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103

C H A P T E R 4

AbdomenCONTR I BUT ION S BY Dan L. Hobbs, MSRS, RT(R)(CT)(MR)CONTR I BUTOR S TO PAST E D IT ION S John P. Lampignano, MEd, RT(R)(CT), Kathy M. Martensen, BS, RT(R),

Barry T. Anthony, RT(R)

CONTENTS

Radiographic Anatomy

Abdominal radiography, 104

Abdominal muscles, 104

Abdominal organ systems, 104

Digestive system

• Oral cavity, pharynx, and esophagus, 104

• Stomach, small intestine, large intestine, 105

Accessory digestive organs

• Pancreas, liver, gallbladder, (spleen), 106

Urinary system, 107

Abdominal cavity

• Peritoneum, mesentery, omentum, 108

• Mesocolon, greater sac and lesser sac, 109

Anatomic relationships

• Intraperitoneal, retroperitoneal, and infraperitoneal organs, 109

Quadrants and regions, 110

Topographic landmarks, 111

Radiographic Positioning

Positioning and exposure factors, 112

Pediatric and geriatric applications, 112

Digital imaging considerations, 113

Alternative modalities, 113

Pathologic indications, 113

Summary of pathologic indications, 114

Basic and special projections, 114

Basic abdomen

• AP supine (KUB), 115

Special abdomen projections

• PA prone, 116

• Lateral decubitus (AP), 117

• Erect AP, 118

• Dorsal decubitus (lateral), 119

• Lateral, 120

Acute abdomen

• Three-way series, 121

Radiographs for Critique, 122

104 CHAPTER 4 ABDOMEN

4

Abdominal RadiographyThis chapter covers the anatomy and positioning for what are sometimes called “plain fi lms” (images) of the abdomen. The most common is an anteroposterior (AP) supine abdomen, also some-times called a KUB (kidneys, ureters, and bladder). These are taken without the use of contrast media.

Plain radiographs of the abdomen (KUB) commonly are taken before abdominal examinations are performed with the use of contrast media to rule out certain pathologies.

Acute abdominal series: Certain acute or emergency condi-tions of the abdomen may develop from conditions such as bowel obstruction, perforations involving free intraperitoneal air (air outside the digestive tract), excessive fl uid in the abdomen, or a possible intraabdominal mass. These acute or emergency conditions require what is commonly called an “acute abdominal series,” or a “two-way” or “three-way abdomen” series, wherein several abdominal radiographs are taken in different positions to demonstrate air-fl uid levels and/or free air within the abdominal cavity.

Abdominal radiography requires an understanding of anatomy and relationships of the organs and structures within the abdomi-nopelvic cavity.

ABDOMINAL MUSCLESMany muscles are associated with the abdominopelvic cavity. The three that are most important in abdominal radiography are the diaphragm and the right and left psoas (so′-es) major.

The diaphragm is an umbrella-shaped muscle that separates the abdominal cavity from the thoracic cavity. The diaphragm must be perfectly motionless during radiography of either the abdomen or the chest. Motion of the patient’s diaphragm can be stopped when appropriate breathing instructions are given to the patient.

The two psoas major muscles are located on either side of the lumbar vertebral column. The lateral borders of these two muscles should be faintly visible on a diagnostic abdominal radiograph of a small to average-sized patient when correct exposure factors are used (see arrows, Fig. 4-1).

Abdominal Organ SystemsThe various organ systems found within the abdominopelvic cavity are presented briefl y in this chapter. Each of these systems is described in greater detail in later chapters devoted to those specifi c systems.

DIGESTIVE SYSTEMThe digestive system, along with its accessory organs, the liver, gallbladder, and pancreas, fi lls much of the abdominal cavity. The pancreas is located posterior to the stomach and is not well visual-ized on this drawing.

The spleen (part of the lymphatic system) is also partially visible in the left upper abdomen posterior to the stomach. The six organs of the digestive system are as follows:1. Oral cavity 4. Stomach2. Pharynx 5. Small intestine3. Esophagus 6. Large intestine

Oral Cavity, Pharynx, and Esophagus The oral cavity (mouth) and the pharynx (oropharynx and laryngopharynx) are common to the respiratory system and the digestive system, as illustrated in Fig. 3-4 of Chapter 3. The esophagus is located in the mediastinum of the thoracic cavity.

RADIOGRAPHIC ANATOMY

Right psoasmajor

Left psoasmajor

Diaphragm

1. Oral cavity

2. Pharynx3. Esophagus

4. Stomach

(Liver) (Spleen)

(Pancreas)

5. Small intestine

6. Large intestine

Right Left

Fig. 4-1. AP abdomen (KUB). Arrows indicate psoas muscles.

Fig. 4-2. Abdominal muscles.

Fig. 4-3. Digestive tract.

ABDOMEN CHAPTER 4 105

4

Stomach and Small and Large Intestines The three digestive organs within the abdominal cavity are the stomach and small and large intestines.

StomachThe stomach is the fi rst organ of the digestive system that is located within the abdominal cavity. The stomach is an expandable reser-voir for swallowed food and fl uids. The size and shape of the stomach are highly variable depending on the volume of its con-tents and on the body habitus.

Gastro is a common term for stomach (the Greek word gaster means “stomach”). Thus the term gastrointestinal (GI) tract or system describes the entire digestive system, starting with the stomach and continuing through the small and large intestines.

Small IntestineThe small intestine continues from the stomach as a long, tubelike convoluted structure about 4.5 to 5.5 meters (15 to 18 feet) in length. The three parts of the small intestine as labeled in Figs. 4-4 and 4-5 are as follows:A. Duodenum (doo″o-de′-num)B. Jejunum (je-joo′-num)C. Ileum (il′-eum)

Duodenum (A): The fi rst portion of the small intestine, the duo-denum, is the shortest but widest in diameter of the three seg-ments. It is about 25 cm [10 inches] in length. When fi lled with contrast medium, the duodenum looks like the letter C. The proxi-mal portion of the duodenum is called the duodenal bulb, or cap. It has a certain characteristic shape that usually is well seen on barium studies of the upper GI tract. Ducts from the liver, gallblad-der, and pancreas drain into the duodenum.

Jejunum and ileum (B and C): The remainder of the small bowel lies in the central and lower abdomen. The fi rst two-fi fths following the duodenum is called the jejunum, and the distal three-fi fths is called the ileum. The orifi ce (valve) between the distal ileum and the cecum portion of the large intestine is the ileocecal valve.

Radiograph of stomach and small intestine (see Fig. 4-5)Air seldom is seen fi lling the entire stomach or small intestine on a plain abdominal radiograph of a healthy, ambulatory adult. This radiograph shows the stomach, small intestine, and proximal large intestine because they are fi lled with radiopaque barium sulfate. Note the duodenal bulb and the long convoluted loops of the three labeled parts of the small intestine located in the midabdomen and lower abdomen.

Large intestineThe sixth and last organ of digestion is the large intestine, which begins in the right lower quadrant at the junction with the small intestine at the ileocecal valve. The portion of the large intestine below the ileocecal valve is a saclike area called the cecum. The appendix (vermiform appendix) is attached to the posteromedial aspect of the cecum.

The vertical portion of the large bowel above the cecum, the ascending colon, joins the transverse colon at the right colic (kol′-ik, referring to colon) fl exure. The transverse colon joins the descending colon at the left colic fl exure. Alternate secondary names for the two colic fl exures are hepatic and splenic fl exures based on their proximity to the liver and spleen, respectively.

The descending colon continues as the S-shaped sigmoid colon in the lower left abdomen. The rectum is the fi nal 15 cm (6 inches) of the large intestine. The rectum ends at the anus, the sphincter muscle at the terminal opening of the large intestine.

As will be seen in body habitus drawings, the shape and location of the large intestine vary greatly, with the transverse colon located

4. Stomach

5. Small intestine:

Duodenal bulb

A. Duodenum

C. Ileum (3/5)

B. Jejunum (2/5)

A

B

C

Ileocecalvalve

Duodenal bulbStomach

Liver

Spleen6. Large intestine:

Right Left

Transverse colon

Right colic(hepatic) flexure

Left colic(splenic)flexure

Ascending colonDescendingcolonIleocecal valve

Cecum

Appendix(vermiform)

Sigmoid colon

Rectum

Anus

Fig. 4-4. Stomach and small intestine.

Fig. 4-5. Stomach and small intestine radiograph.

Fig. 4-6. Large intestine.

high on wide hypersthenic types and low in the abdomen on slender hyposthenic and asthenic types. This is demonstrated in Chapters 14 and 15 in sections on the upper and lower GI systems.


4

SPLEENThe spleen is that part of the lymphatic system that along with the heart and blood vessels is part of the circulatory system. It is an important abdominal organ that occupies a space posterior and to the left of the stomach in the left upper quadrant, as shown in Fig. 4-7.

The spleen may be visualized faintly on plain abdominal radio-graphs, particularly if the organ is enlarged. It is a fragile organ and is sometimes lacerated during trauma to the lower left posterior rib cage.

ACCESSORY DIGESTIVE ORGANSThree accessory organs of digestion, also located in the abdominal cavity, are the (1) pancreas, (2) liver, and (3) gallbladder.

Pancreas The pancreas, which is not seen on a plain abdominal radiograph, is an elongated gland that is located posterior to the stomach and near the posterior abdominal wall, between the duodenum and the spleen. The average length is about 12.5 cm (6 inches). Its head is nestled in the C-loop of the duodenum, and the body and tail of the pancreas extend toward the upper left abdomen. This relationship of the duodenum and the head of the pancreas sometimes is referred to as “the romance of the abdomen.”

The pancreas is part of the endocrine (internal) secretion system and is also part of the exocrine (external) secretion system. The endocrine portion of the pancreas produces certain essential hormones, such as insulin, which aids in controlling the blood sugar level of the body. As part of its exocrine functions, the pancreas produces large amounts (up to 1½ quart [1500 ml] daily) of diges-tive juices that move to the duodenum through a main pancreatic duct as needed for digestion.

Liver The liver is the largest solid organ in the body, occupying most of the right upper quadrant. One of its numerous functions is the production of bile, which assists in the digestion of fats. If bile is not needed for digestion, it is stored and concentrated for future use in the gallbladder.

Gallbladder The gallbladder is a pear-shaped sac located below the liver. The primary functions of the gallbladder are to store and concentrate bile and to contract and release bile when stimulated by an appropriate hormone. The gallbladder in most cases cannot be visualized with conventional radiographic techniques without contrast media. The reason for this is because the gallbladder and the biliary ducts blend in with the other abdominal soft tissues and in most cases cannot be visualized. The anatomy of the gallbladder and biliary ducts is described in greater detail in Chapter 14, Upper Gastrointestional System. Only about 10% to 15% of all gallstones contain enough calcium to allow visualization on a plain abdominal radiographic image.

COMPUTED TOMOGRAPHY CROSS-SECTIONAL IMAGESCross-sectional (axial) computed tomography (CT) images through various levels of the abdomen demonstrate anatomic relationships of the digestive organs and their accessory organs, as well as the spleen.

Fig. 4-8 shows a sectional view of the upper abdomen at the level of T10 or T11 (thoracic vertebrae 10 or 11) just below the diaphragm. Note the proportionately large size of the liver at this level in the right upper abdomen and the cross-sectional view through the stomach to the left of the liver. The spleen is visualized posterior to the stomach in the left upper abdomen.

Fig. 4-9 presents a little lower cross-sectional image through the upper abdomen at the level of T12 (thoracic vertebra 12). The pancreas now is seen adjacent to a portion of the duodenal loop posterior to the distal part of the stomach. Note the air-fl uid level in the stomach with the heavy barium fl uid mixture (white) in the

posterior stomach. The dark air-fi lled portion of the stomach is on top (anteriorly), indicating that the patient was lying in a supine position for this CT scan.

A small inferior part of the spleen is seen in the left posterior abdomen just lateral to the left kidney. The major blood vessels of the abdomen, the inferior vena cava and the aorta, are seen clearly.

Note: The upper pole of the right kidney is not seen in this cross-sectional image because it is situated a little lower than the left kidney due to the presence of the liver (Fig. 4-10).

Liver

Gallbladder

Pancreas

Spleen

Right Left

Liver

Stomach

Spleen

T10 or 11LR

Gallbladder

Duodenum Stomach

Pancreas

Colon(leftcolicflexure)

Spleen

Body of L1 or L2

Aorta

Inferiorvena cava

Major blood

vessels:

Liver

Kidney

Fig. 4-7. Spleen and accessory organs of digestion—pancreas, liver, and gallbladder.

Fig. 4-8. CT image of upper abdomen (level of T10 or T11).

Fig. 4-9. CT image of abdomen demonstrating stomach, liver, gallbladder, pancreas, and spleen (level of L1 or 2).


4

Urinary SystemThe urinary system is another important abdominal system. Although this system is introduced in this chapter, it is discussed in detail in Chapter 16.

The urinary system is composed of the following:• Two kidneys• Two ureters (u-re′-ters)* or (yoo-re–t′-ers)†

• One urinary bladder• One urethra (u-re′-thrah)* or (yoo-re′-thra)†

Each kidney drains by way of its own ureter to the single urinary bladder. The bladder, which is situated above and behind the symphysis pubis, serves to store urine. Under voluntary control, the stored urine passes to the exterior via the urethra. The two supra-renal (adrenal) glands of the endocrine system are located at the superomedial portion of each kidney. The bean-shaped kidneys are located on either side of the lumbar vertebral column. The right kidney usually is situated a little lower than the left one because of the presence of the large liver on the right.

Waste materials and excess water are eliminated from the blood by the kidneys and are transported through the ureters to the urinary bladder.

EXCRETORY OR INTRAVENOUS UROGRAM (IVU)The kidneys usually are seen faintly on a plain abdominal radiograph because of a fatty capsule that surrounds each kidney. The contrast medium examination shown in Fig. 4-11 is an excretory or intrave-nous urogram (IVU), which is a radiographic examination of the urinary system, wherein the contrast medium is injected intrave-nously. During this examination, the hollow organs of this system are visualized with use of the contrast medium that has been fi ltered from the blood fl ow by the kidneys. The organs as labeled are (A) left kidney, (B) left proximal ureter, (C) left distal ureter before emptying into the urinary bladder, and (D) the area of the right suprarenal (adrenal) gland, just above the right kidney.

Note: The term intravenous pyelogram (IVP) often has been used in the past for this examination. However, this is not an accurate term for this exam because pyelo refers to the renal pelvis of the kidney, and the excretory or intravenous urogram includes a study of the entire urinary tract, which includes the total collecting system. (The terms excretory urogram [EU] and intravenous urogram [IVU] are both current and correct terms, but intrave-nous urogram [IVU] is the term that is used most commonly.)

Sectional ImageThis sectional CT image (Fig. 4-12) may appear confusing at fi rst because of the numerous small odd-shaped cross-sectional images that are visualized. However, as you study the relationships between these structures and imagine a thin “slice” view through the level of about L2-L3 of the drawings (see Fig. 4-10) and on the previous page (see Fig. 4-7), you should be able to identify each of these structures as labeled in Fig. 4-12. See how many of the structures labeled A through J you can identify without looking at the answers below.A. Inferior lobe of liver F. L2-L3 vertebraB. Ascending colon G. Left kidneyC. Right kidney H. Left ureterD. Right ureter I. Descending colonE. Right psoas major J. Loops of small intestines (jejunum)

muscleTwo major blood vessels of the abdomen are also seen labeled

as K and L. K is the large abdominal aorta, and L the inferior vena cava.

*Dorland’s illustrated medical dictionary, ed 28, Philadelphia, 1994, WB Saunders.†Webster’s new world college dictionary, ed 3.

Ureter

Urinarybladder

Urethra

Kidney

Suprarenal(adrenal) glands

Right Left

A

B

C

D

L K

J

I

H

G

FE

D

C

B

A

Right Left

Fig. 4-10. Urinary system.

Fig. 4-11. Intravenous urogram (IVU). A, Left kidney. B, Left mid ureter. C, Left distal ureter. D, Region of suprarenal gland.

Fig. 4-12. CT image of abdomen, level of distal poles of the kidneys, and proximal ureters.


4

Abdominal CavityFour important terms that describe anatomy of the abdominal cavity are demonstrated on the drawings to the right and are described below. These four terms are as follows:1. Peritoneum (per″-i-to-ne′-um)2. Mesentery (mes′-en-ter″-e)3. Omentum (o-men′-tum)4. Mesocolon (mez′-o-ko″-lon)

PERITONEUMMost of the abdominal structures and organs, as well as the wall of the abdominal cavity in which they are contained, are covered to varying degrees by a large serous, double-walled, saclike mem-brane called the peritoneum. In fact, the total surface area of the peritoneum is about equal to the total surface area of the skin that covers the entire body.

A greatly simplifi ed cross-section of the abdominal cavity is shown in Fig. 4-13. Two types of peritoneum exist: the parietal and the visceral. The two-layered peritoneum that adheres to the cavity wall is called parietal peritoneum, whereas that portion that covers an organ is called visceral peritoneum. The space or cavity between the parietal and visceral portions of the peritoneum is called the peritoneal cavity. This space is really only a potential cavity because normally it is fi lled with various organs. If all the loops of bowel and the other organs of the abdominal cavity were included in the drawing, little actual space would be left in the peritoneal cavity. This cavity contains some serous lubricating-type fl uid, which allows organs to move against each other without friction. An abnormal accumulation of this serous fl uid constitutes a condition called ascites. (See Pathologic Indications, p. 113.)

Note that a layer of visceral peritoneum only partially covers certain organs that are more closely attached to the posterior abdominal wall (see Fig. 4-13). At this level, the ascending and descending colon, the aorta, and the inferior vena cava are only partially covered; therefore, this lining would not be considered mesentery, and these structures and organs are called retroperi-toneal, as described on the following page.

MESENTERYThe peritoneum forms large folds that bind the abdominal organs to each other and to the walls of the abdomen. Blood and lymph vessels and the nerves that supply these abdominal organs are contained within these folds of peritoneum. One of these double folds that hold the small intestine in place is called the mesentery. Mesentery is that double fold of peritoneum that extends anteri-orly from the posterior abdominal wall to completely envelop a loop of small bowel. The specifi c term for a double fold of perito-neum that loosely connects the small intestine to the posterior abdominal wall is mesentery (Fig. 4-14).

OMENTUMA specifi c type of double-fold peritoneum that extends from the stomach to another organ is called omentum (see Fig. 4-14). The lesser omentum extends superiorly from the lesser curvature of the stomach to portions of the liver. The greater omentum connects the transverse colon to the greater curvature of the stomach inferiorly. The greater omentum drapes down over the small bowel then folds back on itself to form an apron along the anterior abdominal wall.

If one entered the abdomen through the midanterior wall, the fi rst structure encountered beneath the parietal peritoneum would be the greater omentum. Varying amounts of fat are deposited in the greater omentum, which serves as a layer of insulation between the abdominal cavity and the exterior. This is sometimes called the “fatty apron” because of its location and the amount of fat con-tained therein (Fig. 4-15).

Small bowel

Peritoneal cavity

Parietalperitoneum

Visceralperitoneum

Left kidneyRight kidney AortaInferiorvena cava

Retroperitoneal:

Mesentery(double-fold)

Omentum:

Lesseromentum

Greateromentum

Peritonealcavity

Parietalperitoneum

Visceralperitoneum

Small bowel

Mesentery

Stomach

Anterior Posterior

Greateromentum

Greater omentumdrawn up over chest

Transversemesocolon

StomachLiver

LeftRight LeftRight

Fig. 4-13. Cross-section—abdominal cavity (demonstrates peritoneum, mesentery, and retroperitoneal structures).

Fig. 4-14. Midsagittal section—abdominal cavity (demonstrates peritoneum, mesentery, and omentum).

Fig. 4-15. Greater omentum.


4

MESOCOLONThe peritoneum that attaches the colon to the posterior abdominal wall is the mesocolon. Four forms of mesocolon exist, each named according to that portion of the colon to which it is attached—ascending, transverse, descending, and sigmoid or pelvic. The transverse mesocolon is shown in Fig. 4-15 as that visceral peri-toneum that loosely connects the transverse colon to the posterior abdominal wall.

GREATER AND LESSER SACThe drawing in Fig. 4-16 shows the two parts of the peritoneal cavity. The major portion of the peritoneal cavity is called the greater sac and is commonly referred to as simply the peritoneal cavity.

A smaller portion of the upper posterior peritoneal cavity located posterior to the stomach is called the lesser sac. This sac has a special name—the omentum bursa.

This drawing again shows the mesentery connecting one loop of small intestine (ileum) to the posterior abdominal wall. A full drawing of a normal abdomen would, of course, have many loops of small bowel connected to the posterior wall by mesentery.

Mesentery-type folds from which other abdominal organs are suspended use the prefi x meso-, such as the transverse mesoco-lon, which again is shown to be connecting the transverse colon to the posterior abdominal wall.

RETROPERITONEAL AND INFRAPERITONEAL ORGANSThe organs shown in drawing Fig. 4-17 are considered either ret-roperitoneal (retro, meaning “backward” or “behind”) or infraperi-toneal (infra, meaning “under” or “beneath”).

Retroperitoneal Organs Structures closely attached to the poste-rior abdominal wall that are retroperitoneal as shown on this drawing are the kidneys and ureters, adrenal glands, pancreas, duodenum, ascending and descending colon, upper rectum, abdominal aorta, and inferior vena cava.

Remember that these retroperitoneal structures are less mobile and move around less within the abdomen than do other intraperi-toneal organs. Fig. 4-16 shows, for example, that the stomach, small intestine, and transverse colon are only loosely attached to the abdominal wall by long loops of different types of peritoneum and thus change or vary greatly in their position within the abdomen compared with retroperitoneal or infraperitoneal structures. (This is an important consideration in GI positioning.)

Infraperitoneal Organs Located under or beneath the peritoneum in the true pelvis are the lower rectum, urinary bladder, and reproductive organs.

MALE VS. FEMALE PERITONEAL ENCLOSURESOne signifi cant difference exists between male and female perito-neal enclosures. The lower aspect of the peritoneum is a closed sac in the male and not in the female. In the male, the lower peritoneal sac lies above the urinary bladder, totally separating the reproductive organs from those within the peritoneal cavity. In the female, however, the uterus, uterine (fallopian) tubes, and ovaries pass directly into the peritoneal cavity (see Fig. 4-16).

INTRAPERITONEAL ORGANSOrgans within the abdominal cavity that are partially or completely covered by some type of visceral peritoneum but are not retroperi-toneal or infraperitoneal may be called intraperitoneal (intra, meaning “within”). These organs, which have been removed from the drawing in Fig. 4-17, include the liver, gallbladder, spleen, stomach, jejunum, ileum, cecum, and transverse and sigmoid colon.

Ureter

Bladder(malereproductiveorgans)

Right

Retroperitoneal:

Left

Inferiorvena cava

Right adrenal gland

Right kidney

Duodenum

Pancreas

Ascending colon

Descendingcolon

Aorta

Liver

Spleen

“Intra” peritoneal structuresthat have been removed:

Infraperitoneal:

Stomach

Jejunum

Ileum

Gallbladder

Cecum

Transverseand sigmoidcolon

(Lower rectum)

Infraperitoneal:

Lesser sac(omentum bursa)

Greater sac(peritoneal cavity)

Lesseromentum

RectumBladder(Uterus)

Small intestine(ileum)

Mesentery

Transverse colon

Stomach

Anterior Posterior

Fig. 4-16. Sagittal section—abdominal cavity (demonstrates greater and lesser sacs, transverse mesocolon, and infraperitoneal structures).

Fig. 4-17. Retroperitoneal and infraperitoneal organs.

SUMMARY OF ABDOMINAL ORGANS IN RELATION TO THE PERITONEAL CAVITY

Intraperitoneal Organs

Retroperitoneal Organs

Infraperitoneal (Pelvic) Organs

LiverGallbladderSpleenStomachJejunumIleumCecumTransverse colonSigmoid colon

KidneysUretersAdrenal glandsPancreasDuodenumAscending and descending

colonUpper rectumMajor abdominal blood

vessels (aorta and inferior vena cava)

Lower rectumUrinary bladderReproductive organsMale—closed sacFemale—open sac (the

female uterus, tubes, and ovaries, extending into the peritoneal cavity)


4

Quadrants and RegionsTo facilitate description of the locations of various organs or other structures within the abdominopelvic cavity, the abdomen may be divided into four quadrants or nine regions.

FOUR ABDOMINAL QUADRANTSIf two imaginary perpendicular planes (at right angles) were passed through the abdomen at the umbilicus (or navel), they would divide the abdomen into four quadrants. One plane would be transverse through the abdomen at the level of the umbilicus, which on most people is at the level of the intervertebral disk between L4 and L5 (fourth and fi fth lumbar vertebrae), which is about at the level of the iliac crests on a female.

The vertical plane would coincide with the midsagittal plane or midline of the abdomen and would pass through both the umbili-cus and the symphysis pubis. These two planes would divide the abdominopelvic cavity into four quadrants: the right upper quad-rant (RUQ), the left upper quadrant (LUQ), the right lower quadrant (RLQ), and the left lower quadrant (LLQ).

Note: The four-quadrant system is used most frequently in radiography for localizing a particular organ or for describing the location of abdominal pain or other symptoms.

ANATOMY SUMMARY CHART—FOUR-QUADRANT ABDOMEN*

RUQ LUQ RLQ LLQLiverGallbladderRight colic

(hepatic) fl exure

DuodenumHead of

pancreasRight kidneyRight suprarenal

gland

SpleenStomachLeft colic

(splenic) fl exure

Tail of pancreasLeft kidneyLeft suprarenal

gland

Ascending colonAppendix

(vermiform)Cecum2⁄3 of ileumIleocecal valve

Descending colonSigmoid colon2⁄3 of jejunum

*Quadrant locations of structures and organs (primary location on average adult).

NINE ABDOMINAL REGIONSThe abdominopelvic cavity also can be divided into nine regions through the use of two horizontal or transverse planes and two vertical planes. The two transverse/horizontal planes are the trans-pyloric plane and the transtubercular plane. The two vertical planes are the right and left lateral planes (Fig. 4-20).

The transpyloric plane is at the level of the lower border of L1 (fi rst lumbar vertebra), and the transtubercular plane is at the level of L5 (the fi fth lumbar vertebra). The right and left lateral planes are parallel to the midsagittal plane and are located midway between it and each anterior superior iliac spine (ASIS).

Names of Regions The names of these nine regions are identifi ed below. Technologists should be familiar with the locations and names of these nine regions. However, in general, locating most structures and organs within the four-quadrant system is suffi cient for radiographic purposes because of variables that affect specifi c locations of organs, such as body habitus, body position, and age (see organ outlines in Fig. 4-20 for general locations of organs within these nine regions).1. Right hypochondriac 6. Left lateral (lumbar)2. Epigastric 7. Right inguinal (iliac)3. Left hypochondriac 8. Pubic (hypogastric)4. Right lateral (lumbar) 9. Left inguinal (iliac)5. Umbilical

RUQ LUQ

RLQ LLQ

RUQ

RLQ LLQ

LUQ

Right Left

Right lateral plane Left lateral plane

Transpyloricplane

Transtubercularplane

1

Right Left

2 3

4 5 6

7 8 9

Fig. 4-18. Four abdominal quadrants.

Fig. 4-19. Four quadrants with certain abdominal structures.

Fig. 4-20. Nine regions with certain abdominal structures.


4

TOPOGRAPHIC LANDMARKSAbdominal borders and organs within the abdomen are not visible from the exterior, and because these soft tissue organs cannot be palpated directly, certain bony landmarks are used for this purpose.

Note: Remember that palpation must be done gently because the patient may have painful or sensitive areas within the abdomen and pelvis. Also, be sure that the patient is informed of the purpose of this palpation before beginning.

SEVEN LANDMARKS OF THE ABDOMENThe following seven palpable landmarks are important in position-ing the abdomen or locating organs within the abdomen. It is sug-gested that one should practice fi nding these bony landmarks on oneself before attempting to locate them on another person or on a patient for the fi rst time.

Positioning for abdominal radiographs in AP or PA projections requires a quick but accurate location of these landmarks on thin patients, as well as on heavy-set or muscular patients, who will require more fi rm palpation.1. Xiphoid process (level of T9-T10): The tip of the xiphoid

process is the most distal or inferior process of the sternum. This can best be palpated by fi rst gently pressing on the soft abdomen below the distal sternum, then moving upward care-fully against the fi rm, distal margin of the xiphoid process.

This landmark approximates the superior anterior portion of the diaphragm, which is also the superior margin of the abdomen. This, however, is not a primary landmark for posi-tioning the abdomen because of variation in body types and the importance of including all of the lower abdomen on most radiographic images of the abdomen.

2. Inferior costal (rib) margin (level of L2-L3): This landmark is used to locate upper abdominal organs, such as the gallblad-der and/or stomach.

3. Iliac crest (level of L4-L5 vertebral interspace): The crest of the ilium is the uppermost portion of the curved border of the ilium. The iliac crest can be palpated easily by pressing inward and downward along the midlateral margin of the abdomen. The uppermost or most superior portion of this crest is the most commonly used abdominal landmark and corresponds approximately to the level of the midabdomen, which is also at or just slightly below the level of the umbilicus on most persons. If the center of the cassette or image receptor (IR) is centered to this level, the lower abdominal area generally will be included on the lower margin of the IR.Note: Ensuring that all of the upper abdomen, including the dia-phragm, is included on the IR requires centering about 5 cm (2 inches) above the level of the crest for most patients, which usually will cut off some of the important lower abdomen. This then would require a second IR centered lower to include this lower region.

4. Anterior superior iliac spine (ASIS): The ASIS can be found by locating the iliac crest, then palpating anteriorly and inferiorly until a prominent projection or “bump” is felt (more prominent on females). This landmark is commonly used for positioning of pelvic and vertebral structures but can also serve as a sec-ondary landmark for general abdominal positioning.

5. Greater trochanter: This landmark is more easily palpated on thin patients. Gentle but very fi rm palpation generally is required to feel the movement of the trochanter with one hand while rotating the leg internally and externally at the knee area with the other hand. This is not as precise a landmark as the other bony landmarks of the pelvis, but the uppermost margin of the trochanter generally is at about the same level as the upper border of the symphysis pubis. With practice, this can be used as a secondary landmark for abdominal positioning.

6. Symphysis pubis: The symphysis pubis is the anterior junction (joint) of the two pelvic bones. The most superior anterior portion of the pubis can be palpated when the patient is in a supine position. This landmark corresponds to the inferior margin of the abdomen. Palpation of this area, however, may be embarrassing to some patients. With practice, the level of the symphysis pubis or the lower margin of the abdomen can be identifi ed by palpating the greater trochanter with reference to the iliac crest as being at the level of the center of the cas-sette or IR. This then places the lower margin of the IR at the symphysis pubis.

7. Ischial tuberosity: This can be used to determine the lower margin on a PA abdomen with the patient in a prone position. These two bony prominences, which can be palpated most easily on thin patients, bear most of the weight of the trunk when one is seated. The lower margins of the ischial tuberosi-ties are about 1 to 4 cm (1½ inches) below or distal to the symphysis pubis. This landmark may be used for positioning a PA projection of the colon when the rectal area is to be included on the IR. This, however, may be uncomfortable and embarrassing for the patient, and other landmarks can and should be used when possible.

1234

567

1

234

567

Greater trochanter

Crest of ilium

ASIS

Ischial tuberosity

Symphysis pubis

Fig. 4-21. Topographic landmarks. Fig. 4-22. Topographic landmarks.

Fig. 4-23. Topographic landmarks of pelvis.


4

Patient PreparationPatient preparation for abdominal radiography includes removal of all clothing and any opaque objects in the area to be radiographed. The patient should wear a hospital gown with the opening and ties in the back (if this type of gown is used). Shoes and socks may remain on the feet. Generally no pre-exam patient instructions are required unless barium studies are scheduled also.

General Positioning ConsiderationsMake patients as comfortable as possible on the radiographic table. A pillow under the head and support under the knees will enhance comfort for a supine abdomen. Place clean linen on the table and cover patients to keep them warm and to protect their modesty.

Breathing InstructionsOne of the key factors in good abdominal radiography is the preven-tion of motion. Motion may result from voluntary movement, such as breathing, or from involuntary movement, such as peristaltic action of the bowel. The difference between these two types of motion is illustrated in Chapter 2. However, what is important to remember in preventing any potential motion in abdominal radiogra-phy is that the shortest exposure time possible should be used.

A second way to prevent voluntary motion is by providing careful breathing instructions to the patient. Most abdominal radiographs are taken on expiration; the patient is instructed to “take in a deep breath—let it all out and hold it—don’t breathe.” Before making the exposure, make sure that the patient is following instructions, and that suffi cient time has been allowed for all breathing movements to cease.

Abdominal radiographs are exposed on expiration, with the diaphragm in a superior position for better visualization of abdomi-nal structures.

Image MarkersCorrectly placed R and L markers and “up side” markers, such as short arrows, are used for erect and decubitus projections and should be visible without superimposing abdominal structures. Like-wise, markers used for patient ID information in screen-fi lm (analog) systems should be placed so they do not interfere with pertinent anatomy and should be clear and legible. The anatomic side marker must correspond with the patient’s left or right side of the body. The marker must be placed on the IR prior to exposure. It is not acceptable practice to indicate the side of the body either digitally or with a marking pen following the exposure.

Radiation ProtectionGood radiation protection practices are especially important in abdominal radiography because of the proximity of the radiation-sensitive gonadal organs.

Repeat exposures: Careful positioning and selection of correct exposure factors are ways of reducing unnecessary exposure from repeat examinations. Providing clear breathing instructions also assists in eliminating repeats that often result from motion caused by breathing during the exposure.

Collimation: For abdominal radiographs of small patients, some side collimation to skin borders is possible if it does not cut off abdominal anatomy.

Collimation on the top and bottom for adults should be adjusted directly to the margins of the IR or fi lm holder, allowing for diver-gence of the x-ray beam. Essential anatomy will be cut off on average-sized adults if extra collimation margins are shown on the top and bottom borders of a typical 35 × 43-cm (14 × 17-inch) abdominal image.

Gonadal shielding: For abdominal radiographs, gonadal shields should be used for males, with the upper edge of the shield

carefully placed at the pubic symphysis (Fig. 4-24). For females, gonadal shields should be used only when such shields do not obscure essential anatomy in the lower abdominopelvic region. Generally, the decision to shield female gonads on abdominal radiographs should be made by a physician to determine whether essential anatomy will be obscured. The top of an ovarian shield should be at or slightly above the level of ASIS and the lower border at the symphysis pubis.

Pregnancy protection: See Chapter 2, p. 66, regarding safe-guards for potential early pregnancies with abdominal or pelvic projections.

Exposure FactorsThe principal exposure factors for abdominal radiographs are as follows:1. Medium kV (70 to 80)2. Short exposure time3. Adequate mAs for suffi cient density

Correctly exposed abdominal radiographs on an average-sized patient should faintly visualize the lateral borders of the psoas muscles, lower liver margin, kidney outlines, and lumbar vertebrae transverse processes. This requires moderate contrast with medium kV exposure to allow for visualization of various abdominal struc-tures, including possible small semiopaque stones in the gallblad-der or kidneys.

Pediatric ApplicationsAcute abdomen routines for pediatrics generally include only a supine and one horizontal beam projection to show air-fl uid levels. For patients younger than 2 or 3 years of age, the lateral decubitus may be diffi cult to obtain, and an AP erect abdomen with an immobilization device such as a Pigg-O-Stat (Modern Way Immo-bilizers, Inc, Clifton, Tenn) is preferred (see Chapter 19).

Motion prevention is of utmost importance in pediatrics, and short exposure time and higher-speed fi lm and screens are essen-tial. Children younger than 12 or 13 years of age require a signifi -cant reduction in kV and mAs. Confi rmed technique factors for children of various sizes and ages for the equipment that is being used should always be available to minimize repeats due to expo-sure errors.

Geriatric ApplicationsOlder patients often require extra care and patience in explaining what is expected of them. Careful breathing instructions are essen-tial, as is assistance in helping patients move into the required position. Extra radiolucent padding under the back and buttocks for thin patients and blankets to keep patients warm add greatly to their comfort on supine abdomen radiographic procedures.

RADIOGRAPHIC POSITIONING

Fig. 4-24. Gonadal shielding—male.

Fig. 4-25. Gonadal shielding—female (use only if shielding does not obscure essential anatomy).


4

Digital Imaging ConsiderationsThe following summary reviews the guidelines that should be fol-lowed with digital imaging (CR and DR) of the abdomen as described in this chapter:1. Close collimation: Close collimation to the body part being

imaged and accurate centering are most important in digital imaging for the abdomen.

2. Exposure factors: It is important that the ALARA principle (exposure to patient As Low As Reasonably Achievable) be followed and the lowest exposure factors required to obtain a diagnostic image be used. This includes the highest kV and the lowest mAs that will result in desirable image quality. For digital imaging, this may require some increase in kV compared with fi lm-screen imaging.

3. Post-processing evaluation of exposure index: The exposure index on the fi nal processed image must be checked to verify that the exposure factors used were in the correct range to ensure optimum quality with the least radiation to the patient.

Alternative ModalitiesCOMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGINGComputed tomography (CT) and magnetic resonance imaging (MRI) are very useful in the evaluation and early diagnosis of small neoplasms involving abdominal organs such as the liver and pan-creas. With the use of IV contrast media, CT can be used to dis-criminate between a simple cyst and a solid neoplasm.

Both CT and MRI also provide valuable information in assessing the extent to which neoplasms have spread to surrounding tissues or organs. MRI, for example, may be used to demonstrate blood vessels within neoplasms and to assess their relationship and involvement with surrounding organs without the need for contrast media injection.

MRI is also being used to visualize the biliary and pancreatic ducts, as is ERCP (endoscopic retrograde cholangiopancreatogram), a fl uoroscopic procedure in which a contrast medium is injected endoscopically (described in Chapter 22).

SONOGRAPHY (ULTRASOUND)Ultrasound has become the method of choice when the gallblad-der is imaged for detection of gallstones (in the gallbladder or bile ducts). It is of limited use in the evaluation of the hollow viscus of the GI tract for bowel obstruction or perforation, but along with CT, it is very useful in detecting and evaluating lesions or infl ammation of soft tissue organs such as the liver or pancreas. Ultrasound is widely used, along with CT, for demonstrating abscesses, cysts, or tumors involving the kidneys, ureters, or bladder.

Ultrasound with compression, in combination with clinical evalu-ation, can be used successfully to diagnose acute appendicitis.

NUCLEAR MEDICINENuclear medicine is useful as a noninvasive means of evaluating GI motility and refl ux as related to possible bowel obstruction. It is also useful for evaluation of lower GI bleeding.

With the injection of specifi c radionuclides, nuclear medicine imaging can be used to examine the entire liver and the major bile ducts and gallbladder.

Pathologic IndicationsA plain AP supine radiograph of the abdomen (KUB) generally is taken before contrast medium is introduced into the various abdominal organ systems for evaluation and diagnosis of diseases and conditions involving these systems. Pathologic indications and terms specifi cally related to each of these systems are provided in Chapters 14 and 15.

The acute abdomen series, however, as described in this chapter, is performed most commonly to evaluate and diagnose conditions or diseases related to bowel obstruction and/or per-foration. This requires visualization of air-fl uid levels and possible intraperitoneal “free” air with the use of horizontal beam erect or decubitus body positions. Following are terms and pathologic dis-eases or conditions that are related to the acute abdominal series exam.

Ascites (ah-si′-tez) is an abnormal accumulation of fl uid in the peritoneal cavity of the abdomen. It generally is caused by long-standing (chronic) conditions such as cirrhosis of the liver or by metastatic disease to the peritoneal cavity.

Pneumoperitoneum refers to free air or gas in the peritoneal cavity. This is a serious condition for which surgery is required when it is caused by perforation of a gas-containing viscus, such as by a gastric or duodenal ulcer. It also can be caused by trauma that penetrates the abdominal wall.

Small amounts of residual air may be evident radiographically up to 2 or 3 weeks following abdominal surgery. It is best demon-strated with a horizontal beam erect abdomen or chest radiograph, with which even a small amount of free air can be seen as it rises to the highest position under the diaphragm.

Dynamic (with power or force) or mechanical bowel obstruc-tion is the complete or nearly complete blockage of the fl ow of intestinal contents. Its causes include the following:• Fibrous adhesions: The most common cause of mechanically

based obstruction, in which a fi brous band of tissue interrelates with the intestine, creating a blockage.

• Crohn’s disease (Kro–nz): A chronic infl ammation of the intes-tinal wall that results in bowel obstruction in at least half of those affl icted. The cause is unknown. Crohn’s disease is most common in young adults and is characterized by loops of small bowel joined by fi stulas or connected openings with adjacent loops of intestine.

• Intussusception: The telescoping of a section of bowel into another loop, which creates an obstruction. Intussusception is most common in the distal small bowel region (ileus), and it is more common in children than in adults. This condition requires treatment within 48 hours to prevent necrosis (tissue death).

• Volvulus: The twisting of a loop of intestine, which creates an obstruction. Volvulus may require surgery for correction.Ileus–nonmechanical bowel obstruction is categorized as

adynamic (without power or force) ileus and most frequently is caused by peritonitis, or paralytic (paralysis) ileus, which is caused by a lack of intestinal motility. It occurs frequently in postoperative patients, usually 24 to 72 hours after abdominal surgery. In contrast to mechanical obstruction, it rarely leads to perforation, and the radiographic appearance is characterized by a large amount of air and fl uid, with air-fl uid levels visible in a greatly dilated small and large bowel and no visible distinct point of obstruction (unlike a mechanical obstruction).

Ulcerative colitis is a chronic disease involving infl ammation of the colon that occurs primarily in young adults and most frequently involves the rectosigmoid region. In some cases, it becomes a very severe acute process, causing serious complications, such as a toxic megacolon (extreme dilation of a segment of colon) with potential perforation into the peritoneal cavity. Barium enema is strongly contraindicated with symptoms of toxic megacolon.


4

ACUTE ABDOMEN ROUTINEIn addition to the supine and erect or decubitus abdomen, the PA chest is included at some institutions to demonstrate free intraperi-toneal air trapped under the diaphragm. Therefore, the three-way acute abdomen series (AP and erect abdomen plus PA chest) is presented as basic or routine. However, acute abdomen routines vary, depending on the institution. Students and technologists should determine the routine for their departments.

One reason the PA chest is commonly included in the three-way acute abdomen series is that the erect chest best visualizes free intraperitoneal air under the diaphragm. The erect abdomen also will visualize free air if the IR is centered high enough to include the diaphragm; however, the exposure technique for the chest best visualizes small amounts of this air if present.

CONDITION OR DISEASEMOST COMMON RADIOGRAPHIC EXAMINATION

POSSIBLE RADIOGRAPHIC APPEARANCE EXPOSURE FACTOR ADJUSTMENT

Ascites Acute abdomen series General abdominal haziness Increase, depending on severity (+ or ++)

Pneumoperitoneum (air in peritoneal cavity)

Acute abdomen series—erect chest or abdomen

Thin, crest-shaped radiolucency under dome of right hemidiaphragm on erect

Decrease (−)

Dynamic (Mechanical Bowel) Obstruction

Fibrous adhesions Acute abdomen series Distended loops of air-fi lled small bowel

Decrease, depending on severity of distention (− or − −)

Crohn’s disease Acute abdomen series Distended loops of air-fi lled small bowel


Intussusception (most common in children)

Acute abdomen series Air-fi lled “coiled spring” appearance

Decrease (−)

Volvulus (most common in sigmoid colon)

Acute abdomen series Large amounts of air in sigmoid with tapered narrowing at site of volvulus

Slight decrease (−)

Ileus (nonmechanical obstruction), adynamic or paralytic

Acute abdomen series Large amounts of air in entire dilated small and large bowel with air-fl uid levels visualized


Ulcerative colitisSevere case may lead to toxic

megacolon and bowel perforation

Plain AP abdomen Deep air-fi lled mucosal protrusions of colon wall, usually in rectosigmoid region

Decrease (−)

Acute abdomen series for possible free air (Barium enema contraindicated)

Dilated loop of colon Decrease (−)

*Automatic exposure control (AEC) systems are designed to correct exposure density automatically for patient size variances and for these pathologic conditions. If they are calibrated correctly and are used as intended, manual adjustments generally are not needed when AEC is used. However, these exposure adjustments may be needed for more extreme cases, or for repeats, even with AEC. They are also important when manual exposure techniques are set, such as for tabletop or mobile exams when AEC is not used.

SUMMARY OF PATHOLOGIC INDICATIONS

BASIC AND SPECIAL PROJECTIONSThe most common basic and special projections for the abdomen are demonstrated and described on the following pages.

Acute Abdomen (Three-Way, With PA Chest)

BASIC

• AP supine, 121

• AP erect, 121

• PA chest erect, 121

SPECIAL

• Left lateral decubitus (AP), 121

Abdomen (KUB)

BASIC

• AP supine, 115

SPECIAL

• PA prone, 116

• Lateral decubitus (AP), 117

• AP erect, 118

• Dorsal decubitus (lateral), 119

• Lateral, 120


4

Pathology DemonstratedPathology of the abdomen, including bowel obstruction, neoplasms, calcifi cations, ascites, and scout image for contrast medium studies of abdomen.

Technical Factors• IR size—35 × 43 cm (14 × 17 inches),

lengthwise• Moving or stationary grid• 70 to 80 kV range• Technique and dose:

Shielding Use gonadal shields on males (also on females of reproductive age, only if such shielding does not obscure essential anatomy as determined by a physician).

Patient Position• Supine with midsagittal plane centered to midline of table and/

or cassette• Arms placed at patient’s sides, away from body• Legs extended with support under knees if this is more

comfortable

Part Position• Center of cassette to level of iliac crests, with bottom margin

at symphysis pubis (see Notes below)• No rotation of pelvis or shoulders (check that both ASIS are

the same distance from the tabletop)

Central Ray• CR perpendicular to and directed to center of IR (to level of

iliac crest)• Minimum SID of 40 inches (100 cm)

Collimation Collimate closely on sides to skin margins and on top and bottom to IR borders.

Respiration Make exposure at end of expiration (allow about 1 second delay after expiration to allow involuntary motion of bowel to cease).

Notes: A tall hyposthenic- or asthenic-type patient may require two images placed lengthwise—one centered lower to include the symphysis pubis and the second centered high to include the upper abdomen and diaphragm.

A broad hypersthenic-type patient may require two 35 × 43-cm (14 × 17-inches) images placed crosswise, one centered lower to include the symphysis pubis and the second for the upper abdomen, with a minimum of 3 to 5 cm (1 to 2 inches) overlap.

AP PROJECTION—SUPINE POSITION: ABDOMEN

KUB

Abdomen

BASIC

• AP supine (KUB)

35

43

Rcm kV mAs Sk. ML. Gon.

17 75 15 153 34 M 3F 47

Small “model” patient

20 80 22 282 52 M 4F 64

Larger nearer- mradaverage patient

Radiographic Criteria

Structures Shown: • Outline of liver, spleen, kidneys, and air-fi lled stomach and bowel segments and the arch of the symphysis pubis for the urinary bladder region.Position: • No rotation; iliac wings, obturator foramina (if visible), and ischial spines appear symmetric, and outer lower rib margins are the same distance from spine (elongation of iliac wing indicates rotation in that direction).Collimation and CR: • Collimation border to fi lm margins on top and bottom to prevent cutoff of essential

anatomy. • Center of IR (CR) at level of iliac crest. • See note about possible two fi lms.Exposure Criteria: • No motion; ribs and all gas bubble margins appear sharp. • Suffi cient exposure (mAs) and long-scale contrast (kV) visualize psoas muscle outlines, lumbar transverse processes, and ribs. • Margins of liver and kidneys should be visible on smaller to average-sized patients.

flat

Symphysispubis

Coccyx

Sacrum

12th rib

Liver

Transverseprocess (L4)

Left iliaccrest

Leftfemur

Obturatorforamen

Edge ofpsoas major

muscle

Fig. 4-26. AP abdomen (KUB).

Fig. 4-27. AP abdomen (KUB).

Fig. 4-28. AP abdomen.


4

Pathology DemonstratedPathology of abdomen, including bowel obstruction, neoplasms, calcifi cations, ascites, and scout image for contrast medium studies of abdomen.

Note: This projection is less desirable than the AP if the kidneys are of primary interest because of the increased object image receptor distance (OID).


lengthwise• Moving or stationary grid• 70 to 80 kV range• Technique and dose:

Shielding Use gonadal shields on males (also on females of reproductive age, only if such shielding does not obscure essential anatomy as determined by a physician).

Patient Position• Prone with midsagittal plane of body centered to midline of table

and/or IR• Legs extended with support under ankles• Arms up beside head; clean pillow provided

Part Position• No rotation of pelvis or shoulders and thorax• Center of IR to iliac crest

Central Ray• CR perpendicular to and directed to center of IR (to level of

iliac crest)• Minimum SID of 40 inches (100 cm)

Collimation Collimate closely on all sides to skin margins and on top and bottom to IR borders.

Respiration Make exposure at end of expiration.

Note: Tall, asthenic-type patients may require two images placed length-wise; broad hypersthenic types may also require two images placed crosswise.

PA PROJECTION—PRONE POSITION: ABDOMEN

Abdomen

SPECIAL

• PA prone

• Lateral decubitus (AP)

• AP erect

• Dorsal decubitus (lateral)

• Lateral

35

43

R

cm kV mAs Sk. ML. Gon.

20 80 22 282 52 M 2F 47

average size mrad


Structures Shown: • Outline of liver, spleen, kidneys, and air-fi lled stomach and bowel segments and the arch of the symphysis pubis for the urinary bladder region.Position: • No rotation; Iliac wings appear symmetric, and sacroiliac joints and outer lower rib margins (if visible) should be the same distance from spine.Collimation and CR: • Collimation borders to IR margins on top and bottom to prevent cutoff of essential anatomy. • Center of IR (CR) at level of iliac crest (see note about possible two images).Exposure Criteria: • No motion; ribs and all gas bubble margins appear sharp. • Exposure (mAs) and long-scale contrast (kV) are suffi cient to visualize psoas muscle outlines, lumbar transverse processes, and ribs. • Margins of liver and kidneys should be visible on smaller to average-sized patients.

Leftkidney

3rd Lumbarvertebra

Pelvis(ilium)Sacrum

Liver

Transverseprocess

Fig. 4-29. PA abdomen.




4

Pathology DemonstratedAbdominal masses, air-fl uid levels, and pos-sible accumulations of intraperitoneal air are demonstrated. (Small amounts of free intra-peritoneal air are best demonstrated with chest technique on erect PA chest.)

Important: Patient should be on side a minimum of 5 minutes before exposure (to allow air to rise or abnormal fl uids to accu-mulate); 10 to 20 minutes is preferred, if possible, for best visu-alization of potentially small amounts of intraperitoneal air.

Left lateral decubitus best visualizes free intraperitoneal air in the area of the liver in the right upper abdomen away from the gastric bubble.


crosswise to the table (lengthwise with the patient)

• Moving or stationary grid• 70 to 80 kV range• Technique and dose:

Marker: Place arrow or other appropriate marker to indicate “up” side.

Shielding Use gonadal shield on males.

Patient Position• Lateral recumbent on radiolucent pad, fi rmly against table or

vertical grid device (with wheels on cart locked so as not to move away from table)

• Patient on fi rm surface, such as a cardiac or back board, posi-tioned under the sheet to prevent sagging and anatomy cutoff

• Knees partially fl exed, one on top of the other, to stabilize patient• Arms up near head; clean pillow provided

Part Position• Adjust patient and cart so that center of IR and CR are approxi-

mately 2 inches (5 cm) above level of iliac crests (to include diaphragm). Proximal margin of cassette will be approximately at level of axilla.

• Ensure no rotation of pelvis or shoulders.• Adjust height of cassette to center midsagittal plane of patient

to center of IR, but ensure that upside of abdomen is clearly included on the IR.

Central Ray• CR horizontal, directed to center of IR, at about 2 inches (or

5 cm) above level of iliac crest; use of a horizontal beam to demonstrate air-fl uid levels and free intraperitoneal air

• Minimum SID of 40 inches (100 cm)

Collimation Collimate on four sides; do not cut off upper abdomen.

Respiration Make exposure at end of expiration.

LATERAL DECUBITUS POSITION (AP PROJECTION): ABDOMEN


Structures Shown: • Air-fi lled stomach and loops of bowel and air-fl uid levels where present. • Should include bilateral diaphragm.Position: • No rotation; iliac wings appear symmetric, and outer rib margins are the same distance from spine. • Spine should be straight (unless scoliosis is present), aligned to center of IR.

Collimation and CR: • Collimation borders to IR margins to prevent cutoff of essential anatomy. • CR approximately 2 inches (5 cm) above level of iliac crest.Exposure Criteria: • No motion; ribs and all gas bubble margins sharp. • Exposure suffi cient to visualize spine and ribs and soft tissue but not to overexpose possible intraperitoneal air in upper abdomen. • Slightly less overall density than supine abdomen.

Abdomen

SPECIAL

• PA prone


• AP erect


• Lateral

43

35

R


21 80 30 396 68 M 8F 94

average size mrad

Spinousprocess

Vertebralbody

Pedicle

Intestinal gasIliac wing

Diaphragmdome

Fig. 4-32. Left lateral decubitus position (AP).

Fig. 4-33. Left lateral decubitus (AP). (From McQuillen Martensen K: Radiographic image analysis, ed 2, Philadelphia, 2006, WB Saunders.)

Fig. 4-34. Left lateral decubitus (AP). (Modifi ed from McQuillen Martensen K: Radiographic image analysis, ed 2, Philadelphia, 2006, WB Saunders.)


4

Pathology DemonstratedAbnormal masses, air-fl uid levels, and accu-mulations of intraperitoneal air under dia-phragm are demonstrated.

Perform erect radiograph fi rst if patient comes to department ambulatory or in wheelchair in an erect position.


lengthwise• Moving or stationary grid (use erect markers)• 70 to 80 kV range• Technique and dose:

Marker: Include erect marker on IR.

Shielding• Use gonadal shields on males. An adjustable freestanding mobile

shield can be used as for chests.

Patient Position• Upright, legs slightly spread, back against table or grid device

(see Note below for weak or unsteady patients)• Arms at sides away from body• Midsagittal plane of body centered to midline of table or erect Bucky

Part Position• Do not rotate pelvis or shoulders.• Adjust height of IR so the center is approximately 2 inches

(5 cm) above iliac crest (to include diaphragm), which for the average patient will place the top of the IR approximately at the level of the axilla.

Central Ray• CR horizontal, to center of IR• Minimum SID of 40 inches (100 cm)

Collimation Collimate closely on all four sides; do NOT cut off upper abdomen.

Respiration Exposure should be made at end of expiration.

Note: Patient should be upright a minimum of 5 minutes, but 10 to 20 minutes is desirable, if possible, before exposure for visualizing small amounts of intraperitoneal air. If a patient is too weak to maintain an erect position, a lateral decubitus should be taken. For hypersthenic patients, two crosswise IRs may be required to include the entire abdomen.

AP PROJECTION—ERECT POSITION: ABDOMEN

Abdomen

SPECIAL

• PA prone


• AP erect


• Lateral


21 80 30 396 68 M 8F 94

average size mrad

35

43

R

EREC

T


Structures Shown: • Air-fi lled stomach and loops of bowel and air-fl uid levels where present. • Should include bilateral diaphragm and as much of lower abdomen as possible. • Small free, intraperitoneal crescent-shaped air bubble if present seen under right hemidiaphragm, away from gas in stomach.Position: • No rotation; iliac wings appear symmetric, and outer rib margins are the same distance from spine. Spine should be straight (unless scoliosis is present), aligned with center of IR.Collimation and CR: • Collimation borders to top and bottom margins of IR to prevent cutoff of essential anatomy. • CR about 5 cm (2 inches) above level of iliac crest.Exposure Criteria: • No motion; ribs and all gas bubble margins appear sharp. • Exposure is suffi cient to visualize spine and ribs and soft tissue but not to overexpose possible intraperitoneal air in upper abdomen. Slightly less overall density than supine abdomen is preferred.

Lefthemidiaphragm

Righthemidiaphragm

T 12Liver

Air-fluidlevel

Air-filledbowel

Left iliaccrest

Fig. 4-35. Erect AP—to include diaphragm.

Fig. 4-36. Erect AP—to include diaphragm. Bowel obstruction present.

Fig. 4-37. Erect AP.


4

Pathology DemonstratedAbnormal masses, accumulations of gas, air-fl uid levels, aneurysms (a widening or dila-tion of the wall of an artery, vein, or the heart), calcifi cation of aorta or other vessels, and umbilical hernias


crosswise• Moving or stationary grid• 70 to 80 kV range• Technique and dose:

Shielding• Use gonadal shields on males.

Patient Position• Supine on radiolucent pad, side against table or vertical grid

device; secure cart so that it does not move away from table or grid device

• Pillow under head, arms up beside head; support under partially fl exed knees may be more comfortable for the patient

Part Position• Adjust patient and cart so that center of IR and CR is 2 inches

(5 cm) above level of iliac crest (to include diaphragm).• Ensure that no rotation of pelvis or shoulders exists (both ASIS

should be the same distance from tabletop).• Adjust height of IR to align midcoronal plane with centerline of

IR.

Central Ray• CR horizontal to center of IR 2 inches (5 cm) above iliac crest

and to midcoronal plane• Minimum SID of 40 inches (100 cm)

Collimation Collimate to upper and lower abdomen soft tissue borders. Close collimation is important because of increased scatter from higher kV and need for soft tissue visibility.

Respiration Exposure is made at end of expiration.

Note: This may be taken as a right or left lateral; appropriate R or L lateral marker should be used, indicating which side is closest to IR.

DORSAL DECUBITUS POSITION (RIGHT OR LEFT LATERAL): ABDOMEN

Abdomen

SPECIAL

• PA prone


• AP erect


• Lateral

43

35

R


30 80 60 1040 85 M 3F 42

average size mrad


Structures Shown: • Diaphragm and as much of lower abdomen as possible should be included. • Air-fi lled loops of bowel in abdomen with soft tissue detail should be visible in anterior abdomen and in prevertebral regions.Position: • No rotation as evident by superimposition of posterior ribs and posterior borders of iliac wings and bilateral ASISs.Collimation and CR: • Collimation borders to tissue margins of anterior and posterior abdomen. • Center of collimation fi eld (CR) to prevertebral region about 2 inches (5 cm) above level of iliac crest.Exposure Criteria: • No motion; rib and gas bubble margins appear sharp. • Lumbar vertebrae may appear about 50% underexposed with soft tissue detail visible in anterior abdomen and in prevertebral region of lower lumbar vertebra.

R

Prevertebralregion

Iliac wingsGas in

intestines

Fig. 4-38. Dorsal decubitus—right lateral position.




4

Pathology DemonstratedAbnormal soft tissue masses, umbilical hernia, prevertebral region for possible aneurysms of aorta or calcifi cations. This projection may be performed for localization of foreign bodies.


lengthwise to table• Moving or stationary grid• 80 to 85 kV range• Lead blocker placed on tabletop behind

patient to reduce scatter• Technique and dose:

Shielding• Use gonadal shields on males.

Patient Position• Patient in lateral recumbent position on right or left side, pillow

for head• Elbows fl exed, arms up, knees and hips partially fl exed, pillow

between knees to maintain a lateral position

Part Position• Align midcoronal plane with CR and midline of table.• Ensure that pelvis and thorax are not rotated but are in a true

lateral position.

Central Ray• CR perpendicular to table, centered approximately 2 inches

(5 cm) above level of iliac crest to midcoronal plane• IR centered to CR• Minimum SID of 40 inches (100 cm)

Collimation Collimate closely to upper and lower IR borders and to anterior and posterior skin borders to minimize scatter.

Respiration Suspend breathing on expiration.

LATERAL POSITION: ABDOMEN

Abdomen

SPECIAL

• PA prone


• AP erect


• Lateral

35

43

Rcm kV mAs Sk. ML. Gon.

30 80 60 1040 85 M 3F 42

average size mrad


Structures Shown: • Diaphragm and as much of lower abdomen as possible should be included. • Air-fi lled loops of bowel in abdomen with soft tissue detail should be visible in prevertebral and anterior abdomen regions.Position: • No rotation as evident by superimposition of posterior ribs and posterior borders of iliac wings and bilateral ASIS.Collimation and CR: • Collimation borders to tissue margins of anterior and posterior abdomen. • Center of collimation fi eld (CR) to prevertebral region about 2 inches (5 cm) above level of iliac crest.Exposure Criteria: • No motion; rib and gas bubble margins appear sharp. • Lumbar vertebrae may appear about 50% underexposed with soft tissue detail visible in anterior abdomen and in prevertebral region of lower lumbar vertebra.

R

Prevertebralregion

Air inintestines

Fig. 4-41. Right lateral abdomen.




4

ACUTE ABDOMINAL SERIES: ACUTE ABDOMEN

Three-Way Abdomen: (1) AP Supine, (2) Erect (or Lateral Decubitus) Abdomen, (3) PA Chest

Departmental routine: Determine whether departmental protocol includes an erect PA chest as part of acute abdomen series routine. Minimum positions must include at least one erect or decubitus horizontal beam projection abdomen, in addition to AP supine.

Specifi c Clinical Indications for Acute Abdominal Series1. Ileus (nonmechanical small bowel obstruction) or mechanical

ileus (obstruction of bowel from hernia, adhesions, etc.)2. Ascites (abnormal fl uid accumulation in abdomen)3. Perforated hollow viscus (such as bowel or stomach, evident

by free intraperitoneal air)4. Intraabdominal mass (neoplasms—benign or malignant)5. Post-op (abdominal surgery)

Remember to take erect images fi rst if patient comes to the department in an erect position.

Image Receptor, Collimation, and Shielding 35 × 43 cm (14 × 17 inches), moving or stationary grids; collimation and shielding as described on preceding pages

Patient and Part Positioning Note that most department routines for the erect abdomen include centering high to demonstrate pos-sible free intraperitoneal air under the diaphragm even if a PA chest is included in the series.

Breathing Instructions Chest is taken on full inspiration; abdomen is taken on expiration.

Central Ray CR to level of iliac crest on supine and approximately 5 cm (2 inches) above level of crest to include diaphragm on erect or decubitus

Notes:• Left lateral decubitus replaces erect position if the patient is

too ill to stand.• Horizontal beam is necessary for visualization of air-fl uid

levels.• Erect PA chest or AP erect abdomen best visualizes free air

under diaphragm.• For decubitus, patient should be upright or on the side for a

minimum of 5 minutes before exposure, with 10 to 20 minutes preferred to demonstrate potential small amounts of intraperitoneal air.

Acute Abdomen (Three-Way)

BASIC

• AP supine

• AP erect

• PA chest

SPECIAL

• Left lateral decubitus

Fig. 4-44. AP supine.

Fig. 4-45. AP erect.

Fig. 4-46. Left lateral decubitus (special projection, if patient cannot stand for AP erect abdomen).

Fig. 4-47. PA chest erect.


4

RADIOGRAPHS FOR CRITIQUE

Each of the abdominal radiographs below demonstrates at least one repeatable error. These, as well as other radiographs for cri-tique, are available as part of the accompanying audiovisuals. Together, these tools provide a basis for classroom and/or position-ing lab discussion on radiographic critique.

See whether you can critique each of these four radiographs below based on the categories as described in the textbook and as outlined on the right. As a starting critique exercise, place a check in each category that demonstrates a repeatable error for that radiograph.

Answers are provided in Appendix B.

RADIOGRAPHS

A B C D

1. Structures shown ______ ______ ______ ______

2. Positioning ______ ______ ______ ______

3. Collimation and CR ______ ______ ______ ______

4. Exposure criteria ______ ______ ______ ______

5. Markers ______ ______ ______ ______

A B

SCOUTC

Erect

D

Fig. C4-48. Left lateral decubitus abdomen. Fig. C4-49. AP supine abdomen—KUB.

Fig. C4-50. AP supine abdomen—KUB. Fig. C4-51. AP erect abdomen.

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