Kenta Sakaguchi

Regional glucose metabolic reduction in dementia with Lewy bodies is independent of amyloid deposition

PurposeThere is evidence that some cases of patients with dementia with Lewy bodies (DLB) can demonstrate Alzheimer disease (AD) like reduced glucose metabolism without amyloid deposition. The aim of this study was to clarify whether regional hypometabolism is related to amyloid deposits in the DLB brain and measure the degree of regional hypometabolism.MethodsTen consecutive subjects with DLB and 10 AD patients who underwent both Pittsburgh compound B (PiB)-PET and 18F-fluoro-2-deoxyglucose (FDG)-PET were included in this study. Regional standardized uptake value ratio (SUVR)s normalised to cerebellar cortices were calculated in the FDG- and PiB-PET images.ResultsAll AD patients and five DLB patients showed amyloid deposits (PiB positive). In the DLB group the parietotemporal and occipital metabolism were significantly lower than those in the AD group but there was no difference between the posterior cingulate hypometabolism between DLB and AD groups. There were no differences in regional glucose metabolism between PiB positive and negative DLB patients.ConclusionsIn the DLB brain, it is suggested that decreased regional glucose metabolism is unrelated to amyloid deposits, although the hypometabolic area overlaps with the AD hypometabolic area and the degree of parietotemporal and occipital hypometabolism in DLB brain is much larger than that in AD brain.

Performance of 11C-Pittsburgh Compound B PET Binding Potential Images in the Detection of Amyloid Deposits on Equivocal Static Images

The goal of this study was to clarify whether binding potential (BP) images using 11C-Pittsburgh compound B (11C-PiB) and dynamic PET can reliably detect cortical amyloid deposits for patients whose 11C-PiB PET static images are ambiguous and whether visual ratings are affected by white matter retention. Methods: Static and BP images were constructed for 85 consecutive patients with cognitive impairment after 11C-PiB dynamic PET. Cortical uptake was visually assessed as positive, negative, or equivocal for both types of images. Quantitatively, the standardized uptake value ratio (SUVR) from the static image, the nondisplaceable BP from the dynamic image for mean gray matter uptake, and the ratio of gray matter uptake to white matter retention were compared among 11C-PiB–positive, 11C-PiB–equivocal, and 11C-PiB–negative groups. Results: Forty-three scans were visually assessed as 11C-PiB–positive in both the static and the BP images. Ten scans were 11C-PiB–equivocal in the static images. In 8 of them, the BP images were 11C-PiB–positive, whereas the other 2 were 11C-PiB–equivocal. Thirty-two scans were assessed as 11C-PiB–negative in the static images. In the BP images, 4 were 11C-PiB–positive and 2 were 11C-PiB–equivocal. The mean gray matter uptake of 11C-PiB in SUVR and nondisplaceable BP, respectively, showed statistically significant differences among the 11C-PiB–positive, 11C-PiB–equivocal, and 11C-PiB–negative groups. The ratio of gray matter uptake to white matter retention was lower in the BP images than static images from the 11C-PiB–negative and 11C-PiB–equivocal groups, whereas it was higher in the 11C-PiB–positive group. Conclusion: 11C-PiB PET BP images can clarify visual interpretation of clinical static 11C-PiB–equivocal images by reducing the interference of nonspecific white matter retention. We conclude that 11C-PiB–equivocal PET findings on static images reflect cortical amyloid deposits, which can be verified using BP images. Furthermore, quantitative assessments, such as SUVR and nondisplaceable BP, are of no use for correctly rating equivocal visual findings.

18f-fdg Pet/ct Features of Chronic Sclerosing Sialadenitis Presenting as Localized Igg4-related Disease

Chronic sclerosing sialadenitis is a benign inflammatory condition that most commonly affects the submandibular gland in elderly individuals. It is currently known to belong to the spectrum of IgG4-related systemic diseases, which is reflected by systemic involvement on F-FDG PET/CT images. We presented a case of a 73-year-old man with histologically proven IgG4-related chronic sclerosing sialadenitis, unilateral localized form, on whole-body F-FDG PET/CT images that mimicked submandibular carcinoma with lymph node metastasis.

Estimation of activity of administered 18 F-fluorodeoxyglucose by measurement of the dose equivalent rate on the right temporal region of the head

BackgroundPositron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) is now a routine procedure for the management of cancer patients. Intravenous administration of FDG is sometimes halted due to troubles. In such cases, estimations of the FDG dosage injected prior to halting administration may be helpful. We have established a method of estimating the activity of FDG to patients on the basis of the dose equivalent rate on the surface of the right temporal region of the head. The correlation of actual administered dosage with independent variables, such as the dose equivalent rate on the right temporal region of the head, age, sex, and body weight, was analyzed using multiple regression analysis to obtain linear, quadratic, and cubic regression equations.ResultsWhen entering independent variables, the cubic regression equation could be used to estimate an administered dosage with an accuracy of ±10 % for 62 % of all patients and ±20 % for 90 % of all patients.ConclusionsWe conclude that this method is useful for estimating the administered dosage from the dose equivalent rate on the temporal region of the head.