Minimizing liver, bowel, and gastric activity in myocardial perfusion SPECT

When using Tc-99m-tetrofosmin for myocardial perfusion SPECT, increased liv er, intestinal, or gastric activity may create a major problem in the visua l and quantitative interpretation of the inferoposteroseptal walls, particu larly at rest. The aim of this study was to determine what measures were re quired to minimize this extracardial activity. Methods: Ninety-seven patien ts had a SPECT scan at rest without attenuation correction. They were divid ed into 3 groups. Preparation consisted of no action taken (group 1), 150 m t whole milk 10 min after administration of tetrofosmin (group 2), or 450 m t water 10 min before acquisition (group 3). A further 55 patients had a SP ECT scan at rest with attenuation correction. They were also divided into 3 groups, and preparation consisted of 150 mt whole milk 10 min after admini stration of tetrofosmin (group 4), 450 mt water 10 min before acquisition ( group 5), or both whole milk and water (group 6). The presence of activity in liver, bowel, and stomach was determined visually on reconstructed image s. Activity was defined as interfering when it might result in either an un derestimation or an overestimation of the uptake in the myocardial wall. Re sults: Interfering activity was seen in 83% of the patients in group 1, in 74% in group 2, in 33% in group 3, in 61% in group 4, in 67% in group 5, an d in 20% of group 6. Conclusion: The interpretation of inferoposteroseptal wall activity on myocardial rest SPECT images is facilitated by having the patient drink both whole milk and water at specified times before data acqu isition.