Automated blood sampling systems for positron emission tomography

Abstract

) I n s t r AB Scanditronix, SwedenAbs t ra c 5 An automated blood sampling system h a s been constructed and evaluated. Two d i f f e r e n t d e t e c t o r u n i t s i n t h e blood sampling system a r e compared. Results from s t u d i e s of blood-brain b a r r i e r t r a n s f e r of a C -1

Quantitative Analysis for Estimating Binding Potential of the Peripheral Benzodiazepine Receptor with [11C]DAA1106

“…Arterial Blood Sampling: To obtain the arterial input function, an automated blood sampling system was used during the first 12 mins of each PET measurement (Eriksson et al, 1988). The concentration of radioactivity in the arterial blood was measured every second.…”

Performance of a coincidence based blood activity monitor

“…In addition, backgrounds from radioactive daughters and contaminants are eliminated. Such a coincidence based blood sampling device has been reported on by the Karolinska Institute [4]. The device described herein differs in that it uses larger BGO crystals, thereby increasing the sensitivity by a factor of nearly three.…”

“…Since the penetration abil ity depends on the positron energy and hence the tracer isotope, the detection efficiency for these devices is isotope dependent, necessitating an isotope dependent calibration factor to convert measured count rate into absolute activ ity. For example, the probability of penetrating the plas tic tubing in the device described by Eriksson, et al [4] (0.94 mm inside diameter, 1.22 mm outside diameter) is computed to be 85% for 15 0, but only 33% for 18 F-FDG [5], resulting in a low sensitivity for this commonly used PET tracer. In addition, the counting efficiency depends strongly on the density of the material being sampledthe counting rate for identical concentrations of U C in water and in blood differ by 10% [4].…”

“…For example, the probability of penetrating the plas tic tubing in the device described by Eriksson, et al [4] (0.94 mm inside diameter, 1.22 mm outside diameter) is computed to be 85% for 15 0, but only 33% for 18 F-FDG [5], resulting in a low sensitivity for this commonly used PET tracer. In addition, the counting efficiency depends strongly on the density of the material being sampledthe counting rate for identical concentrations of U C in water and in blood differ by 10% [4]. Finally, the plastic scintillator is susceptible to backgrounds from low energy emissions from radioactive daughters and contaminants.…”

“…a large number of detected events for a given concentration), it requires a significant amount of sample handling and preparation time, and thus is both expensive and unsuitable for use with short-lived radio tracers such as 15 0 and 82 Rb. The second method is to continuously withdraw blood with a peristaltic pump, then monitor the blood as it is being withdrawn by directly de tecting positrons with a plastic scintillator and a photomultiplier tube [2,3,4].…”