Download Introduction to Abdominal Radiology

Introduction to Abdominal
Radiology
Dr. LeeAnn Pack
Dipl. ACVR
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)
Indications
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Vomiting
Abdominal pain
Hematuria
Pain on defecation
Abdominal mass
Pendulous fluid filled abdomen
Many many more
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!
Normal Abdomen
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
Structures Normally Seen
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Liver
Spleen
Kidneys
Stomach
Duodenum
Small Intestine
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Cecum
Colon
Bladder
Prostate
Retroperitoneal fat
Structures Not Normally Seen
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Gall bladder
Pancreas
Adrenals
Ovaries
Uterus
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Ureters
Lymph nodes
Mesentery
Vasculature
Radiography of the Liver
• Liver size
– Normal
– Increased
– Decreased
• Liver opacity
– Increased
– decreased
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
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
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
Hepatomegaly
• Generalized with
smooth margins
– Cushing’s
– Fatty infiltration
• Diabetes Mellitus
• Hepatic lipidosis
– Passive congestion
• RHF
– Neoplasia
• LSA
– Inflammation, cholestasis
Hepatomegaly
• General enlargement lumpy margins
– Malignant neoplasia
– Nodular hyperplasia
• Focal enlargement
– Neoplasia
– Nodular hyperplasia
– Cysts, abscesses
Microhepatia
• Stomach shifted cranially – especially
pylorus
– May be functionally normal
– Portosystemic shunt
– Hepatic fibrosis
Changes in Liver Opacity
• Increased
– Mineralization
– Biliary – choleliths
– Parenchymal
• Parasitic cysts
• Granulomatous ds
• neoplasia
• Decreased
– Gas
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
Splenomegaly
• Normal shape, smooth margins
– Drug induced
• Sedatives, anx
– Diffuse infiltrative process
• LSA, HSA
– Vascular stasis
– Splenic torsion
Splenomegaly
• Focal enlargement
– Hematoma
– Nodular hyperplasia
– Neoplasia
• Hemangiosarcoma
• Hemangioma
Splenic Masses
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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
Kidneys
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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
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
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
Stomach
• Dog – crosses from
left to right
• Cat – from left to
midline
Which one is Left? Right?
Small Intestine
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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
VD Abdomen
Small Intestine Obstruction
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
Colon
Urinary Bladder
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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
Urinary Bladder
• Change in Opacity
• Mineral
– Cystic calculi
• Air
– Emphysematous
cystitis
– Iatrogenic
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)
Prostate
• Enlargement
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Hypertrophy
Neoplasia
Prostatitis
Abscess
• Paraprostatic cysts
• Mineralization
Prostatic Adenocarcinoma
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
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)
Reproductive System
• Uterine enlargement
– Metra’s
– Gravid uterus
• Ovarian
enlargement
– Neoplasia
• Enlarged retained
testicle
– neoplasia
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
Enlarged Medial Iliac LN
• Lymphosarcoma
– Most common
• Metastasis from neoplasia in the pelvis
canal or further caudally
– Prostate
– Perineal tumors
Loss of Intra-abdominal Detail
• AKA – loss of serosal surface detail
• Causes:
– Lack of Fat
• Young
• Emaciated
– Peritoneal fluid
– Pancreatitis, Peritonitis
– Carcinomatosis
Thin and Young
Decreased Serosal Surface
Detail
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
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
Free Peritoneal Air