Dynamic susceptibility contrast parametric imaging using accelerated dual‐contrast echo planar imaging with keyhole

Background

Echo planar imaging (EPI) is one of the methods of choice in dynamic susceptibility contrast MRI (DSC‐MRI) because it provides a sufficient temporal resolution. However, the relatively long readout duration of EPI often imposes limitations on increased spatial coverage or the use of multiple contrasts.

Purpose

To develop a DSC‐MRI method using EPIK (EPI with keyhole) to provide dual‐contrast (TE₁ and TE₂) information with a higher spatial coverage than EPI. To compare results from the community‐standard EPI method and the proposed EPIK method.

Study Type

Prospective.

Subjects

One healthy subject and 17 brain tumor patients.

Field Strength/Sequence

3 T/accelerated EPI and dual‐contrast EPIK sequences.

Assessment

After an initial evaluation using healthy in vivo images, the use of the proposed method for DSC‐MRI was verified with brain tumor patients. The parametric images (eg, CBF and CBV) and arterial input function (AIF), obtained from both the EPI and EPIK, were compared.

Statistical Tests

The ratio of AIF peak height of the proposed method to that of EPI was computed. The ratio computation was also performed for the time‐to‐peak (TTP) in the AIF curves. From the obtained CBF and CBV maps, the tumor‐to‐brain (TBR) ratio was also calculated for each imaging method and the results were compared.

Results

For the same temporal resolution (1.5 sec), EPIK yielded dual‐contrast (TEs of 13/33 msec) with an increased spatial coverage (24 slices) and less geometric distortions than EPI; EPI provided single contrast (TE of 32 msec) with 20 slices. The obtained parametric values (eg, AIF peak, TTP, and TBR) had similar characteristics between EPI and the proposed method.

Data Conclusion

The dual‐contrast data produced by EPIK in DSC‐MRI allowed T₁‐corrected parametric images without the need of second contrast injection and an enhanced estimation of the AIF.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2019.

from #Head and Neck by Sfakianakis via simeraentaxei on Inoreader http://bit.ly/2C6qQzK