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FIGURE 4. Patient was 43-y-old woman who consulted our hospital because of chief complaint of large palpable intrapelvic tumor (patient 39). MRI showed huge mass in front of sacrum and on right side of uterus. On basis of its location, mass was considered to be ovarian tumor. (A) This mass generally showed low intensity on T1- and T2-weighted images, suggesting that it contained fibrous components. However, high-intensity area was shown inside mass on T2-weighted image. MRI failed to differentiate whether mass was malignant or benign. (B) 18F-FDG PET showed heterogeneous 18F-FDG accumulation (SUV = 3.93) in this mass lesion, but high 18F-FDG accumulation was not seen in area of strong T2 signal. On basis of these findings, malignancy could not be excluded. After surgical treatment, mass was histologically diagnosed as fibroma. This case was the only false-positive case evaluated by SUV.
