Fast Imaging Techniques
In the work of Mani et al (2013, 2014) we show that reconstructions of the diffusion signal from under-sampled data using the proposed k-q joint undersampling method yields accurate results. Specifically, our results show that accurate reconstruction with less than 5% reconstruction error is possible by using only 2-3 spatial interleaves per diffusion direction. This corresponds to an acquisition time of 6-8 mins for 17 slices at full FOV with a spatial resolution of 1mm2 in-plane. The proposed scheme can significantly accelerate the acquisition of high spatial and angular resolution diffusion imaging by accurately reconstructing crossing fiber architectures from under-sampled data.
Illustration of various HARDI acquisition schemes using a multishot spiral k-space trajectory. e: The proposed incoherent k-q under-sampling scheme jointly and incoherently under-samples the combined k-q space. Here, each q-space point is sampled at different k-space locations using random k-space shots. Only four shots are used here; however, instead of using the same four shots for all q-space points, they are sampled using different shots.
In vivo data at b=1200 s/mm2: (a) boxed region marked shows the reference anatomical location in the brain for which the ODFs are plotted, (b) ODF of fully sampled data, (c) ODF reconstructed using incoherent k-q scheme at R.8, 8, (d) ODF reconstructed using k-only scheme at R.8, (e) ODF reconstructed using q-only scheme at R.4. At acceleration of R.4, the angular resolution of the q-only scheme is compromised. The performance of k-only scheme is better than the q-only scheme. However, at R.8, k-only scheme fails to accurately represent the ODF profiles at many regions marked (arrows marked within in the three ovals). ODFs reconstructed using the incoherent k-q scheme resemble the fully sampled data more closely.
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