Page 22 Flashcards
Most dependent portion of the abdominal cavity in a supine px
Morison pouch (right hepatorenal fossa/ right posterior subhepatic space)
Most dependent portion of the peritoneal cavity in the upright patient
Pelvis
The lesser sac communicates with the greater sac through?
Foramen of Winslow
Most dependent portion of the peritoneal cavity
Cul-de-sac
Left subphrenic space and left subhepatic space communicate freely but separated from
right subphrenic space by?
Falciform ligament
Right subphrenic and subhepatic spaces communicate freely with the pelvic peritoneal cavity via?
Right paracolic gutter
Left subphrenic/subhepatic space separated from left paracolic gutter by?
Phrenicocolic ligament
This is the remnant of the obliterated umbilical VEIN
Ligamentum teres
Xray dx of ascites requires how many __ml of fluid to be seen?
500ml
Xray technique/position most sensitive for free air
Upright chest xray
Pseudomyxoma peritonei may result from?
1) Rupture of appendiceal mucocele 2) intraperitoneal spread of of benign or mucinous cysts of the ovary 3) mucinous adeno CA of the colon/rectum
Popcorn calcification
Uterine leiyomyoma
What are the signs of pneumoperitoneum on supine radiograph?
1) Rigler sign - gas on both sides of bowel wall; 2) gas outlining the falciform ligament, 3) football sign - gas outlining peritoneal cavity, 4) triangual or linear localized extraluminal gas in the RUQ
Post-operative pneumoperitoneum resolves in how many days?
3-4 days
Rice-grain calcifications
Cysticercosis in muscles
Tooth-like/bone calcification
Benign cystic teratoma
Post-operative ileus resolves in how many days?
4-7 days
Dilated bowels
small bowel >2.5-3 days; colon >5 cm; cecum >8 cm
Air-fluid levels
normal = stomach; often = small bowel; NEVER = colon distal to hepatic flexure
How many hours before radiograph can confirm the presence of bowel obstruction?
6-12 hrs
What is the most striking finding of toxic megacolon?
dilatation of transverse colon up to 15 cm
What is the imaging method of choic to confirm small bowel obstruction?
CT (small bowel feces sign)
What is the most specific sign for strangulation obstruction?
lack of enhancement of the bowel wall
Low-density nodal metastases are commonly seen with
Nonseminomatous testicular ca, TB, and lymphoma (occasionally)
Upper limits of normal lymph node size
6mm = retrocrural and porta hepatis; 8mm = gastrohepatic ligament; 10mm = retroperitoneal, celiac and SMA, pancreaticoduodenal, perisplenic, and mesenteric; 15mm = pelvic
What is the hallmark of retroperitoneal fibrosis?
smooth extrinsic narrowing of one or both ureters in the region of L4-L5
Portal venous flow may be altered by?
1) portal blockade by tumor or thrombus, 2) extrinsic compression by ribs or diaphragmatic slips, or tumors on the liver capsule, 3) third inflow from systemic veins - pericholecystic, parabiliary, and epigastric-paraumbilical venous systems
How to differentiate lymphoma from retroperitoneal fibrosis?
Lymphoma extends behind the vessels and displaces them anteriorly, retroperitoneal fibrosis does not
Hepatic arterial flow may be increased by?
1) focal hypervascular lesion, 2) inflammation of adjacent organs (cholecystitis, pancreatitis), 3) aberrant hepatic arterial supply
What is the primary role of imaging patients with chronic hepatitis?
to detect HCC
Diffentiation b/w regenerative and dysplastic nodules
regenerative (no atypia)/low grade nodules (minimal atypia)- portal venous supply = NO arterial enhancement; High grade dysplastic (moderate atypia)- hepatic artery supply = SHOW arterial enhancement, PREMALIGNANT, secrete AFP
How to differentiate HCC from other arterially enhancing lesions (pseudolesion, THAD)?
On delayed imaging, HCC becomes hypointense to surrounding liver, whereas other non-specific lesions are isointense
How to differentiate acute from chronic fibrosis of the liver?
On T1 = hypointense to liver (both); T2 = HIGH due to increase fluid content (acute), T2 LOW (Chronic)
Differentiation b/w dysplastic nodule and small HCC
Dysplastic nodules are almost NEVER hyperintense on T2W compared with HCC
What is the hepatic parenchymal attenuation to suggest hemochromatosis?
> 72 HU
Causes of T1 HYPERintensity in focal liver lesions
fat deposits, blood, pretein, copper, melanin, contrast, ghosting artifact, iron, and edema
How to differentiate portal venous gas vs pneumobilia?
Gas in portal vein extending to liver capsule, while in pneumobilia gas is more central and does not extend to 2 cm of the the liver capsule
Long standing hemochromatosis patients are at risk for?
cirrhosis, HCC, and colorectal ca
Where can you find pseudocirrhosis?
HHT
Causes of T2 HYPOintensity in focal liver lesions
fibrous capsule (HCC, hep adenoma, FNH); fibrous central scar (FNH, fibrolamellar hepatocellular ca)
Hallmark finding in HCC
heterogeneous arterial enhancement with rapis wash out of contrast on venous phase; hypointense on delayed phase
What are the fat containing lesions in the liver?
Hepatic adenoma, HCC, focal fatty deposition, lipoma, teratoma, liposarcoma, postop packing material (omentum), and foacl intrahepatic extramedullary hematopoiesis
How to differentiate HCC from regenerative or dysplastic nodules?
Hypointense on delayed postcontrast phase a feature of HCC, not seen with regenerative or dysplastic nodules on MR
What is Peliosis hepatis?
rare, assoc with chronic wasting from cancer or TB; cystic dilatation of hepatic sinusoids and multiple small blood-filled spaces
How to differentiate amebic from pyogenic abscess?
indistinguishable by imaging; diff is made by history, serology, or aspiration; amebic = most RIGHT lobe with elevation of R hemidiaphragm
What is the normal size of intrahepatic ducts?
does not exceed 40% of diameter of adjacent portal vein, or 2mm in central liver, or 1.8mm in peripheral liver
What is the normal size of extrahepatic ducts?
not exceed 6-7mm in internal diameter
Difference between benign and malignant bile duct strictures
gradual tapering of dilated common duct and minimal wall enhancmenet= BENIGN; abrupt termination of dilated common duct and hyperenhancement on PV phase = MALIGNANT
MRCP may still miss stones of what size?
smaller than 3 cm because they are lost within high signal fluid
What are the diseases that may complicate/cause Cholangiocarcinoma?
Primary sclerosing cholangitis, recurrent pyogenic cholangitis (oriental cholangiohepatitis), Caroli disease
What is the size of the gallbladder when contracted and enlarged?
contracted = <2 cm; enlarged (hydropic) = >5 cm
Adenomyomatosis has no malignant potential. T or F?
TRUE
Adenomatous polyps are potentially premalignant. T or F?
TRUE
Size of polyp that needs to be resected because of risk of cancer
> 10 mm
Normal size of pancreas
3 x 2.5 x 2 cm (head, body, tail)
Normal pancreatic duct size
3-4 mm diameter in the head and tapers toward the tail
What are the signs of resectability of panc ca?
isolated mass, no extrapancreatic dse, no encasement of celiac, SMA
What are the signs of potential resectability of panc ca?
no involvement of celiac, SMA, regional nodes may be involved, limited peripanc extention
What are the signs of unresectability of panc ca?
encasement of celiac/SMA, occlusion of SMV/portal vein, distant mets
How do you define encasement of vessel?
Tumor abutting more than 180deg, focal narrowing, or occlusion
Highest malignant potential among the functioning NET?
80% glucagonoma, 60% gastrinoma, 10% insulinoma
How do you differentiate functioning from non-functioning NET?
Non-functioning usually mas pangit, 80% malignant, larger in size than the functioning NET
What are the 3 imaging appearances of serous cystadenoma?
microcystic (MC), macrocystic, innumerable tiny cysts that appear solid
What type of IPMN carries higher risk of carcinoma?
Main duct IPMN 65%, branch duct IPMN 15%
What is a highly diagnostic feature of serous cystadenoma?
central stellate scar that may calcify
How to differentiate pseudocyst from serous cystadenoma?
septations and lobulated contours are more often associated with serous cystadenoma; pseudocysts = usually shows involution on serial imaging
Normal size
12 x 7 x 3-4 cm (length, width, thickness)
How do you differentiate mass from chronic panc vs adenoca?
Chronic panc - beaded dilatation of panc duct, adenoca - smooth dilatation of panc duc
Cysts found in Cystic fibrosis are true cysts. T or F?
TRUE (pancreatic cystosis - macrocysts of varying size developing from functional remnants of pancreatic ducts
Largest lymphoid organ?
spleen
Cysts found in posttraumatic spleen are true cysts. T or F?
FALSE; usually calcify
Cysts in epidermoid cysts of the spleen are true cysts. T or F?
TRUE
How do you define splenomegaly?
> 14cm, lower edge lower than liver or kidney, extends ventral to ant axillary line
What are the 4 major categories of causes of splenomegaly?
Congestive, myeloproliferative, infectious, infiltrative
Early sign of dysmotility or esophagitis
(transverse folds of the esophageal mucosa from contraction of longitudinal fibersFeline esophagus)
normal thickness of the wall of the distended esophagus
not >3mm
A radiographic marker of GEJ seen on single-contrast barium study
B ring
A radiographic marker of GEJ seen on double-contrast barium study
Z line
How to differentiate primary and secondary achalasia?
Primary = short length of narrowed segment; secondary (cancer) = longer segment >3.5cm
Most sensitve means of diagnosing abnormal GERD in ambulatory patient
Monitoring of esophageal pH for 24hrs
Most patients with hiatus hernia do not have GERD, while most GERD patients have
TRUE
What is the upper limit of normal hiatal width?
15mm
Difference b/w Zenker and Killiam-Jamieson diverticula
(Both upper esophagus) Zenker = hypopharynx, posterior midline, small neck; Killian-Jamieson = below cricopharyngeus, lateral (left), wide neck
Difference b/w pulsion and traction diverticula
(both midesophagus) Pulsion = mucosa and submucosa herniate thru muscularis; Traction = contain all esophageal layers
EPiphrenic diverticula?
lower esophagus, usually on the right side
Least common portion of the GIT to be involved by TB
esophagus
Characterictic radiographic appearance of Barrett esophagus?
high (midesophageal) stricture or deep ulcer in px with GERD
Causes of upper and middle esophageal strictures?
Barrett esopahgus, mediastinal radiation, caustic ingestion, and skin diseases (pemphigoid, erythema multiforme, epidermolysis bullosa)
Causes of distal esophagitis?
GERD, scleroderma, prolonged NGT
Difference b/w pharyngeal and esophageal webs?
Pharyngeal = anterior wall of hypoharynx; Esophageal = anywhere MC in cervical esophagus just distal to cricopharyngeus imppression
Difference b/w benign and malignant strictures?
Benign = smooth tapering concentric narrowing; Malignant = abrupt, asymmetri, eccentri narrowing with irregular nodular mucosa
Hallmark finding of esophagitis
Ulcers
Difference b/w Boerhaave syndrome and Mallory-Weiss tear?
Boerhaave = full-thickness tear in left posterior wall near left crus of diaphragm; MWT = only mucosa torn, longitudinal oriented in distal esophagus
4 common morphologic growth patterns of gastric carcinoma
- polypoid masses
- ulcerative masses
- focal infiltrating tumors (plaque-like lesion w/ central ulcer)
- diffuse infiltrative (scirrhous ca)
Normal gastric wall thickness when distended
antrum = 5-7mm, body = 2-3 mm (duodenum <3mm)
Major cause of chronic gastritis, duodenitis, benign gastric and duodenal ulcers, gastric
H. pylori
4 morphologic patterns of gastric lymphoma
- polypoid solitary mass
- ulcerative mass
- multiple submucosal nodules
- diffuse infiltration
CT findings differentiating gastric LYMPHOMA from carcinoma
- marked wall thickening (>3 cm)
- involvement of additional areas of GI tract
- no invasion of perigastric fat
- no luminal narrowing and obstruction despite extensive involvement
- widespread and bulkier adenopathy
Hallmarks of gastritis
- thickened folds
- superficial mucosal ulcerations (erosions)
Hallmark of benign ulcers
mucosa that is intact to the very edge of an undermining ulcer crater; depth of ulcer greater than width
Gastritis with sparing of the antrum
- Atrophic gastritis
- Menetrier disease
Most of gastric ulcers are benign. T or F?
TRUE
Evidence of malignant ulcers
irregular tumor mass or infiltration of surrounding mucosa; shallow ulcer with width greater than depth
Duodenal tumors
bulb = 90% benign, 2nd and 3rd portion = 50% benign/malignant, 4th portion = most are malignant
Brunner glang hyperplasia vs hamartoma
Hamartoma = >5 mm
Barium studies should be avoided in patients with acute stages of UGI hemorrhage. T or F?
TRUE
Location of Chron disease of duodenum
1st and 2nd portions
Disease/syndrome that have Increased risk for small bowel carcinoma
Adult celiac disease, Crohn dse, and Peutz-jeghers syndrome
Differentials for annular constricting lesions of the small bowel
small bowel adenocarcinoma, annular mets, intraperitoneal adhesions, malignant GIST, lymphoma (rare)
Differentiating finding in lymphoma in comparison w/ GIST and adenocarcinoma?
lymphoma enhances little
Hallmark of mechanical bowel obstruction
point of transition b/w dilated and nondilated bowel
Ddx of annular constricting lesions of the small bowel
adenoca, annular mets, intraperitoneal adhesions, malignant GISTs, lymphoma (rare)
Differentiate exophytic lymphoma vs GIST and adenoca
exophytic lymphoma - enhances little, if any; GIST and adenoca - enhance prominently
Differentiate carcinoid tumors and small bowel adenoca vs melanoma in terms of their mesenteric metastases
carcinoid and SI adenoca - prominent desmoplastic reaction in the mesentery; melanoma - no mesenteric retraction
Patient condition that have increased risk for colon ca
ulcerative colitis, crohn disease, Peutz-Jeghers syndrome, familial adenomatous polyposis
Filling defects seen on barium enema include the ff considerations
polyps, tumor, plaques, air bubbles, feces, mucus, or foreign objects
Syndrome/diseases associated with Hamartomatous polyposis syndrome
Peutz-Jeghers syndrome, Cowden syndrome, Chronkhite-Canada syndrome
“Rules of thumb” for colonic polyps
<5mm = hyperplastic with <5% risk of malignancy; 5-10mm = 90% adenoma w/ 1% malignancy risk; 10-20 mm = adenomas w/ 10% malignancy risk; >20 mm = 50% malignant
Common cause of rectal bleeding in children
Hamartomatous polyps (Juvenile polyps)
Patients with Peutz-Jeghers syndrome have increased risk for what malignancy?
Colon ca, breast ca, uterine and ovarian ca, and early age pancreatic ca
Patients with Cowden disease have increased risk for what malignancy?
breast ca, transitional cell ca (urinary tract)
Difference b/w lymphoma and lymphoid hyperplasia
lymhoma nodules vary in size. lymhoid hyperplasia nodules are uniform in size.
GI metastases often cannot be differentiated from primary tumors by imaging. T or F
TRUE
Crohn disease and metastatic disease may also look exactly alike radiographically. T or F
TRUE
Radiographic hallmarks of Ulcerative disease
granular mucosa, confluent shallow ulcerations, symmetry of disease around lumen, continuous confluent diffuse involvement
CT findings of Ulcerative colitis
1)wall thickening w/ low density submucosal edema 2) narrowing of lumen 3) pseudopolyps and pneumatosis coli with megacolon
Assoc extraintestinal diseases of Ulcerative colitis
sacroiliitis, eye lesions, cholangitis, thromboembolic dse
Complications of ulcerative colitis
1) strictures in transverse colon and rectum 2) colorectal adenoca 3) toxic megacolon 4) massive hemorrhage
Barium studies should be avoided in patients with toxic megacolon. T or F
TRUE
Hallmarks of Crohn disease
early aphthous ulcers, later confluent deep ulcers, predominant right colon, discontinuous involvement, assymetric, strictures, fistulas, sinus formation
Bleedin rate detection of scintigraphy vs angiography
scintigraphy = below 0.1ml/min; angiography = 0.5 ml/min or greater
Radiographic findings of Toxic megacolon
1) marked dilatation >6cm transverse colon with abscence of haustra 2) colonic wall edema and thickening 3) pneumatosis coli 4) evidence of perforation
watershed areas of the colon that are most susceptible to ischemic colitis
splenic flexure and descending colon
CT findings of Pseudomembranous colitis
1) marked wall thickening 2) accordion sign 3) mild pericolonic inflammation 4) ascites
What are the usual locations of the appendix?
Posteromedial aspect of the cecum, may also be pelvic, retrocecal, retrocolic, intraperitoneal, extraperitoneal
What is one reliable way of locating the appendix?
The appendix always arises from the cecum on the same side as teh ileocecal valve
What is the most common cause of acute abdomen?
Acute appendicitis
What are mimickers of AP in women of childbearing age?
Ruptured ovarian cysts, PID
What findings of AP can you see in a radiograph?
Appendiceal calculus (14%), appendiceal abscess or periappendiceal inflammation as soft tissue mass in RLQ, deformed lumen of cecum in RLQ, localized ileus
What is the imaging technique of choice in women of childbearing age and children in
the diagnosis of AP?
US, although MRI competes with US as diagnostic method of choice
the diagnosis of AP? US, although MRI competes with US as diagnostic method of choice What ultrasound scanning technique is quite accurate in providing a definitive diagnosis of AP?
Graded compression technique - slow graded compression applied to area of max tenderness
What are the US signs of appendicitis? (4)
1 non-compressible appendix >6mm diam (outer wall to outer wall), 2 shadowing appendicolith, 3 inflamed periappendiceal fat, 4 increased vascularity of wall
