3D Quantitative Synthetic MRI in the Evaluation of Multiple Sclerosis Lesions

S Fujita,K Kamagata,O Abe,S Aoki,A Hagiwara,N Hattori,S Kato,C Andica,K Yokoyama

doi:10.3174/ajnr.a6930

S Fujita, K Kamagata + Show 7 more

Open Access

https://doi.org/10.3174/ajnr.a6930

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Abstract

Synthetic MR imaging creates multiple contrast-weighted images based on a single time-efficient quantitative scan, which has been mostly performed for 2D acquisition. We assessed the utility of 3D synthetic MR imaging in patients with MS by comparing its diagnostic image quality and lesion volumetry with conventional MR imaging. Twenty-four patients with MS prospectively underwent 3D quantitative synthetic MR imaging and conventional T1-weighted, T2-weighted, FLAIR, and double inversion recovery imaging, with acquisition times of 9 minutes 3 seconds and 18 minutes 27 seconds for the synthetic MR imaging and conventional MR imaging sequences, respectively. Synthetic phase-sensitive inversion recovery images and those corresponding to conventional MR imaging contrasts were created for synthetic MR imaging. Two neuroradiologists independently assessed the image quality on a 5-point Likert scale. The numbers of cortical lesions and lesion volumes were quantified using both synthetic and conventional image sets. The overall diagnostic image quality of synthetic T1WI and double inversion recovery images was noninferior to that of conventional images (P = .23 and .20, respectively), whereas that of synthetic T2WI and FLAIR was inferior to that of conventional images (both Ps < .001). There were no significant differences in the number of cortical lesions (P = .17 and .53 for each rater) or segmented lesion volumes (P = .61) between the synthetic and conventional image sets. Three-dimensional synthetic MR imaging could serve as an alternative to conventional MR imaging in evaluating MS with a reduced scan time.

Highlights

BACKGROUND AND PURPOSESynthetic MR imaging creates multiple contrast-weighted images based on a single time-efficient quantitative scan, which has been mostly performed for 2D acquisition
Three-dimensional synthetic MR imaging could serve as an alternative to conventional MR imaging in evaluating MS with a reduced scan time
Diffuse periventricular lesions are most commonly observed, previous studies have shown that the cortical and juxtacortical lesion load is associated with cognitive impairment.[4,5]

Summary

Methods

Twenty-four patients with MS prospectively underwent 3D quantitative synthetic MR imaging and conventional T1-weighted, T2-weighted, FLAIR, and double inversion recovery imaging, with acquisition times of 9 minutes 3 seconds and 18 minutes 27 seconds for the synthetic MR imaging and conventional MR imaging sequences, respectively. 3D quantitative imaging was performed with 3D-quantification using an interleaved Look-Locker acquisition sequence with a T2 preparation pulse (3D-QALAS) sequence.[16,17] The 3D-QALAS sequence produces 5 raw images that are used to fit relaxation curves based on a least-squares approach. From these quantitative maps, synthetic MR images could be generated by setting arbitrary TRs, TEs, and TIs. 3D-QALAS and conventional imaging (3D T1WI, 2D axial T2WI, 3D FLAIR, and 3D DIR) were performed in the same session on all participants. All images were visually inspected by a radiologic technologist for gross movement artifacts

Results

Discussion

Conclusion