Flashcards in Surgical Radiology, C30 P183-190 Deck (46):
What defines a technically
The film must be “RIPE”:
Rotation: Clavicular heads are
equidistant from the thoracic
Inspiration: Diaphragm is at or below
ribs 8–10 posteriorly and ribs 5–6
Penetration: Disk spaces are visible
but there is no bony detail of the
spine; bronchovascular structures
are seen through the heart
Exposure: Make sure all of the lung
fields are visible
How should a CXR be read?
Check the following:
Tubes and lines: Check placement
Patient data: Name, date, history
Orientation: Up/down, left-right
Technique: AP or PA, supine or
Trachea: Midline or deviated, caliber
Lungs: CHF, mass
Pulmonary vessels: Artery or vein
Mediastinum: Aortic knob, nodes
Hila: Masses, lymphadenopathy
Heart: Transverse diameter should be
less than half the transthoracic
Pleura: Effusion, thickening,
Bones: Fractures, lesions
Soft tissues: Periphery and below the
What CXR is better: P-A or A-P?
P-A, less magnification of the heart (heart
is closer to the x-ray plate)
Classically, how much pleural
fluid can the diaphragm
hide on upright CXR?
It is said that the diaphragm can
overshadow up to 500 cc
How can CXR confirm that
the last hole on a chest tube
is in the pleural cavity?
Last hole is through the radiopaque line
on the chest tube; thus, look for the break
in the radiopaque line to be in the rib cage
How can a loculated pleural
effusion be distinguished from
a free-flowing pleural effusion?
Ipsilateral decubitus CXR; if fluid is not
loculated (or contained), it will layer out
How do you recognize a
pneumothorax on CXR?
Air without lung markings is seen outside
the white pleural line—best seen in the
apices on an upright CXR
What x-ray should be obtained
before feeding via a nasogastric
or nasoduodenal tube?
Low CXR to ensure the tube is in the GI
tract and not in the lung
What C-spine views are used
to rule out bony injury?
What is used to look for
ligamentous C-spine injury?
Lateral flex and extension C-spine films,
What CXR findings may
provide evidence of
traumatic aortic injury?
Widened mediastinum 8 cm (most
Apical pleural capping
Loss of aortic knob
Inferior displacement of left main
bronchus; NG tube displaced to the
right, tracheal deviation, hemothorax
How should a CT scan be
Cross section with the patient in supine
position looking up from the feet
How should an abdominal
x-ray (AXR) be read?
Check the following:
Patient data: name, date, history
Orientation: up/down, left-right
Technique: A-P or P-A, supine or
Air: free air under diaphragm,
Gas dilatation (3, 6, 9 rule)
Borders: psoas shadow, preperitoneal
Mass: look for organomegaly, kidney
Stones/calcification: urinary, biliary,
How can you tell the
difference between a small
bowel obstruction (SBO) and
In SBO there is a transition point
(cut-off sign) between the distended
proximal bowel and the distal bowel of
normal caliber (may be gasless), whereas
the bowel in ileus is diffusely distended
What is the significance of
an air-fluid level?
Seen in obstruction or ileus on an upright
x-ray; intraluminal bowel diameter
increases, allowing for separation of fluid
What are the normal
calibers of the small bowel,
transverse colon, and
Use the “3, 6, 9 rule”:
Small bowel < 6 cm
Cecum < 9 cm
What is the “rule of 3s” for
the small bowel?
Bowel wall should be < 3 mm thick
Bowel folds should be < 3 mm thick
Bowel diameter should be < 3 cm wide
How can the small and large
bowel be distinguished on
By the intraluminal folds: The small
bowel plicae circulares are complete,
whereas the plicae semilunares of the
large bowel are only partially around the
inner circumference of the lumen
Where does peritoneal fluid
accumulate in the supine
Morison’s pouch (hepatorenal recess), the
space between the anterior surface of the
right kidney and the posterior surface of
the right lobe of the liver
What percentage of kidney
stones are radiopaque?
What percentage of
gallstones are radiopaque?
What percentage of patients
with acute appendicitis have
a radiopaque fecalith?
What are the radiographic
signs of appendicitis?
Fecalith; sentinel loops; scoliosis away
from the right because of pain; mass
effect (abscess); loss of psoas shadow;
loss of preperitoneal fat stripe; and, very
rarely, a small amount of free air, if
What does KUB stand for?
Kidneys, Ureters, and Bladder—
commonly used term for a plain film
AXR (abdominal flat plate)
What is the “parrot’s beak”
or “bird’s beak” sign?
Evidence of sigmoid volvulus on barium
enema; evidence of achalasia on barium
What is a “cut-off sign”?
Seen in obstruction, bowel distention,
and distended bowel that is “cut-off”
from normal bowel
What are “sentinel loops”?
Distention or air-fluid levels (or both)
near a site of abdominal inflammation
(e.g., seen in RLQ with appendicitis)
What is loss of the psoas shadow?
Loss of the clearly defined borders of the
psoas muscle on AXR; loss signifies
inflammation or ascites
What is loss of the peritoneal
fat stripe (a.k.a. preperitoneal
Loss of the lateral peritoneal/preperitoneal
fat interface; implies inflammation
What is “thumbprinting”?
Nonspecific colonic mucosal edema
resembling thumb indentations on AXR
What is pneumatosis intestinalis?
Gas within the intestinal wall (usually
means dead gut) that can be seen in
patients with congenital variant or
What is free air?
Air free within the peritoneal cavity
(air or gas should be seen only within the
bowel or stomach); results from bowel or
What is the best position for
the detection of FREE AIR
(free intraperitoneal air)?
Upright CXR—air below the right
If you cannot get an upright
CXR, what is the second
best plain x-ray for free air?
Left lateral decubitus, because it prevents
confusion with gastric air bubble; with
free air both sides of the bowel wall can
be seen; can detect as little as 1 cc of air
How long after a laparotomy
can there be free air on AXR?
Usually 7 days or less
What is Chilaiditi’s sign?
Transverse colon over the liver simulating
free air on x-ray
When should a postoperative
abdominal/pelvic CT scan
for a peritoneal abscess be
POD #7 or later, to give time for the
abscess to form
What is the best test to
evaluate the biliary system
What is the normal diameter
of the common bile duct
with gallbladder present?
< 4 mm until age 40, then add 1 mm per
decade (e.g., 7 mm at age 70)
What is the normal common
bile duct diameter after
removal of the gallbladder?
8 to 10 mm
What U/S findings are
associated with acute
Gallstones, thickened gallbladder wall
( >3 mm), distended gallbladder ( >4 cm
A-P), impacted stone in gallbladder neck,
What type of kidney stone is
not seen on AXR?
Uric acid (Think: Uric acid = Unseen)
What medication should be
given prophylactically to a
patient with a true history of
Methylprednisolone or dexamethasone;
the patient should also receive nonionic
contrast (associated with one fifth as
many reactions as ionic contrast, the less
What is a C-C mammogram?
Cranio-Caudal mammogram, in which
the breast is compressed top to bottom
What is an MLO mammogram?
MedioLateral Oblique mammogram, in
which the breast is compressed in a 45˚
angle from the axilla to the lower