Introduction to Abdominal Radiology Meghan Woodland, DVM

Indications Vomiting/Diarrhea Abdominal Pain Hematuria Abdominal Mass/Distension Tenesmus (Pain on Defecation)

Technical Factors Abdomen has low inherent contrast Collimation Lower kVp Higher mAs Collimation High amount of scatter Use grid (if patient is >10-11cm thick) Take exposure on expiration Multiple soft-tissue opacity structures surrounded by variable amounts of fat = low inherent contrast. Don’t want mAs too high because of diaphragm motion during respiration Use a grid when the patient is >10-11cm thick. No compression of abdominal organs when expiration.

Positioning VD and R lateral views Include from diaphragm to pelvic inlet Fore limbs pulled cranially Hind limbs pulled caudally Additional views as necessary Horizontal beam VD view = free abdominal gas. (L lateral recumbency) Obliques = renal contrast studies Butt shot = legs pulled forward, to evaluate for urethral calculi Large dogs = two films may be necessary. Ensure overlap of structures.

Sandbags, positioning aids. Radiographic techniques: the dog  By Joe P. Morgan, John Doval, Valerie Samii

Radiographic techniques: the dog  By Joe P. Morgan, John Doval, Valerie Samii

Improper positioning. Could miss a diaphragmatic hernia. Example of improper positioning. Should include entire diaphragm – could miss a diaphragmatic hernia in this case.

Unprepared abdomen – Owner can withhold food for 12-24 hours or can promote defecation (walking, enemas) Unprepared Abdomen

“Butt Shot” – Urethral Calculi

Interpretation of Abdominal Radiographs Liver Spleen Kidneys GIT (Stomach, SI, Cecum, LI) Bladder Prostate Extra-abdominal structures Structures normally seen

Structures Not Normally Seen Gall bladder Pancreas Adrenals Ovaries Uterus Ureters Lymph Nodes Mesentery Vasculature

Liver Lateral view: VD view: Caudo-ventral margin angular Should not extend beyond the costal arch Normal gastric axis parallel to ribs or perpendicular to spine VD view: Liver margins not well seen Long axis of stomach perpendicular to spine Normal gastric axis = a line drawn dorsal to ventral through the stomach in the lateral view)

Over-inflation of chest gives false appearance of enlarged liver Hyperinflation of chest – false appearance of liver enlargement

Spleen Size is subjective Lateral view: VD view: Tail of spleen visible, but position varies Not usually seen on this view in cats VD view: Head of the spleen is visualized Caudo-lateral to stomach fundus Cranio-lateral to left kidney Cats : often seen lying along the left body wall No set size parameters

Dog – Lateral View

Dog – VD View

Cat – Lateral View

Cat – VD View

Kidneys Right located cranial to left May be difficult to see in young or emaciated animals Size (only evaluated on VD view) Dogs: 2 ½ to 3 ½ times the length of L2 Cats: 2 to 3 times the length of L2 Lateral view = kidneys may be magnified 2.4-3

Right = renal fossa of the liver Dog – Lateral View

Dog – VD View Difficult to always visualize both kidneys.

Cat – Lateral View

Cat – VD View

Gastrointestinal Tract Stomach Caudal to liver Gastric Axis Less than 3 ICS wide on lateral view VD: Dog = U-shaped Cat = J-shaped U-shaped = crosses midline. Fundus is left and pylorus is right J-shaped = Left cranial abdomen, does not cross midline

Gastric Axis

“U-Shaped” Stomach Dog Dog – VD View

“J-Shaped” Stomach Cat Cat – VD View

Gastrointestinal Tract Small Intestine Size: Width less than 3 times the last rib Duodenum Fixed along the right side Extends caudally from the pyloric region of the stomach Jejunum/Ileum Position Varies Mid-ventral abdomen Small Intestine contains both air and fluid (Dogs have more gas than cats). Terminal ileum = L1-L3 in mid or dorsal abdomen

Gastrointestinal Tract Cecum Comma shaped Mid, right abdomen Not often seen in cats Large Intestine Ascending, transverse and descending colon Size: Width less than 5 times the last rib Dogs – cecum is ventral to L3 on lateral and to the right of midline on the VD. Cats – rarely contains gas therefore not visualized routinely. Ascending colon = extends cranially from the cecum to the right of midline. Transverse colon = crosses to the left of midline at approx. L1. Descending colon = Extends caudally to the left of midline until the pelvic inlet.

Cecum – VD View

Cecum – Lateral View

Megacolon in a Dog Descending colon Transverse Colon Ascending Colon

Transverse Colon Ascending Colon Descending colon Contrast Study

Bladder Size varies Dog: Cat: Oval to ellipsoid Caudal abdomen or pelvic Cat: Ellipsoid Always intra-abdominal (elongated bladder neck)

Bladder more pelvic Dog – Lateral View

Long Bladder Neck Cat – Lateral View

Prostate Intact males ++ Caudal to bladder Symmetrical with smooth margins Size: Lateral: Less than 70% of sacro-pubic distance VD: Less than 50% of pelvic inlet width Larger in intact or older male dogs. Not visualized in male cats.

Extra-Abdominal Structures Soft Tissues Bone (Spine, Pelvis, Hind limbs) Diaphragm Thorax (if visible)

Decreased Abdominal Detail Inability to distinguish organs Causes: Young Animals * Emaciated Animals Peritoneal Fluid Inflammation (Peritonitis, Pancreatitis) Carcinomatosis  Normal finding Contrast is due to fat, therefore decreased fat = decreased contrast Young animals = puppies and kittens less than 6-8 months of age

Emaciated Cat

Abdominal Fluid

Fun Slides How Many Babies?

Where is the foreign body?

What organs are mineralized?

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THE END!