MRI Measurements of Craniospinal and Intracranial Volume Change in Healthy and Head Trauma Cases

Abstract

The volumes of the intracranial space and the craniospinal system as a whole change during the cardiac cycle. These volume changes are caused by the pulsatile arterial inflow to the cranium, venous outflow from the cranium, and cerebrospinal fluid (CSF) flow that oscillates back and forth between the cranium and the spinal canal. The volume changes can be measured accurately and reproducibly using a dynamic, motion-sensitive MRI technique [1]. It appears intuitive that the volume change of the entire craniospinal system (CSVC) should be greater than the intracranial volume change (ICVC). However, since they exhibit varying temporal information, CSVC can be smaller than ICVC. In the present study, these volume changes were measured in healthy humans and trauma cases. In the trauma cases, it was found that CSVC was smaller than ICVC. The cause was found to be increased pulsatility in the venous flow channels. It is suspected that the resulting relationship between ICVC and CSVC is related to the incidence of trauma, and perhaps CSVC being smaller than ICVC could serve as an indicator. The craniospinal system consists of two subcompartments, the intracranial space (skull) and the spinal canal. Cerebrospinal fluid (CSF) oscillates back and forth between these two subcompartments. The system can be modeled with arterial inflow and venous outflow. During systole, arterial blood rushes into the cranium, forcing the CSF out into the spinal canal. As the blood drains through venous channels during diastole, the CSF refills the cranium. Since this is a closed system, the entire craniospinal system volume change (CSVC) can be found by subtracting the venous (V) outflow from the arterial (A) inflow and examining the peak to peak change in the integral of A-V over one cardiac cycle. If the CSF flow is also subtracted from the A-V flow, the intracranial volume change (ICVC) can be obtained similarly. This method is used to measure the intracranial compliance and pressure from the ratio of volume and pressure changes that occur during the cardiac cycle [2]. II. METHODArterial, venous, and CSF flows were measured using a dynamic, motion-sensitive MRI technique [1]. This technique results in cross-sectional images of velocity. This means that the pixel values are proportional to the velocity of the particles. Gray areas are static; black represents velocity in one direction, while white represents velocity in the other. In the sample image (Fig. 2), the large white spot is a jugular vein carrying blood away from the cranium while the large black spots are carotid and vertebral arteries carrying blood into the cranium. The flow rates can be obtained from the images of velocity by integrating velocity values over the lumen area. This sample image is actually 1 of 32 images that are taken per cardiac cycle. Flow rates derived from each image are plotted together to create the flow waveforms in Fig. 3 that illustrate changing flow during one heart beat. Regular biases in the MRI velocity measurements that result from basel...

Cine cerebrospinal fluid imaging in multiple sclerosis

“…Given that the CSF pulse reflects changes in the instantaneous volume of the arterial and venous blood flows within the cranium, (28,29) we conclude that the increased pulsatility exhibited by the aqueductal CSF flow in the MS patients probably reflects changes in blood flow dynamics through the brain parenchyma. Furthermore, given that there is no evidence of altered arterial pulse in MS patients, we postulate that changes in the CSF pulsatility may be due to alterations in the dynamics of the cerebral venous system, as demonstrated in other pathologies.…”

“…Furthermore, given that there is no evidence of altered arterial pulse in MS patients, we postulate that changes in the CSF pulsatility may be due to alterations in the dynamics of the cerebral venous system, as demonstrated in other pathologies. For example, it has been shown that an altered CSF pulse in head trauma patients was directly related to increased pulsatility in the cerebral venous system (28) and that increased CSF pulsatility in leukoaraiosis patients was associated with increased pulsatility in the venous sinuses (11,(33)(34)(35)(36)(37)(38)(39)(40)(41).…”

“…This hydraulic system, which behaves like a second-order low-pass filter, is a finely tuned mechanism that relies on the correct timing of the individual arterial, venous, and CSF pulses (28). Abnormalities in the cerebral arterial and venous pulses can greatly influence the performance of the hydraulic regulatory mechanism, (28,29) resulting in increased CSF pulsatility-something that has previously been implicated in a number of pathologies, including microvascular angiopathy, (30) communicating hydrocephalus (31), and leukoaraiosis (32).…”

Is Lumbar Puncture Needed? – Noninvasive Assessment of ICP Facilitates Decision Making in Patients with Suspected Idiopathic Intracranial Hypertension

“…Different methods of nICP assessment have been reported so far, like MRI-based methodology 6 7 8 21 , optic nerve sheath diameter (ONSD) 4 9 22 23 24 , and tympanic membrane displacement 25 26 27 28 . Although some of them show a high correlation with ICP, none of them have yet reached wider application in clinical practice, nor have they been able to act as a substitute for LPP.…”

“…In cerebral MRI scans, IIH is indicated by the appearance of an empty sella 5 . Although these and other MRI-based techniques 6 7 8 are used in clinical practice, they do have some limitations regarding their accuracy 9 .…”