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Mapping prostatic microscopic anisotropy using linear and spherical b-tensor encoding : A preliminary study

Nilsson, Markus LU ; Eklund, Greta LU ; Szczepankiewicz, Filip LU orcid ; Skorpil, Mikael ; Bryskhe, Karin LU ; Westin, Carl Fredrik ; Lindh, Claes ; Blomqvist, Lennart and Jäderling, Fredrik (2021) In Magnetic Resonance in Medicine 86(4). p.2025-2033
Abstract

Purpose: Tensor-valued diffusion encoding provides more specific information than conventional diffusion-weighted imaging (DWI), but has mainly been applied in neuroimaging studies. This study aimed to assess its potential for the imaging of prostate cancer (PCa). Methods: Seventeen patients with histologically proven PCa were enrolled. DWI of the prostate was performed with linear and spherical tensor encoding using a maximal b-value of 1.5 ms/µm2 and a voxel size of 3 × 3 × 4 mm3. The gamma-distribution model was used to estimate the mean diffusivity (MD), the isotropic kurtosis (MKI), and the anisotropic kurtosis (MKA). Regions of interest were placed in MR-defined cancerous tissues, as... (More)

Purpose: Tensor-valued diffusion encoding provides more specific information than conventional diffusion-weighted imaging (DWI), but has mainly been applied in neuroimaging studies. This study aimed to assess its potential for the imaging of prostate cancer (PCa). Methods: Seventeen patients with histologically proven PCa were enrolled. DWI of the prostate was performed with linear and spherical tensor encoding using a maximal b-value of 1.5 ms/µm2 and a voxel size of 3 × 3 × 4 mm3. The gamma-distribution model was used to estimate the mean diffusivity (MD), the isotropic kurtosis (MKI), and the anisotropic kurtosis (MKA). Regions of interest were placed in MR-defined cancerous tissues, as well as in apparently healthy tissues in the peripheral and transitional zones (PZs and TZs). Results: DWI with linear and spherical encoding yielded different image contrasts at high b-values, which enabled the estimation of MKA and MKI. Compared with healthy tissue (PZs and TZs combined) the cancers displayed a significantly lower MD (P <.05), higher MKI (P < 10−5), and lower MKA (P <.05). Compared with the TZ, tissue in the PZ showed lower MD (P < 10−3) and higher MKA (P < 10−3). No significant differences were found between cancers of different Gleason scores, possibly because of the limited sample size. Conclusion: Tensor-valued diffusion encoding enabled mapping of MKA and MKI in the prostate. The elevated MKI in PCa compared with normal tissues suggests an elevated heterogeneity in the cancers. Increased in-plane resolution could improve tumor delineation in future studies.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
diffusion-weighted imaging, heterogeneity, microscopic anisotropy, prostate cancer, tensor-valued diffusion encoding
in
Magnetic Resonance in Medicine
volume
86
issue
4
pages
9 pages
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85107007467
  • pmid:34056750
ISSN
0740-3194
DOI
10.1002/mrm.28856
language
English
LU publication?
yes
id
b35aed0c-d2d4-4709-85a7-3d95c3545fc4
date added to LUP
2021-12-09 15:40:35
date last changed
2024-06-17 01:04:33
@article{b35aed0c-d2d4-4709-85a7-3d95c3545fc4,
  abstract     = {{<p>Purpose: Tensor-valued diffusion encoding provides more specific information than conventional diffusion-weighted imaging (DWI), but has mainly been applied in neuroimaging studies. This study aimed to assess its potential for the imaging of prostate cancer (PCa). Methods: Seventeen patients with histologically proven PCa were enrolled. DWI of the prostate was performed with linear and spherical tensor encoding using a maximal b-value of 1.5 ms/µm<sup>2</sup> and a voxel size of 3 × 3 × 4 mm<sup>3</sup>. The gamma-distribution model was used to estimate the mean diffusivity (MD), the isotropic kurtosis (MK<sub>I</sub>), and the anisotropic kurtosis (MK<sub>A</sub>). Regions of interest were placed in MR-defined cancerous tissues, as well as in apparently healthy tissues in the peripheral and transitional zones (PZs and TZs). Results: DWI with linear and spherical encoding yielded different image contrasts at high b-values, which enabled the estimation of MK<sub>A</sub> and MK<sub>I</sub>. Compared with healthy tissue (PZs and TZs combined) the cancers displayed a significantly lower MD (P &lt;.05), higher MK<sub>I</sub> (P &lt; 10<sup>−5</sup>), and lower MK<sub>A</sub> (P &lt;.05). Compared with the TZ, tissue in the PZ showed lower MD (P &lt; 10<sup>−3</sup>) and higher MK<sub>A</sub> (P &lt; 10<sup>−3</sup>). No significant differences were found between cancers of different Gleason scores, possibly because of the limited sample size. Conclusion: Tensor-valued diffusion encoding enabled mapping of MK<sub>A</sub> and MK<sub>I</sub> in the prostate. The elevated MK<sub>I</sub> in PCa compared with normal tissues suggests an elevated heterogeneity in the cancers. Increased in-plane resolution could improve tumor delineation in future studies.</p>}},
  author       = {{Nilsson, Markus and Eklund, Greta and Szczepankiewicz, Filip and Skorpil, Mikael and Bryskhe, Karin and Westin, Carl Fredrik and Lindh, Claes and Blomqvist, Lennart and Jäderling, Fredrik}},
  issn         = {{0740-3194}},
  keywords     = {{diffusion-weighted imaging; heterogeneity; microscopic anisotropy; prostate cancer; tensor-valued diffusion encoding}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{2025--2033}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Magnetic Resonance in Medicine}},
  title        = {{Mapping prostatic microscopic anisotropy using linear and spherical b-tensor encoding : A preliminary study}},
  url          = {{http://dx.doi.org/10.1002/mrm.28856}},
  doi          = {{10.1002/mrm.28856}},
  volume       = {{86}},
  year         = {{2021}},
}