Yoshiharu Miyazaki

Posterior cingulate atrophy and metabolic decline in early stage Alzheimer's disease

To test the hypothesis that Alzheimers disease (AD) patients with posterior cingulate/precuneus (PCP) atrophy would be a distinct disease form in view of metabolic decline. Eighty-one AD patients underwent (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and structural magnetic resonance imaging (MRI). Positron emission tomography and voxel-based morphometry (VBM) Z-score maps were generated for the individual patients using age-specific normal databases. The patients were classified into 3 groups based on atrophic patterns (no-Hipp-PCP, atrophy in neither hippocampus nor PCP; Hipp, hippocampal atrophy; PCP, PCP atrophy). There were 16 patients classified as no-Hipp-PCP, 55 as Hipp, and 10 as PCP. The Mini Mental State Examination (MMSE) score was similar among the groups. The greater FDG decline than atrophy was observed in all groups, including the no-Hipp-PCP. The PCP group was younger, and was associated with a greater degree of FDG decline in PCP than the others. There are diverse atrophic patterns in a spectrum of AD. In particular, a subset of patients show PCP atrophy, which is associated with greater metabolic burden.

Effect of an age-mismatched and sex-mismatched normal database on the diagnostic performance of ¹⁸F-FDG PET for Alzheimer's disease: the Ishikawa Brain Imaging Study.

Objectives18F-FDG PET with voxel-based statistical image analysis plays an important role in the diagnosis of Alzheimer’s disease (AD). However, the effect of an age-matched and sex-matched or mismatched normal database (NDB) on the diagnostic performance of 18F-FDG PET has not yet been investigated systematically. The aim of this study was to determine whether an age-matched and sex-matched NDB is necessary for the detection of AD using 18F-FDG PET. MethodsWe generated 11 NDB sets for 18F-FDG PET, including six age-specific NDB sets consisting of participants ranging in age from 20 to 70 years, one age-non-specific NDB set, one age-matched NDB set, two sex-specific NDB sets, each consisting of 20 men or 20 women, and one sex-matched NDB set. The average z-scores in predefined AD-specific regions of interest of the PET images were calculated using those NDB sets and a receiver-operating characteristic analysis was carried out to assess the diagnostic performance of 18F-FDG PET to discriminate 46 patients with AD from 50 normal controls. ResultsThere was no significant difference in each area under the receiver-operating characteristic curve using either age-matched/mismatched NDB sets or sex-matched/mismatched NDB sets. ConclusionThe diagnostic performance of 18F-FDG PET was rather insensitive to differences in age or sex in the NDB, indicating that exact age-matched or sex-matched NDB may not be essential for discriminating patients with AD from normal participants using 18F-FDG PET.

Estimation of cardiac output by first-pass transit of radiotracers

To evaluate cardiac function with various tracers to be used for radionuclide scintigraphy, we examined the validity of a simplified method to measure cardiac output (CO) by modifying the equation of Stewart-Hamilton in the radionuclide study. After a bolus injection of I-123 or Tc-99m tracer, the total injection dose and count in the pulmonary artery during the first transit of the tracer were measured to calculate the CO Index. The CO Index was obtained from the integral of the first transit of radiotracers in the pulmonary artery divided by the total injected count. CO was estimated from the regression formula which was obtained by comparing the CO Index with CO measured by the Doppler echocardiographic method. There were close correlations between the CO Index and CO measured by Doppler echocardiography both in the study with I-123 (n = 13, r = 0.85, p < 0.001) and with Tc-99m (n = 17, r = 0.88, p < 0.001). The regression formula varied according to the radionuclide used for the study (CO = 2.29 × (CO Index)0634 for I-123 and CO = 3.18 × (CO Index)0518 for Tc-99m). CO measured by this method is useful for the assessment of cardiac function with various tracers in routine clinical studies, and this simple method may be utilized for assessment of organ blood flow on the basis of the microsphere model.