Incidence and characteristics of uterine leiomyomas with FDG uptake.
OBJECTIVE
Uterine leiomyomas sometimes show focal 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) images that may result in a false-positive diagnosis for malignant lesions. This study was conducted to investigate the incidence and characteristics of uterine leiomyomas that showed FDG uptake.


METHODS
We reviewed FDG-PET and pelvic magnetic resonance (MR) images of 477 pre-menopausal (pre-MP, age 42.1 +/- 7.3 years) and 880 post-MP (age 59.9 +/- 6.8 years) healthy women who underwent these tests as parts of cancer screening. Of 1357, 323 underwent annual cancer screening four times, 97 did three times, 191 did twice, and the rest were screened once. Focal FDG uptake (maximal standardized uptake value > 3.0) in the pelvis was localized and characterized on co-registered PET/MR images.


RESULTS
Uterine leiomyomas were found in 164 pre-MP and 338 post-MP women. FDG uptake was observed in 18 leiomyomas of 17 of the 164 (10.4%) pre-MP women and in 4 leiomyomas of 4 of the 338 (1.2%) post-MP women. The incidence was significantly higher in pre-MP women than in post-MP women (chi-square, P < 0.001). Of the 22, 13 showed signal intensity equal to or higher than that of the myometrium on T2-weighted MR images, which suggested abundant cellularity, whereas the majority of leiomyomas without FDG uptake showed low signal intensity. Of the 13 women, 12 examined more than twice showed substantial changes in the level of FDG uptake in leiomyomas each year with FDG uptake disappearing or newly appearing. These changes were observed frequently in relation with menopause or menstrual phases.


CONCLUSIONS
Leiomyomas with focal FDG uptake were seen in both pre-and post-MP women with a higher incidence in pre-MP women. Abundant cellularity and hormonal dependency may explain a part of the mechanisms of FDG uptake in leiomyomas. It is important to know that the level of FDG uptake in leiomyomas can change and newly appearing FDG uptake does not necessarily mean malignant transformation.
Nishizawa
Sadahiko
S
Hamamatsu Medical Imaging Center, Hamamatsu Medical Photonics Foundation, 5000 Hirakuchi, Hamamatsu, Shizuoka, 434-0041, Japan. sadahiko@hmp.or.jp
Inubushi
Masayuki
M
Kido
Aki
A
Miyagawa
Masao
M
Inoue
Takeshi
T
Shinohara
Katsura
K
Kajihara
Makoto
M
D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D007889:Leiomyoma / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000378:metabolism; D008875:Middle Aged; D017698:Postmenopause / Q000378:metabolism; D017697:Premenopause / Q000378:metabolism; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D014594:Uterine Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology* / Q000378:metabolism
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18