Distortion correction of echo-planar diffusion-weighted images of uterine cervix

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Abstract

Purpose:

To investigate the clinical utility of the reverse gradient algorithm in correcting distortions in diffusion-weighted images of the cervix and for increasing diagnostic performance.

Materials and Methods:

Forty-one patients ages 25–72 years (mean 40 ± 11 years) with suspected or early stage cervical cancer were imaged at 3T using an endovaginal coil. T2-weighted (W) and diffusion-weighted images with right and left phase-encode gradient directions were obtained coronal to the cervix (b = 0, 100, 300, 500, 800 s mm−2). Differences in angle of the endocervical canal to the x-axis between T2W and right-gradient, left-gradient, and corrected images were measured. Uncorrected and corrected images were assessed for diagnostic performance when viewed together with T2W images by two independent observers against subsequent histology.

Results:

The angles of the endocervical canal relative to the x-axis were significantly different between the T2W images and the right-gradient images (P = 0.007), approached significance for left-gradient images (P = 0.055), and were not significantly different after correction (P = 0.95). Corrected images enabled a definitive diagnosis in 34% (n = 14) of patients classified as equivocal on uncorrected images. Tumor volume in this subset was 0.18 ± 0.44 cm3 (mean ± SD; sensitivity of detection 100% [8/8], specificity 50% [3/6] for an experienced observer). Correction did not improve diagnostic performance for the less-experienced observer.

Conclusion:

Distortion-corrected diffusion-weighted images improved correspondence with T2W images and diagnostic performance in a third of cases. J. Magn. Reson. Imaging 2016;43:1218–1223.

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