Unit 5
Radiography of the Air Contrast BaE
RDSC 233
Bontrager pp. 492-517 (air-contrast only)
The Air-Contrast BaE
Film Critique
Positioning of:
Rt. & Lt. lateral decubitus
RAO & LAO obliques
LPO axial (butterfly)
Ventral decubitus rectum
Upright-transverse
Exposure Factors
Radiographic
Pathology
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 under
fluoroscopy. First, thick barium fills
the sigmoid and descending colon.
Air, and patient positioning is
used to push the column of
barium to the cecum. Excess
barium is drained back
into the bag
Retention
balloon
inflator
Air
inflator
Barium
tube
The Air Contrast Barium Enema
Four components that optimize the AC examination
1. Sufficient inflation of the colon
2. Thick barium to coat the bowel
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)
4. Multiple positions, and extra projections to
demonstrate every area of the bowel in the
double contrast effect
Radiographic Positioning of Additional Views for
the Air Contrast Procedure
Positioning of:
Rt. & Lt. lateral decubitus
RAO & LAO obliques
LPO axial (butterfly)
Ventral decubitus
Upright-transverse
including
Film Critique
Routine AC Colon Positioning
Setup
1. 40” SID (relatively standard)
2. Reciprocating bucky
12:1, 16:1 grid
3. 80-90 kVp range
4. 14” x 17” film, lengthwise
5. ID marker at bottom
6. Rt marker above ID marker
Routine AC Colon Positioning
Preparation
1. Evaluate the order
2. Greet the patient
3. Take History
What is pertinent Hx?
Unlike the single contrast exam
which may fail to demonstrate
pathology of the mucosa of the
bowel that is not ulcerated or
significantly stenosed, the double
contrast effect is preferred for the
demonstration of polyps and
small neoplasms
4. Remove jewelry, check attire, snaps, pins, NG tubes, etc.
5. Explain the exam in layman’s terms
6. Questions?
7. Set technique before positioning
Routine Left and Right Lateral Decubitus Positioning
Set up/Positioning
Flash marker
Same as for the abdomen
decub. The grid & film is
in a film holder.
A horizontal beam
projection to demonstrate
the air-filled, bariumcoated half of the bowel on
the side up.
Sponge
The right lateral decubitus position
shown here, would result in a
film that looks like this
The patient is then rotated 1800
into the right lateral position
Routine Decubitus Positioning
Film Critique
On all films
Patient ID
Rt or Lt marker
Contrast & density
Motion
Artifacts
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
Routine RAO & LAO Positioning
Steps
350-450 obliques Entire spine
(hips & shoulders) in same plane
RAO: CR to iliac crest of
side up (or slightly higher as
indicated on observation of
fluoroscopy)
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 projections
may be included in a routine.
Inclusion of the sigmoid and rectum is usually
not required
The RAO is intended
to lay the rt. colic
flexure out in profile
The LAO
demonstrates
the left
Splenic
flexure
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 a
lateral 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)
Setup and Preparation
Same as an upright
of the abdomen, except
the film is usually
used transverse.
Positioning
4.
Similar to an upright of
the abdomen. Top of
the film to the axilla,
or at least high enough
to include both flexures.
Routine Upright Positioning
(Not in Bontrager)
Criteria
The upright, transverse
projection is designed to
demonstrate the transverse
colon in same manner the
decubs demonstrate the
ascending and descending.
Note that the film seen here
fails to meet the criteria for
a good air contrast exam in
the lumen of the transverse colon is
not coated with barium due to:
1. Barium too thin
2. 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
Significant Pathologies
of the colon
and their
Radiographic Appearances
Diverticulosis
Abdominal hernias
Tape worms
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
A diverticulum (singular) is a
herniated outpouching in the wall of
the colon.
The occurrence of diverticula is
diverticulosis. Inflammation of
diverticula is diverticulitis.
Caused by pressure on the bowel.
Onset is usually over 40 years of
age.
Multiple diverticula of the
sigmoid colon, seen in
air contrast enema.
A high-fiber vegetable diet lessens
the incidence. Digested fiber
passes more easily, due to its soft
jelly-like texture.
Diverticulum, Diverticulosis & Diverticulitis
Symptoms
* Abdominal tenderness
* Nausea or vomiting
* Chills or fever
* Constipation or diarrhea
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.
Diverticula that
perforate the
colon cause
peritionitis, a
severe
complication
of diverticulitis
Diverticulum, Diverticulosis & Diverticulitis
Diverticula are most frequently
seen in the colon, but can occur
in hollow organs, primarily the
stomach and bladder.
This giant diverticulum of
the colon is very rare.
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 Worm
Though 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 containing
mature 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 sufficiently
infested, obstruction.
Some species of larval cysts may incubate
in 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 Cancer
Cancer is the uncontrolled reproduction of mutated
cells, resulting in a useless mass of tissue called a
tumor, malignancy, or neoplasm.
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 an
apple core lesion.
Characteristics of growth
Benign
vs.
Malignant
Slow growth
Undifferentiated **
Non-invasive
Localized
Rapid growth
Highly differentiated *
Highly invasive
Metastatic
* Cells, as seen on
cytologic examination
Colorectal Cancer
An interesting comparison of an AP and PA projection: same patient,
same exam, taken minutes apart. Note the changes in the position of the
barium, and the demonstration of the apple-core lesion. Also, note the
look of the pelvis
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 is
treated by surgery,
chemotherapy, radiotherapy,
or a combination of the
three.
Like all cancer, a cure is
highly dependant on early
detection and intervention
before 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
Symptoms
Diarrhea
Pain in the RLQ
Radiographic appearance: Loops of
Rectal bleeding
bowel are separate due to inflammation. Weight loss
Strictures create a characteristic “string Fever
sign.” Ulcerations and edema create a
Cramping
“cobblestone” appearance.
Stunted growth in children
(though Chron’s is most prevalent
between 20-40 years of age)
Chron’s Disease
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
Prognosis: Drugs control pain,
inflammation, and bleeding; 70%
of patients have surgery. There
is no cure.
Intussusception
Telescoping, or slipping, of one section of bowel into another. Occurs chiefly
in 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.
Intussusception
Cecum
Lateral projection of ileocecal intussusception
Terminal
ileum
Intussusception
1.
3.
An intussusception may be reduced by the pressure
of a barium enema, instead of surgery.
2.
1. Barium reaching the cecum reaches the obstruction
2. 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 the
left is an attempt to outline the impaction with
contrast.
The film on the right shows the result of
a ruptured colon
The end