Eusra Hassan, Presenter: Nothing to Disclose

John Caine, Abstract Co-Author: Nothing to Disclose

Stavros Michael Stivaros PhD, FRCR, Abstract Co-Author: Medical Director, Obsidian Health Limited

Quantitative phase contrast MRI (PCMRI) enables the flow of blood or CSF to be measured over a cardiac cycle. PCMRI in children presents unique challenges in implementation relating to ECG acquisition technique and MRI scanning parameters which this study investigates.

PCMRI was performed to measure flow through the right and left internal carotid & basilar arteries (rICA, lICA, BA), superior sagittal sinus (SSS), straight sinus vein (StrS), CSF through the foramen magnum (FM) and aqueduct of sylvius (AQ). Velocity encoding (venc) was varied based on evidence of under or or oversampling.   PCMRI experiments were perfomed using central ECG gating and then repeated using peripheral pulse gating.  The imaging was analysed by three experienced observers in the field of PCMRI analysis using  the image analysis programme, Segment, to allow the respective flow rates to be calculated. 

Data was collected from 16 children aged 1 to 15 years (mean 4 years 6 months).  Nine children had central and peripheral pulse gating employed.  The mean flow rates measured with peripheral gating was lICA = 0.094mls/s, right ICA = 0.092mls/s, BA = 0.056mls/s, SSS = 0.007mls/s, StrS, = 0.001mls/s, FM = 0.01mls/s, AQ = 0.001mls/s. Mean flow rates with central ECG measurements were lICA = 0.091mls/s, rICA = 0.091mls/s, BA=0.057mls/s,  SSS = 0.042mls/s, StrS = 0.006mls/s, FM = 0.003mls/s, AQ = 0.001mls/s.  No signficant statistical difference was detected  based on the acquisition technique.  Compared to published adult literature, the velocity enconding gradients (venc) in our childhood cohort were significantly different with arterial =120cm/s, venous=25cm/s and CSF=16cm/s.   

Our data shows no significant difference with regard to peripheral versus central pulse measurement for PCMRI acquisition in children. Peripheral PCMRI acquisition is much easier to apply and better tolerated in the paediatric cohort. In addition this work provides child specific venc values for PCMRI assessment, which differs from published adult data.

It is recognised that there exists a complex interaction between cerebral arterial, venous and CSF flow rates in hydrocephalus.  Quantitative PCMRI allows for non-invasive assesment of these haemo/hydrodynamic flows which may one day supsercede invasive intracranial monitoring.  This work looks to develop and validate paediatric focused application of PCMRI for such applications. 

Hassan, E, Caine, J, Stivaros, S, Validation of Quantitative Phase Contrast MRI Assessment of Cerebral Haemo/Hydro Dynamics in Children.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017680.html