Multishot Echoplanar MR Imaging of the Female Pelvis: Comparison with T2 weighted Fast Spin Echo Imaging

PURPOSE: To compare the usefulness of multishot echoplanar imaging (EPI) with T2-weighted fast spin-echoimaging (FSE) for the evaluation of female pelvic organs and pathologic conditions. MATERIALS AND METHODS:Twenty-nine patients with pelvic lesion underwent MR imaging (GE Medical Systems) using a pelvic array coil (GEMedical Systems). Axial EPI (TR/TE=2,000/80, 6mm slice thickness, 2.5mm gap, multishot 16) and T2-weighted FSE(TR/TE=3,400/117, 5mm slice thickness, 1.5mm gap, ETL=12) were obtained. Overall image quality, the parametrialvenous plexus, anatomy of the uterine zone and outer margin, identification of the ovaries, pelvic pathologiccondition, and frequency of artifact, as seen on EPI and FSE imaging were reviewed separately by two radiologists. RESULTS: For overall imaging quality, EPI was superior to FSE in 14% of patients(4/29), equal in 24%(7/29), andinferior in 62%(18/29). For delineation of the parametrial venous plexus, EPI was superior to FSE in 79%(23/29).For uterine zonal anatomy and the outer margin, EPI was inferior to FSE in 55%(16/29) and in 45%(13/29),respectively. On EPI, visualization of the ovary was rated superior to FSE in 0%(0/9), equal in 52%(15/29), andinferior in 48%(14/29). Conspicuity of pelvic pathologic lesions was superior in 14%(4/29), equal in 52%(15/29),and inferior in 48%(14/29). Image distortion and susceptibility artifacts were seen on EPI in six cases, while onFSE motion artifacts were seen in two cases. CONCLUSIONS: As EPI is inferior to FSE in overall image quality,delineation of the normal anatomy of pelvic organs and conspicuity of pelvic lesions, it cannot replace FSE forimaging the female pelvis. However, because EPI reduces imaging time, further technical progress in this area maystimulate the use of ultrafast imaging of the femal pelvis.

Comparison of FSE and EPI with Brain MR Imaging

PURPOSE: To compare the usefulness of echo-planar imaging (EPI) and fast spin-echo (FSE) in routine brain MR imaging. MATERIALS AND METHODS: Twenty-five patients with various intracranial diseases were prospectively examined with T2-weighted MR imaging on a 1.5T unit using FSE, spin echo singl-shot EPI (SS-EPI) and multi-shot EPI (MS-EPI) techniques. For qualitative assessment, overall image quality, discrimination between cortical gray-white matter and between basal ganglia-white matter, lesion conspicuity, image distortion and artifacts (motion, ghost, flow, and susceptibility) were all evaluated using a subjective scoring system ranging from 1 to 4 (1 for the worst and 4 for the best). For quantitative assessment, contrast and contrast-to-noise ratio (CNR) were calculated for cortical gray-white matter, basal ganglia-white matter, and lesion-white matter. RESULTS: Overall image quality, discrimination between cortical gray-white matter, basal ganglia-white matter, and lesion-white matter, lesion conspicuity, image distortion and susceptibility artifacts showed the highest value in FSE and the lowest in SS-EPI. Motion artifacts were seen only in FSE, while flow and ghost artifacts were most commonly seen in SS-EPI. Contrast and CNR of anatomical and pathologic structures showed the highest value in FSE, especially for cortical gray-white matter and basal ganglia-white matter . CONCLUSION: With regard to overall image quality, image distortion, susceptibility artifacts, contrast and CNR, EPI is far inferior to FSE. In routine brain MR imaging., the usefulness of EPI techniques would therefore be very limited.