Kouhei Kamiya MD, Presenter: Nothing to Disclose

Koji Kamagata, Abstract Co-Author: Nothing to Disclose

Akira Nishikori, Abstract Co-Author: Nothing to Disclose

Ryusuke Irie, Abstract Co-Author: Nothing to Disclose

Masaaki Hori MD, Abstract Co-Author: Nothing to Disclose

Masakazu Miyajima, Abstract Co-Author: Nothing to Disclose

Madoka Nakajima, Abstract Co-Author: Nothing to Disclose

Harushi Mori MD, Abstract Co-Author: Nothing to Disclose

Akira Kunimatsu MD, Abstract Co-Author: Speakers Bureau, Terumo Corporation

Hajime Arai, Abstract Co-Author: Nothing to Disclose

Shigeki Aoki MD, PhD, Abstract Co-Author: Nothing to Disclose

Kuni Ohtomo MD, Abstract Co-Author: Research Grant, Bayer AG Research Grant, DAIICHI SANKYO Group

Diffusional kurtosis imaging (DKI) is a new diffusion MRI technique that can be more sensitive to tissue microstructural alterations than conventional diffusion tensor imaging. This study aimed to investigate correlations between the DKI metrics with cognitive function in patients with idiopathic normal pressure hydrocephalus (iNPH), as well as changes before and after the lumbo-peritoneal shunt (LP shunt).

Twenty-nine patients with iNPH were involved. DKI data were obtained using a 3-T system with diffusion gradient in 32 directions. The mean kurtosis (MK) and fractional anisotropy (FA) maps were calculated. Cognitive measures included Mini-Mental State Examination (MMSE), frontal assessment battery (FAB), and trail-making-test-A (TMT-A). Tract-based spatial statistics (TBSS) were used to investigate the correlations between the pre-operative diffusion metrics and the cognitive measures. For those who had post-operative exams, pair-wise analyses of TBSS were also performed to look for alterations before and after the surgery.

Positive correlations with the cognitive function were observed in almost similar regions for FA and MK, predominantly in the frontal lobe and the cingulum (P < 0.05). On MK analyses, more extensive areas of the frontal subcortical white matter showed significant correlations with the FAB and TMT-A, compared with FA analyses. Pre- and post-operative images were available in 8 patients, all of whom experienced clinical improvement after LP shunt. Pair-wise analyses revealed significant decrease of MK in the anterior cingulum after the surgery.

Our results suggest DKI provides additional information of tissue alteration relevant with cognitive dysfunction in iNPH, and is useful especially in subcortical regions where the complexity of fiber direction can be problematic for FA analyses. Although the post-operative decrease of MK seems contradictory at the first glance, it may reflect that the post-operative brain tissue microstructural environment is not the same as the normal healthy state, and that the relationship between diffusion metrics and cognitive function is not preserved after the surgery.

Diffusional kurtosis imaging successfully demonstrated tissue alteration relevant with cognitive dysfunction in idiopathic normal pressure hydrocephalus, especially in the subcortical white matter.

Kamiya, K, Kamagata, K, Nishikori, A, Irie, R, Hori, M, Miyajima, M, Nakajima, M, Mori, H, Kunimatsu, A, Arai, H, Aoki, S, Ohtomo, K, Diffusional Kurotsis Imaging and Cognitive Disturbance in Idiopathic Normal Pressure Hydrocephalus.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017758.html