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Abdominal Anatomy
Overview
Jennifer Green
General Imaging Training Manager

Applications Training for Service - Jennifer Green 2
• Scanning positions
• Sonographic anatomy
• System setup
ABDOMEN

Ultrasound Scan Planes
• Sagittal
• Transverse
• Coronal

Ultrasound Terminology
• Anterior
• Medial
• Superior
• Supine
• Oblique
• Posterior
• Lateral
• Inferior
• Prone
• Decubitus

Ultrasound Terminology
• Hyper echoic
• Echogenic
• Homogeneous
• Hypo echoic
• Echo poor
• Inhomogeneous

Anatomy

Anatomy
• Liver
• Gall Bladder (GB)
• Common Bile
Duct (CBD)
• Pancreas
• Kidneys
• Bladder
• Prostate
• Uterus
• Ovaries

GREAT VESSELS
• Aorta
• Celiac Axis
• SVC
• Renal Arteries
• Hepatic Artery
• IVC
• Renal veins
• Portal vein
• Hepatic Veins

LIVER
• Found in right upper quadrant (RUQ)
• Largest internal organ
• Stores and filters blood
• Produces bile
• Synthesizes many substances
• Performs vast number of metabolic
functions

LIVER
• During deep inspiration!!!,
• Patient position – supine
- left oblique
- left lateral decubitus (LLD)
• Sonographic windows:
– Mid line, inferior to xiphoid process
• Left lobe Sagittal and Transverse
– Inferior & superior to right costal margin
• Right lobe Sagittal and Transverse

GALL BLADDER(GB)
• Found in RUQ
• Contractile sack
• Contains and concentrates bile
• Best seen in LLD or upright position
• Inspiration
• Normal wall thickness 3mm

COMMON BILE DUCT (CBD)
• Conducts bile from the G.B. to the
duodenum
• Found in RUQ, inferior to the G.B.
• CBD runs anterior to the portal vein; distal
part is lateral to the common hepatic
artery
• Best seen in LLD

PANCREAS
• Found in upper mid abdomen; extends
from the hilum of the spleen to the
duodenum.
• Posterior to the stomach,anterior to the
big vessels.
• Gland, produces hormones and digestive
enzymes.

PANCREAS
• Best seen in supine position in inspiration
or pushed up abdomen.
• Sonographic appearance:
– smooth borders; homogeneous, mid gray
echoes
– echogenicity  with age.

KIDNEYS
• Paired organ; 9 –13cms long
• Principal parts: cortex, medulla, sinus...
• Filters metabolic wastes from the blood.
• Normal variants:
– Dromedary humps
– Double collecting system
– Horseshoe
– Ectopic kidney

BLADDER
• It is a symmetrical, hollow, muscular organ.
• Located posterior to the symphysis pubis.
• Shape varies with distention.
• Normal thickness of the distended wall is
< 1cm.
• Provides window for Ob/Gyn, prostate.

BLADDER
• Function:
– Urine delivered through ureters, is
stored in the bladder, and released
through urethra.
– Wall is a smooth echogenic line
– cavity is not seen if collapsed, otherwise
is non echoic.

PROSTATE
• Lies inferior to the urinary bladder,and anterior
to the rectum
• The size of the gland 3.5x4x2.5 cm
• The base is the broadest and it is in contact with
bladder floor
• The urethra and the ejaculatory ducts pass
through the prostate
• Best seen endo rectally (ER), size can be
estimated trans abdominally (TA)

UTERUS
• Pear shaped pelvic organ lying in midline.
• Found in the small pelvis infero-posterior
to the bladder
• Usual size: 7-8x3-5x3-5 cm.
• Uterus is divided into: cervix, corpus,
fundus, cornua.
• Has three layers : endometrium,
myometrium, serous.

UTERUS
• Endometrial cavity is continuous with vagina via
cervix.
• Uterus can be retroverted/flexed or
anteverted/flexed.
• Best seen endo vaginally (EV), need full bladder
for trans abdominal (TA)
– myometrium is midgray with even texture
– endometrium is a thin echogenic line that varies in
intensity with menstrual phase and age.

OVARIES
• Paired pelvic organ, position very variable
alongside the uterus.
• Search lateral/posterior to the uterus.
• Best seen EV.
• Normal post pubertal size approx: 4x3x2 cm
– homogenous midgray echogenicity
– follicles are round, anechoic, on the periphery.

Grey Scale
• U/S is a dynamic examination needing frequent
optimization of the imaging parameters for
consistent good quality of images.
• Sound pathway changes constantly due to
movement of both the patient and the scanner.
• Important parameters: power (MI)
Gain
TGC
Dynamic Range (dB)
Gray Maps.

Power and Gain
• Balance is needed to maintain safety
(ALARA principle) and to obtain the good
image quality through wider dynamic
range.
•  power, than  gain

Time Gain Compensation(TGC)
• The purpose of TGC is to compensate for
attenuation along the propagation path.
• The desired effect is to equalize near to far
field brightness.

Dynamic Range(dB)
• Ratio of largest to smallest echo power.
• High dynamic range image has low contrast due to
numerous available shades of gray, giving high tissue
differentiation
– good for easy patients, superficial structures
• Images of lower dynamic range show increased
contrast. Reduced number of available shades of gray
will poorly differentiate tissues
– good for challenging patients.

Gray Scale Maps
• Apply nonlinear assignment of the display
brightness range among stored range of the
system.
• Manipulation enables emphasis of certain
image elements over each other.

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Editor's Notes