title: Relationship between intracranial pressure and phase contrast cine MRI derived measures of intracranial pulsations in idiopathic normal pressure hydrocephalus.
abstract: Phase contrast cine MRI with determination of pulsatile aqueductal cerebrospinal fluid (CSF) stroke volume and flow velocity has been suggested to assess intracranial pulsations in idiopathic normal pressure hydrocephalus (iNPH). We aimed to compare this non-invasive measure of pulsations to intracranial pressure (ICP) pulse wave amplitude from continuous ICP monitoring. We hypothesised that a significant correlation between these two markers of intracranial pulsations exists. Fifteen patients with suspected iNPH had continuous computerised ICP monitoring with calculation of mean ICP pulse wave amplitude (MWA) from time-domain analysis. MRI measured CSF aqueductal stroke volume and peak flow velocity. Mean MWA was 5.4mmHg (range 2.3-12.4mmHg). Mean CSF stroke volume and peak flow velocity were 65μl (range 3-195μl) and 9.31cm/s (range 1.68-15.0cm/s), respectively. No significant correlation between the invasive and non-invasive measures of pulsations existed (Spearman r=-0.30 and r=-0.27, respectively; p>0.05). We observed marked intra-individual fluctuation of MWA during continuous ICP monitoring of an average of 6.0mmHg (range 2.8-12.2mmHg). The results suggest a complex interplay between measures of pulsations derived from snapshot MRI measurements and continuous computerised ICP measurements, as no significant relationship existed in our data. Further study is needed to better understand the temporal profile of CSF MRI flow studies, as substantial variation in MWA over the course of several hours of ICP monitoring is common, suggesting that these physiologic fluctuations might obscure MRI snapshot measures of intracranial pulsations.
authors: South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia; Department of Neurosurgery, Wollongong Hospital, Level 4, 304 Crown Street, Wollongong, NSW 2500, Australia. Electronic address: m.jaeger@unsw.edu.au.
authors: Matthias
authors: M
authors: Jaeger
authors: Department of Aged Care and Rehabilitation Medicine, Liverpool Hospital, South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia.
authors: Angela K
authors: AK
authors: Khoo
authors: Department of Aged Care and Rehabilitation Medicine, Liverpool Hospital, South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia.
authors: David A
authors: DA
authors: Conforti
authors: Department of Medical Imaging, Liverpool Hospital, Liverpool, NSW, Australia.
authors: Ramesh
authors: R
authors: Cuganesan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002535:Cerebral Aqueduct / Q000000981:diagnostic imaging / Q000503:physiopathology; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid* / Q000000981:diagnostic imaging* / Q000503:physiopathology; D007427:Intracranial Pressure / Q000502:physiology; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged
keywords: CSF flow studies; Intracranial pressure; Intracranial pulsations; Normal pressure hydrocephalus; Phase contrast cine magnetic resonance imaging