Akihiro Kitanaka, Presenter: Nothing to Disclose

Tosiaki Miyati PhD, Abstract Co-Author: Nothing to Disclose

Norio Hayashi PhD, Abstract Co-Author: Nothing to Disclose

Toshifumi Gabata MD, Abstract Co-Author: Nothing to Disclose

Osamu Matsui MD, Abstract Co-Author: Research Consultant, Bayer AG Research grant, Bayer AG Research Consultant, Eisai Co, Ltd Research Consultant, Kowa Company, Ltd

Noam Alperin PhD, Abstract Co-Author: Stockholder, Alperin Noninvasive Diagnostics, Inc

Masako Takanaga, Abstract Co-Author: Nothing to Disclose

Takashi Hamaguchi MS, Abstract Co-Author: Nothing to Disclose

Naoki Ohno MS, Abstract Co-Author: Nothing to Disclose

Hirohito Kan, Abstract Co-Author: Nothing to Disclose

Akihiro Asano, Abstract Co-Author: Nothing to Disclose

We have reported that the apparent diffusion coefficient (ADC) obtained from diffusion MRI in the cerebral white matter significantly changed during the cardiac cycle even when minimizing the bulk motion effect of the brain parenchyma, and this information assists in the diagnosis of idiopathic normal pressure hydrocephalus (I-NPH). However, these changes (delta-ADC) depend on the hemodynamic state such as cerebral blood flow (CBF). The aim of this study was to evaluate hemodynamic-independent biomechanical-information of the brain using regional CBF (rCBF) and delta-ADC.

On a 3.0-T MRI, ECG-triggered multi-phase single-shot diffusion EPI was used with sensitivity encoding and half-scan techniques to minimize the bulk motion effect. The delta-ADC image was obtained from the maximum-minus-minimum ADC value of all cardiac phase images on a pixel-by-pixel basis. Moreover, pseudo-continuous arterial spin labeling method was used to obtain the CBF map on the same slice. We obtained a water fluctuation index (WFI) map defined as the delta-ADC divided by the rCBF. We assessed the WFI in cerebral white matter in healthy volunteers (n = 10).

Mean values of the WFI, delta-ADC and rCBF were 11.2 [mm2/s] [mL/100g/min]-1, 0.16 x10-3 mm2/s, 15.1 mL/100g/min, respectively. There was a good correlation between delta-ADC and rCBF (R2=0.83, P<0.01). This result shows that delta-ADC depends on rCBF, therefore delta-ADC should be normalized by rCBF.

WFI analysis makes it possible to obtain biomechanical information in terms of the degree of fluctuation of the water molecules hemodynamic-independently in the brain.

WFI analysis noninvasively obtains biomechanical information on the brain, and might assist in the diagnosis of I-NPH and brain tumor.

Kitanaka, A, Miyati, T, Hayashi, N, Gabata, T, Matsui, O, Alperin, N, Takanaga, M, Hamaguchi, T, Ohno, N, Kan, H, Asano, A, Hemodynamically Independent Analysis of Cerebral Water Fluctuation Using Diffusion and Perfusion MRI.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034554.html