General Abdominal Radiography Tony Pease, DVM, MS Assistant Professor of Radiology North Carolina State University

Objectives Acquisition of radiographs Abdominal radiographic anatomy Radiographic patterns of abdominal disease Determine normal compared to abnormal How ultrasound is helpful

Reading Chapters 38-40 Pages 483-539

Abdominal Radiography Generally being replaced with ultrasound Ultrasound does not give a global picture Radiographs are a snapshot of disease 1/120th of a second picture Ultrasound is real time

Abdominal Anatomy A lot of organs in a small space Rely on location

Acquiring radiographs Relatively high kVp (70 kVp) Moderate image contrast Some of shades of grey More than bone less than thorax Moderate mAs (8-12 mAs) Minimizes motion artifact Maximizes contrast Enemas and fasting are helpful

Positioning Include caudal thorax Try to include greater trochanter of femur Center beam just caudal to the last rib

Large patients May need two films per view Four films per study Make sure to overlap images

Ventrodorsal Liver Spleen Left Kidney Right Kidney Stomach and duodenum

Left lateral Esophagus Pylorus Duodenum Liver Spleen Left kidney Right kidney Urinary bladder

Right lateral Fundus Liver Spleen Left kidney Right kidney Urinary bladder

Normal cat abdomen

Deep circumflex iliac artery Sometimes confused for medial iliac lymph nodes or ureteral calculi

Positional radiographs Remember gas rises Can manipulate the animal

Can you see the gas?

Lateral horizontal beam

Horizontal beam Place the animal in left lateral Puts the fundus of the stomach down Smaller pylorus is high Gas accumulates near the diaphragm

Now time for the radiographs! Positioning – done Exposure – done Interpretation! Takes radiologists years to become experts You have 9 hours!

Quick word on abdominal masses Hard to tell what organ is involved Best guess based on location What organs are displaced May need ultrasound to be more specific

Some incidental findings Lucency on the ventral aspect of L3-4 Cholesterol granulomas Spondylosis deformans

Lack of ventral aspect of L4 It is where the diaphragm attaches

Cholesterol granuloma Generally in cats

Smooth bridging bone

Spaces of the abdomen Retroperitoneal Peritoneal Dorsal to the colon Contains kidneys, adrenal glands, lymph nodes Continuous with mediastinum Peritoneal Surrounds visceral organs Generally a potential space

Can compare spaces Retroperitoneal space Good detail Peritoneal space Poor detail

Loss of serosal detail Poor radiographic technique Fat content of a puppy or kitten Peritoneal fluid (many types) Carcinomatosis Lack of fat Peritonitis

Peritoneal fluid Soft tissue and fluid are similar opacity Ultrasound superior for peritoneal fluid Emaciation versus fluid Similar appearance Lack of fat to provide contrast Difference is overall size of abdomen

Peritoneal fluid Radiographs very insensitive for detecting Cannot tell fluid type Radiographs or ultrasound! Multiple causes Increased hydrostatic pressure Decreased plasma colloid oncotic pressure Capillary permeability

Mild Severe Severe

Lack of fat cause loss of detail

Is there peritoneal fluid?

Retroperitoneal space Only thing that is dorsal to the colon

Don’t forget that other view

Abdominal lymph nodes Many lymph nodes in abdomen Generally not seen radiographically Even if large Medial iliac lymph nodes are the exception Ultrasound more useful for lymph nodes

Medial iliac lymph nodes

Don’t forget about goats Can help diagnose caseous lymphadenitis

Pneumoretroperitoneum Retroperitoneum communicates with the mediastinum Therefore usually associated with: Subcutaneous emphysema Pneumomediastinum

Need large volume of gas Ruptured trachea Ruptured esophagus Need aerophagia

Pneumoretroperitoneum Not generally clinically important Just a sign of another disease

Even in the cow!

Pneumoperitoneum Can persist 10-14 days after surgery Rupture of a hollow viscus Gastrointestinal perforation Surgical emergency!! External puncture wound

Several places to look

What about large animal?

Foals, calves and pigs Can image abdomen Can do barium enemas Usually standing See fluid layers Can do barium enemas Strictures or atresia ani

Barium enema

Ileus

Traumatic reticuloperitonitis

Traumatic reticuloperitonitis

All about the belly in 1 hour! Radiographs helpful even if large animal Hard to tell where mass comes from Radiographs are a good overview

Questions?