AJR: 3D MR technique shows promise for pelvic imaging in women

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A 3D SPACE MR sequence outperformed conventional 2D weighted MRI techniques of the pelvis, conserving image quality and diagnostic data, providing reconstruction versatility and saving time, according to a study published in the July edition of the American Journal of Roentgenology.

MRI plays a valuable role in noninvasive pelvic imaging of the gynecologic anatomy; however, routine protocols are sometimes modified to address specific diagnostic questions. Standardized pelvic MRI protocols and simplified sequences per exam could help decrease exam time and benefit throughput, explained lead author Nicole Proscia, MD, of the department of radiology at Duke University Medical Center in Durham, N.C., in an interview.

Proscia and colleagues decided to leverage a 3D T2-weighted TSE sequence, sampling perfection with application-optimized contrast with flip-angle evolutions (SPACE), as a standard protocol and single source dataset for post-processing images into any plane. Researchers compared SPACE acquisition time, image quality, presence of artifacts and lesion detection with the pelvic MRI workhorse--2D T2-weighted turbo spin-echo (TSE) sequences in multiple planes.

Forty-four women with an average age of 49.4 years, referred for pelvic MRI for a variety of clinical indications, were enrolled in the study. Standardized MRI sequences for all patients included: three-plane localizer; coronal HASTE; axial T1-weighted 2D TSE; axial, coronal and sagittal T2-weighted 2D TSE; and sagittal T2-weighted 3D TSE with SPACE.

Researchers surveyed five radiologists to determine slice thickness for each 3D plane and then reformatted all 44 sagittal 3D datasets into 2 mm datasets. Radiologists compared 3D datasets with the 2D TSE images acquired in the axial, coronal and sagittal planes and graded them for image quality, artifacts and lesion detection.

“The difference between the mean acquisition time for the sagittal 3D TSE sequence and the mean acquisition time for the 2D TSE sequences in three planes was highly statistically significant,” wrote the authors. Mean acquisition time for 3D images was six minutes 59 seconds compared with the total time of 12 minutes and eight seconds to acquire 2D TSE sequences in threes planes.

Image quality scores for overall image quality, image quality of the uterus, image quality of the ovaries, contrast between the junctional zone and myometrium, contrast between the junctional zone and endometrium, contrast between the cervical stroma and parametrium and contrast between the vagina and surrounding tissue were not significantly different for 2D and 3D datasets, Proscia and colleagues found. Readers preferred 3D reformats over 2D acquired images for contrast between the cervical epithelium and stroma, and they reported fewer motion-related artifacts on the 3D images.

Researchers concluded that replacing separate 2D acquisitions of pelvic MR data with multiplanar reconstructions obtained with the 3D SPACE sequence is a promising tool that provides efficiency, offers comparable image quality and delivers versatility because images can be reconstructed in any orientation.