Accelerated Three-Dimensional Susceptibility Weighted Imaging of the Whole Spine of Fetus at 3T

Abstract

Objectives

To investigate the image quality and capability of generalized auto-calibrating partially parallel acquisition (GRAPPA) accelerated Three-dimensional (3D) susceptibility weighted imaging (SWI) of the whole spine at 3T.

Methods

A total of 37 pregnant women (gestation age 22 to 39 weeks, average 29± 3 weeks) with suspected fetal vertebral anomalies by ultrasound (US) screening underwent 3.0 T MR imaging with 3D SWI, conventional two-dimensional (2D) half-flourier acquisition single-shot turbo spin-echo (HASTE) and 3D true fast imaging with steady-state precession (True FISP). The acquisition time of each protocol was recorded. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were determined in representative interest regions of fetal thoracic vertebrae and compared among three pulse sequences. Two radiologists rated image quality independently in random order on a 5-point scale. Kappa coefficients were computed to assess inter-observer reliability. Receiver operating characteristic curves were generated, and the area under the curve (AUC) was used to compare the diagnostic performance of each protocol in vertebral deformities.

Results

The acquisition time was 15 seconds for 3D-SWI and 17 seconds for 3D True FISP, significantly shorter than conventional HASTE (37 seconds; both P<0.01). Of the three protocols, The SNR was highest on 3D True FISP, while the CNR was highest on 3D SWI. Visualization of all segments of the whole spine by 3D SWI was comparable with 3D True FISP. In contrast, 3D SWI and 3D True FISP depicted cervical and sacrococcygeal vertebrae better than HASTE. The weighted kappa statistic was 0.70-0.89 to evaluate the image quality of all segments of the whole spine, indicating good to excellent interobserver agreement. 3D SWI had the highest diagnostic performance for detecting fetal vertebral anomalies (AUC=0.92)

Conclusions

3D-SWI is feasible for improved visualization of the whole fetal vertebral column and its congenital malformations with adequate image quality and high accuracy, thereby providing a supplementary method to conventional MR imaging.