Imaging Approach for Suspected Gallbladder Polyp

Initial Imaging Strategy

The American College of Radiology recommends transabdominal ultrasound (TAUS) with optimized technique as the primary imaging modality for evaluating suspected gallbladder polyps, using high-frequency probes, color Doppler, and proper patient preparation 1, 2
Key features to document during TAUS include polyp size, morphology, presence of focal wall thickening, vascularity on Doppler, and any suspicious features suggesting malignancy 2

The American College of Radiology suggests that contrast-enhanced ultrasound (CEUS) should be the next step when differentiation between tumefactive sludge, adenomyomatosis, and a true gallbladder polyp remains challenging after optimized TAUS, providing superior characterization through enhancement patterns, vascular patterns, and dynamic features 1, 2, 3
CEUS characteristics that aid diagnosis include non-neoplastic lesions showing late hypoenhancement compared to liver, while neoplastic lesions show marked early enhancement 1
The American College of Radiology recommends that MRI should be considered if CEUS is not readily available or accessible, with MRI characteristics that aid diagnosis including high T1-weighted signal, restricted diffusion, intermediate to high T2 signal intensity, and enhancement patterns 1, 2, 3

The American College of Radiology advises that if there is suspicion for invasive or malignant tumor, immediately refer to an oncologic specialist rather than following routine polyp surveillance algorithms 2
The American College of Radiology suggests distinguishing between tumefactive sludge, adenomyomatosis, and gallstones using higher sensitivity Doppler techniques, comet-tail artifact, and twinkling artifact 2

The American College of Radiology recommends distinguishing the honeycomb pattern from other gallbladder pathologies, including adenomyomatosis, which shows comet-tail artifact at gray-scale imaging or twinkling artifact at color Doppler imaging due to intramural cholesterol crystals and Rokitansky-Aschoff sinuses appearing as intramural cysts, in patients with suspected gallbladder disease 4, 5
Adenomyomatosis can be diagnosed by demonstration of mural hyperplasia that may be diffuse, focal, or segmental with characteristic artifacts, and Rokitansky-Aschoff sinuses can be definitively diagnosed by demonstration of cystic-like structures in the gallbladder wall on MRI, according to the Radiological Society of North America 4, 5, 6
Gallbladder carcinoma may present with focal wall thickening ≥4 mm adjacent to a mass, sessile morphology, or concurrent liver masses, and requires immediate referral to an oncologic specialist, as recommended by the National Comprehensive Cancer Network 4, 5

The European Society of Radiology suggests that if differentiation from adenomyomatosis or malignancy is challenging, contrast-enhanced ultrasound (CEUS) should be the next step, providing superior characterization through enhancement patterns, and MRI should be considered if CEUS is not readily available, with attention to T1/T2 signal characteristics and enhancement patterns 6