Objective: Absolute myocardial blood flow (MBF) is not well-defined in large normal populations, and appears to be heterogeneous in both humans and animals. These factors contribute to the difficulties in defining resting MBF to hibernating myocardium. We therefore assessed absolute baseline and hyperemic MBF in a large population of normal humans. Methods: MBF was quantified by positron emission tomography with oxygen-15-labeled water at baseline and during hyperemia induced by either adenosine or dipyridamole in 131 men and 38 women, aged 21-86 (mean 46612) years. MBF was corrected for workload using the rate-pressure product (RPP). Results: Uncorrected baseline MBF ranged from 0.590 to 2.050 (mean 0.98560.230) ml / min / g (coefficient of variation527%), and corrected MBF from 0.736 to 2.428 (mean 1.33060.316) ml / min / g (coefficient of variation524%). MBF in the inferior region was significantly (P,0.0001) lower than either the anterior or lateral regions. Baseline MBF in females was significantly (P,0.001) higher than in males. Conclusions: These results confirm the heterogeneity of MBF in normals and highlight the difficulty in establishing the lower limit of normal MBF.

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Radionuclide myocardial perfusion imaging (MPI) is among the most commonly performed diagnostic tests in cardiology. Although the diagnostic and prognostic applications of radionuclide MPI are supported by a wealth of observational and clinical trial data, its performance is limited by two fundamental drawbacks. First, conventional MPI by SPECT and PET measures relative perfusion, that

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PET/CT is a useful adjunctive diagnostic tool in the evaluation of diagnostically challenging cases of IE, particularly in prosthetic valve endocarditis. It also has the potential to detect clinically relevant extracardiac foci of infection, malignancy, and other sources of inflammation leading to more appropriate treatment regimens and surgical intervention.

Clustering of classical cardiovascular risk factors is insufficient to account for the excess coronary artery disease (CAD) of patients with diabetes, and chronic hyperglycemia and insulin resistance (IR) are obvious culprits. Whole-body and skeletal muscle IR is characteristic of patients with type 2 diabetes, but whether it extends to the normally contracting cardiac muscle is controversial. We investigated whether type 2 diabetes is associated with myocardial IR independent of CAD in a case-control series (n ‫؍‬ 55) of male nondiabetic and diabetic (type 2 and type 1) patients with or without angiographically documented CAD. Baseline blood flow ( 15 O-water) and insulin-stimulated glucose uptake ( 18 Ffluoro-deoxyglucose) during euglycemic (5.6 mmol/l), physiological hyperinsulinemia (40 mU ⅐ min ؊1 ⅐ m ؊2 insulin clamp) were measured by positron emission tomography in skeletal muscle and normally contracting myocardium. Skeletal muscle glucose uptake was reduced in association with both CAD and type 2 diabetes. In regions with normal baseline perfusion, insulinmediated myocardial glucose uptake was reduced in non-CAD type 2 diabetic (0.36 ؎ 0.14 mol ⅐ min ؊1 ⅐ g ؊1 ) and nondiabetic CAD patients (0.44 ؎ 0.15 mol ⅐ min ؊1 ⅐ g ؊1 ) in comparison with healthy control subjects (0.61 ؎ 0.08) or with non-CAD type 1 diabetic patients (0.80 ؎ 0.13; P < 0.001 for both CAD and diabetes). Neither basal skeletal muscle nor basal myocardial blood flow differed across groups; both skeletal muscle and myocardial IR were directly related to whole-body IR. We conclude that type 2 diabetes is specifically associated with myocardial IR that is independent of and nonadditive with angiographic CAD and proportional to skeletal muscle and whole-body IR. Diabetes 51:3020 -3024, 2002

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