Diagnostic Ultrasound - Abdomen and Pelvis

Gallbladder Carcinoma
TERMINOLOGY
Abbreviations
• Gallbladder carcinoma (GBC)
Definitions
• Most common neoplasm of biliary tree, with worst
prognosis
IMAGING
General Features
• Best diagnostic clue
○ Poorly defined mass in gallbladder (GB) fossa
○ Invasion into liver and adjacent organs
○ Regional metastatic lymphadenopathy (LAN)
• Morphology
○ 3 main morphological types
– Polypoid intraluminal mass: > 1 cm, thickened base,
irregular margins
– Diffuse or focal GB wall thickening: Asymmetric,
irregular, extensive thickening
– Large soft tissue mass infiltrating gallbladder
fossa/replacing GB, ± invading liver
Ultrasonographic Findings
• Grayscale ultrasound
○ Mass is usually hypoechoic relative to normal liver
○ Extraluminal mass infiltrating GB fossa, extending into
liver
○ Heterogeneous irregular GB wall thickening
– Malignant features include thickness > 5 mm,
irregularity, and asymmetry
○ Intraluminal moderately echogenic polypoid mass
– Size > 1 cm independent positive predictor
– Lobulated surface
– Hypoechoic internal echogenicity
○ Gallstones, ± GB wall calcification
○ Additional ominous findings include evidence of local
invasion, LAN, and distant metastases
• Color Doppler
○ Areas of vascularity within the mass
○ Presence of vascular core in > 1 cm polyp
• Contrast-enhanced US
○ Features more likely associated with malignant wall
thickening
– Inner or outer wall discontinuity
– Focal wall thickening > 10 mm
○ Better visualization of intraluminal polyp
○ Early phase hyperenhancement relative to liver, with
washout within 35 seconds: Improved detection,
characterization, and evaluation of invasion
○ Tortuous vasculature
• Newer US technologies under investigation
○ High-resolution US (HRUS): Combination of low- and
high-frequency transducers may help in more accurate
size assessment of intraluminal polyps
CT Findings
• May be useful adjunct when GB wall obscured by stones
• Preoperative evaluation for invasion, LAN, distant mets
MR Findings
• T1WI
○ Iso- or hypointense to normal liver
• T2WI
○ Heterogeneously hyperintense to liver
• T1WI C+
○ Ill-defined early arterial enhancement
○ Fibrous stromal portions of tumor may retain
enhancement on delayed phases
• MRCP
○ Ductal obstruction or invasion, ± biliary dilation
• Primarily used for staging and assessing tumor invasion
○ T1WI C+ sequences (with fat suppression) most helpful
for assessing invasion into adjacent organs and vascular
structures (PV, HA), peritoneal implants
Nuclear Medicine Findings
• PET/CT
○ Avid accumulation of F-18 FDG
○ Difficult to distinguish from inflammation (wall
thickening) or other malignancy
Imaging Recommendations
• Best imaging tool
○ US for initial detection and characterization, CECT or MR
for preoperative assessment and staging
DIFFERENTIAL DIAGNOSIS
GB Polyp: Hyperplastic or Adenomatous
• Mucosal polypoid mass
○ Moderately echogenic without shadowing
○ Nonmobile, attached to wall
○ No vascularity detected on Doppler
• Typically < 1 cm ± multiple = benign cholesterol polyp
Hyperplastic Cholecystoses
• Focal or diffuse wall thickening
○ Focal thickening of the fundus
○ Focal thickening of the mid body ("hourglass GB")
• Intramural cholesterol crystals as tiny echogenic foci with
"comet tail" artifact
○ "String of pearls" on MR
• No adjacent infiltration or lymph node metastases
Chronic Cholecystitis
• Diffuse wall thickening, smooth or irregular contour
• Contracted GB (lumen may be obliterated)
• Gallstones
Xanthogranulomatous Cholecystitis
• Infiltrative intramural inflammatory process resulting in illdefined
GB wall thickening
• Gallstones
• Distinguishing characteristics
○ Presence of intramural hypoechoic/hypodense nodules
○ Mucosal continuity
○ Lack of lymph node involvement and hepatic or biliary
invasion
• Nearly impossible to differentiate from gallbladder
carcinoma preoperatively
Diagnoses: Biliary System
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