Liver Flashcards
What is T1 and T2 relatinship b/w liver and spleen?
Liver is brighter on T1 (because of enzymes). Spleen is brighter on T2 (because spleen is a bag of water)
2 fat related artifacts on MRI
Type 1; “chemical shift” Type 2; “india ink”
In abdominal imaging, Which direction is frequency encoding. Which is phase encoding
Frequency is transverse direction (long direction, long word). Phase encoding is AP (short direction, short word)
How does field strength effect chemical shift artifact (frequeny)
How does receiver bandwith effect Chemical shift (frequency)
Higher field strength (1.5 T to 3T) makes artifact worse
Differences in frequency are LESS noticiable at a high receiver band with.
How does receiver bandwith effect Chemical shift (frequency)
Differences in frequency are LESS noticiable at a high receiver band with.
Type 1 artifact
Due to Gradient. Difference in fat and water causing localization problems. Occurs in Frequency encoding direction
Type 1 artifact is worse with __ and more noticiceable with ___
Higher field strength. Narrower receiver bandwith.
Type 1 artifact occurs with __, and __ echos
Spin echo and gradient echo
Type 2 artifact; dropout occurs on ___ phase. And occurs only w/ __ echo
Opposed phase
In/out of phase runner analogy
there is a slow and fast runner on a track. On out of phase they are at opposite sides. The in Phase, they are at the same spot.
On in/out phase which phase comes first?
Opposed phase is first (2.2 seconds) in pahse is 2nd (4.4 seconds)
What happens if you obtain the out of phase image late
You will have more T2 star effect on outer phase. So the liver artificially loses signal on out of phase. You would notbe able to tell difference b/w fatty liver and iron-rich liver.
Blooming artifact gets __ as time goes on when doing in/out phase
Blooming signal gets worse as time goes on. So the more blooming with air and metal, the more later the acquisition was.
Liver segment I? (What seperates it from liver)
Caudate lobe, Ligamentum venosum and IVC separate it from liver
Liver segments II and III?
Lateral division of left lobe. II-superior. III-inferior.
Liver segments IV?
Medial division of left lobe. IVa-superior. IVb-inferior.
Liver segments V and VIII?
Anterior segments of right lobe. VIII-superior. V-inferior.
which Right lobe Liver segments are Anterior? Which are posterior?
Anterior: 5, 8
Posterior segments of right lobe. VII-superior. VI-inferior.
Third inflow?
Areas of liver supplied by aberrant systemic veins. Porta hepatis, adjacent to gallbladder, adjacent to fissure of ligamentum teres.
The caudate lobe is spared (and may have compensatory hypertrophy) in early cirrhosis because?
It is drained by IVC, which is spared from increased venous pressures.
DDx Hepatic metabolic liver disease (4)
Hepatosteatosis, amyloid, Wilson’s, hemochromatosis
Hepatic steatosis, focal fat patterns
GB fossa, Subcapsular (along falciform), periportal, nodular. (focal fat should not have any mass effect).
Fatty infiltration CT attenuation
On unenhanced: 10 HU less than spleen or under 40HU. On PV; 25 less than spleen.
Wilson’s disease. Where does copper accumilate. Genetic inheritance
Basal ganglia, cornea, liver. Will lead to hepatomegaly/cirrhosis. Autosomal recessive genetic defect.
Which disease has Liver signal dropping out on In-phase
Hemochromatosis
PPPPrimary hemochromatosis. Which organs does it effect? Demographics
Liver and PPPancreas (also myocardium, skin, and joints). In hepatocytes. Mostly white. It will effect women later in life (because they menstrate early in life)
SSSecondary hemochromatosis Which organs does it effect
Liver and SSSpleen. Due to hemosiderosis from frequent transfusions or thallasemia, and depositions in RES (Kupffer cells).
Where does hemochromatosis effect the hand in arthritis?
2nd, 3rd MCP, TFCC. Hook osteophytes (similar to CPPD)
Ddx Hypoattenuating liver (2)
Amyloid. Hepatosteatosis.
Ddx Dense liver (5)
Drugs (*Amiodarone*). Wilson’s. Hemochromatosis. Glycogen storage disease. Thorotrast
Amiodarone effect on liver (and lungs)
Liver Is dense. Lungs have chronic interstitial pneumonia (peripheral areas of dense airspace disease)
Ddx Hepatic infection (4)
Viral hepatitis, candidiasis, pyogenic, echinococcal cyst
HIV manifestations in the liver
Peliosis hepatis (bartonella infection), candidiasis, kaposi sarcoma, PCP, AIDS related lymphoma
Hepatitis findings in liver
Periportal edema, GB edema, Enlarged liver
Candidiasis in liver
Systemic infection seeding to liver (and spleen) on PV drainage. Tiny hypoatenuating microabscesses, immunocompromised patients.
Ddx Multiple tiny hypoattenuating liver lesions (5)
Candidiasis, lymphoma, mets, Caroli disease, Biliary hamartomas (von-Meyerburg)
Hepatic abscess (common causes, common bug, appearance)
caused by bowel process (diverticulitis, appendicitis, crohn’s, bowel surgery. Ascending cholangitis less common). E. Coli. Ring enhancing on CT and MR. Center is T2 bright.
Echinococcal disease (cause). Develops into ___ cyst
ingestion of eggs (echinococcus granulosus, endemic in Mediterrian a/w Sheep raising). Develop into hydatid cysts. hypoattenuating mass with floating membrane or associated daughter cysts. Peripheral calcifications may be present.
Imaging of Hydatid cyst
hypoattenuating mass with floating membrane or associated daughter cysts. Peripheral calcifications may be present.
Early signs of cirrhosis
Expansion of preportal space, atrophy of medial left hepatic lobe. Enlargement of caudate (if caudate >0.65). Empty gallbladder fossa sign
Empty gallbladder fossa sign (cirrhosis)
Hepatic parenchyma surrounding the gallbladder is replaced w/ periportal fat
Secondary manifestations of cirrhosis
Portal HTN, splenomegaly, collaterals, varices. GB wall thickening
Gamna-Gandy bodies
Due to cirrhosis. Splenic microhemorrhages. Hypointense on GRE
Micronodular vs. macronodular cirrhosis
Micro; metabolic causes. Macro; post-viral
Liver nodules in cirrhosis?
Regenerative nodules Dysplastic nodules Small HCC nodules Metastatic disease Hemangiomas
CT features of portal hypertension?
Portosystemic collateral vessels Enlarged portal vein, > 13 mm. Splenomegaly Ascites
Calcifications in liver ddx
Most likely Mets (adenocarcinoma/colorectal). Fibrolamellar and HCC are less common. Fibrolamellar has calcification more often than HCC.
Ddx Malignant hepatic lesions (5)
Epithelioid hemangioendothelioma, HCC, Fibrolamellar carcinoma, Lymphoma, mets,
What liver malignancies may calcify?
Fibrolamellar HCC. Hepatoblastoma. Intrahepatic cholangiocarcinoma. Metastases.
Pathway to HCC
Regenerative nodule –>dysplastic nodule–>HCC
Regenerative nodule
supplied by PV, not premalignant. Low T2, no enhancement
Dysplastic nodule
premalignant. Blood supply still from PV. Variable T1/T2, but the worse it is, the more T2 hyperintense. High grade dysplastic nodules may enhance
Siderotic nodule
Iron-rich regenerative/dysplastic nodule. Hypointense on T1/T2* and hyperatteunating on CT. Not malignant.
HCC features? (size, MRI, biomarker)
Small tumors(< 3cm). Arterial enhancement, PV washout. T2 hyperintense on MR. Elevated AFP. Locally invasive (PV, IVC, bile ducts).
How can you get HCC in a non-cirrhotic adult?
Acute HBV
What does HCC look like on PET
It will not light up.
Fibrolammelar Carcinoma CT features?
Large mass in healthy liver heterogenous enhancement Central scar Difficult to distinguish from FNH. No capsule (unlike HCC)
Central scar features of Fibrolamellar HCC vs. FNH
Fibrolamellar HCC: T1/T2 hypointense.
FNH is T2 hyperintense and enhances late. Its also “wispy”
Metastases to liver features on CT?
Most common liver malignancy. Usually hypovascular. Most commonly from colon. Target appearance. Some cystic/nectrotic, calcification
Ddx Hyperenchancing (vascular) liver mets (5) (‘neuroendocrine mets shine right through)
Neuroendocrine, melanoma, Sarcoma, RCC, thyroid (also Pheo, choriocarcinoma)
Ddx Hypovascular liver mets (2)
Colorectal, pancreatic adenocarcinoma
Liver mets w/ calcifications
Mucinous colorectal, ovarian serous tumors (think adenomas)
Liver mets on MRI (melanoma exception)
T1 hypo, T2 hyper. Melanoma will be T1 hyper.
what is “pseudocirrhosis”
macrondular liver contour due to multiple scirrhous heptic mets. May mimic cirrhosis. Can be seen w/ treated breast cancer.
Liver lymphoma CT features?
Diffuse infiltration, Well-defined, homogeneous low-density nodules, Numerous small nodules resembling microabscesses
Epithelioid hemangioendothelioma
Multiple spherical subcapsular masses. Halo or target appearance. Capsular retraction
Ddx for capsular retraction of liver (6)
Mets, epitheliod hemangioendothelioma, Fibrolamellar, HCC, intrahepatic cholangiocarcinoma, confluent hepatic fibrosis.
Ddx Benign liver masses (3)
FNH, Hemangioma, hepatic adenoma
FNH CT features?
Mini liver central scar with T2 hyperintense ductules and venules w/ arterial enhancement.
Unenhanced, isodense to liver. Arterial phase, immediate intense homogeneous enhancement. May have delayed enhancement of scar. Positive sulfur colloid uptake
Nuc medicine study to cofirm FNH from HCC?
Sulfur colloid scan (FNH has kupffer cells and will light up)
FNH (central scar enhancement pattern). MRI contrast agent.
T2 bright (FL HCC is T2 dark), T1 dark, Enhances arterially and persists longer. Will retain eovist.
Explain Eovist
It is transported into bile duct by OATP transporter. Therefore with FNH, lesion retains OATP tranpoter, but with HCC, the OATP transpoter is gone. Well differentiated HCC is the exception to the rule.
Cavernous Hemangioma CT features?
Disorganized blood vessels supplied by hepatic artery. Unenhanced, hypodense mass. Arterial phase, periphera, dicontinious, progressive nodular enhancement.
Hemangioma enhancement patterns
Classic pattern w/ peripheral discontinous nodular filling. Flash filling. Delayed fill with a central star type of look (can do a late delay for confirmation)
Giant hemangioma features
May not have enhancing center
Nuclear medicine test to confirm hemangioma
Tagged RBC scan
Hepatic adenoma CT features?
Hepatocytes, scattered kupffer cells. No bile ducts. OCPs/anabolic steroids. Surgical removal for fear of rupture or malignant transformatoin. Unenhanced, isodense to liver. Arterial phase, early homogeneous enhancement. Few Kupffer cells, no sulfur colloid uptake
Adenoma MRI
Microscopic fat (drop in in/out), Internal hemorrhage may cause T1 hyperintensity.
Hepatic adenoma types
- Ones w/ fat (HNF Alpha), 2. ones that bleed (inflammatory)
Heptic adenoma (classic location, history, what if they are multiple)
- Right subcapsular region, 2. OCP/steroids, 3. Glycogen storage disease
Ddx Vascular liver disease (3)
Budd-chiari, veno-occlusive disease, cardiac hepatopathy.
CT features of Budd-Chiari syndrome?
Enlarged caudate lobe. Central liver enhances early and peripheral liver enhances late. Lack of venous flow. Collaterals. Edematous peripheral liver.
3 ways to show Budd Chiari
Hypertrophy of caudate. Central liver enhances first (opposte of normal), Budd Chiari nodules.
Budd Chiari clinical triad
Ascites, abdominal pain, hepatomegaly
Hot Quadrate sign
Caudate lobe enhancement. A sign of SVC obstruction. Complex collateral pathway.
Veno-occlusive disease (explain entity. Imaging findings.
destruction of post-sinusoidal venules, patent hepatic veins. Seen in BMT pts. Imaging findings nonspecific, including periportal edema, narrowing of hepatic veins.
Cardiac heptatopathy
Passive hepatic congestion from CHF, constrictive pericarditis, valve disease. Can lead to cirrhosis.
Cardiac hepatopathy imaging clues
Enlarged hepatic veins and IVC. Reflux of contrast. Enlarged/mottled liver.
Numerous liver cysts, differential and how do you differentiate them.
Biliary hamartomas (von-Meyenburg complex) vs. Caroli’s disease. Determine if they communicate w/ biliary system vs. PCKD
Biliary hamartomas - name of disease, cause
Von Meyenburg complexes. Small cystic hepatic lesions that do not communicate w/ biiary tree. Caused by embryologic failure of normal bile duct formation.
MDCT grading of hepatic injury (grades I-V)
I: superficial laceration or subcapsular hematoma <1cm. II, lac or hematoma 1-3cm. III lac or hematoma >3cm. IV; massive hematoma >10cm or destruction/devascularization of a hepatic lobe. V; destruction or devascularization of both hepatic lobes.
Liver transplant: Elevated diastolic flow in HA
Sensitive for severe stenosis (may be post-op due to edema)
Liver transplant: elevated diastolic flow and Tardua Parvus in HA
Specific for severe proximal stenosis.
HHT findings
AVMs in skin (nose), Lungs (shunt to brain, stroke, abscess), liver, Bowel (GI bleed)
Subcapsular hematoma in a pregnant patient
HELLP syndrome (young, first pregnancy, 3rd trimester, eclampsia, DIC
