GI system - unit 3

What s the role of the GI tract/alimentary canal?

route of intake for nourishment, digest and absorb nutrients, eliminates waste products

What are the accessory organs of the GI system?

salivary glands, pancreas, liver, gallblader

What are the indications for a salivary gland imaging procedure?

eval of dry mouth (xerostomia)

rule out blockage of one or several glands/ducts

evaluate palpable mass

What is the patient prep for a salivary gland procedure?

none

What type of collimator is used for a salivary gland procedure?

low energy, parallel hole collimator

How is the patient positioned for a Salviary gland procedure?

seated, facing the camera

head tilted backward with neck extended

chin resting on camera

Why do we position the patient with their head tilted back in a salivary gland imaging procedure?

to prevent the thyroid from obscuring the salivary glands

why do we give the patient lemon juice during a salivary gland imaging procedure? What types of images are we taking after this?

gustatory stimulation

20-minute flow images of tracer clearance from the salivary gland

What is a general normal finding on a salivary gland imaging procedure?

simultaneous, rapid, and symmetrical uptake of all three glands

What are some abnormal findings on a salivary gland image, and what is the cause of each?

hot spots/area of increased uptake = Warthin tumors

cold areas = metastatic lesions

poor response to gustatory stimulation = blockage

Where is the esophagus located?

posterior to the trachea

What are the three parts of the esophagus? What type of muscle is in each?

upper third = striated

middle = combination of striated and smooth

lower third = smooth

What is the dosage for a salivary gland imaging procedure? How is it given?

1-5 mCi Tc-99m pertechnetate via IV

What is the method of uptake of Tc-99m pertechnetate into the salivary glands?

ions are excreted by glands into saliva

What images are taken in a salivary gland imaging procedure? How long are we taking these images for?

dynamic images of the anterior face and neck

1-2 second intervals for 15-20 seconds

what are we looking for in salivary gland initial dynamic imaging?

simultaneous and symmetrical uptake

What additional images are we taking for a salivary gland imaging procedure? And why are we taking these photos?

anterior and lateral views of the head and neck

confirming the normal presence of tracer in the saliva in the oral cavity

What are normal findings for a salivary gland imaging procedure after the first swallow?

rapid decrease in esophageal activity within 5-10 seconds after first swallow

What are normal findings for a salivary gland imaging procedure after 2 minutes?

at 2 min 10% of peak activity remains

What are normal findings for a salivary gland imaging procedure after 10 minutes?

less than 5% of peak activity remains

What are abnormal findings on a salivary gland imaging procedure?

any sort of delay - anything in esophageal track after 2 and 10 min

activity present in esophagus

Achalasia - absence of relaxation of the lower esophageal sphincter

What are the indications for a Esophageal transit procedure?

esophageal motor disorder

efficacy of surgical or mechanical interventions on the lower esophagus

What is an esophageal motor disorder?

difficulty or pain associated with swallowing

What is the patient prep for a Esophageal transit procedure?

NPO for 2 hours

What does NPO mean?

nothing per oral - aka no eating or drinking

What is the dose for an Esophageal transit procedure?

300uCi of Tc-99m sulphur colloid

How is the dose for an Esophageal transit procedure given?

in 15ml of tap water (orally)

What type of collimator is used for a Esophageal transit procedure?

low energy, all purpose

How is the camera positioned over the patient during an Esophageal transit procedure?

entire esophagus with the stomach at the bottom of the FOV

What types of images are we taking for an Esophageal transit procedure? How long is each image taken?

flow/dynamic for total of 10 min

0.25 sec for first 2 min

15 sec intervals for 8 min

How should the patient be instructed during an Esophageal transit procedure?

Pt should take entire dose/water in mouth but not swallow until instructed

have Pt swallow every 15 sec for 10 min

What is gastroesophageal reflux?

complex symptoms including regurgitation of food/liquid, heartburn, and chest pain

gastric or duodenal contents enter the esophagus

What can cause gastroesophageal reflux?

anatomic abnormalities, incompetence of the lower sphincter

fat, alcohol, chocolate, cigarettes

What is the patient prep for a gastroesophageal reflux imaging procedure?

NPO for 8 hrs

If an esophageal transit study is planned on the same day as a gastroesophageal reflux, which should be performed first?

esophageal transit study first

What is the dose for a gastroesophageal reflux imaging study?

300uCi of Tc-99m Sulphur colloid

How is the patient given the dose for a gastroesophageal reflux procedure?

300uCi of Tc-99m sulphur colloid, mixed with 150ml of orange juice and 150ml of 0.1 M hydrochloric acid

Why is the dose for a gastroesophageal reflux procedure mixed with orange juice and hydrochloric acid?

acidity stimulates gastric reflux

What is the estimated amount of fluid we give patients for a gastroesophageal reflux scan?

300ml or 10oz

What are the four factors required to induce gastroesophageal reflux?

oral administration of acidified solution

successive, increased pressure applied to the abdomen

maintenance of supine position

at least 300ml volume in the stomach to oppose the applied pressure

Describe the imaging procedure for a gastroesophageal reflux scan?

give patient dose

fit patient with an abdominal binder

10min after tracer administration begin imaging

position patient supine, w/ stomach at bottom of FOV (including entire stomach

• if esophagus visualized during positioning give patient water to flush esophagus

acquire images for 30 seconds at the pressure points 0,20,40, 60, 80, 100mHg, without deflating between points

take post deflation image

What are normal and abnormal findings for a gastroesophageal reflux study for adults?

normal = <4% reflux

abnormal = > 4% reflux and can be visualized in the images

Why would 24 hr delayed images be performed on a gastroesophageal reflux study?

detection of pulmonary aspiration

What types of findings might you see in a child/infant gastroesophageal reflux study? What dosage do we give to pediatric patients?

shows aspiration, or GER caused by delayed emptying

1mCi of Tc-99m Sulfur colloid in infant formula orally via NG or g-tube

What is the role of the stomach in the digestive system?

food reservoir

breaks down solid food into chyme

controls rate of emptying gastric content into the duodenum

Where does the stomach empty into?

duodenum into small intestine

What is the top portion of the stomach?

fundus

What is the lower region of the stomach before it empties into the small intestine? What is the valve that controls the rate of emptying?

pylorus

pyloric sphincter

What is the patient prep for a gastric emptying procedure?

NPO 4-12 hrs before

What are the indications for a gastric emptying procedure?

confirm gastroparesis as a cause of persistant nausea and vomiting

monitor effects of therapy in patients with abnormal motility - diabetics

What are some factors that affect a gastric emptying procedure?

sex, time of day, composition of meal (volume, caloric content, amount, protein)

What is gastroparesis?

delayed gastric emptying, food staying in stomach and not emptying

What is the dose for a gastric emptying procedure? What are we giving to the patient? How fast should the meal be eaten?

1mCi of Tc-99m Sulfur colloid in eggs (scrambled, liquid), oatmeal

2 slices of white toast, 2 containers of jelly, 200ml of water

should be eaten in 10 min

What are the pediatric tracer(s) used for a gastric emptying study? How is it given?

Tc-99m DTPA in formula, can also do In-111 DTPA in OJ

What is the procedure for a gastric emptying study?

have patient eat breakfast within 10 min, immediately lay down under the camera(sometimes upright)

tape C0-57 marker right of xiphoid process

initial 45min dynamic study, then by 1 min static at 2, 3, and 4 hours post meal

How long are we imaging/taking images in the initial dynamic image phase for a gastric emptying study? and when do we begin imaging?

1 min dynamic images for 45 minutes after patients meal

If we graph the behavior of solids in a gastric emptying study, what type of behavior should we expect to see? What is the normal half-time for solids and why?

linear, 90min half time

3 textures all processed differently in body

If we graph the behavior of liquids in a gastric emptying study, what type of behavior should we expect to see? What is the normal half-time for liquids?

exponential

half time = 30min

What is the gastric emptying half time? What is it used for?

time it takes for the stomach to empty 50% of ingested meal

used to assess gastric transit

This gastric emptying graph demonstrates:

normal liquid emptying

normal/slightly delayed solid emptying

This gastric emptying graph demonstrates:

normal liquid emptying

delayed solid emptying

This gastric emptying graph demonstrates:

delayed liquid emptying

delayed solid emptying

what is a GI bleed?

blood loss from any organ in the GI tract (mouth to anus)

Where does an upper GI bleed ordinate from? What can be a telltale indicator that it’s an upper GI bleed?

esophagus, stomach, duodenum (first part of small intestine)

dark, tarry stools

Where does a small bowel bleed orignate from?

jejunum, ileum

Where does a lower GI bleed originate from? What can be a telltale indicator that it’s a lower GI bleed?

colon, rectum, anus

bright red blood

What are the indications for a GI bleed?

localization of the site of bleeding -active or intermittent

detecting and localization of hemorrhage including retroperitoneal and peripheral locations

Is a GI bleed study usually an emergency procedure? why or why not?

prompt therapy depends on exact localization

usually substantial bleeding in stool

patient can bleed out - find cause to fix in surgery

Is there any patient prep for a GI bleed scan?

no

Are we performing static or dynamic images for a GI bleed?

dynamic to catch the bleed and localize the source of it

What type of radiopharmaceuticals are we using for a GI bleed?

Tc-99m Sulfur colloid

Tc-99m labeled red blood cells

What are the pros and cons of using tc 99m sulfur colloid for a GI bleed?

pros: minimizes background activity, promotes high contrast ratio

cons - rapid clearance, requires pt to be actively bleeding

List the three ways we can label red blood cells for a GI bleed using Tc-99m.

in Vivo

in Vivi/in vitro

in vitro

How are RBCs labeled in vivo for a GI bleed?

What is the general efficiency of using this method?

labeled inside body

inject stannous ion (Sn+2), wait 20-30 min, inject Tc-99m Pertechnetate

variable, 60-90% labeling efficiency

What are the pros of performing a GI bleed scan in Vivo? What are the cons and why?

convenient and easy

can’t see bleeding in the stomach, small bowel, and/or colon because they’re natural areas of uptake of free Tc99m in body

What is the procedure for an in VIvo/In vitro Gi bleed procedure? What is the efficiency rate of labeling?

IV injection of stannous ion

blood sample collected in syringe containig Tc-99m-pertechnetate and anticoagulant (heparin)

reinject labeled sample

~95% efficiency

What are the pros of doing a Tc99m RBC labeled GI bleed procedure in vivo/In vitro?

absence of blood manipulation -less risk of mix ups

low risk of contamination

What is the procedure for an In Vitro GI bleed procedure?

labeling done outside of body, small sample of blood (1-3ml) withdrawn into syringe containing anticoagulant heparin

let sit for 5 min

add sodium hypochlorite and ACD and. Tc-99m pertechnetate

wait 20 min, then inject into patient

Why is in vitro the preferred labeling method for a GI bleed labeled RBC procedure?

high labeling efficiency, superior imaging quality

What type of collimator are we using for a Tc-99m pertechnetate labeled RBC GI bleed procedure?

low energy, parallel hole collimator

how is the patient positioned under the camera for a labeled RBC GI bleed procedure?

supine, often on a stretcher

What anatomy should be included on a GI bleed labeled RBC procedure?

inferior margin of the liver at the top of the FOV

aka Xiphoid process to bladder should be in view

Tc-99m Sulpfur colloid is better for what type of GI bleed?

an active bleed

Which is the preferred tracer for a GI bleed procedure, Tc-999m sulfur colloid or Tc-99m labeled RBCs?

Tc-99m labeled RBCs

What is the dose for Tc-99m Sulfur colloid for a GI bleed?

7-10 mCI

What types of images are being taken for a Tc-99m sulfur colloid GI bleed procedure? What should be done if the GI bleed is not visualized during these initial images

dynamic for 2-3 min

static images ever 1-2 min for 30 min

should take specified count image of upper abdomen

What are the downsides of using Tc-99m Sulfur colloid for a GI bleed procedure?

has rapid clearance, and only good for active bleed

What is the dose for Tc-99m labled RBCs in a GI bleed?

10-15 mCi

up to 30 mCi

What types of images are we taking for a tc99m sulfur colloid GI bleed procedure? Based on what parameter do we use when determining how long to image a patient?

initial flow images for 32 frames

dynamic images 1/min if bleed not visualized

basically keep imaging until you see something`

Why is Tc99m labled RBCs the prefered method?

allows for imaging up to 36 hrs, possible delayed images

lower radiation dose to liver and spleen

preferred for intermittent bleeding

What are the normal areas of uptake using Tc-99m Labled RBCs in a GI bleed procedure?

great vessels of the abdomen, liver, sometimes spleen depending on how well tagged

general outline of kidneys, bladder, small and large intestines, and genital organs

What are the findings using Tc-99m sulfur colloid GI bleed procedure?

positive bleed within 5 min

focal areas

false positives in renal transplant pt due to accumulated tracer

What are the findings using Tc-99m labled RBCs in a GI bleed procedure?

focal areas gradually become more intense

if first pictures are negative use delayed images

What are some general things to be aware of in a GI bleed procedure?

patient in critical condition, keep an eye on them

smell = likely positive

catheter needs to be moved out of FOV

start imaging THEN inject patient

What is a Meckel Diverticulum? What age is it most commonly found in?

pouch on wall of intestines that is present at birth (congenital) often contains gastric mucosa

children

What are some symptoms of a Meckel Diverticulum?

abdominal pain

bloody stools

What are some complications of Meckel Diverticulum?

peptic ulceration

hemorrhage from acid excretion (rupture/tearing)

What is the patient prep for a Meckel Diverticulum imaging procedure?

NPO for 12 hrs

What is the dose for Meckel Diverticulum?

10-15 mCi of tc-99m pertechnetate

How is the camera positioned over the patient for a Meckel Diverticulum imaging procedure?

xiphoid to bladder