OBJECTIVE -The aim of this study was to evaluate the regional effects of type 2 diabetes and associated conditions on cerebral tissue volumes and cerebral blood flow (CBF) regulation.RESEARCH DESIGN AND METHODS -CBF was examined in 26 diabetic (aged 61.6 Ϯ 6.6 years) and 25 control (aged 60.4 Ϯ 8.6 years) subjects using continuous arterial spin labeling (CASL) imaging during baseline, hyperventilation, and CO 2 rebreathing. Regional gray and white matter, cerebrospinal fluid (CSF), and white matter hyperintensity (WMH) volumes were measured on a T1-weighted inversion recovery fast-gradient echo and a fluid attenuation inversion recovery magnetic resonance imaging at 3 Tesla.RESULTS -The diabetic group had smaller global white (P ϭ 0.006) and gray (P ϭ 0.001) matter and larger CSF (36.3%, P Ͻ 0.0001) volumes than the control group. Regional differences were observed for white matter (Ϫ13.1%, P ϭ 0.0008) and CSF (36.3%, P Ͻ 0.0001) in the frontal region, for CSF (20.9%, P ϭ 0.0002) in the temporal region, and for gray matter (Ϫ3.0%, P ϭ 0.04) and CSF (17.6%, P ϭ 0.01) in the parieto-occipital region. Baseline regional CBF (P ϭ 0.006) and CO 2 reactivity (P ϭ 0.005) were reduced in the diabetic group. Hypoperfusion in the frontal region was associated with gray matter atrophy (P Ͻ 0.0001). Higher A1C was associated with lower CBF (P Ͻ 0.0001) and greater CSF (P ϭ 0.002) within the temporal region.CONCLUSIONS -Type 2 diabetes is associated with cortical and subcortical atrophy involving several brain regions and with diminished regional cerebral perfusion and vasoreactivity. Uncontrolled diabetes may further contribute to hypoperfusion and atrophy. Diabetic metabolic disturbance and blood flow dysregulation that affects preferentially frontal and temporal regions may have implications for cognition and balance in elderly subjects with diabetes. Diabetes Care 30:1193-1199, 2007D iabetes is a prevalent condition associated with substantial morbidity attributed to vascular complications (1). Diabetes alters endothelial function (2) and permeability of the bloodbrain barrier, thus affecting microcirculation and regional metabolism (3).Studies in type 1 diabetes have shown that the fronto-temporal cortex and periventricular white matter (3) are more affected by diabetic metabolic disturbance. Single proton emission computed tomography (SPECT) studies suggest that chronic hyperglycemia alters cerebral blood flow (CBF) in the frontal, temporal, parietal, occipital, and cerebellar regions of interest (ROIs) (4,5). Vasoreactivity to acetazolamide is not homogeneous, with a majority of hypoperfused and some hyperperfused ROIs (6). White matter hyperintensities (WMHs) on T2-weighted magnetic resonance imaging (MRI) (7) have been associated with arteriolosclerosis, arising as consequences of aging, diabetes, and other cardiovascular risk factors (8,9). Vascular and neurodegenerative changes in these structures have consequences for regional perfusion, cognitive impairment, and balance in elderly people with type 2 diabetes (10,...

Purpose:To determine whether arterial spin-labeling (ASL) magnetic resonance (MR) imaging findings at baseline and early during antiangiogenic therapy can predict later resistance to therapy. Materials and Methods:Protocol was approved by an institutional animal care and use committee. Caki-1, A498, and 786-0 human renal cell carcinoma (RCC) xenografts were implanted in 39 nude mice. Animals received 80 mg sorafenib per kilogram of body weight once daily once tumors measured 12 mm. ASL imaging was performed at baseline and day 14, with additional imaging performed for 786-0 and A498 (3 days to 12 weeks). Mean blood flow values and qualitative differences in spatial distribution of blood flow were analyzed and compared with histopathologic findings for viability and microvascular density. t Tests were used to compare differences in mean tumor blood flow. Bonferroni-adjusted P values less than .05 denoted significant differences. Results:Baseline blood flow was 80.1 mL/100 g/min Ϯ 23.3 (standard deviation) for A498, 75.1 mL/100 g/min Ϯ 28.6 for 786-0, and 10.2 mL/100 g/min Ϯ 9.0 for Caki-1. Treated Caki-1 showed no significant change (14.9 mL/100 g/min Ϯ 7.6) in flow, whereas flow decreased in all treated A498 on day 14 (47.9 mL/100 g/min Ϯ 21.1) and in 786-0 on day 3 (20.3 mL/100 g/min Ϯ 8.7) (P ϭ .003 and .03, respectively). For A498, lowest values were measured at 28 -42 days of receiving sorafenib. Regions of increased flow occurred on days 35-49, 17-32 days before documented tumor growth and before significant increases in mean flow (day 77). Although 786-0 showed new, progressive regions with signal intensity detected as early as day 5 that correlated to viable tumor at histopathologic examination, no significant changes in mean flow were noted when day 3 was compared with all subsequent days (P Ͼ .99). Conclusion:ASL imaging provides clinically relevant information regarding tumor viability in RCC lines that respond to sorafenib.

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