Effect of registration errors between transmission and emission scans on a SPECT system using sequential scanning

Area of Science:

• Nuclear medicine
• Medical imaging
• Cardiovascular imaging

Background:

• Sequential acquisition of transmission and emission scans in cardiac SPECT eliminates cross-contamination but introduces registration challenges.
• Patient motion between sequential scans can lead to significant artifacts in myocardial perfusion imaging.

Purpose of the Study:

• To evaluate the impact of patient motion on nonuniform attenuation correction in cardiac single-photon-emission computed tomography (SPECT).
• To quantify the effects of translational and rotational motion on myocardial SPECT image quality.

Main Methods:

• Utilized an anthropomorphic thorax phantom and a human volunteer for data acquisition.
• Simulated transverse, axial, and rotational motion between sequential transmission and emission scans.
• Reconstructed SPECT data using filtered backprojection and a modified Chang algorithm for nonuniform attenuation correction.

Main Results:

• Transverse and axial shifts of 2.9 cm resulted in 20%-35% decreases in normalized myocardial SPECT activity.
• A 12-degree rotational shift caused 10%-20% error, comparable to 20%-25% variation without attenuation correction.
• Image quality was seriously affected by registration errors of 2-3 cm in both phantom and human studies.

Conclusions:

• Patient motion, specifically registration errors, poses a significant challenge to accurate nonuniform attenuation correction in cardiac SPECT.
• Even moderate motion can lead to substantial underestimation of myocardial activity, impacting diagnostic interpretation.
• Careful patient immobilization and precise image registration are crucial for reliable cardiac SPECT imaging.