect ectopic gastric mucosa, patients can be pretreated with the following medicines to increase the sensitivity:
(a)Cimetidine

(b) Pentagastrin
(c) Glucagon
(d) All of the above

Answer 42

(d) All can be used, but cimetidine is most commonly used.

Question 43

To prepare a patient for hepatobiliary scintigraphy, which of the following is correct?
(a)Patients need to be NPO for at least 4 h.

(b) No caffeine for 12 h before the test.
(c) No opioid narcotics for at least 4 h or longer.
(d) (a) and (c) only.

Answer 43

(d) For HIDA scan, patients need to be NPO for at least 4 h but not longer than 24 h, and opioid narcotics should be held for at least 4 h. Caffeine does not interfere with this test.

Question 44

For Meckel scintigraphy, which of the following is not correct:
(a)Ectopic gastric mucosa in a Meckel diverticulum is a common cause of gastrointestinal bleeding.

(b) Meckel’s diverticulum is a congenital malformation located in the distal ileum.
(c) Meckel scintigraphy should be performed only when the patient has actively bleeding.
(d) The purpose of Meckel scintigraphy is to localize ectopic gastric mucosa in a Meckel diverticulum.

Answer 44

(c) Meckel scintigraphy should be used when the patient is not actively bleeding. For patients with active bleeding, radiolabeled red blood cell (RBC) scintigraphy should be performed

Question 45

For HIDA scan to evaluate biliary atresia, which of the following is not correct:
(a)It is most commonly performed in newborn infants.

(b) Biliary atresia is characterized by obliteration of the extra hepatic biliary system.
(c) If no bowel activity is visualized, 4-h delayed imaging is required to complete the study.
(d) If no bowel activity is visualized, 24-h delayed imaging is required to complete the study.

Answer 45

(c) A 24-h delayed imaging is often required, unless bowel activity is seen earlier.

Question 46

A Gallbladder Ejection Fraction of at least 35% is considered normal.
(a) True
(b) False

Answer 46

(a) True. Greater than 35% indications acalculous cholecystitis.