1010-62 Impact of Breast Repositioning in Women on SPECT Thallium-201 Myocardial Perfusion Imaging

Abstract

Breast attenuation (BA) is recognized as a cause of artifactual anterior perfusion abnormalities on SPECT thallium imaging (TI) in women. To study the effect of BA on all myocardial regions, we used the change in apparent regional perfusion caused by left breast repositioning as an index of BA. TI was performed on 432 women and 2 redistribution images were acquired: Rl (breast neutral position) and R2 (breast repositioned to upper left). In 11 control pts the R2 image was performed without repositioning. For each pt, 2 separate polar maps were constructed from Rl and R2 short axis slices and were divided into lateral, inferior, septal, anterior, and apical sectors. Mean normalized counts per pixel (MNC) were determined for each sector. The change in apparent perfusion due to breast repositioning for a given sector was computed as (MNC in R2)—(MNC in Rl) and was determined for each sector in all pts. The change in apparent perfusion occurring in a sector due to intrastudy variability was determined as the 95% confidence limits of (MNC in R2)—(MNC in Rl) for that sector in the control subjects. A significant change in apparent perfusion in a sector due to breast repositioning was defined as one which exceeds the 95% confidence limits for intrastudy variability for that sector. Breast repositioning caused a significant change in apparent perfusion in 91% of patients in at least one sector . The number of pts showing a change in apparent perfusion in each sector is shown: n = 432 pts lat int sep ant apex decreased perfusion 19 73 52 126 10 no change 335 288 295 193 207 increased perfusion 78 71 85 113 215 Breast repositioning studies suggest that BA affects SPECT myocardial perfusion imaging in the majority of women. Although the greatest frequency of change in perfusion occurs in the anterior segment, the breast attenuation influences all segments.