If the subject is healthy and the activation region in the LV excluded regions adjacent to the brain tissue, then your finding is odd if the data were analyzed in the subject native space and not using excessive normalization or smoothing.
Biophyscially and based on published studies, Oxygen dissolved in CSF can indeed alter the MRI signal by lowering (at least) the T1 relaxation time. This phenomenon has been well-dcoumented on
patients under anesthesis when imaged using FLAIR (1,2). Look also at some studies on the effects of CSF on the tissue parenchyma signal, but not from the partial volume angle (3-4)
1. Deliganis AV, Fisher DJ, Lam AM, Maravilla KR. Cerebrospinal fluid signal intensity increase on FLAIR MR images in patients under general anesthesia: the role of supplemental O2.
Radiology. 2001;218(1):152-6.
2. Zaharchuk G, Martin AJ, Rosenthal G, Manley GT, Dillon WP. Measurement of cerebrospinal fluid oxygen partial pressure in humans using MRI.
Magn Reson Med. 2005;54(1):113-21.
3. Piechnik SK, Evans J, Bary LH, Wise RG, Jezzard P. Functional changes in CSF volume estimated using measurement of water T2 relaxation.
Magn Reson Med. 2009;61(3):579-86.
4. Hasan KM, Moeller GF, Narayana PA. DTI-based Segmentation and Quantification of Human Brain Lateral Ventricular CSF Volumetry and Mean Diffusivity: Validation,
Age, Gender effects and Biophysical Implications. Magn Reson Imaging 2014 (10.1016/j.mri.2014.01.014).
Khader M Hasan, PhD
Associate Professor of Radiology
MSE 168, Tel 713 500 7690 (FAX 713 500 7684)
University of Texas Health Science Center at Houston
Medical School
Diagnostic and Interventional Imaging
Magnetic Resonance Imaging Research Division
Diffusion Tensor Imaging Lab, Tel 713 500 7683
http://www.uth.tmc.edu/radiology/faculty/khader-m-hasan/index.html<http://www.uth.tmc.edu/radiology/faculty/hasan.html>
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From: SPM (Statistical Parametric Mapping) [[log in to unmask]] On Behalf Of Andy Yeung [[log in to unmask]]
Sent: Monday, February 10, 2014 5:28 AM
To: [log in to unmask]
Subject: [SPM] lateral ventricle activation
Dear all,
I have a subject with only activations in lateral ventricles...
Could it be due to any mis-pre-processing?
Thanks a lot in advance for giving me any advice.
Best,
Andy
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