GI Imaging Flashcards
how are neurologic disorders of the pharynx diagnosed?
- more useful to eval using fluoroscopy
- contrast often necessary
describe dysphagia
- oral stage: involves tongue
- pharyngeal stage: bolus formation
- cricopharyngeal stage: synchronous opening of the upper esophageal sphincter
-cricopharyngeal dysphagia: disorder of the upper esophageal sphincter
describe the 3 main cricopharyngeal diseases
- chalasia: flaccid UES, wide open communication between the pharynx an d esophagus
- achalasia: inadequate relaxation of the cricopharyngeal muscle (barely opens); leads to a relative inability to swallow food or liquids
-pharynx contracts, but barely any of food bolus makes it to esophagus
-with contrast: see contraction of pharyngeal muscles but UES does not open - asynchrony: asynchronous contraction of the pharyngeal muscles and opening of the UES
-can cause regurgitation or food bolus can enter trachea
describe the normal anatomy of the esophagus
- small volume luminal gas can be seen; usually on left lateral
- can occasionally see caudal thoracic esophagus
-fluid filled, usually on left lateral
describe esophogram/esophagography
procedure:
1. plain radiographic exam
2. admin of positive contrast medium per os
3. serial radiographs or fluoroscopy even better
anatomic particularity in cats!
1. herringbone appearance of caudal half of thoracic esophagus
2. versus linear striations in dogs (through whole esophagus) and in the cranial half of cat esophagus
what are 4 common esophageal abnormalities?
- dilations: motility disorders, most common!
- foreign bodies
- strictures
- tumors (uncommon)
describe megaesophagus
- enlarged esophagus, NO etiology insinuated
- classification:
-diffuse dilation
-segmental/focal dilation: surgical!
describe diffuse megaesophagus (3)
- congenital
- acquired:
-inflammation: esophagitis, polymyositis/polyneuritis
-toxicity
-paraneoplastic: thymoma
-metabolic: hypothyroidism, myasthenia gravic
- will see ventral deviation of the trachea on rads!
-will see esophagus dilation dorsal to the ventrally deviated trachea
describe focal/segmental megaesophagus causes
- vascular ring anomalies
-PRAA: ligamentum arterious now dorsal to esophagus, causes extraluminal narrowing/squeezing of esophagus; will see increased fluid accumulation craniodorsal - acquired strictures
- extraluminal compression
- luminal masses: usually soft tissue opaque
-neoplasia uncommon
-abscess/granuloma: commonly caudodorsal
almost always cranial to the heart base! must see narrowing at heart base to diagnose as segmental!
describe hiatal hernias
3 types:
1. sliding hiatal hernia
-dynamic movement, may not see in all projections!
-can track gas inside esophagus as moves
-everything moves cranial and then moves caudal together
- paraesophageal hiatal hernia
- gastroesophageal intussusception
-stomach herniates next to the esophagus, causes many clinical issues!
all seen as soft tissue effect in the caudodorsal mediastinum
describe peritoneal detail
can visualize:
1. ventral liver/falciform fat
2. body wall
3. SI serosal margin
4. abdominal wall
5. urinary bladder
thanks to right amount of allowing us to visualize each structure without covering it up entirely
describe peritoneal detail in peritoneal disease
decreased! due to
- increased soft tissue/fluid opacity: fluid (urine, hemorrhage, ascites, neoplastic effusion) or mass effect
- decreased fat: emaciation or younger animal (<6 months of age)
- technique: underexposure
describe differentials for decreased peritoneal serosal detail due to increased soft tissue/fluid opacity
- hemorrhage:
-rupture of a solid orgam/tumor
-coagulopathies, DIC, warfarin toxicity - peritonitis: more focal
-pancreatitis
-bile peritonitis
-hollow viscous rupture - ascites:
-liver disease
-right heart failure
-protein losing enteropathy/nephropathy - uroabdomen: urinary bladder rupture
- neoplastic effusion: may see a nodular aspect (something more than effusion)
-lymphoma
-hemangiosarcoma
-carcinomatosis/sarcomatosis
-lymphomatosis (more heterogenous)
the more pure the effusion the more uniform the increase in soft tissue opacity
describe causes of increased serosal detail/pneumoperitoneum
pneumoperitoneum:
1. rupture of a hollow viscus (GI, uterus)
2. external penetrating wound
3. recent abdominal surgery: should resolve 9-25 days postop for uncomplicated enterotomy or enterectomy
-radiographic findings: round, triangular, or linear gas outside of the intestine
-technique:
1. if small volume: horizontal beam radiography! need to wait a few minutes to let gas accumulate at highest point
-left lateral VD view, gas adjacent to the non-dependent body wall
-dorsally recumbent lateral view: gas adjacent for falciform fat/xiphoid
describe intra-abdominal mineralization
- fat nodular necrosis/Bates Bodies
-round, smoothly marginated and well defined
-usually cats
-granulomatous mineralization
-incidental - metastatic/paraneoplastic
- altered calcium metabolism: abdominal vasculature
-cushings
-chronic uremia
-vitamin D toxicity
-hypothyroidism
describe mass effects
compress organs
- location: what organs are being displaced and in what direction
- typically have ill defines margins and are soft tissue opaque
- further divide into sections (craniodorsal, cranioventral, etc.) and decide what organs live in each section for your divisions
describe AFAST
- limited ultrasound exams
- focus on ID presence of fluid within the pleural space
- NOT intended to be comprehensive exam; subject to many technical limitations:
-operator skill level
-quality of available equipment
-often performed in suboptimal conditions (stressed patient, loud room, bright ambient lighting) - patient generally not shaved
- lateral recumbency is preferred:
-no difference in free fluid detection rates between patients in L versus R lateral recumbency
-but L lateral shown to be faster - 4 acoustic windows:
-DH: diaphragmatic-hepatic, can also assess gallbladder, pericardium/heart
-SR: splenorenal; left dorsal window, caudal to the 13th rib
-CC: cystocolic: transducer along midline, caudally; can see fluid outside versus within the urinary bladder
-HR: hepatorenal: toughest window to scan, esp in large dogs; transducer just caudal to the 13th rib, dorsally
describe radiographic interpretation of the liver
- changes are non-specific!
-normal radiographic or ultrasonographic appearance to liver does NOT rule out disease! - liver occupies at least 2 intercostal spaces
- has sharp caudoventral margins
- can mildly extend past the costal arch, altered by thoracic conformation
- gastric axis: useful indicator for changes in liver size
-lateral view- parallel to ribs
describe radiographic findings and ddx of hepatomegaly
- caudodorsal displacement of pylorus/gastric axis: weakest sign
- rounding of liver margins: strongest sign
- extends past the last ribs
-need 2 of these 3 signs to be considered hepatomegaly!
-exception: puppies! abdominal organs are proportionally larger than in adults
ddx:
-diffuse: neoplasia (lymphoma, mast cell tumor), endocrinopathies, nodular regeneration, inflammation, infection, congestion (R heart failure), cholestasis, storage disease, amyloidosis
-focal: cyst, hematoma, abscess, neoplasia (carcinoma), granuloma, pedunculated liver masses can be caudal to stomach
describe radiographic findings and ddx of microhepatica
- cranial angulation of pylorus/gastric axis
- decreased distance between stomach and diaphragm
ddx:
1. cirrhosis:
-small, irregular liver, with lobular margins!!
-ascites
- chronic hepatic disease
- portosystemic shunts
-may have urinary calculi, requires additional imaging to diagnose - diaphragmatic hernia:
-change in position
-trauma: diaphragmatic rupture
-congenital: peritoneal-pericardial diaphragmatic hernia
describe liver mineralization ddx (3)
- biliary duct calcification: linear, branching
- cholelith: in gallbladder
- hepatic parenchyma: neoplasia, granulomas, parasitic cysts
describe liver gas ddx
- emphysematous cholecystitis: associated with diabetes mellitus
- hepatic abscess
describe cholelithiasis
- hyperechoic focus with clean distal shadowing
- often incidental in dogs, but can cause biliary obstruction
describe stomach anatomy in dogs and cats
- includes cardia, fundus, body, antrum, and pylorus
- dog: pylorus is to the RIGHT of the midline and elongated
- cat: pylorus is ON the midline, U shaped
- appearance depends on content, volume, and patient position
-when empty: parallel to the ribs/intercostal spaces - need left AND right lateral projections to shift the gas inside the GI tract; air rises and could border efface or highlight abnormalities
-R lateral: gas accumulates in fundus and body
-L lateral: gas accumulates in antrum and pylorus
-DV: rarely done, better outlines the fundus
-VD: see more gas in the body, antrum, and pylorus
describe pyloric pseudomass
- NORMAL fluid filled pylorus on the right lateral projection
-to rule out abnormalities, do a left lateral projection bc gas rises!
describe some important considerations for gastric radiography
- negative findings are also important!
- surgical cases:
-GDV
-pyloric outflow obstruction
-small intestinal obstruction - projections:
- three or four!!
-if suspect 180 GDV though, ONLY take right lateral - fluid gas interface:
-border effacement: fluid/mucous and wall
-gas rising above fluid line can result in a false increase in wall thickness: contrast helps
-BE CAREFUL when eval for wall thickness vs. luminal content (air/fluid interface results in false mucosal thickening); once again, solution is contrast radiography and ultrasonography
describe gastric displacements
good for cranial abdominal mass effects
- cranial displacement could indicate:
-small liver
-diaphragmatic hernia/rupture
-mid abdominal mass: more like a compression of the stomach - caudal displacement:
-hepatomegaly: focal or diffuse
describe intraluminal gastric abnormalities
- ingesta is often present
-abnormal in vomiting animals and 8-12 hr post ingestion - normal content:
-soft tissue opacity with interspersed gas bubbles
-others: foreign bodies, medications, previous positive contrast study
-NOT all foreign bodies cause obstruction! - gastric foreign bodies
-difficult to ID if they are soft tissue opaque/radiolucent
-gastrogram, US, and CT can help
-REMEMBER: left lateral projection = gas in pylorus (could accumulate around the foreign body)
describe gastric dilation
- acute dilation
-aerophagia (gas)
-food bloat (soft tissue)
-mechanical ileus: obstructive foreign body (as in pyloric outflow obstruction)
-functional ileus: anticholinergic drugs, recent surgery, peritonitis/pancreatitis
describe gastric dilation with abnormal positioning” GDV
- acute onset of signs
-vomiting, retching, hypersalivation, abdominal distension, collapse
-SURGICAL EMERGENCY
-if animal not stable enough for rads, just go to sx (if stable though rads are best dx tool) - location of the pylorus is KEY to dx!!
-GDV vs gas dilation
-in GDV (180 degrees), pylorus is to the left and craniodorsally displaced
-seen in RIGHT lateral projection!!
-NOTE: 360 degree GDV; stomach is dilated but normally positioned! - radiographic signs:
-large gas distended stomach: more gas than fluid
-pylorus: craniodorsal and to the left
-double bubble or smurf hat sign
-compartmentalization line
- +/- splenomegaly: variable position
- +/- hypovolemic appearing thorax (small CdVC)
- +/- megaesophagous
- +/- secondary small intestinal dilation
- +/- gastric pneumatosis
describe 360 GDV
- rare! gastric dilation (gas)
- the stomach appears normally positioned but gastric tube cannot be passed!!
- usually also small caudal vena cava
describe pyloric outflow obstruction
- failure of gastric emptying
- enlarged (usually fluid filled) stomach with more formed contents within the pylorus/dudoenum
-left lateral projection super important for ID!! - causes:
-FB
-hypertrophic pyloric stenosis (US and contrast study)
-pyloric neoplasia
-fungal-like infection (pythiosis/swamp cancer)
-intussusception
describe intussusception
- types: gastroesophageal, gastro-gastric, gastroduodenal
- mass effect
- could cause mechanical obstruction (or not)
- target like appearance on US
-too many layers
-in young and older patients: idiopathic, parasitism vs neoplasia
