The ECAT ART Scanner for Positron Emission Tomography. 1. Improvements in Performance Characteristics.
ABSTRACT The widespread use of positron emission tomography (PET) has been to some extent limited by the cost and complexity of PET instrumentation. Recognition of the wider applicability of clinical PET imaging is reflected in the ECAT ART design, a low cost PET scanner targeted for clinical applications, particularly in oncology. The ART comprises two asymmetrically opposed arrays of BGO block detectors. Each array consists of 88 (transaxial) by 24 (axial) crystals, and the arrays rotate continuously at 30 rpm to acquire a full 3D projection data set. Sensitivity and count rate limitations are key performance parameters for any imaging device. This paper reports on improved performance characteristics of the ART, achieved by operating the scanner with a decreased block integration time, reduced coincidence time window, and collimated singles transmission sources. Compared to the standard ART configuration, these modifications result in both improved count rate performance and higher quality transmission scans.
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ABSTRACT: Nuclear Medicine is the specialty of medical imaging, which utilizes a variety of radionuclides incorporated into specific compounds for diagnostic imaging and therapeutic applications. During recent years, research efforts in this discipline have concentrated on the decay characteristics of particular radionuclides and the design of unique radiolabeled tracers necessary to achieve time-dependent molecular images. Various oncology applications have utilized specific PET and SPECT radiopharmaceuticals, which have allowed an extension from functional process imaging in tissue to pathologic processes and nuclide directed treatments. One of the most widely recognized advantages of positron emission tomography (PET) is its use of the attractive, positron-emitting biologic radiotracers that mimic natural substrates. However, a major disadvantage is that these substances are relatively short-lived and unable to be transported great distances. At this time, economic considerations and regulatory guidelines associated with the creation of a PET facility, as well as the operational costs of maintaining both the facility and the necessary procedural documentation, continue to create interesting strategic dilemmas. This commentary will focus on the current approach and anticipated impact of pending regulations, which relate to the manufacture and formulation of a variety of PET radiopharmaceuticals used in clinical research and patient management at Memorial Hospital.Annals of Nuclear Medicine 01/2000; 13(6):379-82. · 1.51 Impact Factor
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ABSTRACT: -Vasculogenic cell-based therapy combined with tissue engineering is a promising revascularization approach destined at patients with advanced coronary artery disease, many of whom exhibit myocardial hibernation. However, so far no experimental data have been available in this context; we therefore examined the biopolymer-supported delivery of circulating angiogenic cells (CACs) using a clinically relevant swine model of hibernating myocardium. -Twenty-five swine underwent placement of an ameroid constrictor on the left circumflex artery (LCx). After 2 weeks, animals underwent echocardiography, rest and stress NH3-PET perfusion, and FDG-PET viability scans. The following week, swine were randomized to receive intramyocardial injections of PBS-control (n=10), CACs (n=8), or CACs + collagen-based matrix (n=7). The imaging protocol was repeated after 7 weeks. Baseline PET myocardial blood flow (MBF) and myocardial flow reserve (MFR) were reduced in the LCx territory (both p<0.001), and hibernation (mismatch) was observed. At follow-up, stress MBF had increased (p≤0.01) and hibernation decreased (p<0.01) in the cells+matrix group only. Microsphere-measured MBF validated the perfusion results. Arteriole density and wall motion abnormalities improved in the cells+matrix group. There was also a strong trend towards an improvement in ejection fraction (p=0.07). -In this preclinical swine model of ischemic and hibernating myocardium, the combined delivery of CACs and a collagen-based matrix restored perfusion, reduced hibernation, and improved myocardial wall motion.Circulation Cardiovascular Imaging 10/2013; · 5.80 Impact Factor
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ABSTRACT: (R)-[(11)C]rolipram and (S)-[(11)C]rolipram have been proposed to investigate phosphodiesterase-4 and, indirectly, cAMP-mediated signaling with PET. This study assessed binding of these tracers to phosphodiesterase-4 in canine myocardium. Seven dogs underwent (R)-[(11)C]rolipram and (S)-[(11)C]rolipram dynamic PET imaging at baseline and with co-injection of saturating doses of (R)-rolipram. Dual-input compartment models were applied to estimate the volumes of distribution (V(T)). The model comprising one compartment for unmetabolized tracer and one compartment for labeled metabolites provided excellent fits to data acquired with (S)-[(11)C]rolipram at baseline and with both enantiomers during co-injection scans. Use of two compartments for unmetabolized (R)-[(11)C]rolipram at baseline was warranted according to Akaike and Schwarz criteria. V(T) estimates obtained with these models were robust (CV ≤ 8.2%) and reproducible (CV ≤ 15%). An important fraction (~65%) of the V (T) of (R)-[(11)C]rolipram at baseline reflects specific binding. Thus, the latter may be a useful index of phosphodiesterase-4 levels in canine myocardium.Molecular imaging and biology: MIB: the official publication of the Academy of Molecular Imaging 03/2011; 14(2):225-36. · 2.47 Impact Factor