An emission-based technique for obtaining attenuation correction data for myocardial SPECT studies

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiopharmacology

Background:

• Attenuation correction is crucial for accurate quantitative analysis in SPECT imaging.
• Current methods often require transmission scans or complex modeling.
• Variations in soft tissue and lung attenuation coefficients are generally small across individuals.

Purpose of the Study:

• To develop and validate a technique for attenuation correction in the thorax using solely emission data.
• To assess the impact of variations in attenuation coefficients on image accuracy.
• To evaluate the clinical feasibility of the proposed method for myocardial perfusion studies.

Main Methods:

• Determining body and lung contours using an external source and 99Tcm-macroaggregated albumin (MAA), respectively.
• Generating an attenuation map based on these contours and known attenuation coefficients.
• Performing simulation studies to evaluate the effect of coefficient variations (±20%).
• Conducting a clinical feasibility study on seven patients undergoing myocardial perfusion SPECT.

Main Results:

• Simulation studies showed less than 15% alteration in left ventricle count distribution despite ±20% variation in attenuation coefficients.
• Clinical scans demonstrated clear demarcation of body and lung boundaries.
• 99Tcm-MAA in the lungs did not significantly affect the interpretation of SPECT studies.

Conclusions:

• The described technique for attenuation correction is feasible for clinical application in myocardial perfusion imaging.
• This method offers significant advantages over existing attenuation correction techniques.
• Accurate attenuation maps can be generated entirely from emission studies, simplifying SPECT protocols.