Inferior attenuation increased Anterior attenuation decreased Prone Imaging Anterior attenuation increased Inferior attenuation decreasedĢ4 Supine/Prone Imaging True perfusion defects are independent of position Attenuation artifacts often change depending on patient position If a defect appears or disappears with a change in position, then it is an artifact Segall et al. Tend to be of mild intensity, but can be moderate Usually follow one of these typical patterns Usually evidence of attenuation on the projection images or the attenuation mapĢ1 Outline Typical patterns of attenuation artifacts Supine/Prone ImagingĢ3 Positional Imaging Supine Imaging Prone Imaging Inferior (“Diaphragmatic”) Attenuation Related to weight/abdominal girth Inferior wall Worse near the base Anterior (Breast) Attenuation Anterior wall Usually sparing the apex Arm Attenuation Arms down imaging Anteroseptal and inferolateral wallsĢ0 Characteristics of Attenuation Artifacts She had no symptoms or ECG changes.įixed defects can represent either myocardial infarction or an artifact due to soft tissue attenuation Difficult to distinguish between them using standard filtered backprojection images alone Soft tissue attenuation is very common Major limitation in the specificity of SPECT imaging for the detection of CADġ2 Outline Typical patterns of attenuation artifacts Supine/Prone Imagingġ3 Outline Typical patterns of attenuation artifacts Supine/Prone Imaging Appropriate hemodynamic response with a fall in BP and an increase in HR. She was referred for dipyridamole stress with nuclear imaging. He was referred for an exercise stress test with nuclear imaging He exercised for 6.5 minutes of a Bruce protocol Peak HR 143 (92% predicted maximal) Peak BP 194/64 During exercise, he had chest pain but no ECG changesĥ Case 2 82 year-old woman with a history of CAD, s/p multi-vessel PCI, HTN, dyslipidemia who presented with chest pain. Hauser, MD, MMSc Director of Nuclear Cardiology Beth Israel Deaconess Medical Center Instructor in Medicine Harvard Medical School Boston, MAĢ Cases Prone imaging Stress: 99mTc-Sestamibi Rest: 201Tlģ Case 1 65 year-old man with a history of HTN who presented with chest pain. A major teaching hospital of Harvard Medical School Attenuation Artifacts Thomas H.
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