Measurement of brain volume change due to acute modification of intracranial pressure
If you would like to help with this study as a master's or bachelor's thesis project, please send Bryn Martin an email with your resume and research interests.
The intracranial volume of brain tissue and fluids in neurological disorders such as Hydrocephalus is known to be abnormal. However, the rate at which the brain tissue volume change occurs is not known. In modeling approaches, such as finite element models of the hydrocephalic brain, it has been assumed that change in brain volume occurs over long periods of time (months or years).
It is possible that intracranial volume of brain tissue and fluids changes in minutes after acute changes in intracranial hydrodynamics. For example, it is known that the brain size can change in a short period after placement of a shunt in hydrocephalus patients. It has also been found that the brain structure can change in a short time scale due to learning new skills such as vocabulary or musical instruments (Lee, Devlin et al. 2007). Studies have also shown that cerebrospinal fluid can flow quickly into the perivascular spaces of the brain and spinal cord and that the perivascular flow can be increased following injury to the neural tissue (Stoodley, Jones et al. 1996; Stoodley, Brown et al. 1997). Collectively, these studies support that the brain tissue volume could change more rapidly than currently thought.
Detection of small changes in brain volume is possible with advanced MRI anatomy techniques. Advances in MRI imaging have provided new automated techniques for fast and accurate measurement of brain anatomy such as volume (Smith, Jenkinson et al. 2004; Heckemann, Hajnal et al. 2006). These techniques have been shown to result in more accurate measurement of brain volume than manual segmentation techniques with ??? error in volume. Thus, the precision of MRI anatomical measurements may be able to detect changes in brain volume that occur due to acute changes in intracranial pressure. However, a specific study to examine these changes has not been conducted.
Hypothesis and research objectives
We hypothesize that a change in intracranial brain tissue and or fluid volumes can be detected in healthy subjects within minutes after introduction of an acute change in mean intracranial pressure due to usage of continuous positive airway pressure or queckenstedt’s test. We expect these changes to occur in a sigmoidal fashion based on the level of intracranial pressure purturbation and time.
Methods and study outline
We propose to conduct high resolution anatomical MRI measurements of the brain and cerebrospinal fluid under normal conditions and under acute modification of intracranial pressure in healthy subjects. The duration of the entire project is estimated to be 1 year.
- Measurement protocol. T1 weighted MRI sequence conducted before and after jugular vein compression or CPAP application (to modify ICP).
- Data analysis. Linear measurement of brain dimensions and volumetric measurement of ventricles and brain.
Expected results and potential impact
This project will quantify brain volume change due to acute modification of intracranial pressure in healthy subjects. If a significant level of brain volume change is detected, the study will support a hypothesis that the brain anatomy is more active than previously assumed.
To be posted.
Heckemann, R. A., J. V. Hajnal, et al. (2006). "Automatic anatomical brain MRI segmentation combining label propagation and decision fusion." Neuroimage 33(1): 115-126.
Lee, H., J. T. Devlin, et al. (2007). "Anatomical traces of vocabulary acquisition in the adolescent brain." The Journal of neuroscience : the official journal of the Society for Neuroscience 27(5): 1184-1189.
Smith, S. M., M. Jenkinson, et al. (2004). "Advances in functional and structural MR image analysis and implementation as FSL." Neuroimage 23: S208-S219.
Stoodley, M. A., S. A. Brown, et al. (1997). "Arterial pulsation-dependent perivascular cerebrospinal fluid flow into the central canal in the sheep spinal cord." J Neurosurg 86(4): 686-693.
Stoodley, M. A., N. R. Jones, et al. (1996). "Evidence for rapid fluid flow from the subarachnoid space into the spinal cord central canal in the rat." Brain Res 707(2): 155-164.