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The correct energy window setting and a stable photopeak position are crucial for good data acquisition. We report a patient whose myocardial perfusion SPECT images showed mildly irregular radiotracer uptake when the patient was prone but not when the patient was supine. Review of the sinogram showed clear interruptions in the sinusoidal shape of the raw data when the patient was prone. Detailed technical evaluation revealed that the artifact was caused by an unstable photopeak position due to malfunction of a power supply board of the γ-camera. This case emphasizes the importance of reviewing the sinogram display and raw data to assess the integrity of data acquisition and to reveal any potential technical problems such as a spontaneous shift of the photopeak.
Key Words: sinogram; artifact; myocardial perfusion SPECT; photopeak
J Nucl Med Technol 2009; 37:188-190
DOI: 10.2967/jnmt.108.061218
Myocardial perfusion SPECT is one of the most common imaging techniques performed in nuclear medicine departments (1,2). Quality control of the γ-camera is essential to produce high-quality images. Usually, uniformity and linearity correction and calibration are done for each system at periodic intervals. One of the most important tests that should be performed daily is energy peaking (3). It is imperative to visually check the energy window in the spectral display mode with the radionuclide to be imaged before data acquisition. However, unexpected or transient faults in γ-camera function may result in image artifacts that should be detected and corrected accordingly. Usually, raw data are reviewed for quality of images and patient motion and then images are processed and a snapshot is made as a final print. However, including an image of the sinogram or linogram in the final print is an easy way to provide important information regarding not only patient motion but also off-peak artifacts. We report a case of myocardial perfusion SPECT in which interruptions in the linogram and sinogram were due to an unstable photopeak position.
CASE REPORT
A 45-y-old woman was referred to our department for myocardial perfusion SPECT because of suspected coronary artery disease. Dipyridamole was infused for 4 min...