Attenuation correction in cardiac SPECT without a transmission measurement

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Biomedical Engineering

Background:

• Nonuniform gamma-ray attenuation significantly impairs SPECT cardiac perfusion imaging accuracy.
• Existing methods for attenuation correction often require additional hardware and increase costs.
• Accurate attenuation estimation is crucial for reliable cardiac imaging interpretation.

Purpose of the Study:

• To develop and evaluate a novel method for estimating chest attenuation in SPECT imaging.
• To correct for artifacts in cardiac perfusion imaging without transmission scans.
• To assess the feasibility and effectiveness of the proposed attenuation correction technique.

Main Methods:

• Dual-energy SPECT acquisition using 99mTc macroaggregated albumin (MAA) with standard 201Tl or 99mTc-sestamibi imaging.
• Lung and body contours derived from MAA and scatter window images, respectively.
• Modified iterative Chang algorithm applied for attenuation correction using segmented regions.

Main Results:

• Successful application in phantoms and patient studies demonstrated improved inferior wall activity.
• The method showed robustness against variations in attenuation values and segmentation thresholds.
• Minimal impact on other cardiac walls and insensitivity to small registration errors were observed.

Conclusions:

• The proposed simple method effectively corrects nonuniform attenuation in male patients.
• Adaptation for female patients and further clinical validation are ongoing.
• This technique offers a cost-effective solution for improving SPECT cardiac imaging quality.