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

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 2015.