Noninvasive MRI assessment of intracranial compliance in idiopathic normal pressure hydrocephalus.
OBJECTIVE
To assess the state and dynamics of the intracranial system in idiopathic normal-pressure hydrocephalus (I-NPH), we determined intracranial compliance using magnetic resonance imaging (MRI).


METHODS
The intracranial compliance index (ICCI), which was defined as the ratio of the peak-to-peak intracranial volume change (ICVC(p-p)) to the peak-to-peak cerebrospinal fluid (CSF) pressure gradient (PG(p-p)) during the cardiac cycle, was obtained from the net transcranial blood and CSF flow measured with phase-contrast (PC) cine MRI. ICCI was determined in patients with I-NPH (N = 7), brain atrophy, or asymptomatic ventricular dilation (VD) (N = 6), and in healthy volunteers (control group; N = 11). The changes in ICCI indices were also analyzed after a CSF tap test (N = 2).


RESULTS
The ICCI in the I-NPH group was significantly lower than in the control and VD groups, whereas no difference was found between the control and VD groups. The ICVC(p-p) was also lower than in the control and VD groups. However, no significant difference was found in the PG(p-p) between groups. The ICCI increased after the tap test.


CONCLUSIONS
Intracranial compliance analysis with MRI makes it possible to noninvasively obtain more detailed information of intracranial biomechanics in the I-NPH and to assist in the diagnosis of I-NPH.
Miyati
Tosiaki
T
Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa, Japan. ramiyati@mhs.mp.kanazawa-u.ac.jp
Mase
Mitsuhito
M
Kasai
Harumasa
H
Hara
Masaki
M
Yamada
Kazuo
K
Shibamoto
Yuta
Y
Soellinger
Michaela
M
Baltes
Christof
C
Luechinger
Roger
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis* / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results