Ultrasound Flashcards
what is the orientation of the image when transducer is in transverse plane with patient lying supine
anterior (skin surface)
posterior
right
left
what is the orientation of the image when transducer is in longitudinal/sagittal plane with patient lying supine
anterior (skin surface)
posterior
superior (head)
inferior (feet)
what is the orientation of the image when transducer is in transverse plane when patient is in right lateral decubitus position
lateral (skin surface)
medial
anterior
posterior
where should the transducer be placed to scan the liver
intercostal
- transducer placed in between ribs following orientation of the ribs
- useful when scanning high riding liver
subcostal
- transducer is angled superiorly just beneath the ICM
name the 6 transducer manipulation
sliding
rocking
sweep
rotate
compression
fan
describe what is does the depth knob control
- important for image quality and presentation
- if depth is too deep, anatomy will appear small at the top of image
- if depth is too shallow, important information at the bottom will be lost
- frame rate is also affected, as each line of information takes longer to return
describe the gain knob
- gain amplifies the overall reflected signals
- increasing gain increases both signals and noise
describe time gain compensation (TGC)
- selectively amplifies signals from deeper structures or suppress signals from superficial tissue
- resulting image would be balanced and uniformed
what is auto optimatization
- automatically adjust TGC and overall gain
what is the focus knob
- focal zone is the point at which the beam is the narrowest with maximum resolution
what is dynamic range (compression)
- determines the number of shades of gray (dB)
- wide range - smoother image
- narrow range - higher contrast
what is harmonic imaging
- reduce noise and clutter
- narrower beam-width
- improve spatial resolution
- reduces noise from side lobes
terms to describe echogenicity
- anechoic: free of echos (describe fluid/liquid)
- echogenic: bright echos
- hyperechoic: brighter than surrounding echoes
- hypoechoic: darker than surrounding echoes
- isoechoic: similar to surrounding echoes
interaction with tissues results in physical effects which can:
- interfere with normal functioning of cells of tissue
- cause structural damage
- result in cell necrosis
type and severity of any physical effect depend on which 2 variables
- mechanism of interaction with tissue
- parameters of exposure
how are the mechanism of interaction categorised
- thermal (heating)
- mechanical
what does the heating effect depend on
- output power
- frequency
- exposure time
- focal zone position
- FOV
- low perfusion
- scanning mode
what are the mechanical effects
bioeffects induced not related to heating
- effects related to cavitation
- effects resulting from radiation force associated with US beam
- effects caused by microstreaming
causes of work related MSK symptoms
- excessive use
- increase freq of repetitive motion
- duration of load on muscles and tendons
- level of muscular effort
- insufficient recovery time due to tight schedule
- habitual arm abduction
- forceful gripping of transducer
- forceful pressure of transducer
- habitual rotation of upper spine
tips to scan safely
- neutral wrist: <15deg ulnar/radial deviation; <15deg flexion/extension
- position patient and equipment as close as possible to prevent arm abduction and trunk bending
- work within ‘reach’ zone: 30cm from body with 30cm range
- proper height of chair and bed
- avoid bending or twisting of trunk
- neck in neutral position: <20deg flexion
- proper seating
- reposition/adjust equipment and monitor (top of monitor to eye level)
name all the small superficial parts for ultrasound
thyroid
breast
scrotum
penile
eyes
lump/bumps
foreign body
lymph node
salivary gland
lungs
which probe should be used for small parts
high frequency linear probe
- wide near field
- excellent resolution
- excellent colour doppler
normal size of thyroid
length = 30-70mm
AP diameter = 12-18mm
transverse diameter = 20-25mm
isthmus diameter = 4-6mm
volume = 18.6ml
probe used for thyroid
high resolution linear probe (7-15MHz)
sector/curve linear probe with small footprint (5-8MHz) for enlarged thyroid lobes
scanning protocol for thyroid
- isthmus measurement (~3mm)
- colour doppler of both sides
- longitudinal scans through each lobe
- axial scans of the whole gland
- identify focal lesions
- evaluate vascular flow
- document enlarged LN/ thrombosed jugular vein
- repeat for left lobe
how does a normal thyroid look like on US
- well circumcised
- echogenic thyroid capsule
- smooth and homogenous echotexture
- hyperechoic to the adjacent muscle
4 types of variant of a thyroid
- broad base
- parallel
- bulge
- stand alone
what is included in a TIRADS
- composition
- echogenicity
- margins
- presence and type of calcification
- shape
- vascularity
when should FNA be considered
nodule >1cm +/- microcalcification/ coarse calcifications
anatomy of parathyroid
- inferior and superior pair of glands
- posteriomedial surface of the capsule of the thyroid
function of parathyroid
makes PTH in response to level of calcium in the blood
- calcium in blood decreases = make more PTH = bones to release calcium into blood
how does a parathyroid look like on US
- usually not seen
- homogeneously hypoechoic
- echogenic thyroid capsule separating the thyroid from the parathyroid
- doppler US –> feeding vessel; internal vascularity seen in a peripheral distribution
how many levels of cervical lymph nodes are there
5
how does cervical lymph node look like on US
on gray-scale:
- hypoechoic compared with adjacent muscles
- oval shape
- presence of nan echogenic hilum
on colour and power doppler
- hilar vascularity
anatomy of breast
- paired organs
- mammary glands
- glands are anchored to pec muscles by suspensory ligaments/ Cooper’s ligaments
- areola: pigmented area surrounding the nipple; made up of sweat and subaceous glands (montgomery gland)
- nipple: centre of areola; where milk exits from Montgomery glands
blood supply of the breast
- axillary artery
- internal thoracic artery
- anterior intercostal arteries
lymphatic drainage of the breast
- anterior axillary nodes and pectoral nodes draining the lateral quadrant
- internal thoracic nodes draining the medial quadrant
- posterior intercostal nodes draining the posterior portion
- lymphatic vessel of opposite breast
- anterior abdo lymph vessels
how does nipple appear on US
- hypoechoic structure at the skin surface that occasionally produce an intense acoustic shadow
- presence of retroareolar ducts and blood vessels
how does normal lymph node look within the axillary tail in US
hypoechoic cortex and hyperechoic fat hilum
differences in breast in different aged women shown in US
young female:
- very little fat in subcutaneous or glandular layer
- appears as homogenously dense or hyperechoic
middle aged women:
- tissue comprises of dense glandular tissue with some fatty replacement
- appears as hyperechoic areas with some hypoechoic area between
older women:
- tissue undergone glandular atrophy and fatty degeneration
- appears mainly hypoechoic
- mammo preferred
during pregnancy and lactation
- breast becomes enlarged and dilated milk ducts can appear as cystic spaces within the breast
what type of probe should be used for breast US
high resolution linear probes
7-17MHz
curvilinear probes
2-9MHz
scanning protocol for breast
- scanned in a systematic way from quadrant to quadrant to ensure that all parts of the breast are scanned (including axilla and all the breast margin)
- both breast should be scanned in this way to compare each other
- record any palpable lump or area of focal thickening
- use dual technique
concerned lesions should be imaged in 2 planes with 3D measurement and described by:
- position on the clockface
- distance from nipple
- distance from skin surface
- distance from pec muscle
reporting guidelines for thyroid imaging is called
TIRADS
reporting guidelines for breast imaging is called
BIRADS
anatomy of scrotum
- sack of skin divided into 2 parts by the perineal raphe
- each side usually consist of:
1. testicle
2. epididymis
3. spermatic cord
4. cremaster muscle
anatomy of testes
- ovoid shaped gland measuring approx 4x3x3cm
- divided into more than 250 conical lobules containing the seminiferous tubules
- rete testis formed by the anastomosis of these tubules in the mediastinum
- connected to the head of the epididymis through the efferent duct
anatomy of the scrotum
- each testicle and epididymis enclosed by a fibrous capsule - tunica albuginea
- tunica albuginea covered by tunica vaginalis
- tunica vaginalis = sac of peritoneum consisting 2 layers - parietal and visceral layer
- visceral layer lines tunica albuginea
- parietal layer lines the inner aspect of the scrotal wall by a small amount of fluid-containing space
- tunica albuginea extends into the posteromedial testis to form mediastinum testis which contains ducts, nerves and blood vessels
how does the epididymis look on US
- 6-7cm long structure located posterolateral to the testis
- divided into a head, body, tail
- head is adjacent to the upper pole of the testis
- body of epididymis is much smaller than the head, courses along the posterolateral aspect of the testis from the upper to the lower pole
- small hypoechoic structure containing numerous echogenic linear structures, which represent the coiled epididymal tube
- tail of epididymis is slightly larger and is located posterior to the lower pole of the testis
where does the scrotum start descending from
- abdominal area to inguinoscrotal area
- from inguinoscrotal to final location in scrotum
scanning protocol of testis
- comparison of right and left testis
- colour doppler of the comparison view
- dimension of right testis - longitudinal and transverse
- right epididymal head, body and tail
- pampiniform plexus - with Valsalva
- image pathologies seen
- repeat 3-6 for left testis
what transducer is used for abdominal US
low frequency curvilinear
1-5MHz to look at deep organs
high frequency linear probe
5-17MHz for superficial scanning
scanning protocol of abdominal US
- systematic approach to evaluate the whole liver, gallbladder and biliary tree
- scan in several planes (longitudinal, transverse and oblique)
- arrested deep inspiration
- left lobe of liver (TS and LS plane) - check patency of left portal vein
- right lobe of liver (TS and LS) - check patency of right portal vein
- gallbladder and biliary system (LS)
- right and left kidneys (TS and LS)
- speen (LS)
- pancreas (TS and LS)
3 lobes of liver
- right
- left
- caudate
blood supply of liver
portal vein - 75%
hepatic artery - 25%
venous drainage of liver
hepatic veins (right, middle, left)
how does normal liver appear on US
- paranchyma appears homogenous
- portal vein and branches seen as tubular structure with echogenic walls
- hepatic vein walls are non reflective
normal gallbladder size
8-10cm long
2-5cm wide
with < 3mm thin walls
what is included in portal triad
bile duct
hepatic artery
portal vein
how does normal gallbladder look like in US
- thin wall, well distended, pear-shaped
- fundus - rounded inferior portion
- body - mid portion
- neck - tapering superior portion
- about 8-10cm long and 2-5cm wide
normal CBD diameter
- grows 1mm for each decade of life
type of transducer used for kidney US
3.5-5MHz curvi linear broadband transducer
how does a normal kidney look on US
size: 9-12cm
shape: bean-shaped
echoes:
- parenchyma appears homogenous and hypoechoic to the liver and spleen
- medullary pyramids appear hypoechoic to the cortex
- renal sinus appears hyperechoic as it contains adipose tissue, intrarenal vessels and renal pelvis
kidney variant
- horse shoe
- fetal lobulation
- double collecting system
- ectopic
- cross fused ectopia
how does normal bladder look like on US
- anechoic
- ovoid shape with smooth wall
variant of spleen
accessory spleen: splenunculus
- splenic tissue outside of spleen
- mostly found around the splenic hilum
- looks like normal splenic tissue
- single or multiple
what is the normal spleen size
< 12cm
transducer used for spleen US
3-5MHz curve linear
how does a normal spleen look like on US
shape: half moon
echoes: medium level echoes
how does a normal pancreas look on US
- homogenous, medium level echogenicity
- becomes more echogenic with age
- even or increased echogenicity compared to the liver
normal size of pancreas
head - 2.5-3cm
neck - 1-2.5cm
body - 2.5cm max
tail - 2.5cm max
