Estimated signal variation in the background was too small (MAD=0.0, sigma=2.6593)

[MirandaChang1]

What happened?

I have been using MRIQC on T1w and T2w scans, and the participant level results generate fine, however towards the end, it shows me the following warnings. This has been consistent across all participants I have run, but the MRIQC json files and html files generate properly. What is this warning referring to and is it something we would need to address? Would this have an effect on the main MRIQC metrics of interest, such as CJV, CNR, SNR, or is it alright?

What command did you use?

apptainer run --cleanenv /home/mchang2/containers/mriqc_24.0.2.sif /home/mchang2/scratch/neuro_prelim_analysis3 /home/mchang2/scratch/mriqc_results2 participant --participant-label BRS0173 --session-id 1 --n_procs 8 --mem_gb 32 --modalities T1w T2w

What version of the software are you running?

MRIQC version 24.1.0.dev0+gd5b13cb5.d20240826

How are you running this software?

Singularity

Is your data BIDS valid?

Yes

Are you reusing any previously computed results?

No

Please copy and paste any relevant log output.

2025-10-23 20:19:45 | INFO     | niworkflows      | Generating visual report
/opt/conda/lib/python3.11/site-packages/mriqc/interfaces/anatomical.py:490: RuntimeWarning: divide by zero encountered in divide
  bg_data[bg_data > 0] = bg_data[bg_data > 0] / bg_spread
2025-10-23 20:21:02 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=2.6593)
2025-10-23 20:21:02 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=2.6593)
2025-10-23 20:21:02 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=2.6593)
2025-10-23 20:21:47 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=726.7093)
2025-10-23 20:21:47 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=726.7093)
2025-10-23 20:21:47 | WARNING  | nipype.interface | Estimated signal variation in the background was too small (MAD=0.0, sigma=726.7093)
2025-10-23 20:21:56 | WARNING  | mriqc            | IMPORTANT: Anonymized quality metrics (IQMs) will be submitted to MRIQC's metrics repository. Submission of IQMs can be disabled using the ``--no-sub`` argument. Please visit https://mriqc.readthedocs.io/en/latest/dsa.html to revise MRIQC's Data Sharing Agreement.
2025-10-23 20:21:56 | IMPORTANT | mriqc            | Participant level finished successfully averaging 00h 02min 48s per subject.
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  MRIQC completed (elapsed time 00h 05min 37s).
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Additional information / screenshots

No response