Introduction to Abdominal Radiology

1. Introduction to Abdominal Radiology Dr. LeeAnn Pack Dipl. ACVR

2. Abdominal Radiography Abdominal Preparation Withhold food for 12-24 hours as needed Give enema 2-3 hours before study Exceptions Critically ill Suspect obstruction (acute abdomen)

3. Indications Vomiting Abdominal pain Hematuria Pain on defecation Abdominal mass Pendulous fluid filled abdomen Many many more

4. Abdominal Imaging Technique VD and lateral views Positioning Include from the diaphragm to the pelvic inlet Femurs are placed perpendicular to the spine Hind legs pulled forward for “butt shot” Exposure is made on expiration Collimate to decrease scatter!

5. Normal Abdomen

6. Technical Factors - Abdomen The image should be made dark enough to penetrate the liver The abdomen has a low inherent contrast Use lower kVp technique and higher mAs A grid should be used to decrease scatter

7. Structures Normally Seen Liver Spleen Kidneys Stomach Duodenum Small Intestine Cecum Colon Bladder Prostate Retroperitoneal fat

8. Structures Not Normally Seen Gall bladder Pancreas Adrenals Ovaries Uterus Ureters Lymph nodes Mesentery Vasculature

9. Radiography of the Liver Liver size Normal Increased Decreased Liver opacity Increased decreased

10. Normal Liver Lateral View Caudoventral margin extends to or slightly caudal to the costal arch Long axis of the stomach should be parallel to the ribs or perpendicular to the spine

11. Normal Liver VD View Long axis of the stomach is perpendicular to the spine Caudal margins of the liver are difficult to visualize on this view

12. Hepatomegaly Caudoventral margin projects caudal to costal arch Liver margins may be rounded Pylorus is displaced caudodorsally and to the left Change in long axis of stomach

13. Hepatomegaly Generalized with smooth margins Cushing’s Fatty infiltration Diabetes Mellitus Hepatic lipidosis Passive congestion RHF Neoplasia LSA Inflammation, cholestasis

14. Hepatomegaly General enlargement lumpy margins Malignant neoplasia Nodular hyperplasia Focal enlargement Neoplasia Nodular hyperplasia Cysts, abscesses

15. Microhepatia Stomach shifted cranially – especially pylorus May be functionally normal Portosystemic shunt Hepatic fibrosis

16. Changes in Liver Opacity Increased Mineralization Biliary – choleliths Parenchymal Parasitic cysts Granulomatous ds neoplasia Decreased Gas

17. Spleen On the VD view the head of the spleen is seen caudolateral to the stomach fundus craniolateral to the left kidney The position of the tail varies More often seen on right lateral In cats seen “laying along left side” sometimes on VD Not seen routinely on lateral

18. Splenomegaly Normal shape, smooth margins Drug induced Sedatives, anx Diffuse infiltrative process LSA, HSA Vascular stasis Splenic torsion

19. Splenomegaly Focal enlargement Hematoma Nodular hyperplasia Neoplasia Hemangiosarcoma Hemangioma

20. Splenic Masses May occur in the head, body or tail Located mid abdomen, left or right May be very large Can cause abdominal organ displacement Can displace stomach cranially and small intestines in various direction depending on location

21. Kidneys Right located more cranial than left Dogs = 2½-3½ * L2 on VD Cats = 2.4-3 * L2 on VD Size should only be evaluated on the VD view due to magnification on the lateral IV contrast can be used if necessary

22. Kidneys Increase in size Acute inflammation Infiltrative process LSA Decrease in size Hypoplasia Fibrosis Renal failure Mineralization – look a kids on both views Focal change in shape ACA

23. Stomach Caudal to liver Axis parallel to ribs Change in size, shape, mineralized, rugal fold abnormal Right vs. Left lateral (air/fluid) Foreign bodies, outflow obstruction

24. Stomach Dog – crosses from left to right Cat – from left to midline

25. Which one is Left? Right?

26. Small Intestine Duodenum – fixed along right side Jejunum and ileum – position varies Normal width = < 3* last rib width Contains both air and fluid Can not determine wall thickness Peyer’s patches, string of pearls

27. VD Abdomen

28. Small Intestine Obstruction

29. Cecum and Colon Cecum mid right abdomen Comma shaped –may contain air Not often seen in cats Colon Ascending, Transverse, Descending Normal width = < 5 * last rib width

30. Colon

31. Urinary Bladder Dog – caudal abdomen or pelvic Cat – always intra-abdominal Vary in size (empty to very distended) Bladder wall changes can not be determined on radiographs

32. Urinary Bladder Change in Opacity Mineral Cystic calculi Air Emphysematous cystitis Iatrogenic

33. Prostate Usually well visualized in intact males Should be symmetrical with smooth margins Enlarged if > 50% of pelvis inlet width (VD) >70% of sacro-pubic distance (lateral)

34. Prostate Enlargement Hypertrophy Neoplasia Prostatitis Abscess Paraprostatic cysts Mineralization

35. Prostatic Adenocarcinoma

36. Pancreatitis The pancreas is not normally seen Increased density and decreased serosal detail in the right cranial quadrant Duodenum may be persistently distended with gas (sentinel sign) Duodenum can be pushed to the right and pyloroduodenal angle is increased

37. Adrenal Glands Seen only when enlarged or mineralized Enlargement Pheochromocytoma Cortical carcinoma Adenoma Adrenal mineralization Dystrophic mineralization of tumors Mineralization of non neoplastic adrenals (cats)

38. Reproductive System Uterine enlargement Metra’s Gravid uterus Ovarian enlargement Neoplasia Enlarged retained testicle neoplasia

39. Enlarged Lymph Nodes Medial iliac (sublumbar) Increased opacity (soft tissue) seen in caudal abdomen ventral to caudal lumbar spine May displace colon ventrally Mesenteric LNN rarely large enough for radiographic detection US is best to evaluate for LAN

40. Enlarged Medial Iliac LN Lymphosarcoma Most common Metastasis from neoplasia in the pelvis canal or further caudally Prostate Perineal tumors

41. Loss of Intra-abdominal Detail AKA – loss of serosal surface detail Causes: Lack of Fat Young Emaciated Peritoneal fluid Pancreatitis, Peritonitis Carcinomatosis

42. Thin and Young

43. Decreased Serosal Surface Detail

44. Free Intra-Peritoneal Gas Penetration of the abdominal wall Surgery (common) Penetrating wounds bullets Bowel perforation Obstruction GI ulcer rupture Large mounts may persist for days or weeks

45. Free Intra-Peritoneal Air Horizontal beam radiography – to detect small volumes of air Lateral view with dog in dorsal recumbency, cranial aspect elevated Air collects under the diaphragm VD view with dog in left lateral recumbency Air up against the liver instead of fundus

46. Free Peritoneal Air