LGI Exam Types, Techniques, and Projections for Radiology Students

Name the two types of LGI exams

single and double contrast studies

Why do we perform a single contrast study?

look for diva: diverticulum, intussusception, volvulus, appendicitis, or anatomy (tonus of the colon)

Why do we perform a double contrast study?

look for APU: apple core sign, polyps, and ulcerative colitis

What is the prep for a patient for an LGI study?

dietary restrictions and laxatives, preparation methods can vary from department to department.

What body position is the patient placed in for the insertion of the enema tip?

Sims position (like an LAO)

What is glucagon used for?

It's an intramuscular injection given by the radiologist to relax the digestive system's peristalsis; for the colon, it relaxes the colon's muscular layer.

What temperature should the barium solution be for an exam, and why?

colder side of lukewarm water for less bowel irritation. This makes it easier for the patient to retain the barium sulfate solution.

What is the method for the double contrast study for an LGI?

Welin method

The pa projection will demo what of the colon?

the entire colon

Where do you center for a PA projection?

MSP & IC (l4/l5)

What body position should the patient be in for a post-evac?

prone for compression of the abdomen and to bring the colon closer to the IR

Why do we take a post-evac?

to make sure that the patient is mostly cleared out most of the barium in order to go home without having an accident on the way.

What is the first projection taken before an LGI study begins? Why?

scout abdomen (KUB) to assess whether the patient is adequately prepped for the test, evaluate colon anatomy, and ensure there is no residual contrast from a previous examination.

The PA axial projection is used to demonstrate what structure?

recto-sigmoid opened up

What is the tube angle for a PA axial and which direction?

30-40 degrees caudad

Where does the CR enter for the PA axial projection?

MSP @ ASIS (S1/S2)

What is the purpose of angling the tube for an axial projection?

to open the S-curve of the rectosigmoid to look for any pathology

What is the tube angle and which direction for the AP axial projection?

30-40 degrees cephalic

Where does the CR enter for an AP axial?

MSP & 2" below the ASIS

Are the colic flexures needed for an AP/PA axial?

no

Which lateral position is used for LGI?

left or right lateral, either one

For what reason is a lateral projection performed?

anterior/ posterior placement of anything in the recto-sigmoid region

Where does the CR enter for the lateral projection?

MCP & S1/S2 (ASIS)

How can you tell if the patient is rotated for the lateral projection?

hips and acetabula and femurs

What must be included for the AP projection?

Entire colon

Where do we center for the AP projection?

MSP & IC (l4/l5)

Can you shield a female? Male?

Female = no, male = yes

The PA oblique projection RAO is used to demonstrate what structures?

Right colic flexure, ascending colon (everything on the right side of the colon)

How many degrees is the patient rotated for an RAO?

35-45 degrees

Where do we center for this projection (PA oblique)?

CR enters L4/L5 (IC) and 2" lateral from the midline toward the elevated side

The PA oblique LAO, will demo what structures?

Left colic flexure (splenic flexure) and the descending colon

Where do we center for an LAO?

CR enters L4/L5 and 2" lateral from the elevated side towards the upside (super techs center 2" higher than the IC to get all of the splenic flexure since it is located higher in the abdomen)

How many degrees is the patient rotated in an LAO?

35-45 degrees

The AP oblique projection, LPO position, is used to demonstrate what structures?

right colic flexure (hepatic flexure), and the ascending colon

How many degrees is the patient rotated?

35-45 degrees

Where do we center for an LPO?

CR enters IC (L4/L5) & 2" toward the elevated side from the midline of the body

The AP oblique projection, RPO position is used to demonstrate what structures?

Left colic flexure (splenic flexure) and the descending colon

How many degrees is the patient rotated for an RPO?

35-45 degrees

Where do we center for an RPO?

IC (l4/l5) & 2" toward the elevated from the midline of the body (super techs center 2" higher from the IC to get all of the splenic flexure)

RPO demonstrates the

left splenic flexure and the descending colon

LPO demos the

right hepatic flexure and the ascending colon

RAO demos the

right hepatic flexure and the ascending colon

LAO demonstrates the

left splenic flexure and the descending colon

Why do we perform decubs?

Air/ fluid levels within the colon for double contrast studies, always looking at the air side up

The AP projection, rt. Lateral decubitus is used to demo what structures?

The lateral side of the descending colon and the medial side of the ascending colon

Where do we enter for a right lateral decub?

MSP & IC (l4/l5)

The AP projection, lt lateral decub. Is used to demo what structures?

The lateral side of the ascending colon & the medial side of the ascending colon

Where does the CR enter for a left lateral decub?

MSP & IC (L4/L5)

What are the breathing instructions?

Expiration for all abdominal imaging

The lateral projection, ventral decub. is used to demonstrate what structure?

Air side up, the posterior aspect of the colon and the posterior recto-sigmoid, since the patient is lying on their stomach

Where do we center for a ventral decub?

MCP & IC (L4/L5)

What must always be included for all rectosigmoid projections?

Enema tip if the doctor did not pull it out.

The upright projections of the colon are used for what reasons?

Air/fluid levels and mobility of the colon

What is a colostomy study?

A barium enema is performed through the patient's colostomy opening in the colon, usually performed months after the surgical procedure for this opening through the abdominal wall

What sections of the bowel can a colostomy be placed?

Any, but mostly within the colon, since that is the most common area for disease

What is the name of the opening of the hole in a colostomy?

Stoma

What is the name of the dynamic study for colons?

Defecography

Appendicitis

inflammation of the appendix caused by an obstruction (commonly from a hardened piece of stool called a fecalith)

Diverticulum

outpouching of the lining of the colon

Diverticulitis

inflammation of the diverticula

Intussusception

a medical emergency where one part of the intestine slides into an adjacent section (like a telescope)

Polyp

a growth or mass protruding from a mucous membrane (in pouching)

Crohn's

inflammatory bowel disease, mostly of the terminal ileum and the cecum; only allows a small trickle of food to pass through... "string sign" seen on radiograph

Volvulus

a medical condition where a loop of intestine twists upon itself, causing a blockage and cutting off the blood supply to the affected segment of the bowel

What is the name of the folds of the large intestines?

Haustra folds

Which flexure is higher?

Left (splenic)

Which flexure is lower?

Right (hepatic)

What is the name of the band that runs the length of the colon?

Teani coli

What is the proximal portion of the colon?

Cecum

What is the distal portion of the colon?

Rectum

What is the purpose of the colon?

Package/eliminate waste + absorb nutrients

Which portion of the colon runs along the right side of the abdomen?

Ascending colon

Which portion runs along the left side of the abdomen?

Descending colon

What is an outpouching of the colon wall?

Diverticulum, Diverticulosis, Diverticulitis

What is an in pouching of the colon wall?

Polyps

Will the appendix fill with contrast if it is infected?

No, it will not

What is twisting of the colon?

Volvulus

What is telescoping of the colon?

Intussusception

Apple core sign is considered

cancer of the colon.

Will a single contrast or double contrast demonstrate ulcerative colitis?

Double

Hirsh Sprung disease occurs in

pediatrics

Toxic mega colon usually occurs in

adults/children

What is scar tissue buildup within the abdomen called?

Adhesions

What pathology is demonstrated using a single contrast study?

DIVA (diverticulum, intussusception, volvulus, and anatomy/appendicitis)

What pathology is demonstrated using a double contrast study?

APU (apple core, polyps, and ulcerative colitis)

Whose responsibility is it to explain a LGI/BE to the patient?

Radiographer

What is the body position to insert the enema tip?

Sims (LAO)

How high is the barium bag supposed to be from the anal canal?

24"

What is the first x-ray image taken and why?

Scout abdomen to see the colon/anatomy, see pathology, and check if the patient did their prep to clean out their colon

What is the last x-ray image taken and why?

Post-evacuation (abdomen) to see if the patient eliminated all the contrast media

Who inserts the enema tube?

Radiologist to ensure the patient doesn't get hurt + radiologist, PA, or rad nurse

What does a single contrast study demonstrate?

DIVA (diverticulum, intussusception, volvulus, and anatomy/appendicitis)

What does a double contrast study demonstrate?

APU (apple core, polyps, and ulcerative colitis)

A Welin method is what type of study?

double contrast

What reason are upright colon performed for?

air fluid levels (double contrast), and to see both flexures at the same time

What is the position for a PA projection?

prone

Where do you center for a PA projection?

MSP and IC (L4/L5) to see the entire colon

What must be included for a PA projection?

the entire colon

What is the tube angle and which direction for the PA axial projection?

30-40 degrees caudad

Where does the CR enter for PA axial?

MSP and ASIS (S1/S2) to see the recto-sigmoid