Sung-Cheng Huang

CHAPTER 27 – Comparison of Ketamine/Midazolam versus Pentobarbital on [18F]Fluorodopa PET Kinetics in Monkeys

A combination of ketamine and midazolam (K/M) produced a safer, shorter-acting anesthesia than pentobarbital (PB) in both vervet and squirrel monkeys. [18F]Fluorodopa positron emission tomography kinetics were examined in 23 vervet and 18 squirrel monkeys using PB and K/M. Relative to PB, K/M reduced recovery times by 32% in squirrel monkeys and 48% in vervets. Systemic metabolism of [18F]fluorodopa was unchanged in both species. Ki, a measure of the blood-brain barrier transport rate of [18F]fluorodopa, was slightly lower with K/M compared to PB in vervet (10%, p = 0.05) and significantly lower in squirrel monkeys (32%, p < 0.01). Ki, the [18F]fluorodopa uptake constant, was unchanged in vervet and slightly lower with K/M in squirrel monkeys (19%, p = 0.10). K/M produced effective immobilization, was suitable for measuring [18F]fluorodopa kinetics, and significantly reduced the time needed for animal recovery.

Intensive insulin therapy is associated with reduced extracellular glucose and increased oxygen extraction fraction after severe traumatic brain injury

Intensive Insulin Therapy is Associated with Reduced Extracellular Glucose and Increased Oxygen Extraction Fraction after Severe Traumatic Brain Injury

Noninvasive Evaluation and Quantification of Regional Myocardial Blood Flow

Radionuclide imaging with T1-201 is widely used for evaluating regional myocardial perfusion. Its value for diagnosing ischemic heart disease and estimating its extent has been well established. However, the distribution of myocardial blood flow can be assessed with this technique only qualitatively, and measurements of regional myocardial perfusion in terms of ml /min /gm myocardium are not possible. Such measurements can conceivably be made with the recently developed positron emission computed tomography (Positron-CT) [1, 2]. This new imaging modality permits noninvasive measurements of indicator tissue concentrations. Cross-sectional Positron-CT images of the heart quantitatively reflect regional tracer tissue concentrations and hence are comparable to autoradiography. They offer the capability of measuring in vivo tissue activity concentrations which previously has been possible only by in vitro counting of tissue samples. Combined use of this new imaging device with tracers of blood flow is likely to permit noninvasive measurements of regional blood flow in the human heart.