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This study examined effects of carbohydrate (CHO), milk-based carbohydrate-protein (CHO-PRO), or placebo (P) beverages on glycogen resynthesis, muscle damage, inflammation, and muscle function following eccentric resistance exercise. Untrained males performed a cycling exercise to reduce muscle glycogen 12 hours prior to performance of 100 eccentric quadriceps contractions at 120% of 1-RM (day 1) and drank CHO (n = 8), CHO-PRO (n = 9; 5 kcal/kg), or P (n = 9) immediately and 2 hours post-exercise. At 3 hours post-eccentric exercise, serum insulin was four times higher for CHO-PRO and CHO than P (p < .05). Serum creatine kinase (CK) increased for all groups in the 6 hours post-eccentric exercise (p < .01), with the increase tending to be lowest for CHO-PRO (p < .08) during this period. Glycogen was low post-exercise (33 ± 3.7 mmol/kg ww), increased 225% at 24 hours, and tripled by 72 hours, with no group differences. The eccentric exercise increased muscle protein breakdown as indicated by urinary 3-methylhistidine and increased IL-6 with no effect of beverage. Quadriceps isokinetic peak torque was depressed similarly for all groups by 24% 24 hours post-exercise and remained 21 % lower at 72 hours (p < .01). In summary, there were no influences of any post-exercise beverage on muscle glycogen replacement, inflammation, or muscle function.

Our laboratory recently demonstrated the pattern of cell surface glycosylation of nonsecretory central airway epithelium (Dorscheid DR, Conforti AE, Hamann KJ, Rabe KF, and White SR. Histochem J 31: 145–151, 1999), but the role of glycosylation in airway epithelial cell migration and repair is unknown. We examined the functional role of cell surface carbohydrates in wound repair after mechanical injury of 1HAEo−human airway epithelial and primary bronchial epithelial monolayers. Wound repair stimulated by epidermal growth factor was substantially attenuated by 10−7M tunicamycin (TM), an N-glycosylation inhibitor, but not by the inhibitors deoxymannojirimycin or castanospermine. Wound repair of 1HAEo−and primary airway epithelial cells was blocked completely by removal of cell surface terminal fucose residues by α-fucosidase. Cell adhesion to collagen matrix was prevented by TM but was only reduced ∼20% from control values with prior α-fucosidase treatment. Cell migration in Blind Well chambers stimulated by epidermal growth factor was blocked by pretreatment with TM but α-fucosidase pretreatment produced no difference from control values. These data suggest that cell surface N-glycosylation has a functional role in airway epithelial cell adhesion and migration and that N-glycosylation with terminal fucosylation plays a role in the complex process of repair by coordination of certain cell-cell functions.

The study assessed a way to increase the intensity and effectiveness of resistance training by comparing training with a slower repetition speed to training with a conventional repetition speed. Slower repetition speed may effectively increase intensity throughout the lifting phase while decreasing momentum.Two studies were done with untrained men (N=65) and women (N=82), (mean age=53.6) who trained two to three times per week for eight to 10 weeks on a 13 exercise Nautilus circuit performing one set of each exercise. Participants exclusively trained using regular speed repetitions for 8 to 12 repetitions per set at 7 sec each (2 sec lifting, 1 sec pause, 4 sec lowering) or a Super Slow training protocol where they completed 4 to 6 repetitions per set at 14 sec each (10 sec lifting, 4 sec lowering). All of the participants were tested for either the 10 repetition-maximum (RM) weightload (regular-speed group) or the 5-RM weightload (slow-speed group).In both studies, Super-Slow training resulted in about a 50% greater increase (p0.001) in strength for both men and women than regular speed training. In Study 1, the Super-Slow training group showed a mean increase of 12.0 kg and the regular speed group showed an increase of 8.0 kg increase (p0.001). In Study 2, the Super-Slow training group showed a 10.9 kg increase and the regular speed group showed an increase of 7.1 kg (p0.001).Super-Slow training is an effective method for middle-aged and older adults to increase strength. Although studies still need to be done with at-risk populations, repetition speed should be considered when prescribing resistance training.

Positron emission mammography (PEM) is a technique to obtain planar images of the breast for detection of potentially cancerous, radiotracer-avid tumors. To increase the diagnostic accuracy of this method, use of minimally invasive methods (e.g., core biopsy) may be desirable for obtaining tissue samples from lesions detected with PEM. The purpose of this study was to test the capabilities of a novel method for performing PEM-guided stereotactic breast biopsies.The PEM system consisted of 2 square (10 x 10 cm) arrays of discrete scintillator crystals. The detectors were mounted on a stereotactic biopsy table. The stereotactic technique used 2 PEM images acquired at +/-15 degrees and a new trigonometric algorithm. The accuracy and precision of the guidance method was tested by placement of small point sources of (18)F at known locations within the field of view of the imager. The calculated positions of the sources were compared with the known locations. In addition, simulated stereotactic biopsies of a breast phantom consisting of a 10-mm-diameter gelatin sphere containing a concentration of (18)F-FDG consistent with that reported for breast cancer were performed. The simulated lesion was embedded in a 4-cm-thick slab of gelatin containing a commonly reported concentration of FDG, simulating a compressed breast (target-to-background ratio, approximately 8.5:1). An anthropomorphic torso phantom was used to simulate tracer uptake in the organs of a patient 1 h after a 370-MBq injection of FDG. Five trials of the biopsy procedure were performed to assess repeatability. Finally, a method for verifying needle positioning was tested.The positions of the point sources were successfully calculated to within 0.6 mm of their true positions with a mean error of +/-0.4 mm. The biopsy procedures, including the method for verification of needle position, were successful in all 5 trials in acquiring samples from the simulated lesions.The success of this new technique shows its potential for guiding the biopsy of breast lesions optimally detected with PEM.

Dystroglycans (DGs) bind laminin matrix proteins in skeletal and cardiac muscle and are expressed in other nonmuscle tissues. However, their expression in airway epithelial cells has not been demonstrated. We examined expression of DGs in the human airway epithelial cell line 1HAEo(-), and in human primary airway epithelial cells. Expression of the common gene for alpha- and beta-DG was demonstrated by reverse transcriptase/ polymerase chain reaction in 1HAEo(-) cells. Protein expression of beta-DG was demonstrated by both Western blot and flow cytometry in cultured cells. Localization of alpha-DG, using both a monoclonal antibody and the alpha-DG binding lectin wheat-germ agglutinin (WGA), was to the cell membrane and nucleus. We then examined the function of DGs in modulating wound repair over laminin matrix. Blocking alpha-DG binding to laminin in 1HAEo(-) monolayers using either glycosyaminoglycans or WGA attenuated cell migration and spreading after mechanical injury. alpha-DG was not expressed in epithelial cells at the wound edge immediately after wound creation, but localized to the cell membrane in these cells within 12 h of injury. These data demonstrate the presence of DGs in airway epithelium. alpha-DG is dynamically expressed and serves as a lectin to bind laminin during airway epithelial cell repair.

We are developing a scanner for simultaneous acquisition of x-ray computed tomography (CT) and single photon emission tomography (SPECT) images of small animals such as mice and rats. The scanner uses a cone beam geometry for both the x- ray transmission and gamma emission projections by using an area x-ray detector and pinhole collimator, respectively. The CT and SPECT data set are overlaid to form a coregistered structural-functional 3D image. The CT system includes a single CCD-based x-ray detector and a microfocus x-ray source. The SPECT scanner utilizes tungsten pinhole collimators and arrays of CsI(Tl) scintillation detectors. We describe considerations and the early performance of a prototype scanner.

A social-cognitive model of nutrition behavior (A. Bandura, 1997) was tested using structural equation modeling of data from 307 food shoppers recruited from 5 supermarkets in Southwest Virginia. The shoppers were participating in the baseline phase of an ongoing nutrition promotion program. As part of the evaluation, data were collected on the self-efficacy and outcome-expectations components of social-cognitive theory as well as on food purchases and intake. The structural analyses presented here support the social-cognitive model. Self-efficacy, physical outcome expectations, age, socioeconomic status, and number of children were important predictors of nutrition behavior among shoppers. Implications for interventions using social-cognitive variables to improve the nutritional content of food purchases and intake are discussed.

Glycosylated structures on the cell surface have a role in cell adhesion, migration, and proliferation. Repair of the airway epithelium after injury requires each of these processes, but the expression of cell surface glycosylation of airway epithelial cells after injury is not known. We examined cell surface glycosylation using lectin-binding profiles of normal and repairing epithelia in Hartley guinea pigs from 0 to 14 days after mechanical injury. The epithelium regenerated completely-over 7 days. In normal trachea, galactose- or galactosamine-specific lectins (14 of 20 tested) labelled epithelial cells, but fucose, mannose, and other sugar-specific lectins (15 tested) did not. GSA-2, a glucosamine-specific lectin, labelled epithelial cells weakly in uninjured tracheas, but intense labelling was noted in basal and non-ciliated columnar cells adjacent to the injury site over 3 h to 14 days after injury. Labelling of these cells peaked at 12 h and 5 days after injury respectively. Similar patterns were seen with lectins AlloA and HAA but not with CPA during repair. The binding of the lectin DSA to proteins collected from primary cultures of airway epithelial cells decreased substantially after treatment for 24 h with either transforming growth factor-beta or interleukin-1beta, but that of the CPA lectin did not. We demonstrate changes in glycosylation profiles of airway epithelial cells coordinate with repair after mechanical injury. These changes may be useful to study mechanisms by which repair is regulated.

In breast scintigraphy, compact detectors with high intrinsic spatial resolution and small inactive peripheries can provide improvements in extrinsic spatial resolution, efficiency and contrast for small lesions relative to larger conventional cameras. We are developing a pixelated small field-of-view gamma camera for scintimammography. Extensive measurements of the imaging properties of a prototype system have been made, including spatial resolution, sensitivity, uniformity of response, geometric linearity and energy resolution. An anthropomorphic torso phantom providing a realistic breast exit gamma spectrum has been used in a qualitative study of lesion detectability. A new type of breast imaging system that combines scintimammography and digital mammography in a single upright unit has also been developed. The system provides automatic co-registration between the scintigram and the digital mammogram, obtained with the breast in a single configuration. Intrinsic spatial resolution was evaluated via calculation of the phase-dependent modulation transfer function (MTF). Measurements of extrinsic spatial resolution, sensitivity and uniformity of response were made for two types of parallel hole collimator using NEMA (National Electrical Manufacturers Association) protocols. Geometric linearity was quantified using a line input and least squares analysis of the measured line shape. Energy resolution was measured for seven different crystal types, and the effectiveness of optical grease coupling was assessed. Exit gamma spectra were obtained using a cadmium zinc telluride based spectrometer. These were used to identify appropriate radioisotope concentrations for the various regions of an anthropomorphic torso phantom, such that realistic scatter conditions could be obtained during phantom measurements. For prone scintimammography, a special imaging table was constructed that permits simultaneous imaging of both breasts, as well as craniocaudal views. A dedicated breast imaging system was also developed that permits simultaneous acquisition and superposition of planar gamma images and digital x-ray images. The intrinsic MTF is nonstationary, and is dependent on the phase relationship between the signal and the crystal array matrix. Averaged over all phases, the MTF is approximately 0.75, 0.57 and 0.40 at spatial frequencies of 1.0, 1.5 and 2.0 cycles per cm, respectively. The phase averaged line spread function (LSF) has a FWHM value of 2.6 mm. Following uniformity corrections, the RMS deviations in flood images are only slightly greater than is predicted from counting statistics. Across an 80 mm section of the active area, the differential linearity is 0.83 mm and the absolute linearity 2.0 mm. Using an anthropomorphic torso phantom with detachable breasts, scatter radiation similar to that observed exiting the breast of scintimammography patients was observed. It was observed that scattered gamma rays can constitute the majority of the radiation incident on the detector, but that the scatter-to-primary ratio varies significantly across the field of view, being greatest in the caudal portion of the breast, where scatter from the liver is high. Using a lesion-to-breast concentration ratio of 6:1, a 1.0 cm3 simulated breast lesion was detectable in lateral images obtained with both the developmental camera and with a clinical camera, while a 0.35 cm3 lesion was detectable in neither. Utilization of the dual x-ray transmission, gamma emission breast imaging system greatly increases the conspicuity of scintimammographic lesions relative to prone imaging, as well as greatly facilitating the localization and identification of structures in the gamma image. The prototype imaging gamma detector exhibits spatial resolution superior to that of conventional cameras, and comparable uniformity of response and geometric linearity. Because of light losses in the crystals, the energy resolution is inferior to that of single crystal NaI(Tl) cameras. Concentration ratios for an anthropomorphic phantom providing realistic scatter conditions and lesion imaging tasks have been identified. A dedicated system for dual modality breast imaging has been developed that provides improved scintigraphic breast imaging relative to the established prone scintimammography techniques.

Repair of the airway epithelium after injury requires that processes such as adhesion and cell migration occur in a defined order. Both of these processes depend on interactions between extracellular matrix (ECM) proteins and appropriate integrins. To study these interactions, we examined monolayer wound repair in a cultured human airway epithelial cell line, 16HBE14o-. Wounds created in confluent monolayers grown on either collagen-IV, laminin-1, or laminin-2 matrix closed quickly in response to 15 ng/ml epidermal growth factor (EGF). Concurrent treatment of cells grown on each matrix protein with EGF and a monoclonal antibody (mAb) to beta1-integrin inhibited wound closure. Treatment with a mAb to alpha2-, alpha3-, and alpha6-integrin blocked wound repair in monolayers grown on collagen-IV but did not do so in monolayers grown either on laminin-1 or laminin-2. Inhibition was not due to cell detachment or apoptosis. These data demonstrate that integrins expressed by airway epithelial cells mediate wound closure on different constitutive ECM proteins. These data suggest that beta1-integrin subunit function is required to permit migration and spreading of epithelial cells, and that alpha-integrin subunits alone do not mediate migration of epithelial cells grown on either laminin-1 or laminin-2. These differences may become important if the matrix protein composition of airway basement membrane changes in disease states such as asthma.

The authors report on studies of a small field of view scintimammography camera based on a position sensitive PMT and a crystal scintillator array. A 5-inch R3292 Hamamatsu PMT was coupled to a variety of scintillators, including pixelized NaI(TI), Csi (Na) and YAP. Laboratory and phantom studies were performed to compare performances of the above scintillator sensors with special emphasis on spatial resolution and scatter rejection. The results of Monte Carlo simulations for different pixel sizes are also presented.

Reverse Geometry X-radiography imaging uses a unique configuration of x-ray source, patient, and x-ray detector to produce high resolution images. With the current system, produced by Digiray, one can obtain a resolution of 16 lp/mm and a contrast sensitivity of 0.2%. Using a lead focusing grid with 100 keV x-rays at 1 mA a dose of less than 20 mR/sec was measured. Typical acquisition times are 1/16 sec for 256 line resolution to 8 sec for 2048 line resolution. An optimized multi-detector system under development should reduce the dose rate to far less than 1 mR/sec and allow the possibility for fast volume CT applications providing laminographic view of the patient. Also `mini-probe' detectors have been developed which may be used to produce in-vitro unobstructured views.

A low dose rate evaluation of several scintillators and wavelength shifters of interest to the CEBAF program was performed with a 60Co line source to a total dose of 160 Gray at a rate of 0.5 Gy/hr in a slowly flowing oxygen atmosphere. The samples included the following: (1) a 2 meter piece of Bicron BC412 scintillator being extensively used in the CEBAF Large Acceptance Spectrometer, (2) a 1 meter long piece of green scintillator doped with a uniquely fast green fluor (G2), (3) wavelength shifting fiber dopedalso with G2, and (4) grooved acrylic-based scintillator that is readout with the WLS fiber. The data indicates that the BC412 shows no loss in intrinsic light output, but does have an attenuation loss amounting to 10% at 1 meter and 16% at 2 meters. The fast green scintillator (and fibers) showed no damage. When read out by WLS fibers, the acrylic scintillator displayed a loss in intrinsic light output, but no change in attenuation.

The phenomenon of crack initiation and propagation in railway rails has appeared as an important problem in engineering and has become an object of intensive research in many scientific centers. Of particular recent interest is the so-called “squat” defect, and a surface crack which propagates from an origin near the rail crown along an inclined path into the rail head. Squat defects have been observed frequently on high-speed BR lines, occasionally on some European lines, and occasionally on Japan’s Shinkansen high-speed line.

We describe the latest results in the development of a tracking detector based on a modular concept using multidrift tubes. Several prototypes have been built and tested. Each module contains about 70 independent drift cells, constituted by anodes centred in a hexagonal cell defined by six cathode wires. A thin hexagonal carbon-fibre envelope, 30 mm in diameter, supports the wire tension and provides gas tightness. Using dimethyl ether as a gas filling, we have obtained radial localization accuracies of about 65 μ m rms per wire and longitudinal accuracies of about 0.9% of the wire length. Ageing measurements show that we can expect good operation of the modules up to an accumulated charge density of about 1 C/cm. Furthermore, owing to the small cell size and high field, the space-charge gain reduction is less than 10% for currents up to 0.5 μA/cm, about 20 times better than observed in conventional MWPCs.

An echocardiographic evaluation of 77 members of a championship childhood swim team showed dimensional variations from normal in most athletes. Cardiac walls were thicker than the 95th percentile of normal: right ventricular anterior wall exceeded the 95th percentile in 100%, interventricular septum in 83% and left ventricular posterior wall in 91%. The left ventricular and left atrial cavities in diastole had mean values at the 50th percentile of normal but showed considerable scatter. The left ventricular cavity in systole had a mean value less than the 5th percentile of normal and also showed wide scatter. The aortic root and the aortic intercusp dimension exceeded the 95th percentile of normal in most subjects, 74% and 77%, respectively. No correlation existed between the coach's estimate of championship ability and echocardiographic wall or chamber sizes. Children who participate extensively in athletic training programs such as swimming may have echocardiograms which are quantitatively different from those of nonathletic younsters.

The need to characterize the radiation hardness of certain classes of devices in terms of atomic displacement damage rather than total absorbed dose is addressed. Resistive-network displacement damage monitors irradiated with 1.0-MeV protons and 7.3-MeV electrons indicate that these radiations are both about twenty times as damaging as /sup 60/Co gamma radiation for the same total absorbed dose. Preliminary results are presented on an alternative monitor consisting of a GaAs LED (light-emitting diode) that offers a two-order-of-magnitude increase in sensitivity over the resistive network monitors. Other characteristics of the two monitors, such as range, linearity, annealing and reuse, and neutron sensitivity, are compared. >

Although most pediatric echocardiographic criteria have been concerned with qualitative aspects of cardiac anatomy, dimensional quantitation has demonstrated utility in children with lesions causing cardiac pressure or volume overloads. Examples of this include following left atrial dimension in children with patent ductus, or ventricular septal defect and right ventricular anterior wall thickness in cor pulmonale. In order to utilize quantitative echographic techniques, normal chamber and great vessel dimensions established during a collaborative study from the Universities of Arizona and Indiana were derived and presented last year at this meeting by Epstein. The study established percentile nomograms which compared direct echocardiographic measurements of walls, chambers and great vessels in unselected normal healthy children to the best correlate, body surface area. These nomograms have been utilized as a basis for reading echocardiograms of children evaluated for various reasons in our cardiac clinics. A number of athletic youngsters with normal hearts were found to have excessive echocardiographic dimensions. Accordingly, it became clear that more definition of the upper 5th percentile was required. In order to define this range, we selected the best available group of highly trained childhood athletes, competitive swimmers.

The purpose of the study is to investigate the performance characteristics of a pinhole SPECT system based on a newly developed modular camera with a pixelated NaI(Tl) crystal with 1.2 mm pixels and 1.4 mm pitch and a 5" R3292 PSPMT. The characteristics are compared to that based on a standard GE AC/T 400 camera with continuous crystal using the same set of tungsten apertures with pinhole diameters of 1.0,1.5 and 2.0 mm. The system spatial resolution and sensitivity were characterized as a function of source-to-pinhole distance and pinhole diameter from the measurements of point spread function (PSF) using /spl sim/150/spl mu/m /sup 99m/Tc point sources. A microSPECT phantom was used to access the system resolution in SPECT imaging and a /sup 99m/Tc-MDP mouse bone SPECT imaging from the modular camera based system was demonstrated. The projection data from the phantom and mouse studies were reconstructed using a 3D OSEM pinhole reconstruction algorithm with geometrical misalignment correction. In general, the modular camera based microSPECT system shows slightly poorer spatial resolution as compared to the GE 400 AC/T camera based system using the same set of pinhole apertures. The phantom study indicates that using the same pinhole aperture of 1 mm the modular camera based system can clearly resolve 1.6 mm rods while the GE 400 AC/T camera based system can well resolve 1.2 mm rods. Reconstructed mouse images demonstrate that high image quality can be obtained with the modular camera based pinhole SPECT system despite its slightly poorer system resolution as compared to that based on a standard camera. In conclusion, the modular camera fitted with a shorter pinhole collimator can achieve high-resolution for high quality small animal imaging. With continuous improvements in detector technology, system design and image reconstruction method, modular camera can be an important component of a high-resolution small animal SPECT imaging system.

We have designed and constructed a small animal SPECT system based on compact, high resolution detectors and multipinhole apertures. The scanner is currently configured with two detectors mounted on a rotating gantry. Each detector comprises a NaI(Tl) crystal array (1/spl times/1/spl times/5 mm elements), a 12 cm diameter position-sensitive photomultiplier tube (Hamamatsu R3292) and a tungsten aperture with 1 or more pinholes. In this study, we performed phantom experiments to characterise the planar and tomographic performance of the scanner. Intrinsic resolution measured with a highly collimated /sup 99m/Tc point source stepped across the detector face was 1.0 /spl plusmn/ 0;.1 FWHM and 2.9 /spl plusmn/ 0.1 mm FWTM. Energy resolution at 140 keV varied from 14% FWIIM for central crystals to 19% for edge crystals and was 20% FWHM for the whole detector normalised spectrum. Intrinsic uniformity for the central field of view was 2.4% differential and 3.8% integral. Reconstructed spatial resolution was 1.2 mm FWHM at the centre of the field of view and 1.2, 1.7 mm FWHM (radial, tangential) at 10 mm off-axis, using typical geometric parameters for mouse and rat brain imaging. Reconstructed images of a micro deluxe hot rod phantom demonstrate the high resolution of the system and indicate similar resolution and improved signal-to-noise is obtained with a 2 pinhole aperture compared with a single pinhole. We conclude that the performance characteristics of this system make it suitable for high resolution imaging of small laboratory animals.

Part oneof this study investigated the effect of aging on social-cognitive characteristics related to physical activity (PA) among adults in the baseline phase of a health promotion intervention. Participants' questionnaire responses and activity logs indicated PA levels and self-efficacy declined with age, while social support and the use of self-regulatory behaviors (e.g., goal setting, planning, and keeping track) increased. With age participants were also less likely to expect PA to interfere with their daily routines and social obligations. Part two of the study was among overweight/obese, inactive participants completing the intervention; it examined whether improvements in psychosocial variables might counteract declining PA associated with age. After treatment, participants were more active and decreased body weight regardless of age, and improved self-efficacy, outcome expectations, and self-regulatory behaviors. In a causal model, increases in self-efficacy at 7-months lead to increased PA levels and, albeit marginally, weight loss at 16 months; increased PA was associated with greater weight loss. Aging adults who were more confident exercised more and as a result lost more weight. This longitudinal study suggests interventions that offset the effect of aging on self-efficacy may be more successful in helping older participants become more active and avoid weight gain.

Characterization of reservoir properties like porosity and permeability in reservoir models typically relies on history matching of production data, well pressure data, and possibly other fluid-dynamical data. Calibrated (history-matched) reservoir models are then used for forecasting production, and designing effective strategies for improved oil and gas recovery. Here, we perform data assimilation of both flow data and deformation data for joint inversion of reservoir properties. Given the coupled nature of the process, joint inversion requires efficient simulation tools of coupled reservoir flow and mechanical deformation. We apply our coupled simulation tool to a real underground gas storage field in Italy. We simulate the initial gas production period, and several decades of seasonal natural gas storage and production. We perform a probabilistic estimation of rock properties by joint inversion of ground deformation data from geodetic measurements and fluid flow data from wells. Using an efficient implementation of the Ensemble Kalman Smoother as the estimator and our coupled multiphase flow and geomechanics simulator as the forward model, we show that incorporating deformation data leads to a significant reduction of uncertainty in the prior distributions of rock properties such as porosity, permeability, and pore compressibility. Research significance 1. We perform joint inversion of flow and surface deformation data for parameter estimation in a real field with complex production-injection history based on the Bayesian inference model and coupled multiphase flow and geomechanics simulation. 2. We develop a computationally efficient implementation of the Ensemble Kalman method for uncertainty reduction. 3. We quantify the value of information from surface deformation data in uncertainty reduction in prior distributions.

We have previously demonstrated the potential of multi-pinhole coded apertures when used in conjunction with compact pixelated detectors for high resolution, high sensitivity small animal SPECT. We are now constructing a prototype SPECT system with three such detectors mounted on a rotating gantry. Each detector comprises a 12 cm diameter circular array of NaI(Tl) crystals, each 1/spl times/1/spl times/5 mm/sup 3/ on a 1.25 mm pitch. Each crystal array is coupled to a Hamamatsu R3292 12.7 cm diameter PS-PMT. Signals from the three detectors are read out by a custom subtractive resistive circuit and multiplexed. Data are acquired by a National Instruments PCI-6110E board running on a Macintosh dual processor G4 computer under Kmax software control. Images are reconstructed using a 3D iterative MAP-EM algorithm based on a multi-pinhole forward and back projector. The trade-off between contrast and variance was studied by simulation for a number of multi-pinhole configurations. We also performed initial planar imaging studies on one of the detectors. Our results indicate that spatial resolution approaching 1 mm full width at half maximum (FWHM) can be achieved with a single pinhole aperture, while improved contrast and variance may result from using optimized multi-pinhole apertures.

✓ The authors have developed a rocking platform that can be used by a wheel-chair patient without additional aid to relieve constant pressure on the body and consequent skin breakdown.