Diagnostic Ultrasound - Abdomen and Pelvis
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Diagnostic Ultrasound - Abdomen and Pelvis

powerstage
09.07.2019 Views

Cystic Liver Lesion Peribiliary Cyst Biliary Hamartoma (Left) Color Doppler US shows peribiliary cysts ſt located adjacent to the portal vein . Peribiliary cysts should not be confused with biliary ductal dilatation, which would have a more tubular and continuous appearance adjacent to the portal vein. (Right) Grayscale ultrasound of the liver shows multiple tiny, echogenic foci with "comet tail" artifacts generated from biliary hamartomas. Differential Diagnoses: Liver Amebic Abscess Hepatic Lymphoma (Left) Sagittal grayscale ultrasound of the liver shows a large, well-demarcated and encapsulated hypoechoic amebic abscess ſt. The contents are heterogeneous due to floating debris st. No vascularity is seen within the abscess. (Right) Transverse abdominal ultrasound in a patient with lymphoma shows multiple markedly hypoechoic nodules ſt throughout the right lobe of the liver, which have a pseudocystic appearance. Hepatic Metastases Ciliated Hepatic Foregut Cyst (Left) Cystic liver metastasis in a patient with metastatic cervical cancer displays a central cystic area ſt as well as an echogenic soft tissue rim and layering debris within the dependent portion of the mass. (Right) Oblique abdominal color Doppler US in a patient with a ciliated hepatic foregut cyst shows a well-defined, ovoid, subcapsular cystic mass ſt in segment IV of the liver st. Internal content of the cystic lesion is relatively homogeneous, and no vascularity is seen. 875

Hypoechoic Liver Mass 876 Differential Diagnoses: Liver DIFFERENTIAL DIAGNOSIS Common • Complicated Benign Hepatic Cyst • Hepatic Metastases • Infection ○ Pyogenic Hepatic Abscess ○ Amebic Hepatic Abscess ○ Fungal Hepatic Abscess • Focal Fatty Sparing • Hepatocellular Carcinoma • Infected Biloma Less Common • Hepatic Lymphoma • Hepatic Adenoma • Focal Nodular Hyperplasia • Atypical Hemangioma • Hepatic Hematoma • Abnormal Bile Ducts • Abnormal Vessels ESSENTIAL INFORMATION Key Differential Diagnosis Issues • Lesions of lower echogenicity than liver parenchyma (compared to purely anechoic lesions) ○ With some low-level internal echogenicity ○ Solid lesion vs. complex cystic lesion Helpful Clues for Common Diagnoses • Complicated Benign Hepatic Cyst ○ Superimposed hemorrhage or infection in hepatic cyst ○ Septation/thickened wall ± mural calcification ○ Posterior acoustic enhancement ○ Solid appearance – If internal debris (clots or fibrin strands) dispersed within cyst ○ Fluid-debris level – If debris settles under influence of gravity ○ No mural nodule ○ Color Doppler – Absence of internal or mural vascularity – Adjacent vessels distorted by large cyst • Hepatic Metastases ○ Hypoechoic metastases tend to be numerous and small – Larger lesions tend to have heterogeneous echogenicity ○ May have irregular or ill-defined borders ○ Hypoechogenicity – May reflect poor cellular differentiation and active growth ○ Suggest hypovascular and hypercellular tumor origin – Lung, breast, lymphoma ○ No posterior acoustic enhancement ○ Causes architectural distortion – If large or numerous ○ Color Doppler may show no vascularity – Most are hypovascular ○ Difficult to differentiate from lymphoma without history of known primary lesion • Pyogenic Hepatic Abscess ○ Cystic mass with irregular border and debris ○ Posterior acoustic enhancement ○ Multiple thick or thin septations ○ Mural nodularity & vascularity ○ Adjacent parenchyma may be coarse & hypoechoic due to inflammation ○ "Cluster" sign: Coalescence of group of abscesses ○ May contain gas within abscess – Reverberation artifact or air-fluid level ○ Changes to anechoic when center becomes necrotic as center enlarges ○ Periportal distribution suggests dissemination along biliary tree ○ Random distribution suggests hematogenous spread • Amebic Hepatic Abscess ○ Abuts liver capsule, under diaphragm ○ More likely to be round or oval-shaped than pyogenic abscess ○ Hypoechoic with fine internal echoes – More common in amebic than pyogenic abscess ○ Internal septa may be present ○ Posterior acoustic enhancement ○ No vascularity seen in wall or septa of abscess ○ Subdiaphragmatic rupture in presence of adjacent hepatic abscess – Suggests amebic nature of abscess • Focal Fatty Sparing ○ Geographic hypoechoic area within echogenic liver ○ Due to direct drainage of hepatic flow into systemic circulation ○ Typical locations – Gallbladder fossa □ Drained by cystic vein – Inferior aspect of segment 4b □ Drained by aberrant gastric vein – Anterior to bifurcation of portal vein □ Drained by aberrant gastric vein – Around hepatic veins ○ No architectural distortion – Vessels course through mass undistorted – No mass effect ○ Does not cross segments • Hepatocellular Carcinoma (HCC) ○ Hypoechoic: Most common US appearance of HCC – Solid tumor – May be surrounded by thin, hypoechoic halo (capsule) ○ Background cirrhotic liver ○ Associated signs of portal hypertension – Ascites, splenomegaly, portosystemic collaterals ○ Color Doppler – Irregular hypervascularity – Portal vein thrombus with arterial neovascularity • Infected Biloma ○ Fluid collection within liver, close to biliary tree, or in gallbladder fossa ○ Debris or septa suggest infected biloma ○ Color Doppler – No vascularity within lesion

Cystic Liver Lesion<br />

Peribiliary Cyst<br />

Biliary Hamartoma<br />

(Left) Color Doppler US shows<br />

peribiliary cysts ſt located<br />

adjacent to the portal vein .<br />

Peribiliary cysts should not be<br />

confused with biliary ductal<br />

dilatation, which would have a<br />

more tubular <strong>and</strong> continuous<br />

appearance adjacent to the<br />

portal vein. (Right) Grayscale<br />

ultrasound of the liver shows<br />

multiple tiny, echogenic foci<br />

with "comet tail" artifacts<br />

generated from biliary<br />

hamartomas.<br />

Differential Diagnoses: Liver<br />

Amebic Abscess<br />

Hepatic Lymphoma<br />

(Left) Sagittal grayscale<br />

ultrasound of the liver shows a<br />

large, well-demarcated <strong>and</strong><br />

encapsulated hypoechoic<br />

amebic abscess ſt. The<br />

contents are heterogeneous<br />

due to floating debris st. No<br />

vascularity is seen within the<br />

abscess. (Right) Transverse<br />

abdominal ultrasound in a<br />

patient with lymphoma shows<br />

multiple markedly hypoechoic<br />

nodules ſt throughout the<br />

right lobe of the liver, which<br />

have a pseudocystic<br />

appearance.<br />

Hepatic Metastases<br />

Ciliated Hepatic Foregut Cyst<br />

(Left) Cystic liver metastasis in<br />

a patient with metastatic<br />

cervical cancer displays a<br />

central cystic area ſt as well<br />

as an echogenic soft tissue rim<br />

<strong>and</strong> layering debris <br />

within the dependent portion<br />

of the mass. (Right) Oblique<br />

abdominal color Doppler US in<br />

a patient with a ciliated<br />

hepatic foregut cyst shows a<br />

well-defined, ovoid,<br />

subcapsular cystic mass ſt in<br />

segment IV of the liver st.<br />

Internal content of the cystic<br />

lesion is relatively<br />

homogeneous, <strong>and</strong> no<br />

vascularity is seen.<br />

875

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