Scatter and attenuation correction for brain SPECT using attenuation distributions inferred from a head atlas

Area of Science:

• Nuclear Medicine
• Neuroimaging
• Medical Physics

Background:

• Sequential transmission scanning (TS)/SPECT is challenging for neurologically impaired patients due to motion artifacts.
• Developing non-transmission-based SPECT attenuation correction methods is crucial for improving diagnostic accuracy in vulnerable patient populations.

Purpose of the Study:

• To develop and validate a novel method of inferring-attenuation distributions (IADs) from SPECT data as an alternative to TS.
• To assess the accuracy of IAD-guided SPECT reconstructions in identifying regional cerebral blood flow (rCBF) deficits in patients with mild dementia.

Main Methods:

• IADs were derived by registering a head atlas to preliminary SPECT reconstructions and applying spatial transformations.
• SPECT data underwent scatter and attenuation correction using IADs.
• Relative rCBF was quantified in 12 regions of interest and compared against gold-standard TS-guided SPECT.

Main Results:

• IAD-guided and TS-guided SPECT scans showed a high correlation (0.92, P < 0.0001) with a mean absolute difference of 7.5%.
• IADs resulted in slight, statistically significant underestimation of rCBF in the left frontal and left central sulcus regions.
• Error analysis attributed discrepancies to scatter/attenuation correction, ROI demarcation, and residual patient motion.

Conclusions:

• SPECT reconstructions using IADs are sufficiently accurate for detecting 10% rCBF deficits common in moderate to advanced dementia.
• The IAD method provides a viable alternative to TS/SPECT, enhancing diagnostic capabilities for immobile patients.