Pitfall in Differentiation of Hemorrhagic Vs. Fatty Lesions in Female Pelvis Using Fat Saturated Sequences With Inversion Recovery - Role of T1 FATSAT Sequence - A Case Report with Radiological Review

T1 hyperintense structure in female pelvis can be either a hemorrhagic lesion or fat containing lesion. FATSAT technique is integral part of workup of any T1 hyperintense structures in female pelvis for differentiation of hemorrhagic lesion and fat containing mature ovarian teratoma for tissue characterization. We present a case of hematometra with blood in bilateral fallopian tubes due to cervical stenosis. The hemorrhagic content appear hyperintense on both T1WI and T2WI. An unexpected signal decrease in FATSAT T2WI inversion recovery sequence (STIR) was encountered. Suppression of signal in tissue with similar T1 relaxation time as fat can lead to diagnostic pitfall in T1WI and T2WI STIR pulse sequence. Also loss of signal on T2WI can be due to T2 "shading" in T1 bright ovarian endometrioma. Hence, fat specific spectral fat saturation on T1WI (FATSAT T1) is strongly recommended for tissue characterization in gynaecological diseases. This sequence is useful in cases of ovarian endometrioma and hematometra.