GI imaging Flashcards
types of x-rays
- Plain radiography, or plain x-ray
- Computed Tomography
- Fluoroscopy — which produces moving/live images of an organ
- Mammography
- Angiography
a diagnostic test that uses radiation waves to take pictures of your body tissues.
X-ray
Different parts of the body absorb the x-rays in varying degrees, describe each
- Dense bone absorbs much of radiation = Bones appear white
- Soft tissue, such as muscle, fat, organs, absorb some, but not as much as bones = shades of gray
- Air does not absorb = black
Provides images of the organs in the abdominal cavity, including stomach, liver, intestines, and spleen
Abdominal X-ray
When an abdominal x-ray is performed to provide pictures of the kidneys, ureters, bladder, it’s called ?
KUB x-ray
Contrast is used
which part of the body has the most radiation when imaged?
CT abdo/pelvis ~14 mSv = 140 cigs
gas or air trapped within the peritoneal cavity, but outside the lumen of the bowel.
Free gas, or pneumoperitoneum
2 causes of free air under diaphagram
- bowel perforation
- insufflation of gas (CO2 or air) during laparoscopy
difference between bowel perforation vs insufflation of gas during laparoscopy
- Both these causes have identical X-ray appearances, but very different clinical significance.
- BOWEL PERF IS A SURGICAL EMERGENCY!
how to evaluate a suspected Pneumoperitoneum? why?
Upright chest X-ray + standard supine abd X-ray
Allows any free intra-abdominal gas to rise up, forming a crescent beneath the diaphragm. It is said that as little as 1ml of gas can be detected in this way.
how does poo appear on imaging
constipation
soft tissue opacities with internal mottled air.
how to image for constipation
Anteroposterior (AP) images of the abdomen and pelvis in the supine position
- visualize and qualify the burden of feces
- visualize the size of the colon,
- assess for colonic obstruction.
what imaging could you get if you are concern for complications of constipation (free air from perforation)
Erect and lateral decubitus images of the abdomen and pelvis to may be added
key radiographic findings of constipation
presence of large fecal burden throughout the colon and a relative paucity or absence of luminal gas.
imaging uses sound waves to produce pictures of the inside of the body
When a sound wave strikes an object, it bounces or reflects back, or “echoes”
US
By measuring US echo waves, it is possible to determine how far away the object is, as well as:
- Object’s size
- Object’s shape
- Object’s consistency
Used to detect changes in the appearance of organs, tissues, and vessels
Also used to detect abnormal masses, such as tumors
Ultrasound
what is Echogenicity
the ability to reflect or transmit US waves in the context of surrounding tissues
Whenever there are structures with different echogenicities, a visible difference in contrast will be apparent on screen
Tissue in body that is more dense or solid
Absorbs more US waves
Less reflective and low amount of echoes when compared with neighboring structures
Appears gray or darker than surrounding tissue
Made up of muscle/fibrous connective tissue
what type of echo/US
Hypoechoic
Reflects sound waves of higher amplitude
Gives off more “echoes”
Appears lighter and brighter than surrounding tissue
Air, fat, gas
Ex: fatty liver would show hyperechoic spots on liver
which type of echo/US
Hyperechoic
Structures that appear black
No internal echoes reflecting back
Fluid and blood filled structures because the beam passes easily through these structures without significant reflection.
Sound waves will travel easily through these uniform substances
which type of echo/US
Anechoic
how thick is the gallbladder wall?
Smooth, thin walls, < 2 mm
what does the biliary tree look like
Narrow caliber - 6mm or less
Uniform ductal walls
Common Bile Duct
