Dynamic PET acquisition with (62)Cu-ATSM provided information on CBF distribution and local elevation of OEF in patients with chronic CVD. The findings of the present study showed the feasibility of the noninvasive molecular imaging method for diagnosing misery perfusion with a single venous tracer injection.

To develop a less-stressful and simple method for measurement of the cerebral metabolic rate of oxygen (CMRO 2 ) in small animals, the steady-state method was applied to injectable 15 O 2 -PET ( 15 O 2 -positron emission tomography) using hemoglobin-containing vesicles ( 15 O 2 -HbV). Ten normal rats and 10 with middle cerebral arterial occlusion (MCAO) were studied using a small animal PET scanner. A series of 15 O-PET scans with C 15 O-labeled HbV, H 2 15 O, and 15 O 2 -HbV were performed with 10 to 15 minutes intervals to measure cerebral blood volume (CBV), cerebral blood flow (CBF), and CMRO 2 . Positron emission tomography scans were started with a tracer injection using a multiprogramming syringe pump, which provides a slowly increasing injection volume to achieve steady-state radioactivity for H 2 15 O and 15 O 2 -HbV scans. The radioactivity concentration of 15 O rapidly achieved equilibrium in the blood and whole brain at about 2 minutes after H 2 15 O and 15 O 2 -HbV administration, which was stable during the scans. The whole brain mean values of CBF, CBV, and CMRO 2 were 54.3 ± 2.0 mL per 100 g per minute, 4.9 ± 0.4 mL/100 g, and 2.8 ± 0.2 lmoL per g per minute (6.2±0.4 mL per 100 g per minute) in the normal rats, respectively. In the MCAO model rats, all hemodynamic parameters of the infarction area on the occlusion side significantly decreased. The steady-state method with 15 O-labeled HbV is simple and useful to analyze hemodynamic changes in studies with model animals.

Background: Multimodal PET/MRI image data simultaneously obtained from patients with early-stage of Alzheimer's disease (eAD) were assessed in order to observe pathophysiologic and functional changes, as well as alterations of morphology and connectivity in the brain. Fifty-eight patients with mild cognitive impairment and early dementia (29 males, 69 ± 12 years) underwent [ 11 C]Pittsburgh compound-B (PiB) PET/MRI with 70-min PET and MRI scans. Sixteen age-matched healthy controls (CTL) (9 males, 68 ± 11 years) were also studied with the same scanning protocol. Cerebral blood flow (CBF) was calculated from the early phase PET images using the image-derived input function method. A standardized uptake value ratio (SUVr) was calculated from 50 to 70 min PET data with a reference region of the cerebellar cortex. MR images such as 3D-T1WI, resting-state functional MRI (RS-fMRI), diffusion tensor image (DTI), and perfusion MRI acquired during the dynamic PET scan were also analyzed to evaluate various brain functions on MRI. Results: Twenty-seven of the 58 patients were determined as eAD based on the results of PiB-PET and clinical findings, and a total of 43 subjects' data including CTL were analyzed in this study. PiB SUVr values in all cortical regions of eAD were significantly greater than those of CTL. The PiB accumulation intensity was negatively correlated with cognitive scores. The regional PET-CBF values of eAD were significantly lower in the bilateral parietal lobes and right temporal lobe compared with CTL, but not in MRI perfusion; however, SPM showed regional differences on both PET-and MRI-CBF. SPM analysis of RS-fMRI delineated regional differences between the groups in the anterior cingulate cortex and the left precuneus. VBM analysis showed atrophic changes in the AD group in a part of the bilateral hippocampus; however, analysis of fractional anisotropy calculated from DTI data did not show differences between the two groups. Conclusion: Multimodal analysis conducted with various image data from PiB-PET/MRI scans showed differences in regional CBF, cortical volume, and neuronal networks in different regions, indicating that pathophysiologic and functional changes in the AD brain can be observed from various aspects of neurophysiologic parameters. Application of multimodal brain images using PET/MRI would be ideal for investigating pathophysiologic changes in patients with dementia and other neurodegenerative diseases.

In patients with head-and-neck cancer, intratumoral distribution of Cu-ATSM and FDG showed a negative correlation in SCC and a positive correlation in adenocarcinoma. The 2 tracers represented different pathophysiological microenvironments in different tumors, suggesting that noninvasive hypoxic tissue imaging with Cu-ATSM would be beneficial in the pretreatment evaluation of head-and-neck cancer.

An 15 O-labeled water (H 2 15 O) steady-state method for quantitative measurement of cerebral blood flow (CBF), which is less stressful to small animals with a few point blood sampling, was developed. After a simulation using a dose meter to achieve stable H 2 15 O radioactivity in the blood with a multiprogramming syringe pump programmed for slowly increasing injection volume, 10 rats were studied with the injection method. Arterial blood was sampled every minute during 6-minute positron emission tomography (PET) scans. After the PET scan, N-isopropyl-p-[ 125 I]-iodoamphetamine ( 125 I-IMP) was injected into the same rat to measure CBF using the autoradiography method based on a microsphere model. Regions of interest were placed on the whole brain in H 2 15 O-PET and 125 I-IMP-autoradiography images, and CBF values calculated from both methods were compared. Radioactivity in the dose meter achieved equilibrium B1 minute after starting the H 2 15 O injection. In rat studies, radioactivity in the blood and brain rapidly achieved equilibrium at 2 minutes after administration. The correlation of CBF values of H 2 15 O PET (49.2±5.4 mL per 100 g per minute) and those of 125 I-IMP autoradiography (49.1 ± 5.2 mL per 100 g per minute) was excellent (y = 1.01xÀ0.37, r 2 = 0.97). The H 2 15 O steady-state method with a continuously increasing injection is useful for CBF measurement in small animal studies, especially when multiple scans are required in the same animal.