A study of uterine leiomyoma with FDG PET-CT

Objectives to investigate FDG uptake in uterine leiomyoma (UL) and assess the influencing factor of FDG uptake.

Methods FDG PET-CT of 1002 healthy females (group 1) and 2991 patients without malignant tumor of uterus (group2) were reviewed retrospectively. The diagnosis of UL were made based on CT and uterine sonography, and some of them on enhancement pelvic CT or MRI. The SUVmax of normal uterine and UL was determined. We defined FDG uptake in UL as Grade I, II, III, Ⅳ when FDG uptake was less or equal (SUVmax＜2.25), mild greater (2.25≤SUVmax＜4), significant greater (4≤SUVmax＜6), and intensive uptake (SUVmax≥6).

Results ULs were found in 174 of group 1 (17.4%) and 313 of group 2 (10.5%) respectively. Total detection rate was 12.2%. 45 (51 ULs) of them (9.2%) were found with increasing FDG uptake. The range of SUVmax in normal uterine is 0.56~2.47 (90% is 1~2.25). The FDG uptake in UL is Grade II in 12 of group 1(57.1%)and 8 of group 2 ( 33.8%), Grade III in 7 (33.3%) and 9 (37.5%)，and Grade Ⅳ in 2 (9.5%) and 7 (29.2%) respectively. 45 cases in Grade II~ Ⅳ were followed up for over 6 monthes and malinant were evacuated finally. Some of them were confirmed by histology after operation. 9 of them were postmenopausal women, and remanent 36 were in different stage of premenopause. There is no significant correlation between the intensity of FDG uptake in UL and menstrual cycle, age, size of UL, CTN.

Conclusions UL generally have mild or no FDG uptake, and uterine malignant tumors generally have intense FDG uptake. So PET/CT has been proved useful in assessing pelvic malignancies including differential diagnosis of tumor in uterine. But our results showed that about 10% of ULs can to have high uptake, and may show false positive result of PET/CT. Clinical follow-up visit with other examination of imageology is necessary if the result of PET-CT is uncertainty.