ultrasonography ch19 Flashcards
The creation of sonographic image (sonogram) depends on three major components:
- the production of high-frequency sound waves
- the reception of a reflected wave or echo
- conversion of that echo into actual image
The body surface that can be scanned can be
external (transabdominal)
internal (transvaginal, transösophageal, endovascular, transrectal)
A tissue that reflects more echoes is depicited ___ on the sonogram
brighter/whiter
hyperechoic
A tissue that transmits more echoes (resulting in less echoes reflected back to the transducer) is depicted __ on the image
darker
hypoechoic
sonloucent
A tissue that transmits all the echoes id sepicted as __ on sonogram
black
anechoic
Posterior acoustic shadowing
when a very dense structure, such as a gallstone or bone, reflects so many echoes that virtually no sound waves are transmitted, the tissue deeper to this structure is displayed as hypoechoic and this phenomenon is called posterior acoustic shadowing.
Posterior acoustic enhancement
when a structure transmits more echoes that the surrounding tissues, such as a cyst in the liver, the sound waves deeper to this structure (compared with surrounding structures) are depicted as hyperechoic and this phenomenon is called posterior acoustic enhancement
two common imaging planes used in ultrasonography
sagittal or longitudinal
transverse
small differences in acoustical impedance will result in:
greater sound transmission
greater differences in acoustical impedance will result in
greater sound reflection
Appearance of commonly encountered tissues on ultrasound: fluid
hypoechoic or anechoic (depending if the fluid is simple or complex (containging debris, pus, blood); may have posterior acoustic enhancement
example: cyst, abscess, gallbladder…
Appearance of commonly encountered tissues on ultrasound: calcium
hyperechoic, may have posterior acoustic shadowing
example: renal stones, bones, calc. in soft tissues
Appearance of commonly encountered tissues on ultrasound: air
hyperechoic foci; may cause posterior acoustic shadowing
examples: gas-forming infections (abscesses, fournier’s gangrene, endometritis),
intraperitoneal air, necrotizing enterocolitis
By convention, two common imaging planes are used:
- saggital or longitudinal plane (long axis)
2. transverse plane (perpendicular to long axis)
What influences resolution of images?
frequency of the soundwaves
higher frequency = higher resultion, more detail BUT shorter penetration
and vice versa
advantages of ultrasonography
no ionizing radiation no known long term side effects real-time images produces little or no patient discomfort small, portable, inexpensive, ubiqutous
disadvantages of ultrasound
difficulty penetrating through bone
gas-filled structures reduce its utility
obese patients may be difficult to penetrate
dependent on the skill of the operator
list types of ultrasound
A-mode B-mode M-mode Doppler Duplex ultrasonography
What is A-mode US
simplest type of US
spikes along a line represent the signal amplitude at a certain depth
used mainly in ophthalmology
what is B-mode US
mode most often used in diagnostic imaging; each echo is depicited as a dot and the sonogram is amde up of thousands of these dots; can depicit real-time motion
(basically US we use)
What is M-mode US
it is used to show moving tructures, such as blood flow or motion of the hear valves
what is doppler US
used to asses blood flow.
pulsed doppler devises emit short bursts of energy that allow for an accurate localization of the echo source
what is duplex ultrasonography
it is used in vascular studies;
it referst to the simultaneous use of both gray-scale (or color doppler) to visualize the structure of, and flow within, a vessel and spectral (waveform) doppler to quantgative flow
Doppler: the direction of flow is represented by colors red and blue.
____indicates flow towards and ____ indicates flow away from transducer.
red towards (higher frequency) , blue away (lower frequency)
appereance of normal gallbladder on US
fluid-filled sonolucent (dark) lumen surrounded by echogenic wall (whitish wall)
4x10cm in size, wall normally no thicker than 3 mm
where will gallstone be impacted
in the neck of the gallbladder or cystic wall
how to differentiate biliary sludge from gallstones
sludge does not produce acoustic shadowing
how to recognize acute cholecystitis on US (3 points)
- thickened gllbladder wall (>3mm)
- pericholecystic fluid
- positive sonographic Murphy sign
HIDA scans include radioactive traces which will show obustrction.
What does it mean when
a) the tracer does not appear in the gallbladder, and
b) when it does not appear in small intestine?
a) obustrction of cystic duct = no tracer in gallbladder
b) obustrction of the common bile duct = no tracer in small intestine
common bile duct (CBD) lies ___ to the portal vein and ___ to the hepatic artery in the porta hepatis
anterior to portal vein
lateral to hepatic artery
measurements of
a. CHD
b. CBD
c. pancreatic duct
a. 4 mm
b. 6 mm
c. 2 mm
normal renal appereance on ultrasound
normal size 9-12 cm in length, 4-5cm width, 3-4 cm thiccc
renal sinus has fat so is brightly echogenic, calyces nor visibke, pyramids hypoechoic
healthy kidney color compared to liver and spleen
renal parenchyma has uniformly low echogenicity (Dark), usually less than that of spleen and liver
kidneys are darker
in patients who experience renal colic (pain) , US is used primarly to evaluate for the presence of ….
hydronephrosis (dilatation of the renal pelvis and calyces)
what is the typical appereance of obstructive uropathy
dilated calyceal system
what does ureter look like at the level of obstructing stone
it can be dilated
if the kidney is sick, it will be darker or lighter than liver/spleen
lighter, ie.more echogenic
what type of ultrasound will we use if we suspect testicular torsion
color doppler US, to see if there is scrotal blood flow
if torsed, then no blood flow
normal abdominal aorta size
no more than 3cm
moving blood within the lumen of the aorta will appear ____ ; thrombus in the wall will appear ____
moving blood: anechoic
thrombus: echogenic
the position of the uterus in the body is described by its ___ and ___
version (angle between cervix and vag)
torsion (angle between uterine body and cervix)
normal position of uterus
anteverted anteflexed
shape and size of uterus
pear-shape
max dimensions: 8cm length, 5cm wide, 4cm AP dimension
normally collapsed state, has thin echogenic stripe or line between the apposing surfaces of the endometrium
A molar pregnancy is suggested by uterine size which is disproportionaly ______ (large or small?) for the gestational age.
large
amount of beta-HCG levels in molar pregnency
excess of 100 000 mIU/mL
Beside large uterus and high beta HCG, what are other symptoms of molar pregnancy
vomiting, vaginal bleeding, toxemia
How is ectopic pregnancy diagnosed?
Ectopic location is diagnosed by a combination of findings that includes absence of an identifiable intrauterine pregnancy, often with an extrauterine, extraovarian solid or cystic mass.
if we have large amounts of free fluid (blood) inside ther abdominal cavity in a woman, that could indicate
ectopic pregnancy
what can we use together with US to distinguish between intrauterine pregnancy, ectopic pregnancy, early abortion
beta hcg + ultrasound
what are goals of first trimester ultrasound
to exclude ectopic pregnancy
to estimate the age of the pregnancy
to determine viability and the number of embryos
what are goals of 2nd and 3rd trimester ultrasound
estimates of amniotic fluid volume
detection of fetal anomalies
determination of placental and fetal positioning
guidanace for invasive studies to determine the likelihood of fetabl viability in the event of premuature birth
How do pelvic inflammatory diseases begin?
as transient endometritis and then they ascend to infection of the tubes and ovaries
how to recognize pelvic inflammatory disease on ultrasound
- ovaries are enlarged and they have multiple cysts and we see periovarian inflammation
- fallopian tubes are fluid-filled and dilated (pyosalpnix)
- there may be fusion of the dilated fallopian tube and ovary (tubo-ovarian complex)
- a multiloculated mass with septations (tubo-ovarian abscess) may be present
- CT can be used for cases of complicated PID or for patients whose history may not suggest the diagnosis
How do malignant ovarian cysts look like on US?
- they have thick and irregular walls
- thick and irregular septations
- internal vascular flow
- solid papillary projections in the tumors
what lesions are called “chocolate cysts”
endometriomas, part of the disease endometriosis
they are filled with brownish-red blood
nonfunctional cysts of ovary include ___ and ____
dermoid cysts and endometriomas
what are dermoid cysts
they are mature teratomas and are most commonly found in women of reproductive age and are bilateral in up to 25% of cases
what cysts can serve as a lead point for ovarian torsion
dermoid cysts (nonfunctional)
symptoms of Stein-Leventhal syndrome
: numerous ovarian follicles (>25/ovary), oligomenorrhea, hirsutism, obesity
how do functional cysts look like on US
they are well-defined, thin-walled, anechoic (black) structures with homogenous internal fluid echogencitiy
do functional cysts require follow up
no
functional cysts include ___ and ____
follicular cysts and corpus luteal cysts
size of ovaries in premenopausal women
2x3x4cm (5-15mL)
what is sonohysterography
procedure in which saline is instilled in the endometrial cavity while transvaginal US images are obtained. Saline distends the normally collapsed endometrial cavity and seperates endometrial walls to allow the delineation of endometrial polyps, submucosal myomas, and adhesions
how to recognize uterine leiomyomas on US
they are heterogenously hypoechoic, solid masses
fibroids may undergo degeneration and calcify and could result in acoustical shadowing
location of fibroids is important to aid in treatment. it can be ____, ____, and ____.
submucosal (bleeding and infertility), myometrial (most common) and subserosal
what is adenomyosis
ectopic endometrial tissue within myometrium
patients position when preforim US for inguinal hernia
supine
what does patient need to do during US exam of inguinal hernia
preform Valsava maneuver to increase intraabdominal pressure
what is normal diemater of appendix
less than 6mm and will compress when pressure is applied with transducer
how to recognize appendicitis on US
diameter of 6mm or more,
noncompressable
tender when paplated with probe
fecalith can be present
how to recognize tendinopathy on US
tendon appears thickened or there is fluid around tendon
how to recognize tendon tear on US
tendon tear appears ad fluid in the tendon or discontinuity of the tendon fibers
what foreign body can be appreciated on US
wood splinters which are sometimes not visible on x-rays can be echogenic (white) on US . other foreign bodies too like metal, glass, plastic
contrast-enhances US involves the use of a _____
microbubble contrast agent
what is contrast-enhanced US used for
to demonstrate vascular flow and soft-tissue prefusion
is microbbuble contrast agent safe?
yes, there is no nephrotoxicity or risk of nephrogenic system fibrosis with it
