RDSC 233 Unit 5Radiography of the Air Contrast BaE Bontrager pp. 492-517 (air-contrast only)

Positioning of:

Rt. & Lt. lateral decubitus RAO & LAO obliquesLPO axial (butterfly)Ventral decubitus rectumUpright-transverse

Film Critique

Radiographic Pathology

Exposure Factors

The Air-Contrast BaE

The Air Contrast Barium Enema

In the late 1970s the air contrast enema was introduced, and quickly became the examination of choice.

An special air contrast enema tip provides for the introduction of air

Coating the colon is done underfluoroscopy. First, thick barium fillsthe sigmoid and descending colon.Air, and patient positioning isused to push the column of barium to the cecum. Excess barium is drained back into the bag

Barium tube

AirinflatorRetention

balloon inflator

The Air Contrast Barium Enema

2. Thick barium to coat the bowel

4. Multiple positions, and extra projections to demonstrate every area of the bowel in the double contrast effect

3. Rolling the patient back and forth to keep the lumen coated. (Some routines require the patient to make a 3600 rotation in the middle of the filming routine)

1. Sufficient inflation of the colon

Four components that optimize the AC examination

Radiographic Positioning of Additional Views for the Air Contrast Procedure

Film Critique

including

Positioning of:

Rt. & Lt. lateral decubitus RAO & LAO obliquesLPO axial (butterfly)Ventral decubitusUpright-transverse

Routine AC Colon Positioning

2. Reciprocating bucky 12:1, 16:1 grid

1. 40” SID (relatively standard)

3. 80-90 kVp range

Setup

4. 14” x 17” film, lengthwise

5. ID marker at bottom

6. Rt marker above ID marker

Routine AC Colon PositioningPreparation

1. Evaluate the order

2. Greet the patient 3. Take History What is pertinent Hx?

4. Remove jewelry, check attire, snaps, pins, NG tubes, etc.

5. Explain the exam in layman’s terms

6. Questions?

Unlike the single contrast examwhich may fail to demonstratepathology of the mucosa of thebowel that is not ulcerated orsignificantly stenosed, the doublecontrast effect is preferred for thedemonstration of polyps and small neoplasms

7. Set technique before positioning

Routine Left and Right Lateral Decubitus Positioning

A horizontal beam projection to demonstrate the air-filled, barium-coated half of the bowel on the side up.

Flash marker

Sponge

CR

Same as for the abdomen decub. The grid & film is in a film holder.

Set up/Positioning

The right lateral decubitus positionshown here, would result in a film that looks like this

The patient is then rotated 1800

into the right lateral position

Film CritiqueRoutine Decubitus Positioning

1. As much anatomy is included as can be included when well centered, primarily for the ascending and descending colon.

2. The bowel is sufficiently inflated

3. The air filled bowel is coated with barium

On all filmsPatient IDRt or Lt markerContrast & densityMotionArtifacts

Routine RAO & LAO Positioning Steps

RAO: CR to iliac crest of side up (or slightly higher as indicated on observation of fluoroscopy)

350-450 obliques Entire spine (hips & shoulders) in same plane

LAO: CR 2”-3” above iliac crest of side up (or significantly higher as indicated on observation of fluoroscopy)

Critique Criteria for Anterior Colon Obliques

Like posterior obliques (that are most commonly used in single contrast studies),anterior obliques are specifically designed to demonstrate the flexures.

In AC studies all four oblique projectionsmay be included in a routine.

Inclusion of the sigmoid and rectum is usually not required

Splenicflexure

The RAO is intended to lay the rt. colic flexure out in profile

The LAO demonstratesthe left

Routine AP Axial Oblique Positioning Steps

In addition to the AP axial film, an AP axial projection combined with an LPO position may better separate the loop of the sigmoid.

It may be used in a single contrast routine, but is frequently used for double contrast.

11” x 14”

300- 400 LPO

CR 300- 400 cephalad

CR centered 2” inferior, and 2’ medial to Rt. ASIS

Criteria Include all of the sigmoid and rectum in an elongated view.

Routine Ventral Decubitus Lateral Rectum Positioning

Steps

The ventral decubitus lateral rectum is a horizontal bean projection to further delineate the rectosigmoid area, in a double contrast effect.

It is otherwise positioned like alateral rectum.

10” x 12” or 11” x 14”

CR at level of ASIS, mid coronal plane

Criteria Include all of the sigmoid and rectum in an lateral, double contrast view.

Routine Upright Positioning(Not in Bontrager)

Same as an uprightof the abdomen, exceptthe film is usuallyused transverse.

Positioning

4.

Setup and Preparation

CR Similar to an upright of

the abdomen. Top of the film to the axilla,or at least high enoughto include both flexures.

Criteria

The upright, transverse projection is designed to demonstrate the transversecolon in same manner the decubs demonstrate the ascending and descending.

Note that the film seen herefails to meet the criteria fora good air contrast exam in

Routine Upright Positioning(Not in Bontrager)

the lumen of the transverse colon is not coated with barium due to:

1. Barium too thin2. Insufficient coating before standing 3. Patient allowed to stand to long before exposure

Exposure Factors

From the “Rules of Thumb”

80 – 90 kVP

Otherwise calculated from abdominal technique

Diverticulosis

Abdominal hernias

Tape worms

Significant Pathologiesof the colon

and their

Radiographic Appearances

Polyps

Colorectal Cancer

Chron’s disease

Intussusception

Institutional colon

Septacemia – Pathogenic microorganisms in the blood.

Ileostomy, jejunostomy, colostomy – ostomy = a surgically formed fistula, most commonly between intestine and the abdominal wall. (vs. otomy = surgical incision, vs. ectomy = removal)

Stoma – A mouth like artificial opening between two body cavities, or a passageway between a cavity and a body surface

Resection – partial excision of a part.

Anastomosis – natural or surgical connection between two tubular structures.

Glucagon – Hormone secreted by alpha cells of pancreas that stimulates liver to change stored glycogen to glucouse. Parentaral administration relaxes smooth muscles of alimentary tract.

Diverticulum, Diverticulosis & Diverticulitis

Caused by pressure on the bowel.Onset is usually over 40 years of age.

A high-fiber vegetable diet lessens the incidence. Digested fiber passes more easily, due to its soft jelly-like texture.

Multiple diverticula of the sigmoid colon, seen in air contrast enema.

A diverticulum (singular) is a herniated outpouching in the wall of the colon.

The occurrence of diverticula is diverticulosis. Inflammation of diverticula is diverticulitis.

Diverticulum, Diverticulosis & Diverticulitis

BaE is the best imaging modality for demonstration of diverticula, though CT better detects abscesses.

Several diverticula in the descending colon, seen on a single contrastBaE.

Most diverticula are left sided, with the highest incidence in the sigmoid.

Symptoms

* Abdominal tenderness* Nausea or vomiting* Chills or fever* Constipation or diarrhea

Diverticula thatperforate thecolon cause peritionitis, asevere complicationof diverticulitis

Diverticulum, Diverticulosis & Diverticulitis

This giant diverticulum of the colon is very rare.

Diverticula are most frequently seen in the colon, but can occur in hollow organs, primarily the stomach and bladder.

When bed-rest and antibiotics do not treat symptoms, or when extensive diverticula lead to fecal stasis, surgical resection of the most effected areas becomes necessary.

Abdominal Hernia

Protrusions of bowel may occur anywhere in muscular wall that contains it. Congenital defect, surgery, trauma, defective collagen synthesis, and strain (weight lifting, pregnancy, obesity) are contributing factors.

Inguinal hernias are common in men, though not to the extent demonstrated here.

Its prevalence is due to the weakened area of the pelvic floor where the testis pass from the pelvic cavity to the scrotum, through the inguinal canal.

Tape WormThough most prevalent in third world countries, intestinal parasites are found on occasion.

Tape worms, of which there are numerous species, may be a few inches to to more than 50 feet. Hooks and suckers in the mouth part adhere to the intestinal wall.

Body segments, which may number in the thousands, are immature, mature, and gravid: ending in segments containingmature eggs, that detach and are eliminated with feces.

Tape Worm The life cycle of a tape worm

After elimination by the host

* Eggs develop into hooked embryo * Embryo are eaten by foraging animals, usually pigs or cattle (intermediate hosts)

* Embryo develop as encysted larvae in muscle tissue

* People ingest larvae in undercooked meat, and the cycle continues

Symptoms include: bloating, discomfort,change in bowel habits, and if sufficientlyinfested, obstruction.

Some species of larval cysts may incubatein the liver, pericardium, and brain.

Polyps Typically, a benign growth of a highly vascularized mucosal lining classified as an adenoma. (Adeno=glandular, oma=tumor)

Though asymptomatic, larger polyps can bleed. Some are pre-cancerous, and turn malignant.

Sessile polyps are broad,slightly raised growths, that may have villous (tendril like) projections into surrounding tissue.

Peunculated polyps are on a stalk, like a mushroom

Among the many diverticula in this radiograph, is a pedunculated polyp

Polyps

Pedunculated polyp

Similar polyp as seen on single contrast BaE

Polyps Sessile polyp

Sessile polyp (close up of)

Colorectal CancerCancer is the uncontrolled reproduction of mutated cells, resulting in a useless mass of tissue called a tumor, malignancy, or neoplasm.

Characteristics of growth Benign vs. Malignant

Slow growth Rapid growthUndifferentiated Highly differentiated Non-invasive Highly invasiveLocalized Metastatic

** * Cells, as seen on cytologic examination

*

Cancer of the colon occurs most frequently in the rectum and sigmoid,and is a leading cause of death.

Shown here, is the classic look of an annular carcinoma (originating from epithelial tissue), commonly called anapple core lesion.

An interesting comparison of an AP and PA projection: same patient, same exam, taken minutes apart. Note the changes in the position of thebarium, and the demonstration of the apple-core lesion. Also, note thelook of the pelvis

Colorectal Cancer

Cancer Though colon cancer is most prevelant in the rectum and sigmoid, it may occur anywhere.

Here, a polypoid mass invades the cecum, and involves the ileal papilla.

Cancer of the colon istreated by surgery,chemotherapy, radiotherapy,or a combination of thethree.

Like all cancer, a cure ishighly dependant on early detection and interventionbefore metastasis occurs.

Crohn’s Disease Also called regional enteriitis, is one of two categories of inflammatory bowel disease, the other being colitis.

Most commonly found in the terminal ileum, but can affect any part of the intestine.

The cause is unknown, but, in theory, the body’s immune system, reacting to a virus or bacterium, inflames all layers of the bowel

SymptomsDiarrheaPain in the RLQRectal bleedingWeight lossFeverCrampingStunted growth in children (though Chron’s is most prevalent between 20-40 years of age)

Radiographic appearance: Loops ofbowel are separate due to inflammation. Strictures create a characteristic “string sign.” Ulcerations and edema create a“cobblestone” appearance.

Chron’s Disease

Prognosis: Drugs control pain,inflammation, and bleeding; 70%of patients have surgery. There is no cure. In addition to the signs of Chron’s

disease, something else shows,in what appears to be the sigmoid colon. What is it?

T-shaped IUD

Intussusception

Telescoping, or slipping, of one section of bowel into another. Occurs chieflyin children, and at the ileocecal junction. In adults, intussusception may be secondary to a tumor or polyp.

Mortality is high if left untreated for more than 24 hours.

Lateral projection of ileocecal intussusception

Cecum

Terminalileum

Intussusception

Intussusception

2.

1.

3.

An intussusception may be reduced by the pressureof a barium enema, instead of surgery.

1. Barium reaching the cecum reaches the obstruction2. Hydrostatic pressure reduces the defect.3. Barium begins to reflux into the ileum, demonstrating success.

Institutional Colon Preciously covered in Unit 1. The film on theleft is an attempt to outline the impaction withcontrast.

The film on the right shows the result of a ruptured colon

The end