PET’s spatial resolution is 3 to 6 mm, and it is sensitive enough for sequential scans of very short duration (eg, 5 to 20 s)

to be acquired, providing detailed information about the kinetic behavior of the radiotracer. This has been particularly important in studying neuroreceptors, and allows Inhibitors,research,lifescience,medical rapid measurement of the very short-lived 15O blood flow agents (eg, total scanning time of 40 s for H2 15O). The major disadvantage of PET lies in its invasiveness and expense, and in the limitations of short-lived radiotracers. For fully quantitative studies, radial arterial lines are necessary to continuously monitor the amount of radioisotope being delivered to the brain by the arterial blood supply However, for paired studies, Inhibitors,research,lifescience,medical in which one is mainly interested in the difference between the two data sets or their relative values, adequate information can be obtained by simply KRX-0401 comparing the regional count rates between the two (Figure 2.), obviating

the need for the arterial catheter. Figure 2 Top: Unprocessed Inhibitors,research,lifescience,medical regional cerebral blood flow (rCBF) scans in a single individual during right finger movement and rest, and the activation pattern resulting from subtraction of the rest from the motor scans, highlighting the primary motor cortex (arrows). … Magnetic resonance imaging MRI is based on the behavior of atoms with unpaired protons in a magnetic field. Most commonly, the signal from Inhibitors,research,lifescience,medical 1H, most abundant in water and lipids, is used to construct images. During the last decade, the traditional use of MRI for anatomical imaging expanded to probe biochemistry and blood flow through two major advances, spectroscopy and ultrafast imaging.

The latter takes advantage of the different magnetic properties of oxyhemoglobin and deoxyhemoglobin to Inhibitors,research,lifescience,medical rapidly measure blood oxygenation in the brain (the blood oxygen-level out dependent [BOLD] method). Because of the improved temporal and spatial resolution of this technique, and because it has no radiation exposure (and, thus, the potential for unlimited repeated scans on a single individual under different cognitive, pharmacological, or hormonal states), it is now the premier imaging tool for research on cognitive neuroscience and clinical neuropsychiatry. MRS detects and resolves the smaller signals from other elements such as 31P and 23Na. Like nuclear magnetic resonance (NMR) spectroscopy, the unique chemical shifts in the spectra of various molecules provide the signal used to create images.