RAD 112_Abdomen Radiography & Anatomy

KUB

Kidneys, Ureters, Bladder - common AP supine abdominal projection.

AP

Anteroposterior - beam enters anterior, exits posterior.

PA

Posteroanterior - beam enters posterior, exits anterior.

SID

Source-to-Image Distance - standard = 40 inches (102 cm).

SBO

Small Bowel Obstruction - dilated bowel loops with air-fluid levels.

AAA

Abdominal Aortic Aneurysm - dilation of abdominal aorta.

Xiphoid process vertebral level

T9-T10.

Lower costal margin vertebral level

L2-L3.

Iliac crest vertebral level

L4-L5.

ASIS vertebral level

S1-S2.

Symphysis pubis vertebral level

Inferior margin of abdomen.

Greater trochanter landmark

Level of the symphysis pubis.

Ischial tuberosity landmark

Most inferior pelvis - positioning when prone.

CR landmark for KUB

Iliac crest (L4-L5).

4 quadrants of the abdomen

RUQ, LUQ, RLQ, LLQ.

9 regions of the abdomen

Right hypochondriac, epigastric, left hypochondriac; right lumbar, umbilical, left lumbar; right iliac, hypogastric, left iliac.

Largest solid organ in abdomen

Liver (RUQ).

Organ that stores bile

Gallbladder (RUQ).

Quadrant containing appendix

RLQ.

Organ that produces insulin and enzymes

Pancreas - retroperitoneal.

Organ that filters blood, recycles RBCs

Spleen - LUQ.

Kidneys classification

Retroperitoneal organs.

Kidneys vertebral levels

T12-L3, right lower than left.

Peritoneum

Double-walled serous membrane of abdomen.

Parietal vs visceral peritoneum

Parietal = cavity wall, Visceral = organ covering.

Mesentery

Double fold of peritoneum supporting intestines.

Omentum

Peritoneal fold from stomach; greater covers intestines, lesser connects to liver.

Intraperitoneal organs

Stomach, liver, gallbladder, intestines, ovaries.

Retroperitoneal organs

Kidneys, ureters, pancreas, adrenals, duodenum, ascending/descending colon, aorta, IVC.

Infraperitoneal organs

Rectum, bladder, reproductive organs.

Routine acute abdominal series

AP supine (KUB), AP erect abdomen, PA chest.

Purpose of acute abdominal series

Detect obstruction, free air, air-fluid levels.

CR location for AP supine (KUB)

Perpendicular at iliac crest (L4-L5).

CR for AP erect abdomen

2 inches above iliac crest - include diaphragm.

Why include diaphragm on erect abdomen

To show free air (pneumoperitoneum).

How long upright before erect abdomen

5 min minimum, 10-20 preferred.

Preferred projection if patient cannot stand

Left lateral decubitus abdomen.

Why left decubitus instead of right

Shows free air against liver, not gastric bubble.

CR for left lateral decubitus

2 inches above iliac crest - include diaphragm.

CR for dorsal decubitus abdomen

Horizontal beam, 2 inches above iliac crest.

Purpose of dorsal decubitus abdomen

Shows aneurysms, calcifications, masses.

Projection best for prevertebral space/calcifications

Lateral abdomen.

Most common cassette size for abdomen

14 × 17 inches.

IR orientation for abdomen

Lengthwise, crosswise for broad patients.

SID for abdomen

40 inches.

Breathing instructions for abdomen

Expose on expiration.

Why is KUB most common

Shows kidneys, ureters, bladder.

Structures to include on KUB

Symphysis pubis, kidneys, psoas margins.

Structures to include on erect abdomen

Diaphragm and as much abdomen as possible.

Primary clinical reason for erect abdomen

Air-fluid levels and free air.

ascites

Fluid accumulation in peritoneal cavity.

Appearance of ascites

Hazy density, bowel loops separated.

ileus

Failure of peristalsis - mechanical or paralytic.

Mechanical ileus appearance

Dilated bowel loops, multiple air-fluid levels.

Paralytic ileus appearance

Entire bowel dilated, no peristalsis.

intussusception

Telescoping bowel into itself.

Intussusception radiographic sign

Coiled spring sign, obstruction.

volvulus

Twisting of bowel loop, obstruction.

Volvulus appearance

Large air-filled loop, 'coffee bean' sign.

pneumoperitoneum

Free air under diaphragm (perforation).

Crohn's disease

Chronic inflammatory bowel disease, often terminal ileum.

Crohn's radiographic appearance

String sign, cobblestone mucosa, narrowing.

ulcerative colitis

Chronic colon inflammation, risk of toxic megacolon.

Ulcerative colitis radiographic appearance

Lead pipe colon - no haustra.

diverticulosis

Outpouchings (diverticula) in colon wall.

diverticulitis

Inflammation of diverticula, possible perforation.

cholelithiasis

Gallstones in gallbladder.

cholecystitis

Inflammation of gallbladder.

urolithiasis

Urinary stones (renal calculi).

Appearance of renal calculi

Radiopaque densities, sometimes radiolucent.

hydronephrosis

Dilation of renal pelvis/calyces due to obstruction.

nephroptosis

Kidney drops lower when upright.

horseshoe kidney

Congenital fusion of kidneys at lower poles.

polycystic kidney disease

Genetic disorder with multiple kidney cysts.

hepatomegaly

Enlarged liver.

splenomegaly

Enlarged spleen.

hepatitis

Liver inflammation (viral).

cirrhosis

Chronic liver scarring/nodules.

pancreatitis

Inflammation of pancreas, may calcify.

ascariasis

Roundworm infestation of intestines.

abdominal X-ray before contrast

Check for obstruction, calcifications, free air.

contrast used for GI tract

Barium sulfate (unless perforation suspected).

avoid barium if perforation suspected

May cause peritonitis if it leaks.

alternative contrast used

Water-soluble iodine (Gastrografin).

IVU

Intravenous Urogram - kidneys, ureters, bladder with contrast.

retrograde urography

Contrast injected into ureters via cystoscope.

barium enema (BE)

Contrast study of large intestine.

double-contrast BE

Barium + air for mucosal detail.

small bowel follow-through

Timed series of small intestine after barium.

ERCP

Endoscopic Retrograde Cholangiopancreatography - evaluates biliary/pancreatic ducts.

Exposure factors for abdomen

70-85 kVp, short time, enough mAs.

lower kVp than chest

Higher contrast needed for soft tissues.

grid used

Reduces scatter, improves contrast.

breathing instruction for abdomen

Expose on expiration.

minimum views for obstruction series

Two - supine and erect (or decubitus).

scout film

Preliminary image before contrast study.

include diaphragm on erect abdomen

Detect free air beneath it.

include symphysis pubis on KUB

To include bladder.

psoas muscles

Muscles located along the spine, important for posture.

CR for lateral abdomen

At iliac crest or 2 inches above if diaphragm needed.