Motokazu S.12, Yusuke K.2, Ichiro T.3, Atsushi H.3, Eiji S.1, Seitaro W.1, Haruto S.1, Tomoki S.1, Kenji K.1, Yusuke T.1, Kouki M.1, Yuichi S.1, Yusuke B.1, Kunihiro H.2, Kensuke K.2, Atsushi N.2

1Department of Gastroenterology, Yokohama Sakae Kyosai Hospital, Kanagawa, Japan
2Department of Gastroenterology and Hepatology, Yokohama City University School of Medicine, Kanagawa, Japan
3Department of Radiology, Yokohama Sakae Kyosai Hospital, Kanagawa, Japan.

Background/Aims: Usefulness of MRI, Diffusion Weighted Imaging (DWI), and Apparent Diffusion Coefficient (ADC) in gallbladder lesions has been reported. Computed DWI (cDWI) is a new technique to create DWI with any b value by computer processing of two different DWIs. In recent years, cDWI has been reported to be highly diagnostic in pancreatic cancer and prostate cancer. However, it has not been reported in gallbladder lesions. In this study, we investigated the diagnostic performance of cDWI combined with ADC in gallbladder lesions.

Methods: Sixty patients who had underwent MRI for gallbladder lesions between December 2008 and December 2020 were included in this study. Gallbladder lesion was defined as gallbladder wall thickening of 3 mm or more, polyp-like lesion, or clinically suspected gallbladder disease. The lesions were diagnosed by pathologically (53 surgical specimens / 4 biopsies) or clinically (3 cases) with at least 1 year of imaging follow-up. ADC was used for qualitative evaluation, malignancy was defined as lower signal than normal liver in ADC assessment. Two radiologists performed qualitative evaluation using the conventional method of DWI with b1000 and the combination of cDWI with b1500 and ADC, and compared the diagnostic performance for benign and malignant.

Results: The total number of patients was 60 (30 malignant/ 30 benign). The final diagnosis was gallbladder cancer in 30 cases, chronic cholecystitis in 23 cases, gallbladder polyps in 3 cases, gallbladder adenomyosis in 2 cases, and xanthogranulomatous cholecystitis in 2 cases. Sensitivity, specificity, and accuracy in comparing b1000-DWI alone and b1500-cDWI + ADC were (96.7% vs. 90.0%, p=0.5), (6.7% vs. 80.0%, p<0.001) and (51.7% vs. 85.0%, p<0.001), respectively. cDWI combined with ADC showed significantly higher specificity and accuracy than the conventional method.

Conclusion: Usefulness of cDWI combined with ADC has shown in the diagnosis of benign and malignant gallbladder lesions. Prospective studies are needed in the future.

Keywords: MRI, gallbladder, computed DWI