assessing the anatomy and physiology and contrast agents of upper gi imaging in different modality...

Assessing the anatomy and physiology and contrast agents of upper GI imaging in different modality

Group of researchers:

Samira sari jalooFaeze abbasi

Fateme komeijaniSepehr ebrahimy

Introduction

Explanation of anatomy and physiology of the esophagus and stomach

Modalities that usually use for assessing the esophagus and stomach

Contrast agents (viscosity , volume) Different samples , movies and animation

Which organs does an upper GI exam evaluation ?

upper gastrointestinal tract radiography , also called an upper GI exam , is an x–ray examination of the:

• Pharynx/throat

• Esophagus

• stomach

• first part of small intestine(also known as the duodenum)

• An x ray examination that evaluate pharynx and esophagus is called barium swallow.

Which organs does an upper GI exam evaluation ?

Assessing of esophagus

esophagus

The esophagus is a long, muscular tube that carries food and saliva from the laryngopharynx to the stomach.

The adult esophagus is approximately 10 inches (24 cm) in length and 3/4 inch (1.9cm) in diameter.

the esophagus has a wall composed of four layers:

Fibrous layer Muscular layer Submucosal layer Mucosal layer

It originates at the level of the sixth cervical vertebrae, or the upper margin of the thyroid cartilage.

The esophagus enters the thorax from the superior portion of the neck. In the thorax the esophagus passes through the mediastinum.

Position of esophagus

anterior to the vertebral bodies and posterior to the trachea and heart.

In the lower thorax the esophagus passes through

the diaphragm at T1O.

Functions of the Esophagus

The esophagus secretes mucus and transports food into the stomach.

It does not produce digestive enzymes, and it does not carry on absorption

it is controlled by the medulla oblongata.

Mechanisms in Esophagus

Food is pushed through the esophagus by a progression of involuntary coordinated contractions and relaxations of the circular

and longitudinal layers of the muscularis called peristalsis(per-i-STAL-sis; stalsis constriction).

Functions of the Esophagus

The passage of food from the laryngopharynx into the esophagus is regulated at the entrance to the esophagus by a sphincter (a circular band or ring of muscle that is normally contracted) called the upper esophageal sphincter (e-sof-aJE -al) (UES) or valve.

Functions of the Esophagus

• Just superior to the level of the diaphragm, the esophagus narrows slightly. This narrowing is a physiological sphincter in the inferior part of the esophagus composed of smooth muscle known as the lower esophageal sphincter (LES) or valve.

The esophagus extends between the pharynx and the cardiac end of the stomach and occupies a constant position in the posterior part of the mediastinum, where its radiographic demonstration presents little difficulty when a contrast medium is used.

Modalities of assessing of esophagus

• The alimentary canal is usually examined using a combination

of fluoroscopy and radiography. Fluoroscopy makes it possible

to observe the canal in motion, perform special mucosal studies, and determine the subsequent procedure required for a complete examination.

• Images are obtained, as indicated, during and after the fluoroscopic examination to provide a permanent record of the findings.

Assessing of stomach

stomach

The stomach is the dilated, saclike portion

of the digestive tract extending between

the esophagus and the small intestine The stomach is typically a J-shaped enlargement of

the GI tract directly inferior to the diaphragm in the epigastric, umbilical, and left hypochondriac regions of the abdomen.

Anatomy of stomach

• The stomach has four main regions: • the cardia• fundus• body• pyloric part.

Stomach function

• Because a meal can be eaten much more quickly than the intestines can digest and absorb it, the stomach functions as a mixing area and holding reservoir.

• At appropriate intervals after food is ingested, the stomach forces a small quantity of material into the first portion of the small intestine.

Barium X-ray examination of the upper gastro-intestinal tract

Barium studies (X-rays) of the esophagus, stomach and duodenum are used to diagnose abnormalities of the gastrointestinal tract, such as tumors, ulcers and other inflammatory conditions, hernias, and obstructions (strictures)

A number of special barium sulfate products are also available. Those with finely divided barium sulfate particles tend to resist precipitation and to remain in suspension longer than the regular barium preparations.

• The speed with which the barium mixture passes through the alimentary canal depends on the suspending medium, the temperature of the medium, and the consistency of the preparation, as well as the motile function of the alimentary canal.

Some barium preparations contain gums or other suspending or dispersing agents and are referred to as suspended or flocculation resistant preparations.

• In addition to barium sulfate, water soluble, iodinated contrast media suitable for opacification of the alimentary canal are available.

• These preparations are modifications of basic intravenous urographic media such as diatrizoate sodium and diatrizoate meglumine.

Iodinated solutions move through the gastrointestinal tract more quickly than barium sulfate suspensions.

An iodinated solution normally clears the stomach in 1 to 2 hours, and the entire iodinated contrast column reaches and outlines the colon in about 4 hours.

An orally administered iodinated medium differs from barium sulfate in the following way:

• 1. It outlines the esophagus, but it does not adhere to the mucosa as well as a barium sulfate suspension does.

• 2. It affords an entirely satisfactory examination of the stomach and duodenum, including mucosal delineation

Before beginning the examination

The radiographer should do the following:• Explain to the patient that the barium sulfate mixture

may taste a little chalky.• Inform the patient that the room may be somewhat

darkened during fluoroscopy.• When the fluoroscopist enters the examining room,

introduce the patient and the fluoroscopist to each other.

Esophageal exam

In esophageal examinations the radiographer should observe the following guidelines:

• Use an exposure time of 0.1 second or less for upright radiographs. The time may be slightly longer for recumbent images because the barium descends more slowly when patients are in recumbent positions.

Remember that barium passes through the esophagus fairly slowly if it is swallowed at the end of full inspiration.

The rate of passage is increased if the barium is swallowed at the end of moderate inspiration.

However, the barium is delayed in the lower part for several seconds if it is swallowed at the end of full expiration.

Keep in mind that respiration is inhibited for several seconds after the beginning of deglutition, which allows sufficient time for the exposure to be made without instructing the patient to hold his or her breath after swallowing.

Stomach exam

In examinations of the stomach and small intestine, the radiographer should observe the following guidelines:

• Use an exposure time of no longer than 0.2 second for patients with normal peristaltic activity and never more than 0.5 second; the exposure time should be 0.1 second or less for those with hyper motility.

• Make exposures of the stomach and intestines at the end of expiration in the routine procedure.

EsophagusCONTRAST STUDIES

The esophagus may be examined by performing a full-column fill. single-contrast study in which only barium or another radiopaque contrast agent is used to fill the esophageal lumen. A double-contrast procedure also may be used.

For this study, barium and carbon dioxide crystals (which liberate carbon dioxide) are the two contrast agents. No preliminary preparation of the patient is necessary.

Barium sulfate mixture

A 30% to 50% weight/volume suspension is useful for the full-column, single contrast technique.

A low-viscosity, high density barium developed for double contrast gastric examinations may be used for a double-contrast examination.

Whatever the weight/volume concentration of the barium, the most important criterion is that the barium flows sufficiently to coat the walls of the esophagus.

• The barium manufacturer's mixing instructions must be closely followed to attain optimum performance of the contrast medium.

The performance of the double-contrast esophageal examination is similar to that of a single-contrast examination. For a double-contrast examination, a free-flowing, high-density barium must be used.

A gas-producing substance, usually carbon dioxide crystals, can be added to the barium mixture or can be given by mouth immediately before the barium suspension is ingested

Single contrast and double contrast

Ct exam

• Esophageal varices in the lower half of the esophageal are caused by portal hypertention.

• Congenital or acquired occlusions of the inferior vena cava stimulate collateral circulation through the azygos Venous system(azygos continuation)

• Ct scan positively distinguish the dilated veins paravertebral masses.

Ct morphology

• Esophageal varices have a variable Ct appearance depending on their size and the extent of underlying disease.

• Non enhanced Ct shows nonspecific thickening of the esophageal wall accompanied by nodular paraesophageal masses.

• On contrast enhanced scan, the varices appear as tubular, tortuous structures that show marked pooling of contrast medium.

Gastrointestinal contrast media

• Bowel opacification is necessary for the adequate evaluation of the gastrointestinal tract and for differentiating it from other structures of soft tissue density.

Contrast media for Ct scan

• Contrast media for the bowel are classified as positive and negative depending on whether the material is hyperattenuating or hypoattenuating.

• Water or methyl cellulose preparations are negative contrast media that facilitate evaluation of the mucosa following intravenous administration.

• Water or methyl cellulose do not superimpose on abdominal vessels and are therefore becoming the new standard for Multislice Ct of the abdomen .

For use in Ct examination

• Water or juice should not be carbonated.• Methyl cellulose preparation can be administrated

orally and have the advantages of high viscosity.• oily or fat containing contrast media are not

recommended for oral administration because of their unpleasant taste, which may lead to noncompliance.

• Full fat milk has been described as a contrast medium for the upper abdomen.

• Air or contrast media as contrast mediaproduve very high negative contrast which is particularly useful in virtual endoscopy of the colon(stomach)

• Carbondioxide has the advantage over air that is readily absorbed by the body and is eliminated by respiration.

• Bowel distention can be further improved with injection of 20-40 mg of n-butylscopolamine (e.g Buscopan) as soon the first symptom(bowel colicis)occur.

Positive contrast media

• Barium sulfate suspensions is iodinated solution are positive contrast media that have universal applications.

• Intestinal structures are clearly identifiable as such even they are poorly distented.

• One advantage of positive contrast media is that they make mucosal surface more difficult to evaluate following contrast materials.

• Iodinated contrast media should be avoided in hyperthyroidism and are contraindicated when patients are scheduled for scintigraphy and radiotherapy.

Contrast media in Ct scanesophagus

• Positive oral contrast material may improve delineation of the esophageal lumen.

• Barium pastes (e.g Esophocat) have high viscosity and therefore may improve the coating of the esophageal mucosa but they are contraindicated there is a risk of aspiration.

• Often oral contrast material passes esophageal as a bolus , which leaves larger portion of esophagus without intraluminal contrast.

Contrast media in Ct scanstomach

Drink 500-1000 ml oral contrast medium(water , juice and methyl cellulose) and antispasmodic (Buscopan)

StomachCONTRAST STUDIES

Two general procedures are routinely used to examine the stomach:

• the single-contrast method and the double-contrast method.

• A biphasic examination is a combination of the single-contrast and double-contrast methods on the same day.

Movie and animation

References

1. Gerard j et al , principles of human anatomy BOOK , edition 12th.

2. Philip w. Ballinger et al , radiographic position and radiologic procedures BOOK (Merrill s atlas)

3. Mathias Prokop, Michael Galanski , Spiral and Multislice Computed Tomography of the Body book

4. Radiology assisstan.com

5. Radiology info.com

contrast agents of upper GI imaging in different modality

Thank for your attention