GI Bleed Scan

Indications:

vomiting blood
passing blood in her stool

Contraindications:

patients with contrast studies under way.
Radiopharmaceutical information:
  • Radionuclide: Tc-99m
  • Radiopharmaceutical: Tc-99m Sulfur Colloid or Tc-99m tagged RBC's
  • Adult dosing: 20-30 mCi
  • Pediatric dosing:
  • Method of administration: IV, drawing, tagging, and reinjection of tagged red blood cells
  • Method of Localization: Angiography, Colonoscopy, barium radiography
  • Physical Half-life: 6 hrs

Patient Preparation:

  • No preparation is necessary, though it is important to not have had any barium studies 48 hours prior to having a GI bleeding scan.

Equipment Used:
Type of Camera or Probe

Gamma Camera

Collimator used:
LEHR
Acquisition Setup:

Dynamic: View(s)
Matrix: 126x126
Time/Frame: 1sec/frame
Number of Frames: 60

Statics: View(s)
Matrix: 126x126
Total Counts or Duration: 500k-750k every 1-2 mins for 20 mins
Whole body: View(s)
Matrix:
Scan Speed:
Start/stop points:

SPECT:
180 or 90 degree configuration
Total Rotation: 180 or 360
Starting point:
Matrix
Time/Azmuiths
Number of Azmuiths:

Procedure:
Describe the procedure from verifying the requisition to completing the scan. Include any patient instructions pre- or post- injection/scan, delays between injection and imaging, and any side effects.

1)RBC imaging- The patient's blood must first be radiolabeled with Tc-99m pertechnetate (20-30 mCi for adult dose). After the tagging, a rapid angiogram sequence is acquired for 1 min, followed by a series of images for typically 1-2 hr. This is done in supine position. The patient may then be routinely reimaged up to 24 hr after injection if no bleeding site is found or if continued blood per rectum is noted. In some departments, the series of images can be viewed as a movie (cine mode), which increases sensitivity of detection
.2) Sulfur Colloid- (10mCi adult dose) may be injected all at once or in fractions. A series of images is then obtained. With a single injection, the study typically lasts approximately 20-30 min because of the rapid clearance of the sulfur colloid from the circulation by the RES. Delayed images are not obtained, but the study can be repeated in its entirely if the patient rebleeds. Cine viewing can also be helpful as described above.

Normal Uptake and common varients:
Insert an image of a normal scan. Describe the normal uptake, and any normal varients visualized.
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There are intense uptakes of 67Ga and 18F-FDG to the large mediastinal mass on the X-ray and CT images. On the 18F-FDG image, there are 3 foci of intense uptake in the abdomen corresponding to bowel on the CT scan.

Abnormal Uptake and causes:
Flow: focal area of increased activity blood pooling in abdominal cavity may also be present.
Statics: focal area peristalses with time. blood pool may persist in abdominal cavit and may or may not move.
If little or no movement, it may be vascular activity or pool in abdominal cavity. Typical foal areas of active bleeding inlude ascending, transverse, descending, and sigmoid olon, right colonic (hepatic0 flexure, left olonic (splenic) flexure, and small bowel.

Artifacts:
-Bad radiotracer tag ould lead to poor results. Do a thyroid image to confirm a bad tag free pertecnetate will go to thyroid, salivary glands, and gastric mucosa.
-Belt buckets, articles in clothing, neklaes, and so forth, may attenuate image.
-A full bladder may mask a bleeding area.
-Intermittence of bleeding compounds the problem of detetion.
-Tc-99m SC (10-20 mCi) may be indicated if there is known active bleeding. The drawback is the relatively quick removal by the reticuloendothelial system (RES) when intermittence is indicated. Do a flow at 1sec/frame for 60 seconds to catch the bleed site. If positive, take full series of immediates (obliques, laterals, posterior) to localize, followed by timed images.

Questions asked in Patient History:

do you have history of cancer? If so for how long?
Do you hae history of bleeding?
Are you bleeding now?
If so, for how long and what is the color of the stool?
do you have ative or history of internal or external hemorrhoids (non-bleeding or actively bleeding)?
Are you taking aspirin?
Do you have any pain?
Do you have a history of diverticulitis?
Crohn's disease, or other disease?
Have you had a colostomy or other surgery?

References: