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Abdominal Anatomy Overview

Jennifer GreenGeneral 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• Inhomogeneou

s


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.

• Sonographic appearance:– 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)• Sonographic appearance:

– 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• Sonographic appearance:

– 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.

Education

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