# Two-shell acquisition for MSMT-CSD protocol recommendation?

**URL:** <https://community.mrtrix.org/t/two-shell-acquisition-for-msmt-csd-protocol-recommendation/8785>\
**Category:** Uncategorized\
**Created:** [June 10, 2026, 3:10pm UTC](https://community.mrtrix.org/t/two-shell-acquisition-for-msmt-csd-protocol-recommendation/8785 "2026-06-10T15:10:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Sebastian\_Navarrete](https://community.mrtrix.org/user_avatar/community.mrtrix.org/sebastian_navarrete/32/4712_2.png) [@Sebastian\_Navarrete](https://community.mrtrix.org/u/Sebastian_Navarrete)\
**Post date:** [June 10, 2026, 3:10pm UTC](https://community.mrtrix.org/t/two-shell-acquisition-for-msmt-csd-protocol-recommendation/8785/1 "2026-06-10T15:10:31Z")

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Hi MRtrix3 experts,

For the past years we have been acquiring single-shell data, but we now want to  
improve our DWI acquisition in order to use MSMT-CSD correctly.

I searched for multi-shell acquisition references and will list some of them here,  
as they may be useful to others as well:

**Thijs Dhollander:**  
[What sequence parameters do you recommend for multi-shell CSD?](https://community.mrtrix.org/t/what-sequence-parameters-do-you-recommend-for-multishell-csd/421)

- 6x b=0
- 20x b=1000
- 60x b=3000

**B.A.T.M.A.N. Tutorial** \*(not 100% certain on the b=0 total volumes):

- 8x b=0 (5 AP; 3 PA)
- 17x b=1000
- 31x b=2000
- 50x b=3000

**Tahedl, M., Tournier, J.-D., Smith, R.E., 2025** — _Structural connectome construction using constrained spherical  
deconvolution in multi-shell diffusion-weighted MRI_. Nat Protoc 20, 2652–2684.  
[https://doi.org/10.1038/s41596-024-01129-1](https://doi.org/10.1038/s41596-024-01129-1)

- 5x b=0 ( AP )
- 1x b=0 ( PA )
- 20x b=1000 (AP)
- 32x b=2000 (AP)
- 50x b=3000 (AP)

* * *

Given that we do not have multiband capability and have time constraints within our  
overall protocol, we plan to acquire a two-shell acquisition (b=0, b=1000, b=X).

Since increasing the maximum b-value increases acquisition time, we are debating  
between two options:

1. Acquiring **more volumes at a lower b-value (b=2000)**
2. Acquiring **fewer volumes at a slightly higher b-value (b=2500)**

Our uncertainty comes from the understanding that higher b-values require more volumes  
to compensate for the reduced signal intensity. We would therefore also like to ask for  
your recommendation regarding the number of volumes at b=2500.

For reference, Tahedl et al. (2025) report the following minimum volume requirements  
for each shell:

- b=2000 s/mm²: 32 volumes (where lmax=6 requires ≥28 volumes)
- b=3000 s/mm²: 50 volumes (where lmax=8 requires ≥45 volumes)

With this in mind, would the following two-shell protocols be considered appropriate,  
or would their quality be questioned?

**Option 1** _(fewer volumes, higher b-value)_:

- 6x b=0 (5 AP; 1 PA)
- 20x b=1000 (AP)
- 40x b=2500 (AP)

**Option 2** _(more volumes, lower b-value)_:

- 6x b=0 (5 AP; 1 PA)
- 20x b=1000 (AP)
- 60x b=2000 (AP)

We are particularly interested in which option would better support tractography using MSMT-CSD.

Thank you in advance,  
Sebastián