This study described and validated a new solid-state singlephoton g-camera and compared it with a conventional-SPECT Anger camera. The compact new camera uses a unique method for localizing g-photon information with a bank of 9 solid-state detector columns with tungsten collimators that rotate independently. Methods: Several phantom studies were performed comparing the new technology with conventional-SPECT technology. These included measurements of line sources and single-and dual-radionuclide studies of a torso phantom. Simulations were also performed using a cardiothoracic phantom. Furthermore, 18 patients were scanned with both the new camera and a conventional-SPECT camera. Results: The new camera had a count sensitivity that was 10 times higher than that of the conventional camera and a compensated spatial resolution that was moderately better. Dual-radionuclide studies using a phantom show the further potential of the new camera for a 2-tracer simultaneous acquisition. Two-minute clinical studies with the new camera and 11-min studies with the conventional camera qualitatively showed good-to-excellent image quality and improved myocardial edge definition for the new camera. Conclusion: These initial performance characteristics of a new solid-state single-photon g-camera offer great promise for clinical dynamic SPECT protocols, with important implications for applications in nuclear cardiology and molecular imaging. Nucl ear medicine has evolved as a clinical and research discipline for the noninvasive assessment of physiologic and molecular function in normal and diseased tissues. Principally performed with nanomolar quantities of administered radiopharmaceuticals and an external scintillation camera, nuclear medicine imaging uses 2 types of modalities: singlephoton imaging (including planar imaging and SPECT) and PET, with the former comprising nearly three fourths of all clinical procedures. With SPECT, myocardial perfusion studies predominate; these studies were performed in approximately 7,000,000 patients in the United States in 2004 and provided images of relative myocardial perfusion at rest and under stress. By assessing the extent of ischemic and infarcted myocardium, SPECT provides noninvasive information that has become central in clinical decision making, determining the need for invasive cardiac catheterization and myocardial revascularization in many patients (1,2).SPECT is typically performed using an Anger scintillation camera, named after its inventor, Hal Anger (3). Most myocardial SPECT is performed with 2 scintillation cameras oriented at 90°and mounted on a gantry that rotates around the patient. Typically, each scintillation camera is equipped with parallel-hole high-resolution collimators. Since collimation is necessary to acquire the projection views, only 0.02% of the photons emitted from the heart are collected. As a result, acquisition times of 10-20 min are required for myocardial SPECT studies. Although new detector technologies using solid-state materials have been explored (...

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The results of planar and single photon emission computed tomography (SPECT) gallium-67 scintigraphy performed before and after treatment were compared in 77 patients with lymphoma at 240 sites. Before treatment, the sensitivity of planar scintigraphy was 78% and the specificity was 97%; after treatment, 84% and 96%, respectively. Before treatment, SPECT had a sensitivity of 85% and a specificity of 98%; after treatment, 92% and 99%, respectively. In addition, SPECT allowed better anatomical localization and showed the entire extent of lesions at 36 sites. SPECT was of special value after treatment in excluding disease at 16 sites with residual masses seen at computed tomography (CT). Long-term follow-up in these patients showed that their condition was in complete remission and that the CT appearance of a residual mass does not always mean residual cancer. Thus, Ga-67 SPECT is a suitable imaging technique for monitoring the response of lymphoma to treatment.

Objective-To assess the eVects of exposure to low concentrations of carbon monoxide (CO), as commonly measured in atmospheric urban air pollution and certain occupational environments, on exercise performance and myocardial perfusion in young healthy men, and the possible need for tighter restrictions on ambient concentrations of CO. Methods-15 young, healthy non-smoking men, 18-35 years old, were exposed blindly and randomly to air or to a mixture of CO and air, followed by an exercise treadmill test with thallium heart scintigraphy. Blood was drawn for determination of carboxyhaemoglobin before and at the end of the exposure, and for lactic and pyruvic acid at the beginning and the end of the exercise test. The main outcome measures include the duration of the exercise test, the maximal eVort expressed in metabolic equivalent units (METs), the mean plasma lactic to pyruvic acid ratio at the end of the ergometry, ECG changes in the exercise test, and perfusion deficits in thallium heart scintigraphy. Results-At the end of exposure to CO, the mean (SD) blood carboxyhaemoglobin concentration rose from 0.59% (0.08%) to 5.12% (0.65%) (p<0.0001). At the end of the exercise period, the mean (SD) plasma lactate/pyruvate ratio, which reflects the level of anaerobic metabolism (69.9 (5.9) after air and 75.9 (7.0) after CO), was not significantly diVerent between the two experimental groups. Exercise induced electrocardiographic changes were noted in only one subject after exposure to CO. No arrhythmias were detected in any of the subjects. Significant diVerences were found in the mean duration of the exercise test (p=0.0012) and the METs (p=0.0001). The mean adjusted diVerence of exercise duration between exposure to air and CO was 1.52 minutes 95% confidence interval (95% CI) 0.73 to 2.32 minutes. The mean adjusted diVerence of METs between exposure to air and CO was 2.04 95% CI 1.33 to 2.76. The models for duration of exercise and METs showed no significant sequence and period eVects. Thallium myocardial perfusion imaging disclosed normal perfusion in all regions of the heart, with no significant diVerences in perfusion between the two exercise tests (after air or CO).Conclusion-Acute exposure to a low concentration of CO which produces blood carboxyhaemoglobin concentrations of 4%-6% significantly decreases exercise performance in young healthy men. No ischaemic electrocardiographic changes or disturbances in myocardial perfusion were found by graded exercise with thallium scintigraphy. Our findings suggest that pollution of atmospheric air by CO at concentrations which are commonly found in urban and industrial environments may exert an adverse eVect on skeletal muscles, manifesting as decreased exercise performance. (Occup Environ Med 1999;56:535-538)