GENERAL ABDOMINAL IMAGING PERITONEAL SPACE, PANCREAS, & SPLEEN

Transcription

1 GENERAL ABDOMINAL IMAGING PERITONEAL SPACE, PANCREAS, & SPLEEN VMB 960 March 25, 2013 REFERENCE Chapters Pages Chapter 37 Pages Chapter 3 Pages OBJECTIVES Radiography and Ultrasound of the Abdomen Peritoneal & Retroperitoneal Spaces Specific Organ Evaluation Pancreas Spleen Patterns of Disease Mass Lesions 1

2 NORMAL ABDOMEN NORMALLY NOT SEEN GB Adrenals Adrenals Pancreas Ureter Ureter GB *Don t forget lymph nodes!* Uterus Abnormal enlargement Mass effect on adjacent organs NORMAL CAT Same organ pattern Spleen smaller Often better serosal detail Increased fat 2

3 ULTRASOUND Pros (compared to Radiographs) Great for evaluating soft tissue changes Real-time imaging Cons Does not provide global picture Highly dependent on user The two modalities complement each other ULTRASOUND PHYSICS US probe emits sound waves into tissue US probe also listens for echoes Echo VOLUME (how loud?) Echo TIMING (how long? ULTRASOUND PHYSICS Acoustic Impedance Inherent property of a substance Determined by Physical Density Speed of Sound in the tissue Two tissues with large difference in AI Creates interface US waves are reflected (an echo) 3

4 ULTRASOUND PHYSICS Frequency Measured in MHz Range 1-18 MHz Lower Frequency Better Penetration Worse Resolution Higher Frequency Better Resolution Worse Penetration ULTRASOUND PHYSICS Multifrequency probes For canine abdomen Average size dog Use a 5-8 MHz probe Deep-chested/Large dog Use a 3-5 MHz probe For feline abdomen Can use MHz probe ULTRASOUND TERMINOLOGY Hyperechoic Hypoechoic Anechoic Isoechoic Relative comparison 4

5 SPACES OF THE ABDOMEN Retroperitoneal Dorsal to colon Kidneys, ureters, adrenal glands, lymph nodes Continuous with the mediastinum Peritoneal Surrounds visceral organs A potential space PERITONEAL SPACE Serosal detail Dependent on normal abdominal fat Poor serosal detail Poor radiographic technique Young animal Peritoneal fluid Emaciation (no fat) Peritonitis Carcinomatosis POOR SEROSAL DETAIL Young animals Less fat Brown fat Lack of fat Emaciation Chronic cachexia 5

6 POOR SEROSAL DETAIL Disease of the peritoneum Peritonitis Carcinomatosis POOR SEROSAL DETAIL Peritoneal effusion Often accompanies other problems (peritonitis) Fluid and soft tissue are the same opacity Radiographs less sensitive to detection vs. US US good to determine cause for loss of detail Fluid type cannot be specified For radiographs or US PERITONEAL FLUID Effusions Heart failure ( hydrostatic pressure) Hypoproteinemia ( colloid oncotic pressure) Capillary permeability (vasculitis) Inflammation Neoplasia Hemorrhage Urine Bile 6

7 PERITONEAL FLUID Wispy ST opacity in falciform fat POOR SEROSAL DETAIL Emaciation or fluid? CHOLESTEROL GRANULOMA Bates body Dystrophic calcification of necrotic mesenteric fat More common in cats 7

8 PNEUMOPERITONEUM Gas opacity in the peritoneal space Abdominal wall penetration Surgery Can persist days post-sx Trauma (puncture) Rupture of a hollow viscus (GI) SURGICAL EMERGENCY! PNEUMOPERITONEUM Sensitivity of ultrasound variable Tend to push superficial gas out of the way May detect if trapped Radiographs Large volumes outline the organs Look at liver and diaphragm/body wall PNEUMOPERITONEUM 8

9 POSITIONAL RADIOGRAPHY Remember Gas rises Manipulate the patient Manipulate the x-ray beam HORIZONTAL BEAM VD Right Left lateral recumbency to avoid gas in fundus Normal Right RETROPERITONEAL SPACE Pneumoretroperitoneum Retroperitoneal space is continuous with the mediastinum Rupture of trachea (or esophagus) 9

10 RETROPERITONEAL SPACE Dorsal to the colon Fluid, mass displaces colon ventrally RETROPERITONEAL MASS COLON POSITION Colon and SI subject to displacement with mass lesions However, they are also variable in normal position Must see a mass lesion also (increase in soft tissue opacity) 10

11 PANCREAS Dog Cat NORMAL PANCREAS - ULTRASOUND PANCREATIC ENLARGEMENT Caudal deviation of colon Lateral and/or ventral deviation of duodenum Silhouetting of greater curvature of stomach Evans. Miller s Anatomy of the Dog, 3 rd ed. Pancreatitis Peritonitis/fluid Persistent gas distension of the duodenum Often difficult to diagnose radiographically! 11

12 Normal Normal 12

13 PANCREATITIS - ULTRASOUND PANCREATITIS - ULTRASOUND CLASSIC APPEARANCE: Hypoechoic, enlarged pancreas Hyperechoic mesentery (inflamed fat) Peritoneal effusion Dilated pancreatic duct, bile duct obstruction SENSITIVITY: Pancreas can appear normal with pancreatitis Dogs US is a more reliable test, especially when acute About 2/3 cases detected Cats Less reliable, more often normal in appearance About 1/4 to 1/3 cases detected 13

14 SPLEEN Typically surrounded by fat Usually easily seen on rads Head on VD Tail on Lateral Not in cats Sedation effects Phenothiazine tranquilizers Anesthetic gases & barbituates SPLEEN Tail on lateral Head on VD SPLEEN Tail can be variable in position Head less mobile 14

15 SPLEEN Breed variants German Shepherd Dog, Retrievers, Sighthounds SPLENIC PATHOLOGY DIFFUSE (Splenomegaly) or FOCAL (Mass) Radiographs Diffuse changes and large focal disease Ultrasound Can better identify small parenchymal lesions Specificity of imaging changes are often nonspecific DIFFUSE SPLENOMEGALY Neoplasia Lymphoma Mast Cell Congestion Sedation Right heart failure Splenic Torsion IMHA Inflammation Infarction Hyperplasia Extramedullary hematopoiesis 15

16 FOCAL SPLENOMEGALY Neoplasia Hemangiosarcoma Hemangioma Lymphoma (less common appearance) Nodular Lymphoid Hyperplasia Hematoma Abscess FOCAL SPLENOMEGALY Head Tail 16

17 FOCAL SPLENIC MASS QUESTIONS? 17

18 General Abdominal Cases VMB 960 March 26, 2013 Additional Resources Index of NORMAL abdominal (and thoracic) radiographs logy Small animal ultrasound videos 7 Year old, MC, Golden Retriever Lethargy for 2 weeks Inappetant ADR Palpable mass in caudal abdomen Bloodwork normal 1

19 Mass Lesions Identify location At least 2 views Normal organs in that location Mass effect How are the organs around the mass affected? Are there clinical signs that can help narrow the differentials? 2

20 Retroperitoneal Mass Kidney Adrenal Ureter Lymph Nodes Other structures? Mass Lesions Common Differentials Cyst Hematoma Abscess Neoplasia Granuloma E Can all appear same on radiographs Ultrasound may help distinguish Fluid content Vascularity Margin Ultrasound Better assess character of the mass 3

21 Ultrasound May reveal associated lesions that would be missed with rads alone Normal 5 Year old, F, Bloodhound Working dog Presented for entropion repair Polyuria/Polydypsia Febrile Leukocytosis on preoperative bloodwork 4

22 Uterine enlargement Pyometra Mucometra Hydrometra Neoplasia Pregnancy Ultrasound 5

23 9 Year old, FS Labrador Retriever Acutely lethargic Panting Abdomen feels distended Pale mucous membranes 6

24 Peritoneal Fluid Effusions Transudates & Exudates Hemorrhage Urine Bile Radiographic Limitations Loss of serosal detail may obscure lesions Ultrasound What next? Surgery Consider your differentials Neoplasia? Metastatic disease evaluation Thoracic radiographs 7

25 Thoracic Radiographs 8 Year old, FS, Miniature Schnauzer Previous bouts of pancreatitis Now febrile, leukocytosis 8

26 Right Cranial Abdomen Liver Pancreas Stomach Duodenum Colon/Cecum Lymph nodes Evans. Miller s Anatomy of the Dog, 3 rd ed. Pancreatic Abscess A sequela to pancreatitis More common in dogs than cats Can be indistinguishable from a cyst More echogenic fluid content Regional inflammation Clinical signs 9

27 Pancreatic Abscess Pancreatic Cysts Pseudocysts Results from pancreatitis Secretions into areas of necrosis Retention Cysts Smaller Due to blockage of small ducts Congenital Cysts Often large, do not change over time Often associated with polycystic disease 10

28 11 Year old, FS Mixed breed dog FS, Mixed breed dog Suspect abdominal mass Inguinal region feels firm 11

29 Sublumbar Mass Medial iliac lymph nodes Periosteal reaction along caudal lumbar vertebrae increase suspicion of neoplasia Rectal exam! 7 Year-old, MC Sheltie PU/PD for 1 week Lethargic and anorexic Hypercalcemia on bloodwork 12

30 Splenic Ultrasound Normal spleen Hyperechoic Fine texture Uniform appearance Splenic lymphoma Can be variable in appearance 6 Month old, FS Maltese Lethargy & vomiting 3 days Slightly tender on abdominal palpation Bloodwork reveals leukopenia 13

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32 Pneumoperitoneum Surgery Penetrating abdominal trauma Gastrointestinal rupture Surgical emergency Case Management Was barium necessary? What test(s) might be more appropriate? Complications associated with barium in the peritoneal space? 15

33 Large Animal Can image horses, cows, etc. Radiographs made while patient standing Creates horizontal gas-fluid interfaces in bowel Often looking for abnormal opacity Mineral, metal Peritoneal gas 16

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