1. University Hospitals Case Medical Center Department of Radiology

2.  The gas pattern  Extraluminal Air  Calcifications  Soft – tissue mass

4.  Source  swallowed air (majority)  bacterial fermentation from food  Normal Gas Pattern OrganGas normallyAir-Fluid Levels StomachYes Small bowelYes, 1-2 loopsYes Large bowelYes, rectosigmoidNo

6.  Normal - Small bowel versus Large bowel Small bowelLarge bowel Centrally locatedPeripherally located Valvulae extend across lumenHaustral markings do not extend across the large bowel Valvulae are spaced close togetherHaustral markings are more widely spaced Normal diameter up to 3cmNormal diameter – 6cm (9cm cecum)

7. SMALL BOWEL LARGE BOWEL

8.  Localized Ileus  Focal irritation of loop(s) of bowel – adjacent inflammation  Causes – cholecystitis, pancreatitis, appendicitis, diverticulitis  Adynamic Ileus  Entire bowel is aperistaltic or hypoperistaltic  Cause - Postoperative Ileus – abdominal surgery  Mechanical Small Bowel Obstruction  Causes  Postsurgical Adhesions – most common  Malignancy – gastric, colon, ovarian  Hernia – inguinal  Gallstone ileus  Intussusception – Ileocolic (most common)  Inflammatory bowel disease

9.  Localized Ileus - Signs  1 or 2 persistently dilated loops of small bowel (>3cm)  Air-fluid levels  Usually gas in the rectum and/or sigmoid colon This patient had underlying acute pancreatitis

10.  Adynamic Ileus (signs)  Diffuse small and large bowel dilitation  Air-fluid levels  Usually gas in the rectum and/or sigmoid colon Post-op Day 1

11.  Mechanical Small Bowel Obstruction (signs)  Multiple dilated loops of small bowel (step-ladder)  Numerous Air-Fluid Levels  Decompressed distal small bowel, No gas in rectum

12.  Mechanical Small Bowel Obstruction (signs)

15.  Locations  Intrapeitoneal (pneumoperitoneum)  Retroperitoneal  Air in the bowel wall (pneumatosis intestinalis)  Air in the biliary tree (pneumobilia)

16.  Intrapeitoneal (pneumoperitoneum)  Causes - rupture of air-containing structure  Perforated peptic ulcer  Trauma  Perforated diverticulitis/appendicitis  Perforation of carcinoma  Post-operative (5-7 days)  Signs  Crescentic lucency beneath the diaphram  Rigler’s Sign – Air on both sides of the bowel wall  Football Sign - Visualization of falciform ligament

17.  Intraperitoneal Air (Pneumoperitoneum)  Crescentic lucency beneath the diaphram

18.  Intraperitoneal Air (Pneumoperitoneum)  Rigler’s Sign – Air on both sides of the bowel wall

19.  Intraperitoneal Air (Pneumoperitoneum)  Football sign - Visualization of falciform ligament

21.  Retroperitoneal  Causes  Rupture of bowel (e.g. ruptured appendicitis or UC)  Trauma – blunt or penetrating  Iatrogenic manipulation – surgery or colonoscopy  Foreign body – causing perforation  Gas-producing infection – perforated diverticulitis

22.  Retroperitoneal - Signs  Streaky, linear appearance outlining extraperitoneal structures (e.g. psoas muscle, kidneys, bladder, aorta, IVC)  Mottled, blotchy appearance – remain in a fixed position

23.  Air in the bowel wall (pneumatosis intestinalis)  Causes  Primary form – pneumatosis cystoides  Left colon – cyst-like collections of air – submucosa/serosa  Secondary form – obstructive and necrotizing disease  Chronic obstructive pulmonary disease  Necrosis of bowel  Necrotizing enterocolitis – infants  Ischemic bowel - adults  Obstructing lesions of the bowel  Hirshsprung’s disease/Pyloric stenosis – children  Obstructing carcinoma - adults

24.  Air in the bowel wall (pneumatosis intestinalis)  Signs  Linear radiolucency paralleling the contour of air in the adjacent bowel lumen

25.  Air in the bowel wall (pneumatosis intestinalis)  Signs  Mottled appearance  resembles air mixed with fecal material

27.  Air in the biliary tree (pneumobilia)  Causes  Incompetent sphincter of Oddi  Prior Sphincterotomy  Prior surgery – reimplantation of the common bile duct  Gallstone ileus  Gallstone erodes through the wall of the gallbladder into the duodenum – forms a fistula between the bowel and biliary system  Gas-forming pyogenic cholangitis

28.  Air in the biliary tree (pneumobilia)  Signs  Tube-like, branching lucencies in the right upper quadrant – overlying the liver  Air in the wall of the gallbladder

30.  Two normal calcifications  Phleboliths  Rib cartilage calcifications

31.  Two normal calcifications  Phleboliths  Small, round calcifications – calcified venous thrombi  Most common in the pelvic veins  Women > men

32.  Two normal calcifications  Rib cartilage calcifications  Amorphous, speckled – along arc of the rib  Occurs with increasing age  Can be confused for biliary or renal calculi

33.  Abnormal calcifications – 4 patterns  Rimlike  Linear/Track-like  Lamellar (Laminar)  Cloudlike, amorphous, popcorn

34.  Abnormal calcifications  Rimlike  Calcifications in the wall of a hollow viscus Procelain GallbladderAtherosclerosis

35.  Abnormal calcifications  Linear/Track-like  Calcifications in the wall of tubular structures Splenic Artery Calc Vas Deferens Calcs

36.  Abnormal calcifications  Lamellar (Laminar)  Calcifications that form inside a hollow lumen Renal CalculiGallstones

37.  Abnormal calcifications  Cloudlike, amorphous, popcorn  Calcification inside a solid organ or tumor Chronic Pancreatitis Uterine Fibroids

39.  Limited evaluation of soft tissue densities  Soft tissue densities are surrounded by other soft tissue or fluid of similar density  Can only detect differences in density  Will show that structures outline

40.  Detecting soft tissue masses/organs  Direct visualization of edges  Indirect evidence of mass – pathologic displacement of air-filled loops of bowel DIRECT VISUALIZATION INDIRECT VISUALIZATION

44.  The gas pattern  Extraluminal Air  Calcifications  Soft – tissue mass

45.  Questions?  Please read the supplemental article on right lower quadrant abdominal pain  Abdomen quiz will be administered on Thursday at 11:30AM before conference