Yasumasa Shimano

Pilot data on telmisartan short-term effects on glucose metabolism in the olfactory tract in Alzheimer's disease

The possible effect of antihypertensive therapy on Alzheimers disease (AD) has been studied, and angiotensin II receptor blockers (ARBs) have been suggested to exert an effect on cognitive decline. The purpose of this study is to clarify the functional effects of telmisartan, a long‐acting ARB, on AD brain using prospective longitudinal 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) studies. For this purpose, brain glucose metabolism of four hypertensive patients with AD was examined with FDG‐PET before and after administration of telmisartan. Studied subjects underwent three FDG‐PET studies at intervals of 12 weeks. Antihypertensive treatment except for telmisartan was started after the first FDG‐PET and continued for 24 weeks. Then 40–80 mg of telmisartan was added after the second FDG‐PET and continued for 12 weeks.Glucose metabolism was significantly decreased during the first 12 weeks without telmisartan use at an area (−10, 21, −22, x, y, z; Z = 3.56) caudal to the left rectal gyrus and the olfactory sulcus corresponding to the left olfactory tract. In contrast, the introduction of telmisartan during the following 12 weeks preserved glucose metabolism at areas (5, 19, −20, x, y, z; Z = 3.09; 6, 19, −22, x, y, z; Z = 2.88) caudal to the bilateral rectal gyri and olfactory sulci corresponding to the bilateral olfactory tracts. No areas showed decreased glucose metabolism after the introduction of telmisartan. In AD, amyloid‐β deposition is observed in the anterior olfactory nucleus (AON) of the olfactory tract. Glucose metabolism in AON may be progressively decreased and preserved by telmisartan.

Concordance between 99mTc‐ECD SPECT and 18F‐FDG PET interpretations in patients with cognitive disorders diagnosed according to NIA‐AA criteria

The purpose of this study was to clarify the concordance of diagnostic abilities and interobserver agreement between 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) and brain perfusion single photon‐emission computed tomography (SPECT) in patients with Alzheimers disease (AD) who were diagnosed according to the research criteria of the National Institute of Aging‐Alzheimers Association Workshop.

Evaluation of both perfusion and atrophy in multiple system atrophy of the cerebellar type using brain SPECT alone

BackgroundPartial volume effects in atrophied areas should be taken into account when interpreting brain perfusion single photon emission computed tomography (SPECT) images of neurodegenerative diseases. To evaluate both perfusion and atrophy using brain SPECT alone, we developed a new technique applying tensor-based morphometry (TBM) to SPECT.MethodsAfter linear spatial normalization of brain perfusion SPECT using 99mTc-ethyl cysteinate dimer (99mTc-ECD) to a Talairach space, high-dimension-warping was done using an original 99mTc-ECD template. Contraction map images calculated from Jacobian determinants and spatially normalized SPECT images using this high-dimension-warping were compared using statistical parametric mapping (SPM2) between two groups of 16 multiple system atrophy of the cerebellar type (MSA-C) patients and 73 age-matched normal controls. This comparison was also performed in conventionally warped SPECT images.ResultsSPM2 demonstrated statistically significant contraction indicating local atrophy and decreased perfusion in the whole cerebellum and pons of MSA-C patients as compared to normal controls. Higher significance for decreased perfusion in these areas was obtained in high-dimension-warping than in conventional warping, possibly due to sufficient spatial normalization to a 99mTc-ECD template in high-dimensional warping of severely atrophied cerebellum and pons. In the present high-dimension-warping, modification of tracer activity remained within 3% of the original tracer distribution.ConclusionsThe present new technique applying TBM to brain SPECT provides information on both perfusion and atrophy at the same time thereby enhancing the role of brain perfusion SPECT