Pseudolesions related to uterine contraction: characterization with multiphase-multisection T2-weighted MR imaging

To evaluate whether multiphase-multisection T2-weighted magnetic resonance (MR) images help exclude pseudolesions mimicking leiomyoma and adenomyosis on static T2-weighted fast spin-echo (FSE) MR images and to characterize temporal changes in uterine signal intensity related to uterine contraction.

T2-weighted FSE and multiphase-multisection single-shot FSE (SSFSE) MR imaging were performed in 43 patients who underwent hysterectomy. Each imaging set was evaluated separately by two independent readers, and receiver operating characteristic analysis was performed. In the 43 patients and in 49 other patients suspected of having pelvic abnormality, a combination of signal intensity changes on FSE and SSFSE MR images was classified into five patterns, and temporal low-signal-intensity changes on SSFSE MR images were characterized.

For detection of leiomyoma on FSE and SSFSE MR images, the respective values of the area under the receiver operating characteristic curve were 0.98 and 0.97 for reader 1 and 0.96 and 0.96 for reader 2; for detection of adenomyosis on FSE and SSFSE MR images, the respective values were 0.82 and 0.84 for reader 1 and 0.80 and 0.89 for reader 2 (P >.05). SSFSE MR images helped exclude pseudolesions in 1%-3% cases of leiomyoma and in 3%-4% cases of adenomyosis. Temporal signal intensity changes were observed in 53% of 368 segments. The most frequent shape of temporal low signal intensity was diffuse followed by ill-defined focal type. Characteristic shape of temporal low signal intensities was band- or sticklike, which was observed in as many as 19% of 368 segments.

Multiphase-multisection T2-weighted SSFSE MR images do not improve accuracy in detection of leiomyoma and adenomyosis compared with FSE MR images; however, they helped characterize features of temporal low signal intensities in the uterus, which are related to uterine contractions.