Comparison of DWIBS/T2 image fusion and PET/CT for the diagnosis of cancer in the abdominal cavity

Abstract

Fusion images of diffusion-weighted whole-body imaging with background body signal suppression and T2-weighted image (DWIBS/T2) demonstrate a strong signal for malignancies, with a high contrast against the surrounding tissues, and enable anatomical analysis. In the present study, DWIBS/T2 was compared with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) for diagnosing cancer in the abdomen. Patient records, including imaging results of examination conducted between November 2012 and May 2014, were analyzed retrospectively. In total, 10 men (age, 73.6±9.6 years) and 8 women (age, 68.9±7.1 years) were enrolled into the current study. Of the enrolled patients, 2 were diagnosed with hepatocellular carcinoma, 1 with cholangiocellular carcinoma, 1 with liver metastasis, 2 with pancreatic ductal adenocarcinoma, 1 with renal cell carcinoma and 1 with malignant lymphoma. Benign lesions were also analyzed, including adenomyomatosis of the gallbladder (5 patients), intraductal papillary mucinous neoplasm (4 patients) and right adrenal adenoma (1 case). All the patients with cancer showed positive results on DWIBS/T2 images. However, only 7 out of 8 patients were positive with PET/CT. One patient with right renal cellular carcinoma was positive with DWIBS/T2, but negative with PET/CT. All the patients with benign lesions were negative with DWIBS/T2 and PET/CT. In conclusion, DWIBS/T2 was more sensitive in diagnosing cancer of organs in the abdominal cavity compared with PET/CT. Furthermore, negative results with DWIBS/T2 and PET/CT were useful for the diagnosis of benign lesions, such as adenomyomatosis of the gallbladder and intraductal papillary mucinous neoplasm.

Keywords: adenomyomatosis of the gallbladder; computed tomography; endoscopic ultrasonography; intraductal papillary mucinous neoplasm; pancreatic ductal adenocarcinoma.

Figure 1.

A representative case of pancreatic cancer in an 83-year-old man who presented with back pain. (A) Abdominal ultrasonography illustrates a low echo lesion (arrowheads) in the head of the pancreas. (B) Contrast-enhanced CT image demonstrating an unenhanced area (arrow). (C) T2-weighted image, which does not show an area with different intensity in the pancreas as compared with the surrounding tissues. (D) DWIBS demonstrating a significantly high intensity area (arrow). (E) DWIBS/T2 shows a high intensity area in the head of the pancreas. DWIBS clearly showed the extent of the cancer, while DWIBS/T2 enabled the evaluation of the extent of the cancer in the anatomical settings. (F) PET/CT shows a significantly high signal at the head of the pancreas; however, it was hard to evaluate the extent of the cancer with PET/CT. DWIBS, diffusion-weighted whole body imaging with background body signal suppression; DWIBS/T2, fusion of DWIBS and T2-weighted image; PET, positron emission tomography; CT, computed tomography.

Figure 2.

A representative case of renal cell carcinoma in an 81-year-old woman who visited our hospital with back pain and was diagnosed with acute cholangitis. (A) Contrast-enhanced CT image, demonstrating an enhanced tumor (arrow) in the right kidney at 10 sec after the administration of contrast medium. (B) The contrast enhancement agent was washed-out tumor at 180 sec. (C) DWIBS/T2 image, demonstrating a high intensity tumor. (D) The tumor is negative on the PET/CT image. DWIBS/T2, diffusion-weighted whole body imaging with background body signal suppression/T2-weighted image fusion; PET, positron emission tomography; CT, computed tomography.

Figure 3.

A representative case of intraductal papillary mucinous neoplasm in an 84-year-old man who was regularly followed-up for hepatitis B surface antibody (+). (A) Magnetic resonance cholangiopancreatography shows a cystic lesion (arrow) in the head of the pancreas. (B) Endoscopic US clearly shows a cystic lesion. (C) A T2-weighted image shows a high intensity area in the head of the pancreas. (D) The high intensity area is negative on the DWIBS image. (E) DWIBS/T2 image demonstrates no positive results in the head of the pancreas. (F) PET/CT is also negative for the cystic lesion in the pancreas head. The cystic lesion was finally diagnosed as an intraductal papillary mucinous neoplasm and the patient was followed-up for 30 months, with not evident changes. DWIBS/T2, diffusion-weighted whole body imaging with background body signal suppression/T2-weighted image fusion; PET, positron emission tomography; CT, computed tomography.