Abdominal radiology 腹部放射線學 台北醫學大學 - 市立萬芳醫院 留偉順 laowilson@hotmail.com
The Normal Abdominal Series Chest Supine abdomen Erect abdomen Left lateral decubitus abdomen
Learning objectives Understanding normal plain abdomen radiographs Understanding abnormal plain abdomen - Calcifications - Gas - Masses - Others
What to Examine l l l l Gas pattern Extraluminal air Soft tissue masses Calcifications
The Check List Bones and joints Calcifications Organs Fat Gas: In and outside of bowel
A memory aid First organs, bones, and stones, Then masses, fat, and gas. Don t forget the corner zones, And you ll always cover your subject
Abdominal Calcifications l l l Rimlike Linear or track-like walls of tubes such as ureter, arteries Lamellar gallstone, myoma
Rimlike Calcification Wall of a hollow viscus Cysts Renal cyst Aneurysms Aortic aneurysm Saccular organs e.g. GB Porcelain Gallbladder
AAA
AAA: CT
Renal Cyst Gallbladder Wall
Lamellar or Laminar l Formed in lumen of a hollow viscus n n n Renal stones Gallstones Bladder stones
Stone in Ureterocoele
Staghorn Calculi
Chronic Pancreatitis
Normal Gas Pattern Gas in the stomach. Some gas in the small bowel. Gas in the rectum and sigmoid.
Gas in stomach Gas in a few loops of small bowel Gas in rectum or sigmoid
Abnormal Gas Patterns l l Functional Ileus n n Localized (Sentinel Loops) Generalized adynamic ileus Mechanical Obstruction n n SBO LBO
Large vs. Small Bowel l l Large Bowel n n Peripheral Haustral markings don't extend from wall to wall Small Bowel n n Central Valvulae extend across lumen n Maximum diameter of 2"
Sentinel Loops Cholecystitis Pancreatitis Ulcer Appendicitis Diverticulitis
Air in Rectum or sigmoid Air in Small Bowel Air in Large Bowel Localized Ileus Yes 2-3 distended loops Air in rectum or sigmoid Generalized Ileus Yes Multiple distended loops Yes- Distended SBO No Multiple dilated loops No LBO No None-unless ileocecal valve incompetent Yes- Dilated
Small Bowel Obstruction: Causes Adhesions 80% Hernia 15% Tumors, intussusception, midgut volvulus, etc.
COLON Obstruction Causes Carcinoma of the colon 80% Volvulus 5% Diverticulitis 5% Fecal impaction 5% Others 5%
Small Bowel Obstruction: Findings Step-ladder dilated bowel loops on supine view Step-ladder air-fluid levels on erect/decubitus views String-of-pearls sign on erect/decubitus views
Small Bowel Obstruction, Supine
Air Filled Small Bowel
Supine Prone Sentinel Loops
String-of-Pearls Sign: Erect
Fluid Filled Small Bowel
LBO
Sigmoid Volulus:
Air in Biliary System Usually secondary to surgery on bile ducts Can be due to biliary-bowel fistula from infection or neoplasm Rarely, can be due to infection
Air in Gall Bladder
Air in Bile Ducts
PNEUMOPERITONEUM FREE AIR: Perforated Gut
Free Air Best views: Erect chest and left lateral decubitus abdomen Erect abdomen is less sensitive Supine abdomen is insensitive
Free Air: Left Lateral Decubitus Right side up, left side down Patient who can t sit or stand Air under right abdominal wall
Imaging findings Large collection of gas Abdominal distension, no gastric air-fluid level "Football sign" = large pneumoperitoneum outlining entire abdominal cavity "Double wall sign" = "Rigler sign" = air on both sides of bowel as intraluminal gas and free air outside (usually requires >1,000 ml of free intraperitoneal gas + intraperitoneal fluid) "Telltale triangle sign" = triangular air pocket between 3 loops of bowel "Inverted V sign" = outline of both lateral umbilical ligaments (containing inferior epigastric vessels) Outline of medial umbilical ligaments (obliterated umbilical arteries) "Urachus sign" = outline of middle umbilical ligament
Free Air: Erect Chest
Crescent sign Free Intraperitoneal Air
Free Intraperitoneal Air Air on both sides of bowel wall Rigler s Sign
Falciform Ligament Sign
Air in Lesser Sac
lateral umbilicus sign (arrow)
urachus sign
Falciform ligament sign
air in the Morison pouch
bowel relief sign (arrow).
Extraperitoneal Air
Pneumoretroperitoneum From perforation of posterior extraperitoneal portions of duodenum or colon Extension from or through the mediastinum
Pneumoretroperitoneum
Supine anteroposterior abdominal radiograph shows a calcified appendicolith (white arrows) in the right lower quadrant. The bowel gas pattern is nonspecific, with mildly dilated, air-filled small bowel loops in the right upper quadrant. The left psoas muscle margin (black arrows) is normal and distinct; the right psoas muscle margin is not seen.
Soft Tissue Masses l l Hepatosplenomegaly n Plain films poor for judging liver size Tumor or cyst n Bowel displacement
Splenomegaly
Body Packer
Bladder Outlet Obstruction pre- and post- cath
Right Renal Cyst
Foreign Body: Battery
Free Peritoneal Fluid- Bladder Ears
Atherosclerosis Calcification Vas Deferens
Nephrocalcinosis Myomatous Uterus
Supine Erect Generalized Adynamic Ileus
Summary Abdominal Series Abdominal Calcifications Normal and Abnormal Gas Patterns Large vs. Small Bowel Soft Tissue Masses