Usefulness of fat-suppressed T1-weighted MRI using orally administered superparamagnetic iron oxide for revealing ampullary carcinomas

OBJECTIVE: To evaluate the value of adding fat-suppressed (FS) T1-weighted magnetic resonance imaging (MRI) with orally administered superparamagnetic iron oxide (SPIO) to the 3-dimensional dynamic MRI for revealing ampullary carcinomas. MATERIALS: Twenty-five patients with ampullary carcinoma who underwent MRI with orally administered SPIO, including a FS T1-weighted fast low-angle shot (FLASH) sequence, a respiratory-triggered turbo spin-echo (RT-TSE) sequence, and the 3-phasic 3-dimensional dynamic images, were enrolled in this study. About 5 min before the examination, a mixture of 8.4 mg of SPIO and 300 mL water was administered orally to all patients. The images were compared quantitatively by measuring the tumor-pancreas (duodenum) contrast-to-noise ratio and, qualitatively, by evaluating tumor conspicuity. Three separate sets of images, that is, the dynamic set, the combination of the dynamic set, and the RT-TSE, and the combination of the dynamic set and the FLASH were analyzed by 2 observers in consensus. RESULTS: For the tumor-pancreas (duodenum) contrast-to-noise ratio, the FLASH was significantly higher than those of the dynamic set and RT-TSE (P < 0.05). The tumor conspicuity with the combination of the dynamic set and the FLASH was also significantly better than those of the dynamic set, and the combination of the dynamic set and RT-TSE (P = 0.001). For 15 tumors that were surgically confirmed, the combined reading of the FLASH imaging and dynamic set allowed more accurate surgical staging (14/15, 93.3%) than did the dynamic imaging set or the combined reading of the dynamic set and RT-TSE (11/15, 73.3%). CONCLUSIONS: Addition of the FS FLASH image using orally administered SPIO to the dynamic MRI is useful for revealing ampullary carcinoma.