Surgical Radiology, C30 P183-190 Flashcards
CHEST
What defines a technically
adequate CXR?
P183
The film must be “RIPE”:
Rotation: Clavicular heads are
equidistant from the thoracic
spinous processes
Inspiration: Diaphragm is at or below
ribs 8–10 posteriorly and ribs 5–6
anteriorly
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 visibleCHEST
How should a CXR be read?
P184
Check the following:
Tubes and lines: Check placement
Patient data: Name, date, history
number
Orientation: Up/down, left-right
Technique: AP or PA, supine or
erect, decubitus
Trachea: Midline or deviated, caliber
Lungs: CHF, mass
Pulmonary vessels: Artery or vein
enlargement
Mediastinum: Aortic knob, nodes
Hila: Masses, lymphadenopathy
Heart: Transverse diameter should be
less than half the transthoracic
diameter
Pleura: Effusion, thickening,
pneumothorax
Bones: Fractures, lesions
Soft tissues: Periphery and below the
diaphragmCHEST
What CXR is better: P-A or A-P?
P184
P-A, less magnification of the heart (heart
is closer to the x-ray plate)
CHEST Classically, how much pleural fluid can the diaphragm hide on upright CXR? P184
It is said that the diaphragm can
overshadow up to 500 cc
CHEST How can CXR confirm that the last hole on a chest tube is in the pleural cavity? P184
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
CHEST How can a loculated pleural effusion be distinguished from a free-flowing pleural effusion? P184
Ipsilateral decubitus CXR; if fluid is not
loculated (or contained), it will layer out
CHEST
How do you recognize a
pneumothorax on CXR?
P184
Air without lung markings is seen outside
the white pleural line—best seen in the
apices on an upright CXR
CHEST What x-ray should be obtained before feeding via a nasogastric or nasoduodenal tube? P184
Low CXR to ensure the tube is in the GI
tract and not in the lung
CHEST
What C-spine views are used
to rule out bony injury?
P184
CT scan
CHEST
What is used to look for
ligamentous C-spine injury?
P185
Lateral flex and extension C-spine films,
MRI
CHEST What CXR findings may provide evidence of traumatic aortic injury? P185
Widened mediastinum 8 cm (most common) Apical pleural capping Loss of aortic knob Inferior displacement of left main bronchus; NG tube displaced to the right, tracheal deviation, hemothorax
CHEST
How should a CT scan be
read?
P185 (picture)
Cross section with the patient in supine
position looking up from the feet
ABDOMEN
How should an abdominal
x-ray (AXR) be read?
P185
Check the following:
Patient data: name, date, history
number
Orientation: up/down, left-right
Technique: A-P or P-A, supine or
erect, decubitus
Air: free air under diaphragm,
air-fluid levels
Gas dilatation (3, 6, 9 rule)
Borders: psoas shadow, preperitoneal
fat stripe
Mass: look for organomegaly, kidney
shadow
Stones/calcification: urinary, biliary,
fecalith
Stool
Tubes
Bones
Foreign bodiesABDOMEN How can you tell the difference between a small bowel obstruction (SBO) and an ileus? P186
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
ABDOMEN
What is the significance of
an air-fluid level?
P186 (picture)
Seen in obstruction or ileus on an upright
x-ray; intraluminal bowel diameter
increases, allowing for separation of fluid
and gas
ABDOMEN What are the normal calibers of the small bowel, transverse colon, and cecum? P186
Use the “3, 6, 9 rule”:
Small bowel < 6 cm
Cecum < 9 cm
ABDOMEN
What is the “rule of 3s” for
the small bowel?
P186
Bowel wall should be < 3 mm thick
Bowel folds should be < 3 mm thick
Bowel diameter should be < 3 cm wide
ABDOMEN How can the small and large bowel be distinguished on AXR? P186
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
ABDOMEN Where does peritoneal fluid accumulate in the supine position? P186
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
ABDOMEN
What percentage of kidney
stones are radiopaque?
P186
≈90%
ABDOMEN
What percentage of
gallstones are radiopaque?
P187
≈10%
ABDOMEN What percentage of patients with acute appendicitis have a radiopaque fecalith? P187
≈5%
ABDOMEN
What are the radiographic
signs of appendicitis?
P187
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 perforated
ABDOMEN
What does KUB stand for?
P187
Kidneys, Ureters, and Bladder—
commonly used term for a plain film
AXR (abdominal flat plate)
ABDOMEN
What is the “parrot’s beak”
or “bird’s beak” sign?
P187
Evidence of sigmoid volvulus on barium
enema; evidence of achalasia on barium
swallow
ABDOMEN
What is a “cut-off sign”?
P187
Seen in obstruction, bowel distention,
and distended bowel that is “cut-off”
from normal bowel
ABDOMEN
What are “sentinel loops”?
P187
Distention or air-fluid levels (or both)
near a site of abdominal inflammation
(e.g., seen in RLQ with appendicitis)
ABDOMEN
What is loss of the psoas shadow?
P187
Loss of the clearly defined borders of the
psoas muscle on AXR; loss signifies
inflammation or ascites
ABDOMEN What is loss of the peritoneal fat stripe (a.k.a. preperitoneal fat stripe)? P187
Loss of the lateral peritoneal/preperitoneal
fat interface; implies inflammation
ABDOMEN
What is “thumbprinting”?
P187
Nonspecific colonic mucosal edema
resembling thumb indentations on AXR
ABDOMEN
What is pneumatosis intestinalis?
P187
Gas within the intestinal wall (usually
means dead gut) that can be seen in
patients with congenital variant or
chronic steroids
ABDOMEN
What is free air?
P188 (picture)
Air free within the peritoneal cavity
(air or gas should be seen only within the
bowel or stomach); results from bowel or
stomach perforation
ABDOMEN What is the best position for the detection of FREE AIR (free intraperitoneal air)? P188
Upright CXR—air below the right
diaphragm
ABDOMEN If you cannot get an upright CXR, what is the second best plain x-ray for free air? P188
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
ABDOMEN
How long after a laparotomy
can there be free air on AXR?
P188
Usually 7 days or less
ABDOMEN
What is Chilaiditi’s sign?
P188
Transverse colon over the liver simulating
free air on x-ray
ABDOMEN When should a postoperative abdominal/pelvic CT scan for a peritoneal abscess be performed? P188
POD #7 or later, to give time for the
abscess to form
ABDOMEN What is the best test to evaluate the biliary system and gallbladder? P188
Ultrasound (U/S)
ABDOMEN What is the normal diameter of the common bile duct with gallbladder present? P189
< 4 mm until age 40, then add 1 mm per
decade (e.g., 7 mm at age 70)
ABDOMEN What is the normal common bile duct diameter after removal of the gallbladder? P189
8 to 10 mm
ABDOMEN What U/S findings are associated with acute cholecystitis? P189
Gallstones, thickened gallbladder wall
( >3 mm), distended gallbladder ( >4 cm
A-P), impacted stone in gallbladder neck,
pericholecystic fluid
ABDOMEN
What type of kidney stone is
not seen on AXR?
P189
Uric acid (Think: Uric acid = Unseen)
ABDOMEN What medication should be given prophylactically to a patient with a true history of contrast allergy? P189
Methylprednisolone or dexamethasone; the patient should also receive nonionic contrast (associated with one fifth as many reactions as ionic contrast, the less expensive standard)
ABDOMEN
What is a C-C mammogram?
P189 (picture)
Cranio-Caudal mammogram, in which
the breast is compressed top to bottom
ABDOMEN
What is an MLO mammogram?
P190 (picture)
MedioLateral Oblique mammogram, in
which the breast is compressed in a 45˚
angle from the axilla to the lower
sternum
ABDOMEN What are the best studies to evaluate for a pulmonary embolus? P189
Spiral thoracic CT scan, V-Q scan, pulmonary angiogram (gold standard)
