Negative signals for adenomyomatosis of the gallbladder upon diffusion-weighted whole body imaging with background body signal suppression/T2-weighted image fusion analysis

Abstract

Differentiation between adenomyomatosis (ADM) and cancer of the gallbladder is necessary during diagnosis. Diffusion-weighted whole body imaging with background body signal suppression (DWIBS) images are able to indicate cancer and inflammation. The fusion of a DWIBS with a T2 weighted image (DWIBS/T2) facilitates both functional and anatomical investigations. In the present study, patient records and images from patients with surgically confirmed ADM from April 2012 to October 2014 were analyzed retrospectively. The enrolled patients, including 6 men (64.2±13.1 years) and 4 women (57.3±12.4 years) were subjected to DWIBS/T2 during routine clinical practice. The diagnosis of ADM was based on magnetic resonance cholangiopancreatography, transabdominal ultrasonography, and endoscopic ultrasonography; ADM was diagnosed definitively when cystic lesions were observed, indicating the Rokitansky-Aschoff sinus. A single patient was indicated to be positive by DWIBS/T2 imaging. The Rokitansky-Aschoff sinus revealed a relatively high signal intensity; however, it was not as strong as that of the spleen. The signal intensity was also high on an apparent diffusion coefficient map, suggesting T2 shine-through. The thickened wall displayed low signal intensity. The aforementioned results indicate that ADM may be negative upon DWIBS/T2 imaging; one false positive case was determined to be ADM, accompanied by chronic cholecystitis. The majority of patients with ADM displayed negative findings upon DWIBS/T2 imaging, and chronic cholecystitis may cause false positives.

Keywords: apparent diffusion coefficient; chronic cholecystitis; diffusion weighted imaging; magnetic resonance cholangiopancreatography.

Figure 1.

Diffusion-weighted whole body imaging with background body signal suppression (DWIBS)/T2-weighted image fusion (DWIBS/T2) of adenomyomatosis of gallbladder. (A and B) DWIBS/T2 observations for gallbladder wall thickening in a 65-year-old woman. High signal intensity is visible in the fundus of gallbladder (A) upon DWIBS/T2 imaging and (B) on the apparent diffusion coefficient (ADC) map, the latter indicating T2 shine-through. (C-F) DWIBS/T2 findings for gallbladder wall thickening in a 63-year-old man. (C) High signal intensity is observed in the fundus of the gallbladder upon DWIBS/T2 imaging. (D) No high signal is visible in the fundus of the gallbladder on the ADC map. The high signal intensity upon DWIBS/T2 imaging was determined as a positive finding, and suspected of malignancy. (E) Magnetic resonance cholangiopancreatography showing the pearl necklace sign. (F) Surgical specimen showing the proliferation of muscle fiber, and the dilated Rokitansky-Aschoff sinus (original magnification, ×40; scale bar, 500 µm). Lymphocyte infiltration is observed. The patient was later diagnosed with chronic cholecystitis and adenomyomatosis.