caa a22 4500 475791428 CHVBK 20180406123712.0 cr unu---uuuuu 170329e20001201xx s 000 0 eng 10.1023/A:1010774426750 doi (NATIONALLICENCE)springer-10.1023/A:1010774426750 Attenuation smear: A ‘paradoxical' increase in counts due to attenuation artifact [Elektronische Daten] [Christopher Hansen, Matt Kramer] Background: Attenuation is a well recognized cause of reconstruction artifacts in SPECT imaging. Occasionally, we have noted an increase in activity extending from the apical septal portion of the ventricle in women with significant breast attenuation. Although the idea that attenuation can produce an increase in activity on the reconstructed images seems paradoxical at first, it is consistent with the process of filtered back projection. Methods: We filled a cardiac phantom with 1 mCi of Technetium-99m, placed it in a water filled anthropomorphic torso phantom and imaged it over a 180° orbit. Next, a breast phantom designed to simulate a significant degree of breast attenuation was placed on the torso phantom and imaging was repeated. The images were reconstructed first using conventional filtered back projection then with maximum likelihood. Results: When the phantoms with and without breast attenuation were reconstructed using filtered back projection and compared, the phantom with breast attenuation had a large ‘smear' of activity extending anteriorly from the apical septal wall which was very similar to the abnormalities previously noted in clinical images; the phantom without breast attenuation had no such defect. This artifact was significantly less prominent when the images were reconstructed using the maximum likelihood technique. Conclusions: Attenuation artifact can also produce a seemingly paradoxical increase in counts on the reconstructed image but this phenomenon is consistent with the workings of filtered back projection. Kluwer Academic Publishers, 2000 attenuation nationallicence myocardial perfusion imaging nationallicence SPECT artifact nationallicence SPECT reconstruction nationallicence Hansen Christopher Section of Cardiology, Temple University Hospital, Philadelphia, Pennsylvania, USA aut Kramer Matt Section of Cardiology, Temple University Hospital, Philadelphia, Pennsylvania, USA aut The International Journal of Cardiac Imaging Kluwer Academic Publishers 16/6(2000-12-01), 455-460 0167-9899 16:6<455 2000 16 10554 https://doi.org/10.1023/A:1010774426750 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1010774426750 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hansen Christopher Section of Cardiology, Temple University Hospital, Philadelphia, Pennsylvania, USA aut NATIONALLICENCE 700 1- Kramer Matt Section of Cardiology, Temple University Hospital, Philadelphia, Pennsylvania, USA aut NATIONALLICENCE 773 0- The International Journal of Cardiac Imaging Kluwer Academic Publishers 16/6(2000-12-01), 455-460 0167-9899 16:6<455 2000 16 10554 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer