Imaging Gallbladder Lesions: What Can Positron Emission Tomography/Computed Tomography Add to the Conventional Imaging Approach?

Abstract

Objective 

Incidental gallbladder lesions are common in imaging studies, although it is not always easy to discriminate benign lesions from gallbladder cancer with conventional imaging procedures. The present study aims to assess the capacity of positron emission tomography/computed tomography (PET/CT) with 2-[¹⁸F]FDG to distinguish between benign and malignant pathology of the gallbladder, compared with conventional imaging techniques (contrast-enhanced CT or magnetic resonance imaging).

Methods 

Positron emission tomography/CT and conventional imaging studies of 53 patients with gallbladder lesions were evaluated and visually classified as benign, malignant, or inconclusive. Agreement between PET/CT and conventional imaging was determined, and imaging findings were correlated with histology or follow-up. Positron emission tomography/CT images were also analyzed semiquantitatively (SUV_max and maximum tumor-to-liver ratio [TLR_max]). The presence of adenopathies and distant metastases was assessed and compared between both imaging procedures.

Results 

According to histology or follow-up, 33 patients (62%) had a malignant process and 20 (38%) had benign lesions. Positron emission tomography/CT and conventional imaging showed a moderate agreement (κ = 0.59). Conventional imaging classified more studies as inconclusive compared with PET/CT (17.0% and 7.5%, respectively), although both procedures showed a similar accuracy. Malignant lesions had significantly higher SUV_max and, especially, TLR_max (0.89 and 2.38 [P = 0.00028] for benign and malignant lesions, respectively). Positron emission tomography/CT identified more pathologic adenopathies and distant metastases, and patients with regional or distant spread had higher SUV_max and TLR_max in the gallbladder.

Conclusions 

Positron emission tomography/CT is accurate to distinguish between benign and malignant pathology of the gallbladder, with a similar performance to conventional imaging procedures but with less inconclusive results. Malignant lesions present higher SUV_max and TLR_max values.