![]() ![]() We thus had a high level of confidence that the vast majority of MPI scans included in the analysis were “truly” normal. By this 3-step process, we ensured that our study population had a low likelihood of CAD and quantitatively normal MPI scans. Third, we confirmed that the remaining group of patients were at low CAD risk as the calculated 10-year Framingham coronary heart disease risk was low and the mean probability of obstructive CAD among symptomatic patients according to Diamond and Forrester prediction rules was also low. Consequently, we were left with 212 subjects. All subjects with a summed stress score (SSS) > 2, summed difference score (SDS) > 0 and those with quantitatively identified wall motion abnormalities were excluded. Second, all MPI scans were compared quantitatively to a database of normal MPI scans from individuals with a low likelihood of CAD obtained on an identical camera. First, we excluded subjects with clinically established CAD or typical angina. To isolate attenuation artifacts from perfusion abnormalities we evaluated only normal MPI studies in a population with a low prevalence of coronary artery disease (CAD). Segmental wall motion analysis was performed using Cedars-Sinai ® Cardiac Suite (QGS) software (Los Angeles, CA). Image processing and perfusion analysis were performed using MIRAGE ® software (Segami Corporation - Columbia, MD). Stress and acquisition protocols conformed to ASNC guidelines. A one-day Technetium-99m tetrofosmin protocol was implemented. Columbia, MD), which “passed” a SPECT phantom study conformed to ACR guidelines scoring “satisfactory” for spatial resolution, uniformity and contrast. We conducted a retrospective cross-sectional evaluation of 459 consecutive clinically-indicated outpatient SPECT-MPI studies performed between August 2007 and July 2008 using an upright-acquisition cardiac-SPECT system MAIcam180 ® (Mid-Atlantic Imaging Services, Inc. In this paper we further examined the association of the attenuation patterns seen in upright imaging with gender and body habitus. We compared the attenuation patterns observed in upright vs. However, attenuation patterns with upright imaging systems have not been described. As with supine acquisition, the recognition of attenuation patterns associated with upright acquisition is important for accurate MPI interpretation. Therefore, practicing physicians are likely to continue to interpret non-corrected upright SPECT-MPI in the future as well. Only recently, the first upright acquisition cardiac-SPECT system capable of AC has been marketed. While attenuation correction (AC] tools are not widely used in general, they are even less used with upright imaging systems. Nonetheless, upright acquisition SPECT instruments are increasing in popularity with the emergence of mobile cardiac-SPECT cameras, commonly used in the physician’s office. Supine acquisition SPECT-MPI is associated with well recognized attenuation patterns. Soft tissue attenuation remains problematic for myocardial perfusion imaging (MPI) with Single Photon Emission Computed Tomography (SPECT). ![]()
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