Purpose:To evaluate the value of diffusion-weighted imaging (DWI) in distinguishing between benign and malignant breast lesions. Materials and Methods:Fifty-two female subjects (mean age ϭ 58 years, age range ϭ 25-75 years) with histopathologically proven breast lesions underwent DWI of the breasts with a single-shot echo-planar imaging (EPI) sequence using large b values. The computed mean apparent diffusion coefficients (ADCs) of the breast lesions and cell density were then correlated. Results:The ADCs varied substantially between benign breast lesions ((1.57 Ϯ 0.23) ϫ 10 -3 mm 2 /second) and malignant breast lesions ((0.97 Ϯ 0.20) ϫ 10 -3 mm 2 /second). In addition, the mean ADCs of the breast lesions correlated well with tumor cellularity (P Ͻ 0.01, r ϭ -0.542). Conclusion:The ADC would be an effective parameter in distinguishing between malignant and benign breast lesions. Further, tumor cellularity has a significant influence on the ADCs obtained in both benign and malignant breast tumors.

OBJECTIVE -To elucidate the effects of pioglitazone treatment on glucose and lipid metabolism in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS -A total of 23 diabetic patients (age 30 -70 years, BMI Ͻ 36 kg/m2 ) who were being treated with a stable dose of sulfonylurea were randomly assigned to receive either placebo (n ϭ 11) or pioglitazone (45 mg/day) (n ϭ 12) for 16 weeks. Before and after 16 weeks of treatment, all subjects received a 75-g oral glucose tolerance test (OGTT); and hepatic and peripheral insulin sensitivity was measured with a two-step euglycemic insulin (40 and 160 mU ⅐ min Ϫ1 ⅐ m -2 ) clamp performed with 3-[ 3 H]glucose and indirect calorimetry. HbA 1c was measured monthly throughout the study period.RESULTS -After 16 weeks of pioglitazone treatment, the fasting plasma glucose (FPG; 184 Ϯ 15 to 135 Ϯ 11 mg/dl, P Ͻ 0.01), mean plasma glucose during OGTT (293 Ϯ 12 to 225 Ϯ 14 mg/dl, P Ͻ 0.01), and HbA 1c (8.9 Ϯ 0.3 to 7.2 Ϯ 0.5%, P Ͻ 0.01) decreased significantly without change in fasting or glucose-stimulated insulin/C-peptide concentrations. Fasting plasma free fatty acid (FFA; 647 Ϯ 39 to 478 Ϯ 49 Eq/l, P Ͻ 0.01) and mean plasma FFA during OGTT (485 Ϯ 30 to 347 Ϯ 33 Eq/l, P Ͻ 0.01) decreased significantly after pioglitazone treatment. Before and after pioglitazone treatment, basal endogenous glucose production (EGP) and FPG were strongly correlated (r ϭ 0.67, P Ͻ 0.01). EGP during the first insulin clamp step was significantly decreased after pioglitazone treatment (P Ͻ 0.05), whereas insulin-stimulated total and nonoxidative glucose disposal during the second insulin clamp was increased (P Ͻ 0.01). The change in FPG was related to the change in basal EGP, EGP during the first insulin clamp step, and total glucose disposal during the second insulin clamp step. The change in mean plasma glucose concentration during the OGTT was strongly related to the change in total body glucose disposal during the second insulin clamp step.CONCLUSIONS -These results suggest that pioglitazone therapy in type 2 diabetic patients decreases fasting and postprandial plasma glucose levels by improving hepatic and peripheral (muscle) tissue sensitivity to insulin. Diabetes Care 24:710 -719, 2001T ype 2 diabetes is characterized by defects in both insulin secretion and insulin sensitivity (1,2). The insulin resistance is established early in the natural history of type 2 diabetes (1-3), but with time there is a progressive failure of ␤-cell function (1,4,5). Based on the pathophysiology of type 2 diabetes, combination therapy with an insulin secretagogue and an insulin sensitizer provides a rational therapeutic approach to reduce blood glucose levels in poorly controlled type 2 diabetic patients (6). Such an approach has been used successfully with sulfonylureas and metformin (7).Recently, a new class of insulinsensitizing agents, the thiazolidinediones, was introduced for the treatment of type 2 diabetic patients (8). Troglitazone, the first thiazolidinedione introduced into the U.S. market, has been...

The hypothalamus plays a central role in the regulation of energy intake and feeding behavior. However, the presence of a functional abnormality in the hypothalamus in humans that may be related to excess energy intake and obesity has yet to be demonstrated in vivo. We, therefore, used functional magnetic resonance imaging (fMRI) to monitor hypothalamic function after oral glucose intake. The 10 obese (34 +/- 2 years of age, BMI 34.2 +/- 1.3 kg/m2) and 10 lean (32 +/- 4 years of age, BMI 22.0 +/- 0.9 kg/m2) subjects with normal glucose tolerance ingested 75 g of glucose while a midsagittal slice through the hypothalamus was continuously imaged for 50 min using a conventional T2*-weighted gradient-echo pulse sequence. After glucose ingestion, lean subjects demonstrated an inhibition of the fMRI signal in the areas corresponding to the paraventricular and ventromedial nuclei. In obese subjects, this inhibitory response was markedly attenuated (4.8 +/- 1.3 vs. 7.0 +/- 0.6% inhibition, P < 0.05) and delayed (9.4 +/- 0.5 vs. 6.4 +/- 0.5 min, P < 0.05) compared with that observed in lean subjects. The time taken to reach the maximum inhibitory response correlated with the fasting plasma glucose (r = 0.75, P < 0.001) and insulin (r = 0.47, P < 0.05) concentrations in both lean and obese subjects. These results demonstrate in vivo, for the first time, the existence of differential hypothalamic function in lean and obese humans that may be secondary to obesity.