Download Slide 1 - Yale School of Medicine

IMAGING for
ABDOMINAL PAIN
42 y.o., obese woman with 6
children. Now has RUQ pain and
tenderness, fever, elev. WBC. Pain
radiates around to under right
scapula
This is a classic history for acute cholecystitis, although ascending
cholangitis may present similarly
The standard imaging is RUQ ultrasound
In abdomen, where is US good, where isn’t it, and why?
Enemies of US are gas and bone, which reflect and don’t transmit sound
Three “big” areas for US in the “abdomen” are the RUQ, kidneys, and
pelvis, because all three can provide a sonographic window without bowel
gas in the way (liver displaces bowel out of the RUQ, kidneys can be
imaged from the flanks, urinary bladder can be filled to lift bowel out of the
pelvis or trans-vaginal and trans-rectal US can get directly to uterus/ovaries
and prostate without intervening bowel)
Also, US is great for fluid (seeing through GB bile to see stones, seeing
dilated bile ducts, determining if renal lesion is cyst or solid, seeing through
urinary bladder)
Pregnant uterus is perfect for US (sonographic window with uterus
displacing bowel, amniotic fluid to transmit sound well, no ionizing radiation)
US findings in acute cholecystitis
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GB stones
Tender GB (sonographic Murphy’s sign)
Distended GB
Thickened GB wall
Pericholecystic fluid
Debris/pus in GB lumen
Hyperemia on color Doppler
Of radiology imaging modalities, US is unique
in that it combines simultaneous physical
exam with imaging
Following image shows stone in GB
Findings diagnostic of GB stone
– Echogenic focus in GB lumen
– Acoustical shadowing
– Mobile (moves with change in position of
patient)
HIDA scan is alternative imaging if GB not visible on US
Following HIDA scan shown as typical example of nuclear
medicine study
– Uses Technicium 99m
– What lights up depends on what carrier molecule is attached
– Compared to other radiology imaging modalities, nuclear studies
are only partly about imaging anatomy (the anatomy is typically
“fuzzy” on nuclear imaging), but it is also very much about
function and physiology (more than other modalities)
This HIDA shows serial images of counts obtained at 5minute intervals, with normal activity entering GB, giving
functional information that cystic dust is patent, making acute
cholecystitis unlikely
14 y.o girl who initially had crampy,
periumbilical pain, that is now more
steady and localized to the RLQ.
Has focal tenderness in RLQ,
mildly increased WBC, and slight
fever.
The history suggests acute appendicitis
With a classic history and physical for appendicitis, in the
hands of an experienced surgeon, no imaging may needed
Imaging is otherwise needed, particularly if the history or
exam is atypical
Plain X-rays would not be indicated because usually
appendicitis would be soft tissue/fluid pathology against a
normal soft tissue background (no contrast) and would be
invisible
Following X-ray shows a calcified fecalith (appendicolith)
projected just lateral to right SI joint in patient with
appendicitis, but this is very insensitive sign, visible on X-ray
in fewer than 5% of cases
Although CT is an excellent imaging exam for appendicitis
(95%+ sensitivity and positive predictive value), radiation is an
issue, particularly in a young patient
How much radiation does patient get with abdominal/pelvic
CT?
– PA CXR gives only about 3-days-worth of radiation that we all
get anyway from natural sources
– Abdominal and pelvic CT may give as much as 100 times
radiation of PA CXR
What is risk of the radiation from A/P CT?
– Very little prospective data
– Worst case guess: Out of 1000 A/P CTs in pediatric patient, may
cause one additional cancer in a lifetime
– Always need to weigh risk versus benefit (CT information may
provide very large benefit)
For pediatric patient, as long as radiology
dept. has experience, US is preferred over
CT for initial imaging of suspected
appendicitis
Although its sensitivity is not as good as
that of CT when used on all patients, US is
effective in smaller pediatric patients, has
no radiation, and has a very high positive
predictive value
Findings of appendicitis on US
– Dilated (usually >6mm), non-compressible, tender
bowel-like structure in RLQ attached to cecum
– No peristalsis
– May see closed end, appendicolith, hyperemia on
color Doppler, adjacent inflamed fat or abscess
Following image shows abnormal appendix
on US in patient with appendicitis
Following images show appendicitis on CT
To review a CT, scroll up and down (visually in this case)
through images to integrate the slices into a 3-D mental image
of one structure at a time (liver, each kidney, colon, etc.)
Oral barium has been given in this case, opacifying the ileum
making it easier to identify the appendicitis (since its lumen is
obstructed and will not fill with contrast)
For appendix, find ascending colon in right flank, follow down
to tip of cecum, and appendix will be recognized as tubular
structure off cecum, but only if one mentally integrates the
slices going inferiorly
The appendix is dilated, and has “fuzzy fat” around it
(inflamed, edematous mesenteric fat)
Following coronal image on patient with
appendicitis shows appendicolith in dilated
appendix
Multidetector spiral CT rapidly obtains very
thin axial slices, allowing acquisition of a
volume of data, and subsequent
reconstruction of multi-planar images
70 y.o. male with fever, increased
WBC, and LLQ pain and
tenderness
This is typical history for diverticulitis, most
commonly involving the sigmoid colon
Plain X-rays not usually helpful because it’s
soft tissue/fluid pathology on soft tissue
background, although some complications of
diverticulitis (free intraperitoneal perforation,
obstruction) could be imaged on X-ray
US not usually used because there is no
good sonographic window, and patients are
older
Following CT images show sigmoid diverticulitis
Visually scroll through the images to follow the
descending colon down to the sigmoid, where the
colon wall and mucosal folds are very thickened
Also note the “fuzzy fat” around the sigmoid, due
to inflammation/edema
This case is uncomplicated diverticulitis, without
macroscopic abscess, which if of sufficient size
would require drainage, usually by interventional
radiology
40 y.o. male with intermittent
severe right flank pain radiating to
groin, and hematuria
The likely diagnosis is a right ureteral stone
Because the most common ureteral stone composition is
calcium oxalate, they are often visible on plain X-ray (but only
about 60% since many stones measure only a few mm, hard
to see in a large patient)
Therefore X-ray not usually used for initial dx, although helpful
for urologic F/U
CT is gold-standard imaging study for showing ureteral stones
(nearly 100% sensitivity), based on original literature articles
from Yale Radiology Dept.
But, CT has issue of radiation, particularly in patients who
may be young and repeatedly present in ED with stones
Current practice trends will include an expanded role for US
based on patient history/age and urinalysis
Following 3 CT images show a right UVJ stone
causing right hydronephrosis and hydrouereter
Study done with “Yale protocol,” using no oral or
IV contrast (no oral contrast because not looking
for intraperitoneal pathology, no IV contrast since
virtually all ureteral stones will be opaque enough
to be visible and contrast might actually obscure
stone)
Stone is at UVJ where most small stones hold up
(most stones are small), while large stones hold
up at UPJ
80 y.o. male with severe abd. pain,
hypotension, and a pulsatile abd.
mass
The story suggests a ruptured abdominal aortic aneurysm
with a mortality of as much as 50%, so patient needs to go to
OR (don’t send unstable patients to radiology)
In ED, a quick US could be done, and would usually be able
to show an AAA if present, but US unreliable in ruling out the
other critical question of rupture/bleed
If patient is stable, not hypotensive, CT is indicated
– No oral contrast is needed: pathology is not intraperitoneal
– No IV contrast is needed: the 2 key pathologies (AAA,
retroperitoneal bleed) are both visible because they are
contrasted against retroperitoneal fat
– If IV contrast were given in this case, the bleed may not light up
at all because it is a clot without blood flow; only bleeding that
occurred in the 60 sec between contrast injection and scanning
would light up
The following 3 CT images show a large
ruptured AAA with retroperitoneal bleed
Note that this is a completely
retroperitoneal bleed because the kidney
is displaced, and the descending colon is
elevated anteriorly
The following 4 CT images of a trauma case show a lacerated
spleen and left kidney, with associated minimal intraperitoneal
bleed and large retroperitoneal bleed
The case is shown to emphasize the importance of IV
contrast administration to show solid organ pathology (blood
in splenic lacerations in this case, but also for tumor, e.g.)
If IV contrast had not been given in this case, the splenic
lacerations may have been hard to see
Note that IV contrast does not light up the blood in the
lacerations (that’s clotted blood without flow), but it does light
up the normally perfused splenic tissue to produce a density
difference (contrast)