title: MR appearance of normal uterine endometrium considering menstrual cycle: differentiation with benign and malignant endometrial lesions.
abstract: Background The thickness and signal intensity (SI) of normal uterine endometrium on T2-weighted (T2W) imaging changes depend on the menstrual cycle phase. Cases of normal endometrium that appear similar to endometrial lesions sometimes occur, and may result in misdiagnosis. Purpose To investigate normal endometrial appearance in luteal phase (LP) compared to that in follicular phase (FP), and to differentiate these appearances with those of endometrial lesions. Material and Methods Thirty-two normal volunteers prospectively underwent magnetic resonance (MR) examinations during LP and FP. Patients with pathologically confirmed endometrial polyps ( n = 9), hyperplasia ( n = 7), and cancer ( n = 15), who underwent MR examinations, were evaluated for comparison. Endometrial appearance was categorized into the following five types on sagittal T2W imaging and compared between LP, FP, and endometrial lesions: type 1, homogeneous higher SI; type 2, homogeneous iso SI; type 3, a bright midline and a peripheral iso SI layer; type 4, a lower/iso SI central line; and type 5, heterogeneous lower/iso SI. Endometrial thickness and SI were measured and also compared. Results Endometrial lesions were more frequently categorized as type 5 than normal endometrium ( P < 0.05). Endometrial thickness in LP (mean, 1.0 cm) was significantly greater than that in FP (0.6 cm), but not significantly different from polyps (1.1 cm), hyperplasia (1.0 cm), and cancer (0.9 cm). SI in FP was significantly higher than that in LP and that of all endometrial lesions. Conclusion Differentiation between normal endometrium in LP and endometrial lesions may be difficult based on thickness alone. Heterogeneous low SI may help to differentiate normal endometrium from endometrial lesions. Performing MR imaging during FP may also help due to higher SI of normal endometrium.
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Fuki
authors.initials: F
authors.lastname: Shitano
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Aki
authors.initials: A
authors.lastname: Kido
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Kataoka
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Kiguchi
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Fushimi
authors.affiliation: 2 Department of Gynecology and Obstetrics, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Konishi
authors.affiliation: 1 Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D016889:Endometrial Neoplasms / Q000000981:diagnostic imaging*; D004717:Endometrium / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008597:Menstrual Cycle; D014599:Uterus / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Uterine endometrium; endometrial lesions; luteal phase; magnetic resonance imaging (MRI)