[Ultra-low field magnetic resonance in the diagnosis of ovarian lesions].

To investigate the diagnostic capabilities of ultra low field MRI in the characterization of adnexal conditions, 46 women (aged 17 to 83 years) with US diagnosis of tubo-ovarian diseases were examined with MRI. An 0.064 T permanent magnet was used (toshiba Access), with T1- and T2-weighted spin-echo (SE) sequences, 3D T1-weighted gradient-echo (GE) sequences and, in 5 patients, a STIR sequence. Compared with surgical (37 patients), needle biopsy (3 patients) and clinical follow-up (6 patients) findings, MR diagnostic accuracy was 86.9%, which is comparable with literature data at higher field strength. The most common diagnostic error in our series was in the differential diagnosis between dermoid cyst and endometriosis which exhibited similar MR patterns. This limitation seems to be overcome by using STIR sequences with 60 ms T1 which, at this field strength, can suppress fat signal completely, whereas blood signal intensity remains high. The MR signal patterns of each group of conditions are also reported: in some cases, such patterns differ from those reported at higher field strength due to different T1 and T2 tissue relaxation times.