Clinicopathological correlation of 18F-FDG PET in characterizing gall bladder wall thickening

Abstract

Introduction: Thick walled gallbladder is difficult to characterize on conventional imaging. 18F-FDG PET was used to differentiate benign and malignant wall thickness and compared with histopathology. Methods: Thirty patients with GB wall thickening (focal > 4 mm and diffuse > 7 mm), underwent ultrasound, CT scan and 18F-FDG PET. Histopathology of the specimen was compared with imaging findings. Results: The mean age was 48.22 ± 31.33 years with a M:F 1:4. Twenty patients had diffuse and 10 had focal thickening. On conventional imaging, lesion was benign in 13, malignant in 15 and indeterminate in two. On 18F-FDG PET, lesion was benign in 12, malignant in 13 and indeterminate in 5. Histopathology was malignancy in 12; benign in 18- chronic cholecystitis in 11, xanthogranulomatous in 4, IgG4 related in 2 and polyp in 1. The mean GB wall thickness was 7.79 ± 3.59mm (10.34 malignant and 6.10 in benign, p = 0.001). At a cut off of 8.5mm the sensitivity and specificity of detecting malignancy was 94% and 67%. The mean SUV uptake was 7.46 (benign 4.51, malignant 14.26, p=0.0102). At a cut off of 5.95 the sensitivity and specificity of detecting malignancy was 92% and 79%. For 18F-FDG PET overall sensitivity was 91%, specificity 79%, PPV 77%, NPV 92% and diagnostic accuracy was 84%. Conclusion: 18F-FDG PET is a reliable method of differentiation between benign and malignant thickening of the gall bladder particularly when wall thickness and SUV value is taken into account.Tabled 1Statistical analysis of imaging in thick walled GBImaging modalityUSGCECTPET CTSensitivity(%)57.14100.0090.91Specificity(%)62.5072.2278.57PPV(%)40.0066.6776.72NPV(%)76.92100.0091.67Diagnostic accuracy(%)60.8682.1484.00 Open table in a new tab