Although it has been reported that estrogen receptor (ER) expression coupled with glucose metabolism using ER imaging agents for PET, such as 16α-[18F]-fluoro-17β-estradiol and FDG PET, is useful for the differential diagnosis of leiomyomas and leiomyosarcomas, there were still some overlapping cases [21]. This evidence concerns the gene ESR1 and leiomyoma.