A side-by-side comparison of diagnostic imaging modalities for cholelithiasis. Panel (a) is a transabdominal ultrasonography of the right upper quadrant. It reveals multiple hyperechoic, irregular structures within the gallbladder lumen. These structures exhibit classic posterior acoustic shadowing, where ultrasound waves are reflected or absorbed, resulting in a dark, anechoic void distal to the stones. Panel (b) is a contrast-enhanced computed tomography (CT) scan in the axial or coronal plane of the same patient. The CT shows the gallbladder as a well-defined, hypoattenuating, fluid-filled structure located adjacent to the liver. In contrast to the ultrasound, the CT scan demonstrates no high-density (calcified) structures within the gallbladder lumen, illustrating the higher sensitivity of ultrasonography for detecting certain types of biliary stones compared to standard CT. The image serves as an educational comparison of imaging sensitivity in gastroenterology and radiology.

This abdominal ultrasound image displays a diagnostic view of the gallbladder containing cholelithiasis (gallstones). The gallbladder appears as a prominent, elongated, anechoic (black) sac-like structure. Inside the lumen, multiple hyperechoic (bright) foci are visible along the dependent wall, representing gallstones. Crucially, the image demonstrates the classic diagnostic sign of posterior acoustic shadowing, where dark, vertical hypoechoic bands extend inferiorly from the stones, indicated by black arrowheads. This phenomenon occurs as the dense stones attenuate the ultrasound beam, preventing sound waves from reaching deeper tissues. The surrounding liver parenchyma shows a normal, homogeneous intermediate echogenicity. This visual is typical for diagnosing symptomatic or asymptomatic gallstone disease in a clinical or preoperative setting.

Diagnostic ultrasound images of the gallbladder in two planes: (a) sagittal view and (b) decubitus view. Both images reveal cholelithiasis, characterized by the presence of hyperechoic (bright) foci within the anechoic (fluid-filled) lumen of the gallbladder. White arrows in both frames highlight specific gallstones. The gallbladder wall appears thin and without significant distension, indicating cholelithiasis without acute cholecystitis. The liver parenchyma is visible adjacent to the gallbladder as a medium-echogenicity structure. These views are utilized in clinical practice to confirm the presence and mobility of stones, as the decubitus position helps redistribute luminal contents to differentiate mobile stones from stationary polyps. The image serves as an educational example of biliary imaging in the context of suspected gallstone pancreatitis or symptomatic cholelithiasis.

This abdominal ultrasound image displays a diagnostic view of the gallbladder containing a prominent 2.7-cm gallstone (cholelithiasis), indicated by a blue arrow. The gallstone appears as a curvilinear, highly hyperechoic structure within the gallbladder lumen. Characteristically, there is a clear, well-defined area of posterior acoustic shadowing distal to the calculus, resulting from the attenuation of ultrasound waves by the dense calcified object. The gallbladder itself appears as a sac-like structure with primarily anechoic (fluid-filled) contents, although scattered low-level internal echoes are present, suggesting the presence of biliary sludge. The surrounding liver parenchyma shows a uniform echotexture. This image is a classic representation used in radiology and gastroenterology for teaching the sonographic diagnosis of uncomplicated cholelithiasis, emphasizing the 'bright' appearance of stones and the diagnostic importance of acoustic shadowing.