Contributions of subdiaphragmatic activity, attenuation, and diaphragmatic motion to inferior wall artifact in attenuation-corrected Tc-99m myocardial perfusion SPECT

✍ Scribed by Alexander G. Pitman; Victor Kalff; Bruce Van Every; Borghild Risa; Leighton R. Barnden; Michael J. Kelly

• Publisher: Springer
• Year: 2005
• Tongue: English
• Weight: 340 KB
• Volume: 12
• Category: Article
• ISSN: 1071-3581
• DOI: 10.1016/j.nuclcard.2005.04.010

✦ Synopsis

Background:

Subdiaphragmatic activity and diaphragmatic motion both contribute to inferior wall artifacts in technetium 99m myocardial perfusion single photon emission computed tomography (spect).

Methods and results:

We used an anthropomorphic phantom with ventricular wall activity, liver/spleen inserts containing variable tc-99m activity, and variable vertical (diaphragmatic) motion amplitude. spect and transmission scans were obtained on a ge optima nx camera. data were processed by use of filtered backprojection or attenuation correction (ac). resulting myocardial activity maps were analyzed with standardized inferior-anterior and anterior-lateral wall ratios. at a subdiaphragmatic-myocardial activity ratio of 0.5:1, inferior wall attenuation predominates, producing a cold artifact. ac corrects inferior wall activity to the level of the anterior wall irrespective of diaphragmatic motion. at a subdiaphragmatic-myocardial activity ratio of 1:1, inferior wall counts vary widely depending on the proximity of subdiaphragmatic activity to the ventricle. with increasing diaphragmatic amplitude, the overlap of subdiaphragmatic activity and inferior wall worsens, leading to a complex mixture of cold and hot artifacts, not corrected by ac.

Conclusions:

Concentration and proximity of subdiaphragmatic tc-99m activity relative to myocardium comprise a major factor in the nature and severity of inferior wall artifacts. if the subdiaphragmatic tc-99m concentration is equivalent to that in the myocardium, complex, potentially uninterpretable hot and cold inferior wall artifacts are produced.