New Computer-Aided Diagnosis of Dementia Using Positron Emission Tomography: Brain Regional Sensitivity-Mapping Method

Purpose: We devised a new computer-aided diagnosis method to segregate dementia using one estimated index (Total Z score) derived from the Brodmann area (BA) sensitivity map on the stereotaxic brain atlas. The purpose of this study is to investigate its accuracy to differentiate patients with Alzheimer’s disease (AD) or mild cognitive impairment (MCI) from normal adults (NL). Methods: We studied 101 adults (NL: 40, AD: 37, MCI: 24) who underwent 18FDG positron emission tomography (PET) measurement. We divided NL and AD groups into two categories: a training group with (Category A) and a test group without (Category B) clinical information. In Category A, we estimated sensitivity by comparing the standard uptake value per BA (SUVR) between NL and AD groups. Then, we calculated a summated index (Total Z score) by utilizing the sensitivitydistribution maps and each BA z-score to segregate AD patterns. To confirm the validity of this method, we examined the accuracy in Category B. Finally, we applied this method to MCI patients. Results: In Category A, we found that the sensitivity and specificity of differentiation between NL and AD were all 100%. In Category B, those were 100% and 95%, respectively. Furthermore, we found this method attained 88% to differentiate ADconverters from non-converters in MCI group. Conclusions: The present automated computer-aided evaluation method based on a single estimated index provided good accuracy for differential diagnosis of AD and MCI. This good differentiation power suggests its usefulness not only for dementia diagnosis but also in a longitudinal study.浜松医科大学学位論文　医博第695号（平成27年3月16日

3D-SSP images.

<p>Employing 20 NL subjects in Category A as a reference database, all subjects' 3D-SSP Z-score images were prepared. Average Z-score images of 20 NL (A) and 18 AD (B) in Category A. Average Z-score images of 20 NL (C) and 19 AD (D) in Category B. Average Z-score images of a total of 24 MCI (E), 10 AD-converters (F) and 14 non-converters (G). The color bar denotes the levels of Z-score based on 20 NL subjects in Category A.</p

SUVR and sensitivity of Brodmann area.

<p>*SUVR: standard uptake value ratio (mean ± SD).</p><p>**CBL: cerebellum.</p

The dot plots of Total Z-score.

<p>The dot plots of Z_NL-AD in Category A (A), Z_NL-AD in Category B (B), and AD-converters (MCI+) and non-converters (MCI-) (C).</p

Subject characteristics.

<p>*MMSE = mini-mental state examination.</p

BA on 3D-SSP images.

<p>BA on 3D-SSP MRI template images (A) and sensitivity-distribution maps of BA on 3D-SSP images among NL and AD in Category A (B). The color bar denotes the levels of sensitivity to differentiate NL and AD in Category A.</p