Hajime Kitagaki

Regional cerebral glucose metabolism in dementia with Lewy bodies and Alzheimer's disease

Objective: To delineate the features of regional cerebral metabolic rate of glucose(CMRglc) in dementia with Lewy bodies (DLB). Methods: We compared absolute CMRglc in 12 patients with a clinical diagnosis of DLB, 12 patients with a clinical diagnosis of Alzheimers disease (AD), and 12 normal volunteers (NC), using 18F-fluorodeoxyglucose (FDG) and PET. The three groups were matched for age and sex, and there were no differences in disease duration or severity of cognitive disturbances between the DLB and AD groups. Results: CMRglc was significantly lower in patients with DLB than in that of NC in most parts of the brain, except the sensorimotor cortices, basal ganglia, thalamus, and pons. Between the DLB and AD groups, there were significant regional CMRglc differences in the medial and lateral occipital lobes. In DLB and AD, the CMRglc reduction patterns were similar, though the global metabolic reduction was larger in DLB, and the occipital CMRglc reduction in DLB could differentiate DLB from AD. The relative occipital CMRglc(normalized to the sensorimotor CMRglc) was a useful measure for the differential diagnosis of DLB from AD. The sensitivity and the specificity were 92% when using the minimal value of the normalized occipital CMRglc in the NC group as the cut-off point. Conclusion: These different regional CMRglc reductions substantiate the pathologic, neurochemical, and clinical differences between DLB and AD.

Impact of white matter changes on clinical manifestation of Alzheimer's disease: A quantitative study

Background and Purpose There have been conflicting results involving the clinical significance of white matter changes in patients with Alzheimer’s disease (AD). We studied the association between the volume of white matter hyperintensities (WMHs) on T2-weighted images and cognitive, neurological, and neuropsychiatric symptoms. Methods The subjects were 76 AD patients who had WMHs but no obvious cerebrovascular diseases. We quantified the volume of WMHs by using fast-fluid–attenuated inversion recovery images and whole brain atrophy by using 3D spoiled gradient-echo images. Effects of WMHs and brain atrophy on dementia severity, cognitive function, neuropsychiatric disturbances, and neurological findings were examined. Results Whole brain atrophy was significantly associated with dementia severity and cognitive disturbances, as well as with grasp reflex and some kinds of neuropsychiatric disturbances. After we controlled for the effects of brain atrophy, duration of symptoms, and demographic factors, we found that WMH volume was not associated with global cognitive disturbances or dementia severity but was significantly associated with urinary incontinence, grasp reflex, and aberrant motor behaviors. Brain atrophy and WMH volume were not significantly correlated either before or after controlling for age, sex, education, and duration of symptoms. WMH volume was associated with hypertension, but brain atrophy was not positively correlated with any vascular risk factors. Conclusions Our results support the hypothesis that WMHs in AD patients are superimposed phenomena of vascular origin. WMHs contribute to specific neurological and neuropsychiatric manifestations but not to global cognitive impairment, which is more closely associated with brain atrophy.

Regional cerebral blood flow difference between dementia with Lewy bodies and AD

Article abstract The authors studied 14 patients with dementia with Lewy bodies (DLB), 14 patients with AD, and 14 healthy control subjects with N-isopropyl-p-[123I]iodoamphetamine SPECT. Comparison with the statistical parametric mappings revealed that relative cerebral blood flow was lower in the occipital lobes and higher in the right medial temporal lobe in the DLB group than in the AD group. Decreased occipital perfusion and relatively well preserved medial temporal perfusion are features that distinguish DLB from AD.

Medial temporal and whole-brain atrophy in dementia with Lewy bodies A volumetric MRI study

Objective: Dementia with Lewy bodies (DLB) is emerging as a common cause of degenerative dementia. A recent pathologic study has indicated that the medial temporal lobe in patients with DLB was less atrophic than that in patients with AD. The purpose of this study was to examine whether medial temporal MRI volumetry was useful to differentiate DLB from AD clinically. Methods: We compared the volumes of the hippocampal formation, amygdaloid complex, and whole brain in 27 patients with probable DLB (based on the criteria of the Consortium on DLB International Workshop), 27 patients with probable AD(based on criteria of the National Institute of Neurological Disease and Stroke/Alzheimers Disease and Related Disorders Association), and 27 normal elderly subjects using an MRI-based volumetric technique. The three groups were matched for age and sex. Severity of cognitive disturbances represented by their Mini-Mental State Examination score was comparable between the DLB and AD groups. Results: Hippocampal volume (normalized to intracranial volume) in the DLB group was significantly larger than that in the AD group, but significantly smaller than that in the normal control group. There were no significant differences in the amygdala and whole-brain volume between the DLB group and the AD group, but the atrophies of the amygdala and whole brain were more severe in the DLB group than those in the control group. Conclusions: These findings indicate the usefulness of MRI hippocampal volumetry in clinically discriminating patients with DLB from patients with AD.

Estimation of liver function using T1 mapping on Gd-EOB-DTPA-enhanced magnetic resonance imaging.

Objectives:To investigate the ability of T1 mapping of liver on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging for the estimation of liver function. Materials and Methods:Local institutional review board approved this study. Ninety-one patients (64 men, 27 women; mean age, 67.4 years) were classified into 4 groups as follows: normal liver function (NLF), n = 16; chronic hepatitis (CH), n = 38; liver cirrhosis with Child-Pugh A (LCA), n = 20; and liver cirrhosis with Child-Pugh B (LCB), n = 17. Look-Locker sequences (single slice multiphase imaging using gradient-echo sequence with inversion recovery pulse) were obtained before and at 3, 8, 13, and 18 minutes after Gd-EOB-DTPA administration. T1 mapping of liver parenchyma was calculated from the Look-Locker sequence. T1 relaxation time of liver and reduction rate of T1 relaxation time between pre- and postcontrast enhancement were measured. The Bonferroni t test was used for comparisons between the 4 groups. Results:Precontrast T1 relaxation times were significantly longer for LCA and LCB than for NLF, and that of LCB was longer than that of chronic hepatitis (P < 0.05). Postcontrast T1 relaxation times were significantly longer for LCB than for other groups at all time points. Those of LCA were longer than those of NLF at all time points. Reduction rates were significantly lower for LCB than for the other groups at ≥8 minutes. Conclusions:Evaluation of hepatic uptake of Gd-EOB-DTPA using T1 mapping of liver parenchyma can help estimate liver function.

Cortical activation during retrieval of arithmetical facts and actual calculation: A functional magnetic resonance imaging study

Abstract By using functional magnetic resonance imaging (fMRI), the neural substrates involved in mental recitation of the single‐digit multiplication table and serial subtraction were studied. The former depends mostly on well‐learned arithmetical facts, while the latter requires arithmetic processing. Activation during each task was compared with that in a number counting control. During the recitation of single‐digit multiplication, the activated regions included the area lying along the left intraparietal sulcus, the premotor and supplementary motor areas, and the posterior portion of the left inferior frontal gyrus. The areas activated during serial subtraction included these areas as well as the bilateral prefrontal and right parietal areas. From the results obtained during retrieval of the multiplication table in this study and previous studies, it was concluded that semantic memory of the multiplication table is stored in the area lying along the intraparietal sulcus and that the frontal areas play an executive role in utilizing the semantic memory of arithmetical facts. It was assumed that the arithmetical facts requiring actual calculation are also stored in the same region. The additional activation during serial subtraction compared with the activation during retrieval of the multiplication table is probably due to the processes of actual calculation. These processes include proper alignment of digits, which may have caused the right parietal activation, and maintaining digits needed for the mental serial subtractions, which may have caused the bilateral prefrontal activation.

Usefulness of Diffusion-Weighted Imaging and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in the Diagnosis of Prostate Transition-Zone Cancer

Background: Conventional T2-weighted (T2-WI) magnetic resonance imaging (MRI) has poor sensitivity for prostate transition-zone (TZ) cancer detection. Purpose: To retrospectively evaluate the clinical value of diffusion-weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) in combination with T2-WI for the diagnosis of TZ cancer. Material and Methods: Twenty-six TZ cancers in 23 patients with at least one tumor (tumor size >10 mm) located predominantly in the TZ were included in the study. Sixteen peripheral-zone (PZ) cancers in 12 patients with PZ cancer but without TZ cancer (control group) were selected by step-section pathologic maps. All patients underwent MRI and radical prostatectomy. MRI was obtained by a 1.5T superconducting system with a phased-array coil. Imaging sequences were T2-WI with fat saturation (FST2-WI), DW-MRI (single-shot echoplanar image, b=0 and 1000 s/mm2, apparent diffusion coefficient [ADC] map findings), and DCE-MRI (3D fast spoiled gradient recalled [SPGR], contrast medium [0.2 mmol/kg], total injection time 5 s, image acquisition 30, 60, and 90 s). Sensitivity, specificity, accuracy, and positive predictive value (PPV) for the diagnosis of TZ cancer were evaluated in four protocols: A) FST2-WI alone, B) FST2-WI plus DW-MRI, C) FST2-WI plus DCE-MRI, D) FST2-WI plus DW-MRI plus DCE-MRI. Results: Sensitivity, specificity, accuracy, and PPV in protocol A (FST2-WI alone) were 61.5%, 68.8%, 64.3%, and 76.2%, respectively. FST2-WI plus DW-MRI (protocol B) improved the sensitivity, specificity, accuracy, and PPV. In FST2-WI plus DW-MRI plus DCE-MRI (protocol D), the number of true-negative lesions increased and false-positive lesions decreased, and the sensitivity, specificity, accuracy, and PPV were 69.2%, 93.8%, 78.6%, and 94.7%, respectively. There was a significant difference between protocols A and D (P<0.05). Conclusion: Adding DW-MRI to FST2-WI in the diagnosis of prostate TZ cancer increased the diagnostic accuracy. The addition of DCE-MRI may be an option to improve the specificity and PPV of diagnosing TZ cancer with FST2-WI and DW-MRI.

Automated segmentation of human brain MR images aided by fuzzy information granulation and fuzzy inference

This paper proposes an automated procedure for segmenting an magnetic resonance (MR) image of a human brain based on fuzzy logic. An MR volumetric image composed of many slice images consists of several parts: gray matter, white matter, cerebrospinal fluid, and others. Generally, the histogram shapes of MR volumetric images are different from person to person. Fuzzy information granulation of the histograms can lead to a series of histogram peaks. The intensity thresholds for segmenting the whole brain of a subject are automatically determined by finding the peaks of the intensity histogram obtained from the MR images. After these thresholds are evaluated by a procedure called region growing, the whole brain can be identified. A segmentation experiment was done on 50 human brain MR volumes. A statistical analysis showed that the automated segmented volumes were similar to the volumes manually segmented by a physician. Next, we describe a procedure for decomposing the obtained whole brain into the left and right cerebral hemispheres, the cerebellum and the brain stem. Fuzzy if-then rules can represent information on the anatomical locations, segmentation boundaries as well as intensities. Evaluation of the inferred result using the region growing method can then lead to the decomposition of the whole brain. We applied this method to 44 MR volumes. The decomposed portions were statistically compared with those manually decomposed by a physician. Consequently, our method can identify the whole brain, the left cerebral hemisphere, the right cerebral hemisphere, the cerebellum and the brain stem with high accuracy and therefore can provide the three dimensional shapes of these regions.

Demonstration of decreased posterior cingulate perfusion in mild Alzheimer's disease by means of H215O positron emission tomography.

Although decreased posterior cingulate metabolism in Alzheimers disease (AD) has been previously reported, there have been no reports on posterior cingulate perfusion. In this study we evaluated posterior cingulate perfusion as a relative value using statistical parametric maps (SPMs) and as an absolute value using conventional region of interest (ROI) settings. Twenty-eight subjects, including 14 patients with mild AD (mean age: 66.4±12.1 years) and 14 normal controls (65.9±7.3 years) were studied. Regional Cerebral blood flow (CBF) was measured with H215O and positron emission tomography (PET). In the SPM analysis, the left posterior cingulate and left parietotemporal CBFs were significantly decreased in the patients with mild AD (P<0.001). At a louver statistical threshold (P<0.05), the right posterior cingulate and right parietotemporal CBFs were also significantly decreased in the AD patients. In the ROI studies, the left parietal and posterior cingulate CBFs in the patients with mild AD were significantly lower than those of the normal controls by analysis of variance and post-hoc Scheffés test (P<0.001). We conclude that posterior cingulate perfusion is decreased in mild AD, reflecting the pathological changes and metabolic reduction in the posterior cingulate gyrus that have previously been reported to occur in mild AD.

Neuronal substrates for semantic memory: A positron emission tomography study in Alzheimer's disease

We examined 57 patients with mild Alzheimer’s disease by using three kinds of verbal semantic memory tests (category fluency, confrontation naming and generation of verbal definition) and correlated each score with regional cerebral glucose metabolism determined by 18F-fluorodeoxyglucose and positron emission tomography. The scores of all three verbal semantic memory tests correlated significantly with regional cerebral glucose metabolism in the left inferior temporal gyrus, even after controlling for the effects of age, sex and educational attainment. In contrast, the scores of the word recall test did not correlate significantly with regional cerebral glucose metaboliosm in the left inferior temporal gyrus, neither before nor after controlling for these confounders. Our results suggested that the left inferior temporal lobe contributes to verbal semantic memory.