Diffusion tensor magnetic resonance imaging of the pancreas

Noam Nissan*, Talia Golan, Edna Furman-Haran, Sara Apter, Yael Inbar, Arie Ariche, Barak Bar-Zakay, Yuri Goldes, Michael Schvimer, Dov Grobgeld, Hadassa Degani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To develop a diffusion-tensor-imaging (DTI) protocol that is sensitive to the complex diffusion and perfusion properties of the healthy and malignant pancreas tissues. Materials and Methods: Twenty-eight healthy volunteers and nine patients with pancreatic-ductal-adenocacinoma (PDAC), were scanned at 3T with T2-weighted and DTI sequences. Healthy volunteers were also scanned with multi-b diffusion-weighted-imaging (DWI), whereas a standard clinical protocol complemented the PDAC patients' scans. Image processing at pixel resolution yielded parametric maps of three directional diffusion coefficients λ1, λ2, λ3, apparent diffusion coefficient (ADC), and fractional anisotropy (FA), as well as a λ1-vector map, and a main diffusion-direction map. Results: DTI measurements of healthy pancreatic tissue at b-values 0,500 s/mm2 yielded: λ1=(2.65±0.35) × 10-3, λ2=(1.87±0.22) × 10-3, λ3=(1.20±0.18) × 10-3, ADC=(1.91±0.22) × 10-3 (all in mm2/s units) and FA=0.38±0.06. Using b-values of 100,500 s/mm2 led to a significant reduction in λ1, λ2, λ3 and ADC (p<.0001) and a significant increase (p<0.0001) in FA. The reduction in the diffusion coefficients suggested a contribution of a fast intra-voxel-incoherent-motion (IVIM) component at b≤100 s/mm2, which was confirmed by the multi-b DWI results. In PDACs, λ1, λ2, λ3 and ADC in both 0,500 s/mm2 and 100,500 s/mm2 b-values sets, as well as the reduction in these diffusion coefficients between the two sets, were significantly lower in comparison to the distal normal pancreatic tissue, suggesting higher cellularity and diminution of the fast-IVIM component in the cancer tissue. Conclusion: DTI using two reference b-values 0 and 100 s/mm2 enabled characterization of the water diffusion and anisotropy of the healthy pancreas, taking into account a contribution of IVIM. The reduction in the diffusion coefficients of PDAC, as compared to normal pancreatic tissue, and the smaller change in these coefficients in PDAC when the reference b-value was modified from 0 to 100 s/mm2, helped identifying the presence of malignancy.

Original languageEnglish
Article numbere115783
JournalPLoS ONE
Volume9
Issue number12
DOIs
StatePublished - 30 Dec 2014

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