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Gastrointestinal
radiology
Gastrointestinal radiology
The field of gastrointestinal radiology
encompasses the study of the:
• gastrointestinal tract (pharynx, esophagus,
stomach, duodenum, small bowel, and colon)
• solid abdominal viscera (liver, gallbladder, biliary
tract, pancreas and spleen)
• peritoneal cavity (mesentery and omentum)
• abdominal wall.
Gastrointestinal radiology –
the methods
• Abdominal plain films (KUB)
(KUB stands for Kidneys, Ureters and Bladder and is a common short term for an abdominal x-ray.)
• Barium studies
• Ultrasound
• Computed Tomography
• Nuclear medicine
• Magnetic Resonance Imaging
• Angiography and Interventional Radiology
Plain Film of the
Abdomen
Plain Film of the Abdomen
The prognostic value of an erect and supine abdominal X-ray
was studied prospectively in 97 patients with an acute
abdomen. Although 64 (66%) of the radiographs showed an
abnormality, the surgical registrar altered his clinical diagnosis
on only seven occasions and changed his management on
four....
The investigation was of immediate clinical value in only 4% of
the patients, and its use could probably be limited without
detriment to patients.
Evaluation of the plain abdominal X-ray in the acute abdomen.
Stower MJ, Amar SS, Mikulin T, Kean DM, Hardcastle JD.
J R Soc Med. 1985 Aug;78(8):630-3.
Plain Film of the Abdomen
• Often the starting point for the work up of abdominal
problems
• Upright abdominal x-rays are requested to look for
pneumoperitoneum or fluid levels in obstruction or
ileus.
• Erect and supine films are used to confirm the
diagnosis of intestinal obstruction.
Plain Film of the Abdomen
Indications for requesting abdominal films
Bowel obstruction - abnormal gas pattern
Free air - abnormal gas pattern
Abscess - abnormal gas pattern
Calculi or other abnormal intra-abdominal
calcifications
Radiopaque foreign bodies
Plain Film of the Abdomen
Erect abdominal x-ray
The film is placed under the
patient and the camera is
positioned over the patient.
Supine abdominal x-ray
The film is placed in the back of
the patient and the camera is
positioned in front of the patient.
The x-rays travel through the abdomen, revealing structures
because they are surrounded by fat.
Plain Film of the Abdomen
The normal appearance of gas:
• Gas is usually present in stomach
• The small bowel may be partially filled
with gas
• Gas may also be seen throughout the
entire colon
Radiolucent fat which surrounds intraabdominal organs allows for
visualization of the soft tissue:
• Liver - posterior margin visible where
outlined by retroperitoneal fat.
• Spleen - often visible
• Kidneys - outlines may not be seen in its
entirety because of overlying gas and
stool
• Psoas muscles - margins usually visible
but may not be seen in its entirety
Plain Film of the Abdomen
Small Bowel
Large Bowel
Distinguishing Features of Small and
Large Bowel.
Small Bowel
Colon
Location
Central
‘Picture
Frame’
Mucosal
Folds
Continuous
(Plicae
Circulares)
Interrupted
(Haustra)
Diameter
< 3cm
< 6 cm
(Cecum < 9
cm)
Fecal
Content
Rarely
Usually
Plain Film of the Abdomen
- the „normal” calcifications (with no clinical significance):
Vascular - veins of the pelvis (phleboliths)
Costal cartilage
Mesenteric lymph nodes
Injection sites
Prostate gland
Plain Film of the Abdomen
- the „normal” calcifications (with no clinical significance):
vascular - veins of
the pelvis
(phleboliths)
Plain Film of the Abdomen
- the „normal” calcifications (with no clinical significance):
costal cartilage
Plain Film of the Abdomen
- the „normal” calcifications (with no clinical significance):
lymph nodes
Plain Film of the Abdomen
- the „normal” calcifications (with no clinical significance):
Injection sites
Plain Film of the Abdomen
- abnormal calcifications
"Stones" - renal calculi, cholelithiasis, bladder calculi,
appendiciolith
Appendicitis fecalith
Ureteral calculus
Vascular - calcifications, aneurysm
Atherosclerosis
Abdominal Aortic Aneurysm
Pancreatic - chronic pancreatitis
Chronic Pancreatitis
Leiomyoma (uterine fibroid)
Leiomyoma
Tumor calcification
Other
Plain Film of the Abdomen
- abnormal calcifications
renal calculi
Plain Film of the Abdomen
- abnormal calcifications
ureteral calculus
Plain Film of the Abdomen
- abnormal calcifications
appendicitis fecalith
The flat plate reveals some round opacities which are calcified bile contents associated with the
appendicitis. They are not always present with appendicitis but their presence imply a high risk for
appendicitis.
Plain Film of the Abdomen
- abnormal calcifications
atherosclerosis
Plain Film of the Abdomen
- abnormal calcifications
chronic pancreatitis
Plain Film of the Abdomen
- abnormal calcifications
leiomyoma
Plain Film of the Abdomen
- indications for requesting abdominal films
Bowel obstruction - abnormal gas pattern
Free air - abnormal gas pattern
Abscess - abnormal gas pattern
Calculi or other abnormal intra-abdominal
calcifications
Radiopaque foreign bodies
Bowel obstruction - abnormal gas pattern
Adynamic ileus - leads to increased gas throughout the Gl tract,
multiple air-fluid levels, and gas in the rectum.
There is gas in the
small bowel, colon
and distal bowel
Case of adynamic ileus
from pain medications
- the bowel is not
moving.
The pathophysiology is
that bowel has lost its
motility.
Bowel obstruction - abnormal gas pattern
Mechanical small
bowel obstruction –
leads to a ladder-like
arrangement of dilated small
bowel loops, also termed a
"stacked coin" appearance.
There is very little or absent
gas in the colon.
supine
When the small bowel
dilates greater than 3
cm it is abnormal.
Bowel obstruction - abnormal gas pattern
Mechanical small
bowel obstruction When we stand such a patient
up in an upright view, we have
appearance from air-fluid
levels which is called „stair
step” or „step latter”.
The reason for the stair-step
is because small bowel is
fixed diagonally.
upright view
Bowel obstruction - abnormal gas pattern
Mechanical small
bowel obstruction –
„stair step” or „step latter” sign
Bowel obstruction - abnormal gas pattern
Mechanical small bowel
obstruction
X-ray using a horizontal beam technique
Supine abdominal x-ray
Bowel obstruction - abnormal gas pattern
Mechanical small
bowel obstruction –
„The string of pearls sign” can be
seen on abdominal radiographs
obtained with the patient in the
upright position or on decubitus
abdominal radiographs.
Also commonly referred to as the
"string of beads sign", the sign
consists of a row or line of several
small air bubbles obliquely or
horizontally oriented in the
abdomen
left lateral decubitus
Bowel obstruction - abnormal gas pattern
Mechanical small
bowel obstruction –
String of pearls sign in a patient
with small-bowel obstruction .
Left lateral decubitus
radiograph of the abdomen
demonstrates a row of small air
bubbles (arrows).
The obliquely oriented row of air bubbles
represents small amounts of air trapped
between the valvulae conniventes along the
superior wall of predominantly fluid-filled,
dilated small-bowel loops.
The meniscal effect of the surrounding fluid
gives the trapped air an ovoid or rounded
appearance.
left lateral decubitus
The appearance of the string of pearls sign
depends on the combination of air, fluidfilled bowel loops, and peristaltic
hyperactivity.
Bowel obstruction - abnormal gas pattern
Mechanical small bowel obstruction – „String of pearls sign”
Air trapped at corners of valvulae conniventes (arrows)
Almost always seen in obstructed fluid-filled small bowel loops
Bowel obstruction - abnormal gas pattern
Mechanical large bowel obstruction –
leads to a distended colon but absence of gas in rectum and/or
distal colon, +/- small bowel distension.
supine
Dilated colon (with haustra)
upright
Air-fluid levels
Free air - abnormal gas pattern
Free intraperitoneal air (pneumoperitoneum) - MUST
have either an upright or left lateral decubitus view, will see a
crescent of air under the diaphragm or outlining the liver.
A pneumoperitoneum can be a normal finding in post op patients or
patients on peritoneal dialysis; history is important.
Free air - abnormal gas pattern
Radiographic signs of
free air:
1. Air under diaphragm
2. Rigler’s sign
3. Football sign
UPRIGHT
Free air - abnormal gas pattern
Air under diaphragm
Abdominal X-ray using a horizontal beam technique: pneumoperitoneum with free
air between the liver and anterior abdominal wall (asterisk)
If the patient cannot sit up, order a left lateral decubitus. This will
allow air to accumulate over the edge of the liver
Free air - abnormal gas pattern
anteroposterior abdominal radiograph
Rigler’s sign
Extensive free intraperitoneal air is seen,
which outlines the outer wall of multiple loops
of air-filled bowel.
Notice the discernible white stripe (arrows) of
bowel wall between the intraluminal air and the
free intraperitoneal air.
Explanation:
Gas normally outlines only the luminal surface of the
bowel wall and not the serosal surface, which has a degree
of opacity similar to that of adjacent peritoneal contents.
When at least a moderate amount of free intraperitoneal
air exists, however, this free air is more likely to
accumulate between bowel loops, thus permitting
visualization of the outer walls of the bowel. This is the
classic appearance of the Rigler sign.
supine
A variant of the Rigler sign occurs when only the outside
of the bowel wall is visible because the lumen is filled
with fluid
Free air - abnormal gas pattern
Abdominal x-ray:
1. Pneumoperitoneum
with a large oval lucency
overlying the entire
abdomen (football sign)
2. Visibility of both sides
of the bowel wall
(Rigler’s sign, white
arrow)
3. Falciform ligament
outlined by air on both
sides (black arrow)
supine view
Free air - abnormal gas pattern
supine position
erect position
Plain Film of the Abdomen
Radiopaque foreign bodies
Barium Studies of the
GI Tract
Upper GI and small bowel series = Barium swallow x-ray
Small bowel enema = enteroclysis
Lower GI series = Barium enema
Barium Studies of the GI Tract
Upper GI
• An upper GI and small bowel
series is a set of x-rays taken to
examine the esophagus,
stomach, and small intestine.
• X-rays are taken after the patient
has swallowed a barium
suspension
• This procedure is called "upper
gastrointestinal tract
radiography" when the
esophagus, stomach and
duodenum are evaluated or a
"barium swallow" when only the
pharynx and esophagus are
evaluated.
Barium Studies of the GI Tract
Upper GI
Barium Studies of the GI Tract
Upper GI
• The passage of the barium
through the esophagus,
stomach and duodenum is
monitored on the
fluoroscope.
• Additionally, some patients
are asked to swallow bakingsoda crystals to create gas
and further improve the
images; this procedure has
the modified name of "aircontrast" or "double-contrast
upper GI."
The normal anatomy of the esophagus
From: http://anatquest.nlm.nih.gov/xml-images/
The normal anatomy of the esophagus
Esophagus containing contrast medium
AP radiograph
Arcus aortae
Diaphragma
Ostium cardiacum
Fundus gastricus
From Wolf-Heidegger’s Atlas of Human Anatomy, 4th Edition
The normal anatomy of the esophagus
Trachea
Esophagus containing contrast
medium
Esophagus
Lateral radiograph
Hilum pulmonis
From Wolf-Heidegger’s Atlas of
Human Anatomy, 4th Edition
Middle (aortic)
esophageal
constriction
Diaphragma (distal to the
plate), Cupula dextra
Epiphrenic
esophageal
dilatation
Diaphragma (close to the
plate), Cupula sinistra
Lower
esophageal
constriction
Esophageal Foreign Body
Esophageal Foreign Body
Routine cervical and thoracic X-rays in the antero-posterior and lateral
positions identify most of:
metal objects, steak bones, and free mediastinal or peritoneal air
Fish or chicken bones, wood, plastic, most glass, and thin metal
objects are not readily seen.
Most foreign bodies pass harmlessly through the GI tract and are
eliminated in the stool.
Retained foreign bodies may cause GI mucosal erosion, abrasion,
local scarring, or perforation and should be removed within 24 hours.
Any sharp object or battery in the esophagus must be removed
immediately.
Esophageal Foreign Body
Imaging study:
1. If the swallowed object may be radiopaque, a single
frontal radiograph that includes the neck, chest, and
entire abdomen is usually sufficient to locate the
object.
2. If the object is below the diaphragm, further
radiographs are generally unnecessary.
3. If the object is in the esophagus, frontal and lateral
chest radiographs are necessary to precisely locate
and better identify the object and to be sure that the
foreign body is not, in fact, 2 adherent objects.
Esophageal Foreign Body
Radiopaque foreign
body – acoin,
just below the
cricopharyngeal
muscle
Biplane radiographs of the esophagus
Esophageal Foreign Body
Radiopaque foreign bodies –
the metal buttons,
Biplane radiographs of the esophagus
just below the
cricopharyngeal muscle
Esophageal Foreign Body
Radiopaque foreign body
– a coin,
just above the
gastroesophageal
junction
Esophageal Foreign Body
A pin in the
pyriform sinus
Esophageal Foreign Body
Radiopaque foreign body – a
piece of chicken bone
just above the junction of the
throat and the esophagus
Esophageal Foreign Body
Imaging study:
4. Radiolucent objects in the esophagus may be better
visualized by repeating the study after having the patient
drink a small amount of dilute contrast. This should not be
done if endoscopy is planned.
5. Special care must be taken if the esophagus could
possibly be obstructed or perforated.
6. When a foreign body is strongly suspected on clinical
grounds, visualization by endoscopy, which has the added
advantage of allowing removal of the object, may be the
most efficient method of management.
Esophageal Foreign Body
Radiolucent foreign body
– a piece of meat
Spot radiograph
Esophageal Foreign Body
Radiolucent foreign body –
a piece of meat
Esophageal Foreign Body
Imaging study:
7. Radiolucent objects may be also visualized by
repeating the esophagram after swallowing a bit of
cotton wool.
Esophageal Foreign Body
Radiolucent foreign body
– a fishbone
A cotton pledget soaked in an opaque
medium like barium should go down
smoothly. If stucked anywhere in the
esophagus – a presumptive diagnosis is
made.
Esophageal Foreign Body
The foreign body was visualized on plain X-rays in only
27-48% of cases
Negative radiological findings do not rule out the possibility of a
foreign body in the crico-pharynx and esophagus.
Persistence of symptoms even in the absence of positive clinical
or radiological signs warrants an endoscopic examination.
Anatomy of the
stomach
Anatomy of the stomach
The stomach consists of the cardia adjacent to the
gastroesophageal junction, fundus, body, antrum,
and pylorus. The fundus is dome shaped and
extends above and to the left of the cardia toward the
left hemidiaphragm. The body extends from fundus to
the lower end of the lesser curve, which is known as
the incisura angularis. The antrum extends from the
incisura to the pyloric canal.
Cardiac
Incisure
Angular
Incisure
Antrum
supine
Anatomy of the stomach
Upper GI
double-contrast upper GI
Anatomy of the stomach
Barium Studies of the GI Tract
In addition to the standard upper GI series, a physician may
request a detailed small bowel follow-through (SBFT),
which is a timed series of films.
• After the preliminary upper GI series is complete, the patient will drink
additional barium sulfate, and will be escorted to a waiting area while the
barium moves through the small intestines.
• X-rays are initially taken at 15-minute intervals until the barium reaches
the colon (the only way to be sure the terminal ileum is fully seen is to
see the colon or ileocecal valve).
• The interval may be increased to 30 minutes, or even one hour if the
barium passes slowly.
Barium Studies of the GI Tract
Small bowel follow-through
• The passage of the barium through the esophagus, stomach, and
small intestine is monitored on the fluoroscope.
• The test usually takes around three to six hours.
Barium Studies of the GI Tract
Enteroclysis
• Enteroclysis is a fluoroscopic (real-time) type of X-ray of the
small intestine.
• This test is done in a hospital radiology department.
• A barium-based liquid contrast material (a mixture of barium
and methylcellulose) is infused by a rate-controlled pump
through a tube from the nose or mouth, through the
esophagus, and through the stomach until the tip reaches the
duodenum.
• When in place, contrast medium is
introduced and x-ray images are viewed on
a fluoroscopic monitor to visualize how the
contrast moves through the bowel
structures.
Barium Studies of the GI Tract
Enteroclysis
A tube is placed down
through the stomach into the
small intestine, often under
endoscopic control.
Barium Studies of the GI Tract
Enteroclysis
V
a
Jejunum
Eneteroclysis study showing the jejnum
The jejunum, has a feathery appearance due to the numerous
folds, valvulae conniventes (plicae semi circulares)
Barium Studies of the GI Tract
Barium enema
A barium enema is given in
order to perform an x-ray
examination of the large
intestine
This test may be done in an
office or a hospital radiology
department.
During the procedure, a well
lubricated enema tube is
inserted gently into the
rectum.
The barium is then allowed
to flow into the colon.
A small balloon at the tip of
the enema tube may be
inflated to help keep the
barium inside.
Barium Studies of the GI Tract
Barium enema
Barium Studies of the GI Tract
Barium enema
Single contrast barium enema
Barium Studies of the GI Tract
Barium enema
The flow of the barium is
monitored by radiologist on
an x-ray fluoroscope screen.
Air may be puffed into the
colon to distend it and
provide better images –
a double contrast study
The enema tube is removed
after the pictures are taken.
Double contrast barium enema
Barium Studies of the GI Tract
splenic flexure
hepatic flexure
sigmoid colon
rectum
Barium Studies of the GI Tract
COLON
Small bowel
Small Bowel
Colon
Location
Central
‘Picture
Frame’
Mucosal
Folds
Continuous
(Plicae
Circulares)
Interrupted
(Haustra)
Diameter
< 3cm
< 6 cm
(Cecum < 9
cm)
Fecal
Content
Rarely
Usually